INSTITUT DE RADIOPROTECTION
ET DE SÛRETÉ NUCLÉAIREANALYSIS OF DATA FOR UPDATINGDIAGNOSTIC REFERENCE LEVELS IN
RADIOLOGY AND NUCLEAR MEDECINE
2019 - 2021 REPORT

THE PUBLIC SERVICEEXPERT

FOR NUCLEAR AND RADIOLOGICAL RISKS
IRSN’s mission includes the provision of expertise,research projects, protection, planning for the future,and the sharing of resources to the benefit of the French
public authorities and the public at large.
IRSN can boast unrivalled capacity to combine the expertiseof researchers and experts in order to plan ahead for thequestions of the future about changes involving the nuclear
and radiological risks and how to control them.
IRSN teams aim to ensure that society at large is awareof their works and can share their knowledge. With thisapproach, they help to improve a wide access to
information and boost dialogue with stakeholders.
IRSN contributes to French public nuclear safety andsecurity policies, as well as health, environmental andcrisis management policies.
As a public industrial and commercial establishment
supervised jointly by the French Minister of theEnvironment, the French Minister of Defence, and theFrench Ministers of Energy, Research and Health, IRSN
comprehensively integrates its initiatives in the
Government's modernisation policies with its risk
management approach and by implementing a CSR policy.

IRSN
HAS
AROUND

Technological progress and developments in techniques
using ionising radiation, in the field of imaging,radiotherapy, and nuclear medicine, are advancing at a
rapid rate. The essential contribution of these techniques
is these days a given, as testified by the regular increasein patients’ lifespans.
Regularly assessing the risks associated with these changes
with respect to therapeutic benefits is at the heart of IRSN’s
missions. Optimising practices using ionising radiation is
also a constant objective of the Institute.
To fulfil these missions in these fields, IRSN:

carries out expert appraisals for the benefit of
the authorities and, more generally, the publicauthorities;
monitors the exposure of patients, medical
staff, and the public;collects and analyses data to update diagnostic
reference levels for practitioners.

In support of these expertise and monitoring activities, inorder to keep up to speed with all the latest scientificknowledge, the Institute conducts research programmesin collaboration with hospital teams and national,
European, and international partners.

1,816

EMPLOYEES

includingmany engineers,
doctors,
agronomists,
veterinarians,
technicians,
experts andresearchers.

To carry out its work
effectively, IRSN has

A BUDGETOF AROUND€271
millions
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RESUME
En application de la réglementation relative aux
niveaux de référence diagnostiques (NRD) et
notamment la décision de l’ASN n°2019-DC-0667, lesétablissements de radiologie et de médecine nucléaire
doivent transmettre annuellement à l’IRSN desdonnées dosimétriques relatives aux actes d’imagerie
dont ont bénéficié leurs patients. L’IRSN est chargéd’analyser ces données en vue de la mise à jour desvaleurs des NRD.
Ce rapport présente les résultats de l’analyse desdonnées recueillies sur la période 2019-2021. Ces
résultats ont été comparés aux valeurs de NRD envigueur depuis juillet 2019 afin d’examiner la nécessitéd’une mise à jour.
Ce septième bilan de l’analyse des données françaises
relatives aux NRD permet d’établir un état des lieux dela mise en œuvre des modalités introduites par ladécision de l’ASN n°2019-DC-0667, en particulier en
pédiatrie et en radiologie interventionnelle.
La participation des établissements apparait commestabilisée autour de 50% pour la radiologie
conventionnelle, et 90% pour la scanographie et lamédecine nucléaire. La participation a été très
importante pour la radiologie interventionnelle
nouvellement introduite par la décision de l’ASN
n°2019-DC-0667.
Chez l’adulte, l’analyse des données collectées de 2019
à 2021 montre que les valeurs du 75e centile sontinférieures aux valeurs des NRD en vigueur dans tous
les domaines : de 20 % à 30 % en radiologie
conventionnelle, de 30 % à 54 % en radiologieinterventionnelle, de 14 % à 60 % en scanographie et de
1 % à 22 % en médecine nucléaire. Cette analyse
montre également une baisse globale des valeurs du
75e centile des indicateurs dosimétriques par rapport àla période 2016-2018, de 19 % en radiologie
conventionnelle, 8 % en scanographie et 4 % en
médecine nucléaire.
En pédiatrie, il est noté une augmentation du nombred’évaluations exploitables reçues. Cependant, lenombre total de données reçues reste trop faible pourobtenir une robustesse statistique pour la majorité desexamens.

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Sur la base de l’analyse des évaluations dosimétriques
transmises à l’IRSN au cours de la période 2019-2021,
de résultats d’analyses complémentaires conduites par
l’IRSN en collaboration avec les professionnels de santéet de la consultation de ces derniers, ainsi que d’avis
d’expertise produits à la demande de l’ASN, l’IRSN
formule les recommandations suivantes : du fait de la baisse globale des valeurs du 75e centile
des indicateurs dosimétriques réviser les valeurs de
NRD dans tous les domaines, en priorisant lascanographie pour laquelle une évolution vers des
NRD par indication clinique doit être envisagée ; faire évoluer la définition de certains NRD et lesdonnées collectées. Par exemple, en radiologieinterventionnelle, ajouter le kerma dans l’air au
point de référence comme indicateur dosimétriquecomplémentaire au PDS et au temps de scopie, en
médecine nucléaire, définir un seul NRD en termesd’activité massique (MBq/kg) pour les examens qui
s’y prêtent, et, en scanographie, faire évoluer les
NRD pour prendre en compte les indications
cliniques tel que déjà recommandé dans leprécédent bilan ; définir de nouveaux NRD. Par exemple, en
radiologie conventionnelle, créer un NRD pour latomosynthèse mammaire et le CBCT dentaire sur labase des recommandations formulées par l’IRSN
dans ses avis publiés fin 2021 et début 2023
respectivement. En radiologie interventionnelle,
envisager de créer un NRD en rythmologie, et, enmédecine nucléaire, engager une concertation avec
les professionnels de santé sur la mise en place de
NRD pour de nouveaux examens en particulier en
TEP ; envisager la suppression des NRD associés à certains
examens devenus peu fréquents, tels que lascintigraphie rénale au DTPA ainsi que lascintigraphie cérébrale à l’ECD et HMPAO en
médecine nucléaire ou le rachis dorsal de profil enradiologie conventionnelle ; en pédiatrie, poursuivre les efforts pour latransmission des données.

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINEABSTRACTIn order to comply with the French regulations
regarding the diagnostic reference levels (DRL),
healthcare facilities performing medical imaging
procedures are required to send samples of “patient”
dosimetric data to the IRSN each year.

On the basis of the analysis of dosimetric datatransmitted to IRSN during the period 2019-2021 andthe results of additional analyses conducted by IRSN incollaboration with health professionals, IRSN makes thefollowing recommendations:

IRSN is responsible for analysing this data in order toupdate the DRL values.

 Due to the overall decrease in the 75th percentile
values of the dosimetric indicators, revise the DRL
values in all areas, prioritising CT for which a movetowards DRLs by clinical indication should beconsidered.
 Change the definition of some DRLs and the datacollected. For example, in interventional radiology,
add the air KERMA at the reference point as an extra
dosimetric indicator alongside the dose area
product and the radioscopy time; in nuclear
medicine, define a single DRL in terms of specificactivity (MBq/kg) for the examinations that lendthemselves to it; and, in CT, upgrade the DRLs totake into account the clinical indications as alreadyrecommended in the previous IRSN report.
 Define new DRLs. For example, in conventional
radiology, create a DRL for digital breast
tomosynthesis and dental CBCT based on therecommendations proposed by IRSN in its notices
published in late 2021 and early 2023 respectively.
In interventional radiology, consider creating a DRL
in rhythmology, and, in nuclear medicine, engage in
consultation with healthcare professionals on theimplementation of DRLs for new examinations,particularly in PET.
 Consider removing DRLs associated with certain
examinations that have become infrequent, such as
renal scans with DTPA, brain perfusion SPECT with
ECD in nuclear medicine, and thoracic spine lateralradiographs in conventional radiology.
 In paediatrics, continue efforts to transmit data.

This report presents the results of the analysis of
dosimetric data over the period 2019-2021. Results arecompared to DRL values defined by the regulations inforce since July 2019 to examine the need for an
update.
This seventh report on the analysis of French data
relating to DRLs makes it possible to take stock of theimplementation of the methods introduced by ASN
resolution 2019-DC-0667, in particular in paediatrics
and interventional radiology.
The participation of professionals appears to bestabilised at around 50% in conventional radiology and
90% in CT and nuclear medicine. Participation was very
high for interventional radiology, newly introduced by
ASN resolution 2019-DC-0667.
In adults, the analysis of the data collected from 2019
to 2021 shows that the 75th percentile values are lower
than the DRL values in force in all areas: by 20% to 30%
in conventional radiology, by 30% to 54% ininterventional radiology, by 14% to 60% in CT, and by
1% to 22% in nuclear medicine. This analysis also shows
an overall decrease in the 75th percentile values of
dosimetric indicators compared to the period 20162018, by 19% in conventional radiology, 8% in CT, and
4% in nuclear medicine.
In paediatrics, an increase has been observed in thenumber of usable assessments received. However, thetotal quantity of data received remains too low to
obtain statistical robustness for the majority of
examinations.

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CONTENTS
1. INTRODUCTION............................................................................... 8
2. COLLECTION AND ANALYSIS OF DIAGNOSTIC REFERENCELEVEL DATA..................................................................................... 9
2.1 OVERVIEW OF REGULATIONS ................................................................................................ 9
2.2 NATURE OF DATA COLLECTED ............................................................................................. 10
2.3 DATA COLLECTION............................................................................................................... 10
̅ Collection methods ..................................................................................................... 10
̅ Data collection period ................................................................................................. 10
2.4 DATA ANALYSIS................................................................................................................... 11̅ Data validation criteria................................................................................................ 11
̅ Selection of data for analysis....................................................................................... 11
̅ Statistical indicators .................................................................................................... 12
̅ Presentation of analysis results ................................................................................... 13
2.5 CONSULTATION OF STAKEHOLDERS .................................................................................... 14

3. CONVENTIONAL RADIOLOGY......................................................... 16
3.1 CONTRIBUTION OF DEPARTMENTS ..................................................................................... 16
̅ Conventional radiology (apart from dental practices) ................................................. 16
̅ Dental practices........................................................................................................... 16
3.2 DATA DISTRIBUTION BY EXAMINATION TYPE...................................................................... 18
̅ Adult examinations ..................................................................................................... 18
̅ Paediatric examinations .............................................................................................. 19
3.3 SUMMARY OF CONVENTIONAL RADIOLOGY RESULTS ......................................................... 20
̅ Adult examinations ..................................................................................................... 20
̅ Paediatric examinations .............................................................................................. 22

4. INTERVENTIONAL RADIOLOGY ...................................................... 29
4.1 CONTRIBUTION OF DEPARTMENTS ..................................................................................... 29
4.2 DISTRIBUTION OF DATA BY TYPE OF PROCEDURE ............................................................... 30
4.3 SUMMARY OF INTERVENTIONAL RADIOLOGY RESULTS....................................................... 30

5. COMPUTED TOMOGRAPHY ........................................................... 35
5.1 CONTRIBUTION OF DEPARTMENTS ..................................................................................... 35
5.2 DISTRIBUTION OF DATA BY EXAMINATION TYPE................................................................. 36
̅ Adult examinations ..................................................................................................... 36
̅ Paediatric examinations .............................................................................................. 37
5.3 SUMMARY OF COMPUTED TOMOGRAPHY RESULTS ........................................................... 37
̅ Adult examinations ..................................................................................................... 37
̅ Paediatric examinations .............................................................................................. 39

6. NUCLEAR MEDECINE ..................................................................... 43
6.1 CONTRIBUTION OF DEPARTMENTS ..................................................................................... 43

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6.2 DATA DISTRIBUTION BY EXAMINATION TYPE...................................................................... 44
̅ Adult examinations ..................................................................................................... 44
̅ Paediatric examinations .............................................................................................. 45
6.3 SUMMARY OF NUCLEAR MEDICINE RESULTS ...................................................................... 46
̅ Adult examinations ..................................................................................................... 46
̅ Paediatric examinations .............................................................................................. 48

7. DRLs: SUMMARY, RECOMMENDATIONS AND PERSPECTIVES ........ 53
7.1 SUMMARY: ......................................................................................................................... 53
7.2 RECOMMENDATIONS AND PERSPECTIVES........................................................................... 53
7.3 CONCLUSIONS ..................................................................................................................... 54

8. GLOSSARY ..................................................................................... 55
ABBREVIATIONS ....................................................................................................................... 55
TITLES OF NUCLEAR MEDICINE EXAMINATION TYPES ............................................................... 57

9. ANNEX .........................................................................................598
10. REFERENCES .................................................................................. 59

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INTRODUCTION
1.

INTROD UCT ION

This document presents the report on IRSN’s analysis of diagnostic reference levels data for the 2019-2021 period, in linewith its mission under Article R.1333-61 of the French Public Health Code.
Diagnostic reference levels (DRLs) have been implemented in France since 2004 (1) based on the recommendations of ICRP
publication 73 “Radiological Protection and Safety in Medicine” (2) and European Commission Guide RP109 (3), with a viewto optimising doses in line with the requirements of Council Directive 97/43/Euratom (4) and then Directive
2013/59/Euratom (5).
DRLs are an indispensable and effective tool for optimising doses delivered to patients. They provide dosimetric indicators
for the quality of practices and are intended to identify and monitor situations requiring improvement and quantify theeffectiveness of an optimisation approach. They should not be confused with “dose limits” or “optimum doses”.
The managers of conventional radiology, CT, and nuclear medicine facilities have to assess annually the doses delivered totheir patients during diagnostic or interventional procedures in accordance with ASN resolution 2019-DC-0667 of
18 April 2019 pertaining to DRLs (6) currently in force. Analysing this data, by comparison of their median values with the
DRLs in force, should enable professionals to situate their practice against a national benchmark and undertake
improvements in the event that the value exceeds the DRLs without good reason. Conversely, particularly low exposureswith regard to achievable dose values (AD) must also be questioned, and any reduction in the doses delivered mustsystematically be accompanied by an assessment of the quality of the images obtained in order to avoid any loss of diagnostic
performance and any risk of performing unusable examinations. Healthcare professionals must submit the results of theirdose assessments to IRSN.
IRSN is responsible for analysing the data submitted at a national level. It publishes a periodic report to present datacollection and analysis methods and results. This analysis enables IRSN to put forward recommendations for updating the
DRL regulations with a view to improving their application and effectiveness.
French regulations pertaining to DRLs have therefore been revised several times: first in 2011 (7) and more recently by ASN
resolution 2019-DC-0667 (6) approved by the Order of 23 May 2019 (8). In particular, these regulatory changes have taken
into account the recommendations made by IRSN in its previous reports (9–11).
This seventh report of the analysis of French data relating to DRLs covers the 2019–2021 period and is therefore the firstreport which takes place over a period of application of the latest aforementioned ASN resolution 2019-DC-0667. The reportmakes it possible to judge the effectiveness of the adaptations introduced by this resolution, in particular concerning thecollection of data in paediatrics and the introduction of interventional radiology. It also allows IRSN to issue newrecommendations with a view to continuous improvement of DRLs in France.

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IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINECOLLECTION AND ANALYSIS OF DIAGNOSTICREFERENCE LEVEL DATA
2.

COLLE CTI ON AND ANA LYSIS OF DIAG NOST IC REFERENCE LEVEL DA TA

2.1 OVERVIEW OF REGULATIONSIn accordance with Article R.1333-61 of the French Public Health Code, for procedures which present, by the doses delivered
or by their frequency, a radiation protection issue for patients, diagnostic reference levels (DRLs) are established andupdated by the ASN, taking into account the results submitted to IRSN, which is responsible for collecting and analysing thedata required for this periodic update. To this end, IRSN receives the results of dose assessments carried out from the activity
managers (conventional radiology, interventional radiology, computed tomography, or nuclear medicine). Figure 1 below
presents the principle for DRL implementation in France, and the roles of healthcare professionals, authorities, and IRSN.
ASN resolution 2019-DC-0667 of 18 April 2019 on DRLs (5), in force since 1st July 2019, specifies how to implement thecollection and analysis of DRL data.
The dose assessments carried out annually by healthcare professionals must cover, for each device (CT and interventional
radiology) or department (conventional radiology and nuclear medicine), two procedures appearing in the aforementioned
ASN resolution. These assessments must include data on at least 30 patients per examination for all examinations, except in
paediatrics and for image-guided interventional procedures for which only a minimum of 10 patients are required.
In paediatrics, dose assessments are mandatory if 5% of procedures performed on a medical device involve children (under
18 years of age).
ALL INSTITUTIONSWITH MEDICALIMAGING UNITSInternet application anddatabasehttps://basenrd.irsn.fr

COLLECT
dosimetric data on patientgroups

COLLECTS, CHECKS andANALYSES data at national level
ORGANISES or COLLABORATES inadditional targeted studies on specificpractices (interventional radiology,
cardiac CT scans, paediatric imaging,etc.)

COMPARE their datawith the DRLs and
ANALYSE the data as wellas any causes forexceeding the DRLs

 SEND their data to IRSN

 Implement an OPTIMISATION
approach

PUBLISHES periodic assessments:
Analyses data at national
level, recommends andproposes DRL updates

AUTHORITIESREGULATE:• DRLs field of application• List of examinations• Doses and DRL values

Figure 1: Principle for DRL implementation in France, roles of institutions with medical imaging facilities, authorities
and IRSN.

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2.2 NATURE OF DATA COLLECTED
Depending on the imaging type, data are collected for one or two DRL quantities:

 dose area product (DAP) for conventional radiology and orthopantomography;
 Mean glandular dose (MGD) for digital mammography;
 volume computed tomography dose index (CTDIvol) and dose length product (DLP) for computed tomography;
 total activity and administered activity per body weight for nuclear medicine.
The result of the dose assessment is the median value of 30 (or more) values collected from groups of patients with therelevant dose values.
Patient morphology has a major impact on the dose delivered. Regulations therefore require patient height and weight tobe recorded during dose assessments (see section 2.4).

In mammography and orthopantomography, dose is not assessed for a group of patients but with a single measurement onphantom performed during external quality control (12; 13): MGD and DAP respectively.

IRSN collects some parameters and information in addition to DRL quantities, in order to check the consistency of the data
received:

 for conventional radiology: high voltage, filtration, focus-to-detector distance (FDD), detector technology and size; for computed tomography: high voltage and pitch (in helical mode); in interventional radiology: the radioscopy time, the air KERMA at the reference point, the number of radiography images,
the mobile or fixed equipment, the use of rotational mode; for nuclear medicine: the radiopharmaceutical administered.

2.3 DATA COLLECTION
̅

Collection methods

Since 2011, IRSN has collected data over the internet using an IT application (https://basenrd.IRSN.fr). The system has
improved the quality of information submitted and facilitated discussions between IRSN and professionals, thanks toautomatic checks during data entry.
In addition to its data entry and submission functions, the DRL application offers professionals the opportunity to compare
their dose assessment median values to the DRL in force, as soon as they have finished entering their data. They can also
view their data submission history to improve monitoring of the doses they deliver.

̅

Data collection period

This report presents the analysis of the data collected for 2019, 2020 and 2021.

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2.4 DATA ANALYSIS̅

Data validation criteria

Despite the automated checks performed by the DRL application during data entry, some data received by IRSN containerrors. Unrestrictive automated checking criteria for data consistency were selected in the app in order to avoid discouraging
users who might have their data refused.
In this respect, each assessment submitted by institutions is checked by IRSN. Only data validated after verification are used
for performing national-level statistical analyses.
For example, in computed tomography, the complementary DRL quantities combination, CTDIvol and DLP, can be used tocheck data consistency. This is because the DLP/CTDIvol ratio corresponds to the length exposed (length examined plus
additional radiation (overranging) at the start and end of helical CT acquisition), which is characteristic of the acquisition
performed. This makes it easy to identify, for example, a scan of the sinuses among brain examinations or an abdomenpelvis acquisition in an assessment labelled “chest-abdomen-pelvis” due to an inconsistent acquisition length. Checking thisparameter is fairly discriminating, which explains why there is a higher level of unused data than in conventional radiology(see paragraph 5.2 of this report).
Similarly, for interventional radiology, the DAP and Kair1 pair of indicators (when the air KERMA is available, which is often
the case) enables data consistency to be checked (see focus section in the “interventional radiology” chapter of this report).
The DAP/Kair ratio corresponds to the average area of the field during the examination at the reference point. This area canbe neither extremely small nor extremely large and an analysis of this ratio allows the presence of inconsistent data to be
detected.
During checks, if some patient data appears inconsistent, the median values of the DRL quantities are recalculated to exclude
them.

̅

Selection of data for analysis

Despite the checks described in the preceding section, validated dose assessments may contain data errors or data that areconsidered not to represent current practices (abnormally high or low DRL quantities, patient morphology (BMI), acquisition
lengths, etc.).
Data are therefore consolidated prior to analysis by applying the following criteria:
•

•

•
•
•

1

for adult examinations, exclusion of patients:o aged under 15;
o with a BMI of less than 18 or more than 35, except for nuclear medicine;for paediatric examinations, exclusion of patients:o aged over 18;
o whose weight does not correspond to the selected category;in computed tomography: exclusion of patient examinations presenting particularly low or high acquisition lengths;
in interventional radiology: exclusion of data with a particularly low or high DAP/Kair ratio;
exclusion of data including fewer than 25 patients after application of the previously cited validation and selection
criteria (or fewer than 10 data items for paediatric procedures and interventional radiology).

Kair is the air KERMA at the reference point as defined by the IEC (14). No DRL is set by the regulations for this quantity. However, it is possible to transmit
this data to IRSN, in addition to the DAP and the radioscopy time.
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The age limit for paediatrics varies between 15 and 18 depending on sources, so broader criteria have been applied. For
adult examinations, patients in the 15-18 age range have been accepted, since they were likely to have been examinedfollowing an adult protocol. For paediatric examinations, patients in the 15-18 age range have also been accepted if theirweight falls within a defined category. It should be noted that selecting children by weight category is a more relevant
criterion than by age.
In adult conventional radiology and computed tomography (except for the CT part of nuclear medicine examinations; seebelow), in which the volumes of data received are higher and the reduction in DRL quantities is most marked, the 75th and50th percentile values have been calculated for each year, and it is the 2021 values that are presented for potential DRL
updates. Nevertheless, all data (2019 to 2021) have been kept for producing the radiology and computed tomography
histograms presented in the Annex to this report.
In nuclear medicine (including the CT part of nuclear medicine examinations), interventional radiology, dental radiology, andpaediatrics (all fields), the 75th and 50th percentile values have been calculated for the entire 2019-2021 period, and not foreach year individually. This is for the following reasons:•••lower volumes of data received (paediatrics, nuclear medicine, interventional radiology);
slower change in doses delivered (nuclear medicine);less frequent dose assessments (orthopantomography, where data collection is associated with a five-year quality
control).

The fact that data collected over a 3-year period are being analysed means that several dose assessments for a single
examination from a single unit are available for the period. In order to avoid statistical bias linked to over-representation ofunits subject to several dose assessments over the 2019-2021 period, only the latest data received have been kept forcalculating the 75th and 50th percentiles and presented in the histograms in the Annex.
In mammography, the DRL has no longer been applicable since 21 January 2021 following the entry into force of the new
quality control procedures for digital mammography units (15), and so the data received over the incomplete period from
1st January 2019 to 20 January 2021 (the frequency for sending mammography data is five years) have not been analysed.

̅

Statistical indicators

MedianNational DRLs are based on the median values, per unit, of dosimetric data collected by healthcare professionals for groupsof 10 or 30 patients. At local level, this median value needs to be compared to the DRL by healthcare professionals in order
to assess their practice. At national level, the distribution of these unit median values is analysed to determine the 75th
percentile.
By convention, in this report, the term median is used for a unit's representative dose value. For the national distribution ofunit median values, the term 50th percentile will be employed to define the statistical measure used to establish the AD.
This convention also applies to nuclear medicine, where the national mean of mean unit activities previously used is replacedby the 50th percentile (national) of median activities (per unit).
75th and 50th percentiles
Conventional radiology, interventional radiology, and computed tomography
In conventional radiology, interventional radiology, and computed tomography, the DRL is defined as the 75th percentile ofthe distribution of results (dosimetric data median values) of dose assessments for a given examination. This is an alert level
above which practices could be considered sub-optimal, or even abnormal, in terms of dose delivered to the patient.
In addition, the 50th percentile of the dose assessment results distribution is used to define the AD (see figure 2 below).

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Nuclear medicine
In nuclear medicine, the 50th percentile of the medians per unit is used to define the DRL.

Number of units

50th percentile
or median
25th percentile 75th percentile

25%
Dose value

Figure 2: Definition of main statistical measures for dose data distribution for a given examination type.
75th to 25th percentile ratio
Medical imaging practices involve high degrees of disparity, with patient exposure levels that can vary by significantly for anapparently similar diagnostic performance.
Data heterogeneity is symptomatic of disparity in practices. In order to assess it, the results presented in this report, as withthe previous report, are supplemented by a measure that is representative of dispersion of values: the 75th to 25th percentile
ratio.

̅

Presentation of analysis results

The results of analyses performed by IRSN on the data submitted by health professionals are presented for each of the
medical imaging fields concerned: conventional radiology, interventional radiology, computed tomography, and nuclear
medicine.
These results offer an assessment of the application of DRL regulations in establishments performing medical imaging
procedures, through their participation in submitting data to IRSN.
The data breakdown submitted for the various examination types is also analysed and compared with the frequency of the
medical imaging procedures in France. Although professionals had the freedom to choose the examinations they haveassessed, this analysis assesses the representativeness of data collected with regard to national practices. The results for
paediatrics are separated from those for adults.
The percentage of data submitted for each examination out of all the data received by IRSN for each imaging field is shown,
together with the proportion of data that IRSN has been able to use.
Finally, analysis summaries are given in order to assess, for each examination, the positioning of statistical measures withregard to the DRLs and the results of the previous report. The results for paediatrics are, once again, separated from those
for adults. It should be noted that when there are fewer than 10 assessments used per procedure, it is considered that thedata volume is too small for the results to be discussed, and the positioning of the statistical measures with regard to the
DRLs is not calculated.

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Detailed analyses for each examination type are presented in the Annex of this report. The Annex includes the following foreach examination where the amount of data collected allows analysis, and per dosimetric value (DAP, MGD, CTDIvol, DLP,
activity and administered activity per body weight):national distribution graphs for dose assessment results;
a table of the main statistical measures;graphs presenting the change in the 75th and 50th percentiles in conventional radiology and computed tomography,
and the 50th percentiles in nuclear medicine, since 2011.

When there are fewer than 20 assessments, these analyses are not detailed in the Annex to this report.
For better readability of this report, the titles of the types of examinations have sometimes been abbreviated, particularlyin the figures (see Glossary).
For each of the areas, the results presented lead IRSN to issue recommendations for improving the DRL system.

2.5 CONSULTATION OF STAKEHOLDERS
The stakeholders (ASN, ANSM, ADF, AFTMN, CNPCV, G4, GACI, SFMN, SFPM and SoFRa) were consulted on 20 May 2022 togather their feedback on the 2016–2018 report and present to them the initial results for the 2019–2021 period.
Certain comments received on this occasion have led IRSN to submit recommendations that are not necessarily directly
related to the results of this report but which may also contribute to the improvement of the DRL system, in particular:
In interventional radiology, consider:

the creation of DRLs for two rhythmology procedures considered to be the most irradiating: atrial fibrillation
ablation and ventricular resynchronization (= triple or multisite cardiac stimulation); the “rhythmology” group of
the Société Française de Cardiologie (French cardiology society) must be consulted to carry out this work;
the introduction, in the long term, of interventional procedures performed under CT examination, in particular byengaging in reflection on interventional cardiology procedures (TAVI, mitral valvuloplasty) or interventional vascularradiology (peripheral vascular angioplasty, other procedures to be specified) performed in operating theatres or
hybrid rooms, and not in dedicated radiology rooms.

In nuclear medicine:consider removing DRLs for examinations that have become too infrequent, as illustrated by the results of thisreport:o renal scans with DTPA,o brain scans with ECD and HMPAO;
Define a single DRL in terms of activity per body weight (MBq/kg) for the examinations that lend themselves to it,
rather than a combination of activity and activity per body weight as is currently the case;
Consider the implementation of DRLs:
o for new examinations, particularly in PET, such as:brain PET with 18F-FDG,
PET with 18F-Choline,
PET with 18F-DOPA (brain, full body),
PET with gallium 68 (somatostatin receptors, PSMA);o in a second phase, for new scanning examinations, such as, for example:
dual-isotope (iodine-123 and 99mTc-MIBI) scans of the parathyroid glands,
brain scans with DaTSCAN;
o for computed tomography acquisitions of the trunk and the full body combined with bone scans.

Recommendations from stakeholder consultation are specifically mentioned, in each relevant part of this report, where theyarise.

14

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINEFOCUS – PAEDIATRIC DRLs: THEIR SPECIFIC ISSUES
Problems with implementation of paediatric DRLs
Since DRLs were implemented under French regulations in 2004, IRSN has observed that the volume of data received
each year for paediatric examinations has been extremely low. Over and above the fact that this presents a problem
for updating DRLs, this data gap suggests that paediatric procedures may be subject to very little assessment.
Solutions implemented for increasing the use of DRLs in paediatrics
Following IRSN‘s observations and proposals, ASN resolution 2019-DC-0667 amended regulations in order toincrease the assessment of paediatric procedures:•the minimum number of dose assessments for children to be included has been reduced from 30 to 10, in
order to encourage collection in institutions that perform a low number of paediatric examinations;•the collection and analysis of one paediatric dose assessment per year is required when at least 5% ofprocedures performed on a medical device involve children.

Positive impact of the regulations in force since July 2019
Compared to previous years, the collection of data relating to 2020 and 2021 has developed positively. The numberof institutions that sent paediatric data and the quantity of these data more than doubled in all areas between 2016–2018 and 2019–2021: in conventional radiology, the number of assessments submitted increased from 184 to 435(+57%), in computed tomography from 91 to 202 (+55%), and in nuclear medicine from 31 to 111 (+72%).
Furthermore, the increasing deployment of patient dose management system software (DACS - Dose Archiving andCommunication System) is contributing to the greater use of paediatric DRLs. By systematically recording DRL dosevalues used, DACS makes it easier to collect and analyse data for the least frequent procedures, such as paediatricprocedures.
However, there are still not enough assessments to carry out a robust assessment of practices in this area
Despite this improvement, the number of assessments per examination remains insufficient overall: in conventional
radiology, only 5 out of 16 examinations identified in ASN resolution 2019-DC-0667 received a sufficient number ofassessments (more than 20) allowing for a detailed analysis, and in computed tomography only 3 out of 11
examinations. In nuclear medicine, all the examinations sent to IRSN included fewer than 20 assessments per
examination and therefore could not give rise to a detailed analysis.
Under these conditions, in paediatrics, it remains difficult to assess the evolution of doses delivered in a robust
manner. Therefore, IRSN recommends continuing efforts and encouraging healthcare professionals to submit data
by reminding them that it is possible to collect data over a period of more than one year.

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15

CONVENTIONAL RADIOLOGY3.

CONVENTI ONAL RADI OLOG Y

3.1 CONTRIBUTION OF DEPARTMENTS
For conventional radiology, the main institutions involved in radiography procedures are:•the radiology departments of public and private healthcare institutions;•private practices (radiology, pneumology, rheumatology);•

occupational health departments, municipal healthcare centres, prison healthcare departments, etc.;•

dental practices.

̅

Conventional radiology (apart from dental practices)

The total number of conventional radiology departments or practices needs to be estimated in order to assess thecontribution of departments. In the previous report covering the period 2016–2018, the estimate of the number of
institutions performing conventional radiology procedures had been updated. The method for estimating the evolution of
the annual participation of institutions carrying out conventional radiological procedures since 2004 had thus been adapted
to present the participation rates using the estimated number of institutions based on a linear regression between theestimates for 2005 (5,100 institutions) and 2018 (3,000 institutions).
In keeping with this principle, figure 3 below indicates that, since 2016, approximately 50% of institutions performing
conventional radiology procedures have complied with the regulatory provisions relating to DRLs. This means that theparticipation rate of institutions has still not increased in recent years.
It should be noted that the drop in the participation of institutions observed in 2011 is linked to the implementation of datatransmission over the Internet that year. Furthermore, the apparent decrease in participation between 2014 and 2015 isprobably attributable to stricter data collection conditions for 2015 (data transmission authorised until 31 January in 2015,
as opposed to 31 March in 2014).
In conventional radiology, 68% of the data come from the private sector (Figure 5 below). According to IRSN estimates, threequarters of facilities are private institutions, and a third are public or non-profit institutions. Data source distribution
therefore seems consistent with distribution of facilities and activity between the public and private sector.

̅

Dental practices

For dental practices, the increase of new accounts on the DRL application, and therefore of healthcare professionals able tosubmit data, is presented in figure 4 below. Over the years, the number of new accounts continues to increase. At the endof 2021, the number of practices signed up (able to send data to IRSN) was 763. However, it should be noted that applicationaccounts fell in 2021. Furthermore, it should be noted that, by the end of 2022, about 35% of practices signed up between
2014 and 2021 had never sent any data.

16

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINE

100%

90%

Percentage of institutions
submitting dose assessment results

80%

70%

60%

50%

51%

51%

51%

2017

2018

2019

47%

44%

43%

2014

2015

52%

49%

39%

40%

30%

30%

24%

25%

2008

2009

24%

21%

20%

13%
8%

10%

0%

< 0.1 % 0.9%
2004

2005

2006

2007

2010

2011

2012

2013

2016

2020

2021

Figure 3: Change in annual participation of institutions performing conventional radiology procedures since 2004 (excluding
dental).

Number of dental practices
signed up per year

250
202

200

201
144

150
100

72

50
0

0

1

2012

2013

15

2014

36

2015

47

45

2016

2017

2018

2019

2020

2021

Year
Practices that had never sent data by the end of 2021

Practices that had sent data at least once by the end of 2021

Figure 4: Number of new dental practice application accounts for the DRL application per year (creation of new accounts).
The number of new practices signed up each year and the proportion of those that sent data at least once before the end of2021 are represented.

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17

Public and private non-profit sector

Private sector

Dental practices

100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

Figure 5: Source of data used for DRLs, over the period 2019–2021, according to the type of examination and sector of
activity, in conventional and dental radiology.

3.2 DATA DISTRIBUTION BY EXAMINATION TYPE
̅

Adult examinations

Figure 6 below shows the distribution of dose assessments, per examination type, submitted to IRSN by healthcare
professionals from 2019 to 2021, together with the proportion of data that IRSN has been able to use.
For all examination types, except orthopantomography and mammography, the use rate for submitted data is over 90% oreven 95%.
The use rate for orthopantomography is now around 80%, slightly up on the previous report (around 70%). This lower rate
can mainly be explained by the fact that identical data submitted several times during the data collection period was nottaken into account, for the reasons stated in the paragraph on “Selection of data” in chapter 2.4 above.
The distribution of examinations is almost equivalent to that observed in the previous report, with the exception of the
proportion of orthopantomography and paediatric examinations, which increased by four points (5.1% to 9.1%) and two
points (1.8% to 4%), respectively. It should be noted that the proportion of abdominal examinations dropped again in thisreport: from 4.7% (period 2016–2018) to 3.4% (period 2019–2021).
In adults, three types of examinations account for just over 40% of the data: frontal chest, pelvis AP and lumbar spine AP.
This distribution appears to be consistent with the frequency of X-ray examinations carried out in France (16).
As stated previously, in mammography, the DRL as defined by ASN resolution 2019-DC-0667 has no longer been applicablesince 21 January 2021, following the entry into force of the new methods of quality control of digital mammography facilities,
and so the data received over the incomplete period were not analysed. For this reason, all dose assessments received areshown as not used in figure 6 below.

18

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Frontal chest (PA)18.6%

Pelvis AP

15.3%

Lumbar spine AP

10.3%

Orthopantomography

9.1%

Chest LAT

7.1%

Mammography

7.1%

Cervical spine

6.9%

Hip

6.6%

Lumbar spine LAT

5.8%

Paediatrics

4.0%

Lumbar spine AP

3.9%

Abdomen AP
Thoracic spine LAT

3.4%
1.8%

Dose assessment results used
Dose assessment results not used

Figure 6: Percentage distribution by type of examination of radiography dose assessments for which results were submitted
to IRSN from 2019 to 2021 (total number of assessments submitted: 10,860)

̅

Paediatric examinations

The proportion of data concerning paediatrics is reduced, but to a lesser extent than in the previous report, with 4% of datasubmitted (see figure 6 above) compared to approximately 2% in the previous report (i.e., 435 assessments out of a total of
10,860 assessments submitted over the period, compared to 184 out of 10,343 over the previous report period), while
approximately 10% of all the procedures carried out in France concern children (16).
Figure 7 below shows the distribution by type of examination, for children, of the dose assessments submitted to IRSN byhealthcare professionals.
Examinations of frontal chest (PA) for children weighing 10 to 20 kg, total frontal spine AP (excluding wire chamber
technology) and chest (AP) for children weighing 5 to 10 kg are the most frequently assessed procedures.
The changes brought in by ASN resolution 2019-DC-0667 have enabled the quantity of data received to be increased,compared to the previous report. However, the lack of data in paediatrics is still a major limitation to the establishment andregular updating of DRLs.

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19

Chest (PA) [10–20 kg]

113
61

Total frontal spine (excluding EOS) [30–50kg]
Chest (AP) [5–10 kg]

50

Chest (PA) [20–30 kg]
Pelvis (AP) [15–25 kg]

39
28
24

Total spine frontal + LAT EOS [30–50 kg]
Chest (AP) [3–5 kg]

23

Retrograde cystography [3–10 kg]
Abdomen AP [6–20 kg]

17
17
15

UGI [3–15[kg]Retrograde cystography [10–20 kg]

13

Pelvis (AP) [35–50 kg]

12

Abdomen AP [20–30 kg]
Abdomen AP [3–6 kg]
Barium enema [3–5 kg]
Barium enema [5–20 kg]

11
6
4
2

Dose assessment results used
Dose assessment results not used

Figure 7: Distribution by examination type of the number of child radiography dose assessments for which results were
submitted to IRSN from 2019 to 2021 (total number of assessments submitted: 435).

3.3 SUMMARY OF CONVENTIONAL
RADIOLOGY RESULTS̅

Adult examinations
The results of the dose assessments submitted by conventional radiology professionals in terms of DAP are presented intable 1 below.
It shows:•

the number of assessments used for 2021 and the period 2019–2021 (N),•patient median weight and BMI values,•

the DRLs and ADs in force (DRL and AD),•the 75th percentile and 50th percentile values for data collected in 2021,•

the 75th to 25th percentile ratio for 2021,•

the position of the 75th percentile for 2021 with regard to the DRL in force (% DRL),•

the percentage of dose assessments data received in 2021 higher than the DRL in force (> DRL),•

the 2021 75th percentile variation with regard to the 2018 value stated in the previous report.

Table 2 below shows the specific results for orthopantomography.
The results are not presented for mammography, for the reasons stated previously.

20

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Table 1: Summary of results of conventional radiology data analysis (excluding orthopantomography and mammography) by
adult examination type, for 2021, expressed in terms of dose area product (DAP).
(2019-2021)

Medianweight(kg)

MedianBMI(kg/m2 )

DRL

AD

P75

P50

ratio

Chest PA621 (1908)

70.5

24.8

200

150

155

110

2.16

Chest LAT

259 (732)

70.0

24.7

550

400

408

290

1.95

-26%

6%

-17%

Abdomen AP

110 (341)

70.0

24.8

3400

2300

2586

1406

2.59

-24%

7%

-17%

Pelvis AP

503 (1585)

70.0

24.9

3800

2750

2708

1905

2.15

-29%

8%

-21%

Hip AP/LAT

231 (688)

70.0

25.2

1350

950

1069

731

2.17

-21%

10%

-10%

Cervical spine AP/LAT

248 (712)

69.0

24.5

400

250

270

170

3.00

-33%

6%

-17%

Thoracic spine AP

154 (403)

68.5

24.5

1000

750

764

582

2.14

-24%

10%

-15%

Thoracic spine LAT

58 (182)

69.0

24.8

1150

900

900

632

1.99

-22%

19%

-45%

Lumbar spine AP

366 (1063)

70.0

25.1

2700

1950

2042

1392

2.19

-24%

11%

-15%

Lumbar spine LAT

228 (602)

70.0

25.2

3900

2650

3088

2180

2.16

-21%

13%

-13%

Examination typeN
2021

DAP (mGy.cm2 )P75/P25

% DRL

> DRL

Variation

-23%

10%

-16%

Table 2: Summary of results of orthopantomography data analysis for 2021, expressed in terms of dose area product (DAP).
Examination type
Orthopantomography

N
2021

DAP (mGy.cm2 )P75/P25(2019-2021)

DRL

AD

P75

P50

238 (765)

150

100

129

102

ratio
1.87

% DRL

> DRL

Variation

-14%

12%

-4%

Detailed analyses by examination type are presented in the Annex to this report in the form of datasheets. For eachexamination type for which the data collected can be analysed, these datasheets show:

DAP distribution graphs for 2019–2021;
a table with associated statistical data;changes in results since 2011.

Apart from the lateral thoracic spine examinations, the results show a drop of 10–20% in the 75th percentile values compared
to 2018. Thus, the overall drop in the values of the dosimetric data observed over the period 2016–2018 (down 7% compared
to 2013–2015) is confirmed and consolidated in this report (down 19% compared to 2016–2018). Lateral thoracic spine
examinations, as in the previous report, are those for which the least number of dose assessments were analysed in 2021
(58 assessments in 2021; 30 assessments in 2018). In 2018, a 43% increase in the 75th percentile value compared to 2015
had been observed, but the representativeness of the result was questionable due to the low number of data. In 2021, the75th percentile value was 900 mGy.cm², which is more than 20% lower than the DRL in force, and therefore returns to a value
consistent with data from previous years (excluding 2018).
Overall, the 75th percentile values for 2021 were 20%-30% below the DRLs in force for all examinations. A revision of the
DRLs could therefore be envisaged.
There is still a high level of data dispersion, with a 75th/25th percentile ratio of around 2 to 3. This result may raise questions
about dose optimisation and associated image quality. However, it is not possible to discuss this result from the point ofview of image quality. This is because, as stated in the previous report, the concept of image quality is complex, andsubjectivity makes it difficult to assess. An assessment of the diagnostic performance of equipment needs to be associatedwith the system for optimising doses delivered to patients in order to ensure that it does not negatively impact examination
quality. In particular, if local median values are below the achievable dose values (AD), image quality, rather than dose,should be considered as a priority in the optimisation process.
As stated previously, the detailed data analysis results for mammography are not presented. In this regard, IRSN conducteda study in 2020 and proposed to ASN, in its notice No. 2021–001932, a change in the method of collecting data and the DRL
value in mammography, in order to better analyse the clinical practices of sites, as well as a new DRL for the rapidly
expanding breast tomosynthesis technique (see dedicated focus).

2

https://www.irsn.fr/sites/default/files/documents/expertise/avis/2021/Avis-IRSN-2021-00193.pdf
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21

The number of assessments submitted for orthopantomography for 2019–2021 doubled compared to the previous
assessment established for 2016-2018, rising from 371 to 765. It was therefore possible to produce an analysis for 2021. The
75th percentile in dental radiology in 2021 was very similar to that obtained for the previous report, and below the DRL byaround 14%.
In line with what has been done in digital mammography and breast tomosynthesis, IRSN conducted, at the request of ASN,
a study on the doses delivered with cone-beam computed tomography (CBCT) for dental radiology and proposed to ASN, in
its notice No. 2023–000063, the implementation of a DRL for this increasingly used technique (see dedicated focus).

̅Paediatric examinations

The results of the dose assessment analyses for paediatric radiology are presented in table 3 below.
For each weight category, this table shows the number of assessments used (N) for 2019–2021, the minimum, median andmaximum weight of children, the 75th percentile value (75th), the 50th percentile value (50th), the 75th to 25th percentile ratio
and, for the examinations for which sufficient data have been collected, the position of the 75th percentile for the periodwith regard to the DRL in force (% DRL), as well as the percentage of dose assessments received over the period above the
DRL in force (> DRL).
Only full spine AP examinations (excluding wire chamber technology) for children weighing 30 to 50 kg and chest AP
examinations for the 5–10 kg, 10–20 kg and 20–30 kg categories include sufficient data in terms of DAP (more than 20
paediatric assessments) and may give rise to a detailed analysis (see Annex to this report).
Only abdomen examinations for the 3–6 kg and 20–30 kg categories as well as barium enema examinations for all categories
had too few assessments (< 10) for the results to be discussed.
The child weight categories for the different examinations defined in ASN resolution 2019-DC-0667 have changed from theOrder of 2011. It is therefore not possible to compare the results of the previous report established for the period 20162018. In addition, the weight categories defined for children in ASN resolution 2019-DC-0667 do not correspond to theweight categories defined at European level (17). A revision of these weight categories would allow comparisons to be madewith the results of other European countries.
For chest AP examinations in children, the results are slightly lower than the DRLs set out in ASN resolution 2019-DC-0667,
by around 6 to 8% for all categories except the 10–20 kg category. Approximately 20% of the submitted assessements areabove the DRL.
For chest AP examinations of children in the 10 to 20 kg category, the result is around 20% higher than the DRL set out in
ASN resolution 2019-DC-0667, with approximately 40% of the submitted assessments above the DRL. This may be explainedby a difference concerning the institutions represented in the collected DRL data for the 5–10 and 20–30 kg categories. Thisis because the institutions submitting data for these two categories are mainly university hospitals specialised in or used topaediatric radiology, whereas this is not the case for the 10–20 kg category. This illustrates the need to disseminate goodradiation protection practices for patients in institutions specialised in and/or used to paediatric radiology to all institutions
treating children.
For full spine AP examinations, in the 30–50 kg category, the result is very slightly below the DRL set out in ASN resolution
2019-DC-0667, by around 2%, with just over 20% assessments above the DRL.
Conversely, full spine AP and LAT examinations with wire chamber technology gives a result well below the DRL set out in
ASN resolution 2019-DC-0667, by around 20%, with no assessment above the DRL.
For pelvis (AP) examinations, in the 15–25 kg category, and for retrograde cystography, in the 3–10 kg and 10–20 kg
categories, the results are well below the DRL, by around 40–60%. As the number of assessments submitted for retrograde
cystography is still quite low (11 and 10, depending on the weight category), these results should be discussed with due
caution. Furthermore, very high 75th and 25th percentile ratios were observed for these examinations, illustrating theheterogeneity of the results.
For Upper gastrointestinal series (UGI) , in the 3–15 kg category, the results are above the DRL by around 30%, withapproximately 40% of the submitted assessments above the DRL and a 75th and 25th percentile ratio above 2.5. These results,
as with retrograde cystography, illustrate a disparity in practices. It should be noted that these examinations cover several
indications which do not result in the same dose level. It would probably be useful to refine this indication to better definea DRL accordingly.

3

https://www.irsn.fr/sites/default/files/2023-02/Avis-IRSN-2023-00006.pdf

22

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINEA new revision of DRLs in paediatric conventional radiology does not seem necessary in the short term. The results for fullspine AP and LAT examinations with wire chamber technology and pelvis AP examinations for the 15–25 kg category, which
are much lower than the currently applicable DRLs, could justify a lowering of the DRL; however, there are still insufficientdata, and these need to be confirmed for the drafting of the next report that will cover the 2022–2024 data collection period.
It is also necessary to monitor the evolution of the results of UGI and retrograde cystography examinations and to implement
actions to encourage and standardise the optimisation of practices by the centres for these examinations, such as, forexample, the development of a best practices guide by the healthcare professionals concerned. Indeed, it seems that some
centres have implemented advanced approaches to optimising paediatric doses which could usefully be disseminated more
widely.
Table 3: Summary of results of conventional radiology data analysis by paediatric examination type, in terms of dose area
product (DAP) for 2019–2021
Examination type

DAP (mGy.cm2)

Weightcategory(kg)

N
2019-2021

Medianweight
(kg)

DRL

P75

P50

ratio

[3 - 5]

13

3.5

9

8.5

4.5

[5-10]

39

7.6

13

11.95

[10–20]

82

14.0

19

[20-30]32

24.0[15–25]20[35–50]P75/P25

% DRL

> DRL

2.13

-6%

15%

8.93

2.12

-8%

21%

23

17

2.38

20%

40%

35

33

25

1.71

-6%

22%

18.0

120

66

42

1.91

-45%

5%

11

44.0

510

517

492

1.35

1%

27%

[3–6]

3

3.0

20

21

14

1.84

-

33%

[6–20]

13

11.5

80

86

45

2.88

8%

38%

[20–30]

7

24.1

280

221

218

1.35

-

0%

[30–50]

44

42.5

800

787

619

1.96

-2%

23%

[3–10]

11

6.9

550

320

108

8.40

-42%

9%

[10–20]

10

13.2

1000

385

347

2.14

-62%

10%

[3–15]

10

7.8

150

195

127

2.66

30%

40%

[3–5]

4

3.7

300

80

46

4.93

-

0%

[5–20]

1

9.0

400

118

118

1.00

-

0%

[30–50]

15

42.0

850

660

392

2.56

-22%

0%

Chest

Pelvis (AP)

Abdomen AP

Full Spine AP(excluding wire chamber technology)

Retrograde cystography

UGI

Barium enema

Full spine AP+LAT(wire chamber technology)

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FOCUS – CONVENTIONAL RADIOLOGYDRL IN DIGITAL MAMMOGRAPHY AND BREAST TOMOSYNTHESIS
See IRSN notice No. 2021–00193 of 3 December 20214
At the request of ASN, IRSN - with the assistance of the relevant learned societies5 - conducted surveys on the dosesdelivered to patients in 2D digital mammography (CR (computed radiography) and DR (direct radiology) systems)
and breast tomosynthesis.
A collection of data on doses delivered in 2D digital mammography (DR systems only) and breast tomosynthesis was
conducted from March to July 2021 among healthcare professionals.
The following indications were selected in the study on 2D DR mammography and tomosynthesis facilities:

mammography in breast cancer screening campaigns;

mammography for individual breast cancer screening (excluding campaigns);tomosynthesis procedures, regardless of their clinical indication.

Indications excluded from the scope of the study, because they do not systematically affect both breasts or may be
additional examinations using different protocols and incidences of bilateral screening mammograms, were as
follows:

any magnifications and centred images;



images of inflammatory breasts, symptomatic breasts, treated breasts, or prostheses;images taken during biopsies;



examinations carried out by angiomammography.

The 2D CR systems do not have an MGD display, the dose indicator chosen for the study on 2D DR systems. This iswhy, an analysis of the data from external quality control reports for CR systems, submitted to IRSN by the ANSM in
September 2021, was conducted.
The data used by IRSN for this study concerned:


80 CR 2D mammography facilities;



77 facilities and 5,300 patients for 2D DR mammography;

44 facilities and 3,009 patients for tomosynthesis.

The results of the IRSN study illustrate that, although tomosynthesis does not currently feature in organised breast
screening campaigns, its use is tending to be expanded, and most equipped centres use it systematically for this typeof screening. The 75th percentiles of MGD are 35% higher in tomosynthesis than in 2D DR mammography. Thesefindings confirm the need to implement DRL in breast tomosynthesis.
MGDs clearly increase with compressed breast thickness in 2D CR / DR mammography and tomosynthesis.
Therefore, an analysis of the indicators by breast thickness interval is necessary.
Furthermore, this study shows, in 2D DR mammography and tomosynthesis, extensive variability in the MGD
recorded on patients according to the brand of mammography equipment:

in 2D DR mammography, the 75th percentile of MGDs per patient ranges from 1 to 2.3 mGy;in tomosynthesis, the 75th percentile of MGDs per patient ranges from 1.4 to 2.9 mGy.

In 2D CR mammography, the MGD measured during external quality control varies little between mammographyequipment brands.

45

https://www.irsn.fr/sites/default/files/documents/expertise/avis/2021/Avis-IRSN-2021-00193.pdf
Société Française de Radiologie, Fédération Nationale des Médecins Radilogues, Société d'Imagerie de la Femme, Société Française deSénologie et de Pathologie Mammaire, Association Française du Personnel Paramédical d'Electroradiologie, Société Française de Physique
Médicale

24

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINE

Whether in 2D CR/DR mammography or tomosynthesis, the results obtained in the IRSN study in terms of MGD are
consistent with the recent literature on this subject. However, the small differences observed between the indicators
obtained in the IRSN study and recent literature may be explained by the difference in method and sample size ofthe different studies.
The analysis of the 75th percentiles of threshold contrast visibility of the 2D CR facilities shows a lesser performance
than for the 2D DR facilities (in the order of 25 to 50%), whereas the 75th percentile of the dose measured duringexternal quality control in 2D CR mammography is about 20% higher than that of 2D DR mammography. With respect
to the overall image quality visual score, given the high variability of visual score results with large standard
deviations, the differences between brands are included in the ranges of variation. It is therefore difficult to compare
the performance of the facilities on the criterion of visual score on an anthropomorphic phantom.
These results demonstrate the need to incorporate image quality in the delivered dose analysis. However, they also
illustrate the difficulty of correlating the image quality on a test object for measuring the threshold contrast visibility
with the image quality on an anthropomorphic phantom, let alone in clinical use.
These results also raise the issue, already stated in a previous IRSN notice (18), of the reduced performance of 2D
CR mammography facilities which deliver more dose for a lower threshold contrast visibility than 2D DR facilities.
Currently, ASN resolution 2019-DC-0667 defines a single DRL for 2D DR and 2D CR digital mammography based on
the mean glandular dose (MGD) measured during annual external quality control at 45 mm equivalent breast
thickness. As IRSN’s study shows that the MGDs vary according to the thickness of the compressed breast, it appears
necessary to upgrade the DRL framework by extending the data collection to all breast thicknesses for 2D DR
mammography and tomosynthesis facilities which enable dose readings to be taken on patients under clinicalconditions. Therefore, IRSN recommends that facilities collect 2D DR mammography and tomosynthesis data every
3 years for at least 50 patients per facility, regardless of the thickness of the compressed breast. IRSN also
recommends integrating, in addition to the mean glandular dose (MGD), the compressed breast thickness among
the elements to be submitted to IRSN as part of the data collection required under the regulations. Lastly, IRSN
recommends setting the DRL, regardless of breast thickness and incidence, at 1.7 mGy in 2D DR mammography and2.3 mGy in tomosynthesis.
For 2D CR mammography facilities, the clinical and technical performance of these facilities is a topic of concern.
IRSN recommends taking measures to avoid the commissioning of new 2D CR mammography facilities andencourage the replacement of facilities currently in operation.

ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDICINE – IRSN

25

FOCUS – CONVENTIONAL RADIOLOGYDRL IN DENTAL CBCT
See IRSN notice No. 2023–00006 dated 11 January 20236
At the request of ASN, IRSN, with the aid of professional bodies from the sectors concerned7, conducted a survey
in 2 phases, from May to July 2021, then from February to March 2022, on the doses delivered by CBCT in dental
radiology examinations among all healthcare professionals using this technique, for the following nine indications:

indications in adults:
 single implant without guide, without sinus lift; multiple implant with guide, without sinus lift; jaw implant with sinus lift; dental extraction: bilateral wisdom teeth; single impacted tooth extraction;
 periodontal assessment;
 endodontics;



indications in children: impacted tooth in children aged approximately 12;
 cleft palate in children aged approximately 8 to 10.

In light of feedback from previous surveys in three European countries, the dose area product (DAP) data associatedwith the parameters usually selected for a standard patient, in terms of morphology and indication, were collected.
228 dental and medical imaging institutions responded to the survey. However, the data used by IRSN only concern
150 institutions, 85% of which are in the dental sector, a proportion consistent with the national installed base of
facilities. This is because the variable quality of the data collected required complex checking, and a large quantityof this data could not be used.
Statistical analysis of the data shows that, in the dental sector, the 75th percentile values of the DAP vary relatively
little between the indications, at around 700 mGy.cm², except for periodontics and impacted teeth in children. In
the medical imaging sector, the values are higher and more pronounced variations are observed between
indications.
However, the size of the panel of institutions whose data has been used is small compared to the size of the installed
base, estimated at at least 2,700 devices. Furthermore, even after verification, uncertainties persist for part of thedata used, particularly for indications relating to several teeth (multiple implants and bilateral wisdom teeth, forexample) or for which a significant unexplained discrepancy has been observed between the dental sectors andmedical imaging (jaw implant, for example). Finally, in the absence of a regulatory quality control framework for
devices used in CBCT imaging, it is not possible to guarantee that the DAPs displayed by the machines correspond to
the reality of patient exposure.
Overall, the 75th percentile values for DAPs obtained in the CBCT French user survey are significantly higher than the
DRLs in force in other countries such as Finland, the UK, Switzerland, and Sweden. The only exceptions are, on the
one hand, Japan, whose DRL values are very high, and, on the other, endodontics examinations, for which the valueof the Swiss DRL is close to the French result.
Considering all these elements and due to the previously detailed study limits and the insufficient number of datacollected in paediatrics and for the periodontics indication in adults, IRSN therefore recommends keeping only three
indications in adults: the single implant without guide and without sinus lift, single impacted tooth extraction, andendodontics. IRSN recommends expressing the DRL in terms of DAP, a value used in countries that have defined
DRLs and already used for orthopantomography, and setting the same value (700 mGy.cm²) for the three indications
chosen.

6
7

https://www.irsn.fr/sites/default/files/2023-02/Avis-IRSN-2023-00006.pdf
In the medical imaging sector: Société française de radiologie (SFR), Fédération nationale des médecins radiologues (FNMR), Société française dephysique médicale (SFPM); in the dental sector: the Dental radiation protection commission (Commission radioprotection dentaire - CRD), incorporating
the Association dentaire française (ADF), the Chirurgiens-dentistes de France (CDF), the Fédération des syndicats dentaires libéraux (FSDL), the Ordrenational des chirurgiens-dentistes (ONCD) and the Union dentaire (UD)26

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINEIn the absence of a regulatory quality control framework, particularly relating to the quality of the acquired images,
IRSN does not consider it necessary, at this stage, to set ADs in addition to the DRLs. ADs are meant, in particular, tohighlight the importance of maintaining sufficient image quality when doses become low.
During the expert appraisal which led to the publication of IRSN notice No. 2023–00006 of 11 January 2023, IRSN
was faced with radiation protection issues linked to the use of dental CBCT systems: failure to comply with certain
regulatory obligations, lack of knowledge of the possibilities of adjusting devices to optimise doses, errors in the
documentation of certain manufacturers, and the need to formalise practices through protocols for performing
procedures. Implementing DRLs for dental CBCT examinations would be of real aid to healthcare professionals for
detecting unoptimised delivered dose levels.
With the aim of advancing radiation protection for patients in the dental field, IRSN therefore issued, in this notice,global recommendations that need to be implemented at the same time. Indeed, the establishment of new DRLs will
only be meaningful if these recommendations, including those relating to the implementation of a quality control
framework for dental CBCT, to the training of users of dental CBCT devices, and to the improvement of information
provided by device manufacturers and suppliers, are implemented in parallel.

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27

SUMMARY – CONVENTIONAL RADIOLOGY
Analysis of conventional radiology dose assessments shows:






a still limited participation rate of radiology structures, stabilised at around 50%;an increase in the proportion of orthopantomography and paediatric examinations, which increased by 4 and2 points respectively compared to the previous report;
in adults:o the 75th percentile values of 2021 are 20 to 30% below the DRLs in force;o an overall 19% reduction in conventional radiology dose indicators compared to 2016–2018, which confirms
the previously observed drop of 7% compared to 2013–2015;
o still a high level of data dispersion, with a 75th/25th percentile ratio of around 2 to 3;
in children:o the changes made in ASN resolution 2019-DC-0667 enabled an increase in the quantities of data received
compared to the previous report; however, the lack of data in paediatrics still constitutes a major limit for theestablishment and regular updating of DRLs;
o for full spine AP and LAT examinations with wire chamber technology and pelvis AP examinations for the
15–25 kg category, results are well below the DRL;o for UGI and retrograde cystography examinations, very high ratios between the 75th and 25th percentile values,
illustrating the heterogeneity of results and which may illustrate a diversity of practices and/or indications.

RECOMMENDATIONS – CONVENTIONAL RADIOLOGY
Analysis of conventional radiology dose assessments leads IRSN to make the following recommendations:in adults:o revise the DRLs;o monitor the evolution of data for thoracic spine LAT and possibly question whether to keep thisexamination within the DRL system, since it remains the examination with the lowest number ofassessments submitted;
in paediatrics:
o monitor the evolution of the results of full spine AP/LAT examinations with wire chamber technology
and pelvis AP examinations for the 15–25 kg category to potentially consider the revision of the DRLs ofthese examinations;o monitor the evolution of the results of UGI and retrograde cystography examinations and possibly revise,in the long term, the definition of these DRLs based on feedback received since 2019;o investigate the relevance of revising weight categories to fall into line with European recommendations
and thus enable comparisons to be made;o continue to encourage the submission of paediatric data by reminding practitioners that it is possible tocollect data for more than one year.

In addition, IRSN recommends:oo28

in mammography, revising the DRL for digital mammography and introducing a DRL for breast
tomosynthesis taking into account the notice published by IRSN in December 2021 (19);in dental CBCT, introducing a DRL for certain indications taking into account the notice publishedby IRSN in January 2023 (20).

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINEINTERVENTIONAL RADIOLOGY
4.

INTERVENTI ONAL RADI OLOG Y

4.1 CONTRIBUTION OF DEPARTMENTS
ASN resolution 2019-DC-0667 introduced DRLs for certain image-guided interventional procedures. These are therefore
new procedures monitored over the period covered by this report. The main institutions concerned are those carryingout endovascular image-guided interventions (EIGIs), in cardiology and/or neuroradiology. To assess the participationof the departments in these specific areas, it is possible to draw on the “FINESS” files of the healthcare activity
authorisations (21) and the “Open CCAM” database (22).
According to FINESS data, at the end of 2020 there were around 193 institutions performing interventional cardiology
activities (excluding paediatrics and rhythmology) and around 41 institutions performing interventional neuroradiology
activities.
On this basis, the interventional cardiology participation rate shows an increase from 46 to 70% year-on-year from 2019
to 2021, with 84% of institutions sending data at least once during this period. In neuroradiology, participation shows
an increase from 61 to 85% year-on-year with a total of 100% of institutions sending data during this period. These
positive results illustrate the degree of support from institutions for the DRL system. However, the results should beanalysed with caution, given that the number of institutions carrying out these activities is not entirely known. The small
number of institutions authorised to carry out interventional neuroradiology activities (41) should also be highlighted.
Thus, even with 100% of institutions having sent data at least once over the period, the number of assessments in thisarea remains low (25 to 35 per year) and just within the limit of the 20 assessments necessary for the reliability of theresults. The low number of assessments for a large proportion of the procedures has led to an analysis over the threeyear period and not per year for the interventional radiology area in general.
For image-guided interventional procedures concerning areas other than cardiology and neuroradiology, the number of
institutions concerned is difficult to establish as there is no dedicated activity designation in the healthcare activity
authorisation files. For this reason, the contribution from departments illustrated in figure 8 below is presented as an
absolute number and not as a percentage as in the other areas.
200

180

163

Number of institutions
submitting dose assessment results

160

138

133

140

122
120

100

89

88
74

80

60

49

40

25

32

41

35

20

0

2019

2020

Cardiology

2021

Neuroradiology

2019-2021

Other specialities

Figure 8: Number of institutions that have submitted dose assessments for interventional radiology, by area of activity.

ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDICINE – IRSN

29

4.2 DISTRIBUTION OF DATA BY TYPE OF PROCEDURE
Figure 9 below presents the percentage distribution, by type of procedure, of dose assessments submitted to IRSN byhealthcare professionals from 2019 to 2021, together with the proportion of data that could be used by IRSN.
The rates of use of the submitted data are low; they range from approximately 50% for coronary angiography to 72%
for biliary drainage with transcutaneous implanting of prosthesis. However, these low data use rates are not linked todata quality, but to the removal of “duplicates” to allow data analysis over a three-year period and not year by year.
This is due, in the field of interventional radiology, to certain facilities being dedicated to certain specialities and specificprocedures; hence, many institutions only perform a small number of types of procedures considered in the list of ASN
resolution 2019-DC-0667. Therefore, many of them send data for the same procedures on the same facility every year.
In this case, for the analysis over the three-year period, so as not to give more weight to one facility over another, only
the assessment for the last year is kept. For example, for coronary angiography, out of a total of 550 submitted
assessments, only 275 were used in this report. Of the 275 unused assessments, only 16 were not used for data quality
reasons. This means that 259 assessments were not used due to the analysis over three years.
Coronary angiography and coronary artery angioplasty account for approximately 60% of the data. It is not possible tosay precisely whether this distribution appears consistent with the frequency of the procedures carried out in France.
This is because some of the procedures considered fall within the scope of therapeutic interventional radiology and are
not analysed in the EXPRI study, which only concerns diagnostic activities (16).
Coronary
Coronary artery angioplasty (excluding CTO)
Single level vertebroplasty
Hepatic chemoembolization
Cerebral arteriography
Embolization of a cerebral aneurysm
Biliary drainage with transcutaneous implantation of prosthesis
Uterine fibroid embolization
Intrahepatic portosystemic shunt
Embolization of bronchial arteries
Embolization of a cerebral AVM
Embolization of post-partum bleeding

7.0%
6.0%
5.8%
4.6%
3.6%
3.3%
2.2%
1.8%
1.5%
0.7%

29.6%

34.0%

Dose assessments used
Dose assessments not used

Figure 9: Percentage distribution by type of procedure of dose assessments in interventional radiology, the results ofwhich were submitted to IRSN from 2019 to 2021 (total number of assessments submitted: 1,620).

4.3 SUMMARY OF INTERVENTIONAL RADIOLOGY RESULTS
The results of the dose assessments transmitted by interventional radiology professionals in terms of DAP, radioscopy
time, and air KERMA at the reference point are presented in tables 4, 5 and 6 below. This is because, in addition to the
DAP and the radioscopy time defined at regulatory level, it was possible, for each institution, to submit additional andoptional data in terms of the number of radiography and air KERMA images at the reference point (see paragraph 2.4 ofthis report). As enough data was transmitted on the air KERMA at the reference point, these data could be analysed.
Results for the number of radiography images are not presented because too many inconsistencies were found. The
origin of these inconsistencies must be investigated in order to attempt to strengthen the reliability of the datasubmitted on this aspect for the next report.
For each of the procedures considered, the following are presented for 2019–2021:
 the number of assessments used (N), patient median weight and BMI values, the DRLs and ADs in force (DRL and AD), the 75th and 50th percentile values for the collected data, the 75th to 25th percentile ratio,
 the position of the 75th percentile with regard to the DRL in force (% DRL), the percentage of dose assessments data received over the DRL in force (> DRL).

30

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINE

Although the 75th percentiles of the radioscopy times are quite close to the DRLs set out by ASN resolution 2019-DC0667, overall the 75th percentiles of the DAP are far below (between 30% and 54%). There may be several reasons for
this:
-

-

The SFPM study used for the determination of DRLs in interventional radiology (23; 24) was carried out on the basisof a data collection dating from the end of 2015 to January 2016; the DRLs in force are therefore based on alreadyold data.
In the SFPM study, the analyses were carried out based on the distributions of doses per patient and not on the
distribution of medians per facility; the analysis of the median per facility is the analysis method used in theframework of the analysis reports carried out by IRSN every three years and which is recommended by the ICRP(25); this analysis method reduces the variations linked to each procedure (patient morphology, complexity of theprocedure, etc.) and therefore the dispersion of data.

Given these results, IRSN recommends revising the value of DRLs in interventional radiology based on the results of thisreport.
The numerous data on air KERMA can be compared with the results of the SFPM and RAY ACT 2 studies (23; 24; 26).
These data have proven to be very useful for data verification. IRSN recommends establishing, in addition, a DRL on thisdose indicator based on the results of this report (see dedicated focus).
Table 4: Summary of results of interventional radiology data analysis by type of procedure in adults, for 2019 – 2021,
expressed in terms of dose area product (DAP).
Medianweight(kg)

MedianBMI(kg/m2)

DRL

AD

P75

P50

275

76.0

26.1

38

21

20.0

240

77.0

26.3

80

45

40.7

Cerebral arteriography (3 or more axes)

48

69.5

24.1

105

65

52.7

40.1

1.77

-50%

2.1%

Embolization of a cerebral aneurysm

38

67.0

24.0

190

130

129.8

96.2

1.80

-32%

0.0%

Embolization of cerebral
arteriovenous malformation

16

71.0

24.2

285

170

199.8

152.3

1.69

-30%

6.3%

Hepatic chemoembolization

55

77.5

26.3

240

115

155.5

101.7

2.49

-35%

12.7%

Embolization of bronchial arteries

20

69.8

23.8

135

70

74.7

51.3

3.21

-45%

0.0%

Embolization of a uterine fibroid

33

64.5

23.5

130

55

59.5

35.5

2.11

-54%

0.0%

Embolization of post-partum bleeding

7

69.0

24.5

295

170

139.2

100.1

2.02

-50%

0.0%

Intrahepatic portosystemic shunt (IPS)

21

74.5

25.3

190

95

127.0

96.3

2.38

-33%

9.5%

Biliary drainage with transcutaneous
implanting of prosthesis

42

66.3

23.3

45

20

23.5

17.5

3.23

-48%

4.8%

Vertebroplasty (1 vertebral level)

69

67.0

24.2

60

30

27.8

15.0

9.24

-54%

4.3%

Examination type

N

Coronary angiography
Coronary artery angioplasty(except chronic total occlusion)

DAP (Gy.cm2)

P75/P25
ratio

% DRL

> DRL

14.6

2.00

-47 %

1.5%

28.6

2.09

-49%

2.1%

ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDICINE – IRSN

31

Table 5: Summary of results of interventional radiology data analysis by type of procedure in adults, for 2019 – 2021,
expressed in terms of radioscopy time.
Examination typeN

Medianweight(kg)

MedianBMI(kg/m2)

DRL

AD

P75

P50

P75/P25
ratio

% DRL

> DRL

Coronary angiography

275

76.0

26.1

6

4

4.3

3.2

1.74

-28%

8.4%

Coronary artery angioplasty (except
chronic total occlusion)

240

77.0

26.3

15

10

12.9

10.3

1.65

-14%

15.0%

Cerebral arteriography (3 or more axes)

48

69.5

24.1

13

8

12.6

10.2

1.74

-3%

25.0%

Embolization of a cerebral aneurysm

38

67.0

24.0

58

37

50.2

43.8

1.74

-13%

15.8%

Embolization of cerebral
arteriovenous malformation

16

71.0

24.2

68

45

75.8

57.4

1.80

+11%

37.5%

Hepatic chemoembolization

55

77.5

26.3

27

18

26.7

21.7

1.80

-1%

21.8%

Embolization of bronchial arteries

20

69.8

23.8

38

25

26.2

24.1

1.23

-31%

5.0%

Embolization of a uterine fibroid

33

64.5

23.5

29

25

21.5

15.4

1.90

-26%

6.1%

Embolization of post-partum bleeding

7

69.0

24.5

25

15

20.1

18.9

1.45

-20%

0.0%

Intrahepatic portosystemic shunt (IPS)

21

74.5

25.3

39

25

28.6

21.5

1.61

-27%

4.8%

Biliary drainage with transcutaneous
implanting of prosthesis

42

66.3

23.3

18

11

15.0

11.4

2.20

-17%

2.4%

Vertebroplasty (1 vertebral level)

69

67.0

24.2

9

6

6.9

4.1

5.02

-23%

11.6%

Radioscopy time (min)Table 6: Summary of results of interventional radiology data analysis by type of procedure in adults, for 2019 – 2021,
expressed in terms of air KERMA at the reference point.
Medianweight(kg)

MedianBMI(kg/m2)RAY ACT 2

SFPM

P75

P50

224

76.0

26.0

353

-

258.2

187.5

1.89

196

77.0

26.3

920

-

626.0

448.0

1.96

Cerebral arteriography (3 or more axes)

38

69.8

24.1

-

720

364.4

261.6

1.64

Embolization of a cerebral aneurysm

30

67.1

24.0

-

2765

2258.61177.5

2.53

Embolization of cerebral
arteriovenous malformation

14

70.5

24.1

-

3235

2154.71532.4

1.90

Hepatic chemoembolization

48

77.5

26.3

-

1000

935.2

586.7

2.28

Embolization of bronchial arteries

18

70.0

23.8

-

845

350.8

320.3

2.03

Embolization of a uterine fibroid

27

64.0

23.4

-

700

314.8

206.0

2.08

Embolization of post-partum bleeding

7

69.0

24.5

-

940

722.8

501.3

2.65

Intrahepatic portosystemic shunt (IPS)

17

74.5

25.5

-

810

717.2

292.2

3.24

Biliary drainage with transcutaneous
implanting of prosthesis

32

65.9

23.3

-

310

140.9

102.3

2.87

Vertebroplasty (1 vertebral level)

43

68.0

24.2

-

610

358.6

224.0

4.25

Examination type

N

Coronary angiography
Coronary artery angioplasty (except
chronic total occlusion)

Kair at reference point (mGy)

P75/P25
ratio

The analyses per type of procedure are detailed in the Annex to this report in the form of datasheets. For each type ofprocedure for which the data collected enables an analysis to be made, these datasheets present:

 DAP, radioscopy time, and air KERMA distribution graphs for 2019–2021;
 a table showing the associated statistical data.
Given that these procedures were introduced in 2019 in the ASN resolution, it is not possible to analyse the evolutionof results in relation to the results of previous reports.
Insofar as the 75th percentiles for 2019–2021 in terms of DAP are 30% to 54% below the DRLs in force, a revision of the
DRLs appears necessary.
Significant data dispersion is noted, particularly for the DAP with a 75th/25th percentile ratio of 2 to slightly more than 3(apart from vertebroplasty). The highest 75th/25th ratios are observed for therapeutic procedures. Differences in thecomplexity levels of interventions could explain a large proportion of these dispersions. The results for the radioscopy
times appear to be less variable.

32

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINEWith regard to vertebroplasty, a 75th/25th ratio greater than 9 is observed. The reason for this is the submission of datafor both mobile and fixed units. Separate data analysis leads to a 50th percentile in terms of DAP that is 10 times higher
for fixed units than for mobile units. Hence, under the term “vertebroplasty”, different types of procedures performedon different units are grouped together, which leads to a very wide dispersion of data. In the future, it would certainly
be advisable to better define this typology of procedure in order to refine the results.
Finally, ASN resolution 2019-DC-0667 currently requires the submission of data in interventional radiology for at least
10 consecutive adult patients and not for at least 30 patients as for the other areas. This choice to limit the quantity ofdata sent by the centres had been made when the aforementioned resolution was drawn up, in order to encourage theparticipation of the institutions. However, in order to reinforce the robustness of dose assessments, it would now beadvisable to increase the minimum quantity of data required for dose assessments in interventional radiology. To thisend, it would be interesting to study the relevance of a mass data transmission from DACS, even if the data wereincomplete, since information on patient weights and sizes is rarely available in these databases. This study could beinitiated in the field of interventional radiology and, if this principle proves satisfactory, it could be extended to the otherareas.
FOCUS – INTERVENTIONAL RADIOLOGYAIR KERMA AT THE REFERENCE POINT
Although this data is optional, a large proportion of the assessments submitted in interventional radiology
specified the air KERMA values at the reference point (14) (60 to 100% of the assessments depending on theprocedure).
These data, which are easily accessible, are very often used by professionals (medical physicists, doctors, etc.) asa means of alert, particularly as a complement to the DAP, the rationale for this being that, for procedures
requiring small fields, the DAP can remain low while air KERMA at the reference point can be high. Users havetherefore already become accustomed to looking at this dose indicator and have spontaneously submitted it to
IRSN.
This indicator has proven to be very useful for IRSN in the context of data verification. The DAP/Kair ratio should
approximate the average field area used during the procedure. Thus, data with an inconsistent DAP/Kair ratio
were excluded from the analysis.
It is not possible to compare the results obtained with DRL values since this indicator is not defined in theregulations. However, it is possible to compare the results of this report with the results of the studies used to
upgrade DRLs in interventional radiology, namely the RAY’ACT-2 study and the SFPM study (23; 24; 26).
For most procedures, the results in terms of air KERMA at the reference point (see table 6 above) are far below
the results obtained during the SFPM and RAY’ACT-2 studies, in particular for the embolization of bronchialarteries and embolization of a uterine fibroid. This is also true for brain arteriography (3 or more axes), but forthis procedure, a bias in the data is possible because some of the data transmitted may concern fewer than 3axes. Similarly, for vertebroplasty, the data submitted to IRSN concern procedures carried out on mobile units or
fixed units with very different dose levels. The same reasons as stated above for the results of DAP values can be
put forward to explain the difference between the results of this report and the results of the RAY'ACT 2 andSFPM studies (data from studies that are recent or less recent; study of the distribution of doses per patientversus the median distribution of doses from the units).
IRSN therefore recommends establishing, in addition to the DRLs in terms of DAP and radioscopy time, a DRL on
air KERMA at the reference point based on the results of this report.

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33

SUMMARY – INTERVENTIONAL RADIOLOGY
Analysis of interventional radiology dose assessments shows:








a high degree of participation by interventional cardiology and neuroradiology institutions since theintroduction in 2019 of the DRLs newly defined in the regulations;75th percentiles for 2019–2021 that are 30% to 54% below the DRLs in force;a high level of data dispersion, particularly for DAP with a 75th/25th percentile ratio of around 2 to 3 (excluding
vertebroplasty);
an even higher level of vertebroplasty data dispersion with a 75th/25th percentile ratio, for DAP, higher than 9
due to the consideration of data relating to both mobile and fixed units;a large amount of data transmitted in terms of air KERMA at the reference point, which is very useful for data
validation;
inconsistent results in terms of the number of radiography images.

RECOMMENDATIONS – INTERVENTIONAL RADIOLOGY
Analysis of interventional radiology dose assessments has led IRSN to issue the following recommendations: revise the DRL values; monitor the evolution of the results of vertebroplasty procedures and, possibly, revise in the long term thedefinition of its DRL based on feedback since 2019; add the air KERMA at the reference point as an extra DRL quantity in addition to the DAP and the radioscopytime; investigate the origin of inconsistencies in the data in terms of the number of radiography images in order tomake the data received for this indicator more reliable;

 consider increasing the quantity of patient data to be requested for each assessment submitted by studying

the relevance of a mass data transmission from DACS without patient weights and sizes, with the aim ofobtaining average data more representative of clinical practice; consider, from proposals of stakeholders consulted on the DRL system in 2022:
o the creation of DRLs for two rhythmology procedures considered to be the most irradiating: atrial
fibrillation ablation and ventricular resynchronization (= triple or multisite cardiac stimulation); the“rhythmology” group of the Société Française de Cardiologie (French cardiology society) must be
consulted to carry out this work;o the introduction, in the long term, of interventional procedures performed under CT examination, inparticular by engaging in reflection on interventional cardiology procedures (TAVI, mitral valvuloplasty) orinterventional vascular radiology (peripheral vascular angioplasty, other procedures to be specified)
performed in operating theatres or hybrid rooms, and not in dedicated radiology rooms.

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5.

COM PUTE D TOMOGRAPHY

5.1 CONTRIBUTION OF DEPARTMENTS
For the 2019–2021 period, IRSN used the heavy equipment authorisation data available on the data.gouv.fr website to
update the estimate of the total number of CT devices used for diagnostic radiology. According to these data, their
number has continued to increase compared to the 2016–2018 period, from 1,184 devices in 2019 to 1,279 in 2021.
In addition, it should be noted that:-

insofar as CT examinations for simulation in radiotherapy do not fall within the scope of the DRLs, they are nottherefore dealt with in this assessment;
scanning acquisitions performed in positron emission tomography (PET) examinations are covered in the nuclear
medicine section.

Dose assessments were submitted for around 90% of units in 2019–2021. Participation even exceeded 90% in 2020 (seefigure 10 below). This increase of 5 points over 2020 is probably due to the changes made by ASN resolution 2019-DC0667. This resolution requires an annual assessment of the doses of at least two procedures for each CT device, whereas
previously this was the requirement for each institution; institutions with several CT scanners could therefore focus on
only a fraction of the devices. However, this increase did not continue into 2021.
In computed tomography, distribution of data sources is balanced between the public sector and the private sector (seefigure 11 below), except for the special case of paediatrics. This data source distribution is consistent with the
distribution of scanners between the public and private sectors, which had been estimated at around 47% and 53%
respectively in the previous report (27).
100%

91%
90%

83%

Percentage of units for which
dose assessment results have been submitted

78%

77%

80%

85%

85%

2017

2018

87%

86%

80%

70%

58%

60%

47%

50%

44%

43%

40%

30%

41%

25%

20%

14%
10%

0%

0.1%
2004

2%
2005

2006

2007

2008

2009 2010

2011

2012

2013

2014

2015

2016

2019

2020

2021

Figure 10: Change in annual participation of institutions performing computed tomography procedures since 2004.

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35

Public and private non-profit sector

Private sector

100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

Figure 11: Source of data collected for computed tomography DRLs, for 2019–2021, according to the type of examinationand sector of activity.

5.2 DISTRIBUTION OF DATA BY EXAMINATION TYPE
̅

Adult examinations

Figure 12 shows the distribution, by percentage, of dose assessments submitted by professionals per examination type,
together with the proportion of data that IRSN has been able to use.
The examinations with the greatest number of dose assessments are the brain, followed by the chest, and finally theabdomen-pelvis (AP) region. This moves the chest into second position, compared to third in the previous report. This
could be an effect of the Covid-19 crisis, which led institutions to take a closer look at chest examinations.
For the examinations introduced by ASN resolution 2019-DC-0667 (front sinus, abdomen-chest, heart (retrospective),heart (prospective)), little data were transmitted, in particular for the two examinations of the heart and the abdomenchest.
Brain
ThoraxAbdomen-pelvis
Lumbar spine
Chest-abdomen-pelvis
Front sinus
Paediatric examinations
Chest-abdomenHeart (retrospective)
Heart (prospective)

19.9%
18.9%
17.9%
14.0%
13.5%
8.7%
3.0%
2.4%
1.0%
0.9%

Dose assessments used
Dose assessments not used

Figure 12: Distribution by examination type of computed tomography dose assessments for which results were
submitted to IRSN from 2019 to 2021 (total number of assessments submitted: 6,697)

In total, around 88% of computed tomography data submitted to IRSN have been used for national analysis, which
represents an improvement compared to the previous report, for which this percentage was around 80%.
The brain examination remains the procedure with the lowest rejection rate (around 9%) because the BMI criterion does
not apply. The prospective heart and the chest-abdomen region are the examinations with the highest rejection rate(around 20% to 30%), which may be explained by the acquisition length validation criterion (see paragraph on data
analysis in chapter 2.4 of this report).

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Paediatric examinations

The number of paediatric CT assessments, although having increased compared to the previous report, is still very low
with, on the one hand, fewer than 3% of all data relating to CT examinations (see figure 12), compared to 2% in theprevious report, and only 7 to 37 dose assessments submitted to IRSN per examination type and weight category (seefigure 13), compared to 1 to 17 assessments in the previous report. As in the previous assessment, brain and chest
examinations are most frequently subject to dose assessments. Despite regulatory changes, the volume of data received
still does not allow a robust assessment of practices at national level.
37

Brain [0–10 kg]

35

Brain [10–20 kg]
Brain [20–30 kg]

26
24

Chest [10–20 kg]

21

Chest [20–30 kg]

16

Chest [0–10 kg]

11

Petrous bone [10–20 kg]

9Abdomen-pelvis [30–50 kg]
Abdomen-pelvis [10–20 kg]

8

Petrous bone [20–30 kg]

8

Abdomen-pelvis [20–30 kg]

7

Dose assessment results used
Dose assessment results not used

Figure 13: Distribution by examination type and weight of the number of child CT dose assessments for which results
were submitted to IRSN from 2019 to 2021 (total number of assessments submitted: 202).

5.3 SUMMARY OF COMPUTED TOMOGRAPHY RESULTS̅

Adult examinations

Tables 7 and 8 below show the results of analyses of adult computed tomography data collected between 2019 and
2021, by examination, in terms of CTDIvol and then DLP.
These tables show:

the number of assessments used for 2021 and the period 2019–2021 (N),

the median weight and BMI values for patients associated with the collected data,the DRLs and ADs currently in force,the 75th and 50th percentile values for the data collected in 2021,

the 75th to 25th percentile ratio for 2021,



the position of the 75th percentile for 2021 with regard to the DRL in force (% DRL),

the percentage of dose assessments data received in 2021 higher than the DRL in force (> DRL),

the 75th percentile variation in 2021 compared to the 2018 value published in the previous report.

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Table 7: Summary of adult computed tomography analyses, by examination, for 2021 data, in terms of volume computed
tomography dose index (CTDIvol). The last 4 examinations in the table are examinations newly introduced by ASN
resolution 2019-DC-0667, with the calculations made for the 2019–2021 period and not for 2021 alone.
(2019-2021)

Medianweight(kg)

MedianBMI(kg/m2)Brain

431 (1,245)

70.0

24.7

Chest

406 (1,176)

73.0

25.4

Chest-abdomen-pelvis

295 (775)

70.5

24.9

11

Abdomen-pelvis

389 (1,049)

71.0

25.0

13

11

9.5

8.2

1.35

-27%

1.0%

-6%

Lumbar spine

304 (834)

72.0

25.4

28

23

21.6

19.3

1.27

-23%

3.0%

-10%

Front sinus

(515)

70.0

24.7

14

-

6.9

5.5

1.56

-51%

1.0%

-

Chest-abdomen

(129)

71.0

24.8

11

9.5

8.6

7.4

1.33

-22%

3.1%

-

Heart (prospective)

(42)

74.8

25.0

26

18

16.2

10.5

2.43

-38%

4.8%

-

Heart (retrospective)

(59)

74.0

26.0

44

30

33.2

27.3

1.48

-25%

5.1%

-

Examination typeN
2021

CTDIvol (mGy)

P75/P25

% DRL

> DRL

Variation

AD

P75

P50

ratio

46

40

39.6

36.6

1.17

-14%

2.8%

-3%

9.5

7.5

6.6

5.5

1.52

-30%

2.5%

-11%

9.5

9.1

7.8

1.34

-18%

3.7%

-10%

DRL

Table 8: Summary of adult computed tomography analyses, by examination, for 2021 data, in terms of DLP. The last 4
examinations in the table are examinations newly introduced by ASN resolution 2019-DC-0667, with the calculations
made for the 2019–2021 period and not for 2021 alone.
(2019-2021)

Medianweight(kg)

MedianBMI(kg/m2)

DRL

AD

P75

P50

ratio

Brain

431 (1,245)

70.0

24.7

850

725

734

673

Chest

406 (1,176)

73.0

25.4

350

275

248

208

Chest-abdomen-pelvis

295 (775)

70.5

24.9

750

650

620

534

Abdomen-pelvis

389 (1,049)

71.0

25.0

625

525

475

408

1.38

-24%

2.1%

-3%

Lumbar spine

304 (834)

72.0

25.4

725

625

621

537

1.40

-14%

6.9%

-5%

Front sinus

(515)

70.0

24.7

250

-

101

81

1.56

-60%

0.4%

-

Chest-abdomen

(129)

71.0

24.8

550

475

415

359

1.37

-25%

2.3%

-

Heart (prospective)

(42)

74.8

25.5

375

325

259

171

2.28

-31%

7.1%

-

Heart (retrospective)

(59)

74.0

26.0

875

550

624

505

1.48

-29%

1.7%

-

Examination typeN
2021

DLP (mGy.cm)

P75/P25

Variation

% DRL

> DRL

1.19

-14%

3.5%

-1%

1.52

-29%

3.2%

-13%

1.33

-17%

3.7%

-10%

-

-

-

For the examinations of the brain, chest, abdomen-pelvis, chest-abdomen-pelvis and lumbar spine, there was a 1% to
13% decrease in CTDIvol and DLP compared to the previous report.
The 75th percentiles for 2021 in terms of CTDIvol and DLP are below the DRLs in force since 1 July 2019 by 14 to 60% for
all examinations considered. They are slightly lower than the AD for almost all examinations. Aside from theexaminations of the chest and abdomen-pelvis, the examinations introduced by the 2019 ASN resolution (frontal sinus,
chest-abdomen, prospective and retrospective heart) were mainly among those with the 75th percentiles the furthest
below the DRLs. The downward trend of DRL quantities for this region seems more marked than for the brain, forinstance. This downward trend could be explained by technological developments, and particularly the widespread use
and improvement of iterative image reconstruction algorithms, with this type of algorithm being more effective on theabdomen-pelvis region than on the brain. In addition, institutions performing very low-dose examinations for specificindications on certain anatomical regions have submitted data leading to extremely low minimum doses compared tothe previous report; this is the case in particular for the chest and lumbar spine, for example.
The quantity of data collected over the 2019–2021 period is satisfactory for the examinations of the brain, chest,
abdomen-pelvis, chest-abdomen-pelvis, and lumbar spine since, for each of them, several hundred assessments were
submitted. For the examinations introduced in the ASN resolution 2019-DC-0667 (frontal sinus, chest-abdomen,prospective and retrospective heart), only the frontal sinus examination accounts for more than 100 assessments. The
data for these new examinations were therefore aggregated over 3 years in order to be able to make an analysis.
The results for each type of examination over the 2019–2021 period are detailed in the Annex to this report. The figures
representing the change in the CTDIvol and DLP since 2011 show a continuous decrease of the 75th percentiles regardlessof the type of examination.
As stated in the previous report, the DRL values of ASN resolution 2019-DC-0667 were established on the basis of data
dating from 2015, and the drop in the decrease in the values of DRL quantities observed over the period 2016–2018(12% compared to the period 2013–2015) is confirmed in this report (8% drop compared to the period 2016–2018(excluding new examinations)). Overall, the results over the period were 28% below the DRLs. It therefore seems
necessary to revise the values of computed tomography DRLs.

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Furthermore, as illustrated in the previous report, defining DRLs by anatomical region leads to combining data that isvery heterogeneous because they present significantly varying clinical objectives. A change in the definition of DRLs in
computed tomography to DRLs by clinical indication must be considered.
To this end, device diagnostic performance assessment should be taken into account in the DRL framework in order tobe able to ensure that the examination quality requirements associated with delivered doses are complied with.
However, as outlined in the conclusions of the European EUCLID project (28), the assessment of image quality for thedetermination of DRLs based on a clinical indication is not a trivial task. International studies are needed to establish
guidelines on image quality criteria relevant for the assessment of DRLs based on a clinical indication.

̅Paediatric examinations

Table 9 below shows the results of analyses of data submitted in terms of CTDIvol and DLP for the paediatric computed
tomography examinations. The table shows the number of assessments used (N) over the 2019–2021 period, themedian, minimum and maximum weights of patients concerned by the data collected, the value of the 75th percentile,
the value of the 50th percentile, the 75th and 25th percentile ratio, and the percentage of dose assessments received overthe period above the DRL in force (> DRL) and, for examinations for which sufficient data have been collected, theposition of the 75th percentile over the period with regard to the DRL in force (% DRL).
As in the previous report, apart from the brain (all categories) and the chest (all categories), the number of assessments
is too low (<10) for the results to be discussed. However, there was an increase in the number of assessments received
for these examinations, which was in the order of 4 to 12 in the 2016–2018 report and which is 12 to 30 for the 2019–2021 report.
Only brain examinations for all categories contain sufficient data – over 20 assessments – and can be analysed in detail(see Annex).
Regarding the brain and chest, regardless of the weight category, the results in terms of CTDIvol are slightly lower thanthe DRLs of ASN resolution 2019-DC-0667, in the order of 0 to 12% according to the categories. As far as DLPs areconcerned, this is not the case for all these examinations.
Consequently, it does not appear necessary to propose a possible adjustment of the DRLs in the short term. However,
the weight categories defined for children in ASN resolution 2019-DC-0667 do not correspond to the weight categories
defined at European level. A revision of this information would make it possible to draw comparisons with the results ofother European countries (17).

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Table 9: Summary of paediatric computed tomography analyses, by examination, in terms of volume computed
tomography dose index (CTDIvol) and dose length product (DLP).
Examination type

Brain

Weightcategory(kg)

N

Medianweight(kg)

0 to <10

CTDIvol (mGy)
DRL

P75

30

6.2

20.0

10 to <20

27

13.0

20 to <30

20

10 to <20

DLP (mGy.cm)

P50

P75/P25
ratio

% DRL

> DRL

DRL

P75

P50

P75/P25
ratio

% DRL

> DRL

18.8

16.0

1.44

-6%

7%

320

297

259

1.49

-7%

10%

22.0

21.9

20.8

1.27

0%

26%

360

399

364

1.19

11%

52%

23.5

26.0

25.0

21.6

1.22

-4%

20%

470

450

415

1.18

-4%

20%

9

16.0

43.0

46.3

34.72

1.49

-

33%

240

242

210

1.35

-

33%

20 to <30

7

24.0

51.0

43.0

38.4

1.18

-

14%

330

245

229

1.49

-

0%

0 to <10

12

6.7

1.1

0.97

0.82

1.33

-12%

8%

20

17.7

14.3

1.45

-12%

17%

10 to <20

17

15.0

1.3

1.20

1.00

1.62

-8%

18%

26

30.7

22.5

2.01

18%

35%

20 to <30

16

23.3

1.4

1.39

1.05

1.88

-1%

19%

40

40.8

28.8

2.10

2%

25%

10 to <20

4

13.3

2.0

1.39

1.25

1.24

-

0%

65

43

39

1.15

-

0%

20 to <30

3

23.0

2.5

2.36

2.02

1.35

-

33%

95

89

77

1.34

-

33%

30 to <50

6

39.3

4.0

3.91

3.51

1.22

-

17%

180

159

152

1.06

-

17%

Petrous bone

Chest

Abdomen-pelvis

FOCUS – COMPUTED TOMOGRAPHY
RADIATION PROTECTION OF CHILDREN EXPOSED TO CT SCANS
For several years, IRSN, along with the European scientific community, has been interested in paediatric radiation
protection because children are particularly sensitive to the effects of ionising radiation compared to adults.
IRSN periodically analyses the exposure of the French population to ionising radiation due to diagnostic medical
imaging examinations, in line with the missions entrusted to it under the Public Health Code. In addition to thestudy concerning the medical exposure of the general population during 2017 (16), IRSN conducted a specificstudy concerning computed tomography procedures in children under 16 years of age based on a representative
sample of health insurance beneficiaries in France between 2012 and 2018 (29). Over this period, the number ofCT procedures is constant, with an average of 14 scans per year per 1,000 children. However, a variation in thenumber of procedures per year per 1,000 children is observed depending on age: approximately 15 scans for
those under 1 year of age; fewer than 10 between 1 and 9 years of age; then increasing to over 35 scans at
15 years of age. Finally, this study shows that children exposed to computed tomography had, for the vast
majority, only one examination per year, and depending on the year, 11–16% of them had several.
Since CT and MRI (magnetic resonance imaging) have a large number of common indications and therecommendations of healthcare professionals are consistent with the transfer of certain CT procedures to MRI,a study of the evolution of MRI procedures was also carried out. This study shows that, unlike computed
tomography, the annual frequency of MRI procedures increased significantly (+59%) over the study period.
Furthermore, IRSN also conducted an epidemiological study aimed at assessing the risk of radiation-induced
cancer following exposure to a scan in childhood. Launched in 2009, the “Enfant Scanner” (“Child Scan”) cohort
involved approximately 100,000 children exposed to a first CT scan before the age of 10, between 2000 and 2010.
An initial analysis of approximately 65,000 children revealed low excess risk of brain tumours and leukaemia. The
inclusion of additional children and the extension of cohort follow-up until 2016 confirmed the previously
observed excess risks. These results were published in 2022 (30; 31).
In addition, at European level, a study was also conducted by the International Agency for Research on Cancer(WHO-IARC). This European project, called “EPI-CT”, was launched to quantify the excess risk of cancer associatedwith exposure to ionising radiation due to the performance of one or more scans in children and young adults.
The study incorporated a cohort of 1 million children and young adults who received at least one CT scan in 276
radiology departments in Belgium, Denmark, France, Germany, the Netherlands, Norway, Spain, Sweden andGreat Britain between 1977 and 2014. This study shows an excess risk of developing brain cancer after CT scansof the head in children and young adults; this risk increases as the cumulative dose increases (32). For 10,000
children that received a single CT scan of the head (estimated dose of 38 mGy on average), 1 brain cancer

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attributable to exposure to ionising radiation is expected to be observed in the 5–15 year period following theexamination8.
As illustrated in this report, it should be noted that, with regard to the brain and the chest, the results in termsof CTDIvol in children are slightly lower than the DRLs of ASN resolution 2019-DC-0667, by up to 12%. Furthermore,according to data from previous IRSN reports, a downward trend has been observed since 2011 in the dosesdelivered by scanners for paediatric examinations of the brain, abdomen-pelvis, and chest (see figure 14 below).
However, this reduction should be considered with caution because of the small quantity of data collected during
these periods.

Examination

500

Brain (10 kg)

Average dose-length product (mGy.cm)

Abdomen-pelvis (20 kg)
Chest (20 kg)

400

300

200

100

2011-122013-152016-18

PeriodFigure 14: Development of dose values in computed tomography (dose length product) in children, for 3
anatomical regions (brain 10 kg, abdomen-pelvis 20 kg, and chest 20 kg) monitored as part of the DRL system
However, it can be emphasised that, owing to the period of performance of the CT examinations (prior to 2014)
considered in the aforementioned “Enfant Scanner” (“Child Scan”) and “EPI-CT” studies, the dose levels taken
into account in these studies are higher than the dose levels delivered on average today for the same
examination.
Be that as it may, these studies reinforce the importance of radiation protection rules for this particularly
radiation-sensitive paediatric population, based on the principles of justification and optimisation of CT scans, as
recapitulated in the WHO guide recently translated into French (33).
Finally, it should be recalled that in its 2018 report relating to the “fleet of scanners and recommendations
relating to radiation protection in medical imaging” (34), IRSN found, in the field of paediatrics, an inconsistency
in the system of reimbursement of imaging procedures that could favour radiological examinations to thedetriment of examinations not using ionising radiation, such as MRI and ultrasound. Indeed, the CCAM provides
for the application of “modifiers”, which make it possible to evaluate certain specific circumstances for the
performance of procedures. For paediatrics, there are modifiers, particularly in computed tomography, forchildren under the age of 5, which make it possible to evaluate the specific circumstances for the performance ofthe procedure. There are none for non-irradiating examinations such as ultrasound and MRI in paediatrics, while
there is also the problem of the time required, particularly for sedation, for these techniques.

8

https://www.irsn.fr/FR/Actualites_presse/Actualites/Pages/20221206_EPI-CT.aspx#.Y9jjV3CZPIUANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDICINE – IRSN

41

SUMMARY – COMPUTED TOMOGRAPHY
Analysis of computed tomography dose assessments shows:

a computed tomography institution participation rate that has risen to around 90%;
for adults:o a distribution of examinations selected by professionals for dose assessments with chest examinations
to the fore (2nd location in quantity of data submitted after the brain), probably due to the Covid-19
crisis;o a fairly small quantity of data submitted for the examinations introduced in 2019 by the latest revisionof the ASN resolution on DRLs;
o for all the examinations considered, the 75th percentiles for 2021 in terms of CTDIvol and DLP below
the DRLs by 14% to 60%, and slightly below the ADs;o an overall decrease of 8% in computed tomography dose indicators compared to 2016–2018, which
confirms the previously observed decrease of 12% compared to 2013–2015;
in paediatrics:
o a significant increase in the number of assessments received, but the low volume of data still does notallow a robust assessment of practices at national level;o for the brain and chest, slightly lower CTDIvol results than the DRLs, which is not the case for all
categories in terms of DLP.



RECOMMENDATIONS – COMPUTED TOMOGRAPHY
Analysis of computed tomography dose assessments for 2019–2021 leads IRSN to make the following
recommendations:




42

plan, as a priority, for computed tomography DRL updates to take into account clinical indications;provide, for examinations for which a DRL per clinical indication would not be defined, a revision to DRL
values in adults;
in paediatrics:
o study the relevance of revising weight categories in order to align with European
recommendations and thus allow comparisons to be made;o continue to encourage healthcare professionals to submit data, by reminding them that it ispossible to collect data over a period of more than one year.

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINENUCLEAR MEDECINE
6.

NUCLEAR MEDE CINE

6.1 CONTRIBUTION OF DEPARTMENTS
Nuclear medicine departments were surveyed based on information published by ASN. There were 231 nuclear
medicine departments listed at the end of 2015; 236 at the end of 2017 (35); and 239 in 2021 (36).
Figure 15 below presents the change in the number of nuclear medicine departments that submitted dose assessment
results for the years 2004 to 2021.
Participation has stabilised since 2014, with around 90% of departments having submitted data.
In nuclear medicine, as in the previous report, the distribution of data sources is balanced between the public sector
and the private sector (see figure 16 below), except for the special case of paediatrics and brain perfusion. This data
source distribution is consistent with the distribution of facilities between the public and private sector (35). For
paediatrics and brain perfusion, data comes primarily from the public sector, which could be explained by the specificnature of this type of examination and a low data submission rate.
100%

91%
90%

85%

87%

87%

2015

2016

91%

92%

2017

2018

94%

91%

88%

81%

Percentage of institutions
submitting dose assessment results

80%

69%

70%

62%
60%

61%

59%

51%
50%

45%
38%

40%

30%

20%

10%

7%

0%

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2019 2020

2021

Figure 15: Change in annual participation of institutions performing nuclear medicine procedures since 2004.

ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDICINE – IRSN

43

Public and private non-profit sector

Private sector

100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

Figure 16: Source of data collected for computed DRLs, for 2019–2021, by examination type, in nuclear medicine.

6.2 DATA DISTRIBUTION BY EXAMINATION TYPE
̅

Adult examinations

Figure 17 below shows the distribution of dose assessments submitted by nuclear medicine professionals to IRSN by
examination type, in line with the list defined by ASN resolution 2019-DC-0667, together with the proportion of datathat IRSN has been able to use.
Paediatrics is shown for all examinations in order to present the volume of paediatric data by comparison with all datasubmitted for nuclear medicine. It is detailed in the next section.
The number of dose assessments for PET examinations is now ahead of the number for bone scanning, which regularly
accounted for the largest number of dose assessments since 2004. This is due to the fact that data are now received forthe computed tomography part of the PET examinations, which increases the overall volume of data relating to these
examinations (nuclear medicine part alone, computed tomography part alone, or both).
The number of assessments for 18F-FDG PET and the paediatric examinations has thus increased by 4 points since theprevious report in relation to the regulatory changes made by the 2019 ASN resolution.
Depending on the examination, the data use rate for the 2019–2021 period varies between 56% and 86%. The unused
data submitted are almost exclusively redundant data (identical examination type and unit type). For statistical reasonsand in order to avoid over-representation of some institutions, only the most recent dose assessment was taken into
account for calculating the national indicators. This is particularly the case for 18F-FDG PET, the examination for which
the most data is received. Moreover, for the PET scan, some machines are managed by legal entities dedicated to thisactivity who submit data for this examination every year. Repeating assessments for the same examination over a 3year period can still be useful for centres for monitoring doses delivered.
Dynamic renal scanning includes scans with DTPA and MAG3. However, renal scans with DTPA only represent 8% of thedata received for this examination category, i.e., less than 1% of all data received for all nuclear medicine examinations
combined. This low quantity of data received is undoubtedly linked to supply difficulties for this pharmaceutical productand the low number of examinations carried out. Furthermore, this examination represents little interest in dosimetricterms, so its removal could be considered from the list of examinations concerned by the DRLs. Similarly, the brain
perfusion SPECT with ECD and HMPAO examinations were those that had the lowest number of dose assessments
submitted. This is because brain examinations are increasingly performed using PET. Removal of this examination could
also therefore be considered from the list concerned by the DRLs.

44

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINETumour FDG PET

21.0%

Bone scan

19.9%

Myocardial perfusion SPECT 99m-Tc

13.1%

Lung perfusion scan

11.8%

Thyroid scan 99m-Tc

8.8%

Dynamic renal scan

6.8%

Paediatric examinations

6.8%

Radionuclide ventriculography (LVEF)

5.8%

Thyroid scan 123-I

3.3%

Myocardial perfusion SPECT 201-TI

1.8%

Brain perfusion SPECT

Dose assessment results used
Dose assessment results not used

1.1%

Figure 17: Distribution by examination type of nuclear medicine dose assessments for which results were submitted to
IRSN from 2019 to 2021 (total number of assessments submitted: 1,642).

̅Paediatric examinations

The volume of assessments submitted for paediatric nuclear medicine remains very low, accounting for less than 6% of
all data received. This number has, nonetheless, increased by 4 points compared to the previous report.
ASN resolution 2019-DC-0667 now makes it compulsory to carry out dose assessments when 5% of the procedures
carried out on a medical device concern children (under 18 years of age). These new provisions have generated anincrease in the quantity of data transmitted, but this remains insufficient for obtaining a robust analysis. The details of
the data transmitted are shown in figure 18 below.
Dynamic renal scan [5–15 kg]
Renal cortical scan [5–15 kg]
Bone scan [5–15 kg]
Bone scan [25–35 kg]
Bone scan [15–25 kg]
Renal cortical scan [15–25 kg]
Bone scan [35–45 kg]
Tumour FDG PET [45–55 kg]
Bone scan [45–55 kg]
Tumour FDG PET [35-45 kg]
Renal cortical scan [25–35 kg]
Tumour FDG PET [15–25 kg]
Dynamic renal scan [15–25 kg]
Tumour FDG PET [25–35 kg]
Tumour FDG PET [5–15 kg]
Renal cortical scan [35–45 kg]
Dynamic renal scan [25–35 kg]

16
16
12
11
9
9
7
5
4
4
4
4
4
3
1
1
1

Dose assessment results used
Dose assessment results not used

Figure 18: Distribution by examination of the number of child nuclear medicine dose assessments for which results
were submitted to IRSN from 2019 to 2021 (total number of assessments submitted: 111).

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45

6.3 SUMMARY OF NUCLEAR MEDICINE RESULTS̅

Adult examinations

Tables 10 and 11 below present the summary of analysis of data submitted for all nuclear medicine examinations subject
to DRL regulations (except the CT part of PET examinations). Tables 12 and 13 present the results of the analyses of thedata collected between 2019 and 2021 for the CT part of the PET examinations introduced by the 2019 ASN resolution
in terms of CTDIvol and DLP, respectively.
These tables show, for the 2019–2021 period:
 the number of assessments used, the median weight for patients associated with the collected data, the DRLs in force, the 50th percentile values for the data collected [and the 75th percentile values for the CT part of a PET-CT with FDG
procedure],
 the 75th to 25th percentile ratio,
 the position of the 50th percentile [or 75th percentile for the CT part of a PET-CT with FDG procedure] with regard to
the DRL in force (% DRL), the percentage of dose assessments received for the period above the DRL in force (> DRL), and the 50th percentile variation for the period with regard to the 2018 value published in the previous report.
The results for each examination type for 2019-2021 are detailed in the report Annex.
It should be noted that, for dynamic renal scans with DTPA and brain perfusion SPECT scans with ECD and HMPAO, theposition of the median with regard to the DRL in force cannot be used in this report because there are insufficient data.
For all other examinations, the analysis shows, over the 2019–2021 period, that the median values of the administeredactivities are 1 to 22% lower than the DRL in force. The same applies to the medians of the administered activities per
body weight, which are 1 to 26% lower than the DRL in force. The largest deviations were noted for FDG-PET, withadministered activities and administered activities per body weight being 22% and 26% lower than the DRLs in force.
The overall decrease in the values of the dose indicators observed over the period 2016–2018 (3% compared to theperiod 2013–2015) is confirmed in this report (4% compared to the period 2016–2018).
With regard to the CT part of the PET scans introduced by the 2019 ASN resolution, the results are also less than the
DRLs in terms of DLP and CTDIvol, whether for scans to mid-thigh or to the feet. The largest deviations are recorded forhead-to-foot scanning, in the order of 30%.

46

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINE

Table 10: Summary of results of analysis of nuclear medicine data by adult examination type, for 2019-2021 data, interms of administered activity.
20192021

Medianweight(kg)

Bone

99mTc HDP/DPD

219

Lung perfusion scan

99mTc MAA

153

Examination type

Thyroid scanRadiopharmaceutical / protocol

Dynamic renal scan

Brain perfusion SPECT
Tumour FDG PET

Administered activity(MBq)

P75/P25
ratio

% DRL

> DRL

Variation

DRL

P50

72.0

670

662

1.13

-1%

40%

+0%

72.5

225

194

1.49

-14%

35%

-7%

123 I (sodium iodide)

47

70.0

8

7.5

1.25

-6%

36%

-4%

99mTc (sodium pertechnetate)

112

69.8

110

108

1.44

-2%

46%

+18%

1 day/1st inj.

136

77.5

285

267

1.22

-6%

29%

-4%

1 day/2nd inj.

136

77.5

785

760

1.23

-3%

38%

-1%

2 days/1st inj.

26

79.3

615

550

1.45

-11%

23%

-12%

Myocardial perfusion 99mTc
SPECT with stress test MIBI/tetrofosmin
and/orpharmacologicalstimulation
201 Tl(thallium chloride)
Equilibrium
radionuclide
ventriculographyN

2 days/2nd inj.

26

79.3

615

535

1.50

-13%

19%

-10%

1st injection

20

75.5

110

101

1.44

-8%

20%

-5%

Reinjection

18

75.5

37

35

1.66

-5%

33%

-5%

76

70.5

740

733

1.08

-1%

36%

-1%

99mTc MAG3

87

69.0

180

177

1.63

-2%

43%

-2%

99mTc DTPA

9

68.0

255

168

1.41

-

11%

-32%

99mTc human serum albumin/red

blood cells

99mTc ECD

2

71.0

800

727

1.03

-

0%

+2%

99mTc HMPAO

12

70.0

695

656

1.24

-

42%

-1%

18F FDG

193

70.0

245

191

1.35

-22%

8%

-10%

Table 11: Summary of results of analysis of nuclear medicine data by adult examination type, for 2019-2021 data, interms of administered activity per body weight.
Examination typeBone

Medianweight(kg)

Activity per BW(MBq/kg)
DRL

P50

219

72.0

9.5

1 day/1st inj.

136

77.5

3.7

1 day/2nd inj.

136

77.5

10.3

9.7

1.21

-6%

33%

-3%

2 days/1st inj.

26

79.3

7.7

7.0

1.52

-9%

27%

-5%

2 days/2nd inj.

26

79.3

7.7

7.0

1.48

-9%

15%

-7%

99mTc HDP/DPD

Myocardial perfusion 99mTc
SPECT with stress test MIBI/tetrofosmin
and/orpharmacologicalstimulation
201 Tl(thallium chloride)
Tumour FDG PET

2019202
1

Radiopharmaceutical / protocol

N

P75/P25
ratio

% DRL

> DRL

Variation

9.2

1.12

-4%

29%

-1%

3.5

1.23

-6%

29%

-4%

1st injection

20

75.5

1.4

1.38

1.45

-1%

40%

+2%

Reinjection

18

75.5

0.5

0.48

1.58

-5%

17%

-1%

193

70.0

3.5

2.6

1.24

-26%

6%

-14%

18F FDG

Table 12: Summary of analyses performed on the CT part of a full body PET-CT scan with FDG for scans to mid-thigh andfoot in adults, for 2019–2021 data, in terms of volume computed tomography dose index (CTDIvol).
Examination type

CTDIvol (mGy)N

P75/P25

% DRL

> DRL

1.36

-21%

4%

1.41

-33%

0%

2019-2021

DRL

AD

P75

P50

ratio

PET-CT with FDG
head to mid-thigh

100

7

5

5.5

4.7

PET-CT with FDG
head to foot

32

7

5

4.7

4.1

ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDICINE – IRSN

47

Table 13: Summary of analyses performed on the CT part of a full body PET-CT scan with FDG for scans to mid-thigh andfoot in adults, for 2019–2021 data, in terms of dose length product (DLP).
Examination typePET-CT with FDG
head to mid-thighPET-CT with FDG
head to foot̅

DLP (mGy.cm)

N

P75/P25

% DRL

> DRL

1.39

-13%

10%

1.49

-32%

0%

2019-2021

DRL

AD

P75

P50

ratio

100

650

500

566.4

493.1

32

1200

900

817.4

726.5

Paediatric examinations

The results are presented in table 14 below.
There were dose assessments for seventeen examination types (taking into account weight categories). Only four ofthem represent 10 or more assessments submitted, thereby allowing the results of the statistical analyses to be
discussed: renal cortical scans with 99mTc-MAG3 (5 to <15 kg), dynamic renal scans with 99mTc-MAG3 (5 to <15 kg), andbone scans with 99mTc-HDP/99mTc- DPD (5 to <15 kg and 25 to <35 kg).
For these four examinations, the analysis shows, over the period 2019–2021, differences between the median values of
the administered activities compared to the DRL in force of between -17% and +20%.
Although, over the 2019–2021 period, more examinations led to assessments than in previous periods, the quantity ofdata received is still too low to have a clear vision of practices and to update the DRLs in force, despite regulatory
developments concerning paediatrics.
Table 14: Summary of results of analysis of paediatric nuclear medicine data, by examination type.
Examination type

Dynamic renal scan

Renal cortical scan

Bone

Tumour FDG PET

48

Weight category (kg)NMedianweight (kg)

Administered activity
(MBq)
DRL

P50

P75/P25
ratio

%DRL

>DRL

-17%

15%

[5–15]

13

9.0

25

20.7

1.29

[15–25]

4

18.0

35

33.1

1.11

-

0%

[25–35]

1

29.0

45

40.9

-

-

0%

[35–45]

0

-

50

-

-

-

-

[5–15]

13

10.0

20

23.9

1.57

20%

69%

[15–25]

8

19.8

35

39.3

1.64

-

50%

[25–35]

4

27.8

50

41.7

1.20

-

25%

[35–45]

1

40.0

60

67.7

-

-

100%

[5–15]

10

11.3

95

103.6

1.09

9%

90%

[15–25]

8

18.3

170

153.1

1.08

-

13%

[25–35]

10

30.0

240

237.6

1.05

-1%

30%

[35–45]

6

39.3

310

298.9

1.05

-

0%

[45–55]

4

50.5

375

404.8

1.27

-

50%

[5–15]

1

12.9

40

68.7

-

-

100%

[15–25]

3

20.0

70

70.2

1.07

-

67%

[25–35]

3

29.5

100

100.8

1.17

-

67%

[35–45]

3

40.5

125

124.5

1.20

-

33%

[45–55]

4

50.0

150

140.4

1.26

-

50%

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINEFOCUS - NUCLEAR MEDICINELUNG SCANS: 2022 SURVEY AND RECOMMENDATIONS
A lung scan is an examination that may include two phases: a ventilation scan using either technetium aerosols
or krypton 81m and the lung perfusion scan. This examination may include either or both of these two phases.
When technetium aerosols are used, the ventilation scan usually precedes the perfusion scan. The activity of99m
Tc (macroaggregated albumin – MAA) administered for the perfusion scan needs, in this case, to besignificantly high as to mask the ventilation signal (1:4 ratio between administered activities for ventilation andperfusion, according to SFMN recommendations (37)). This is not the case when the ventilation examination takes
place in advance, or when it is performed using krypton 81m (the difference in energy of the gamma rays also
allows simultaneous acquisition for ventilation and perfusion).
To date, only one DRL has been defined for lung perfusions scans at 225 MBq. The data received by IRSN
aggregates examinations carried out with or without ventilation with 99mTc. The DRL thus determined isundoubtedly too high for procedures without ventilation or with ventilation using krypton 81m and is probably
underestimated for procedures including ventilation with technetium 99m.
In the report published in 2020 for the period 2016–2018 (27), IRSN had recommended carrying out a specificstudy to distinguish between examinations performed with or without 99mTc ventilation in order to be able topropose a more relevant definition of the DRL currently in force. This study was conducted in summer 2022 by
IRSN with the help of the relevant learned societies (AFTMN, SFMN, SFPM and SoFRA).
Collected data
The aim was to collect retrospectively or prospectively, from voluntary departments, series of MAA activities
administered to adult patients (at least 30), distinguishing between the three procedures: perfusion after
ventilation with technetium (Technegas, etc.), perfusion with ventilation with krypton, and perfusion alone.
Since the administered activities in lung scans are not dependent on the morphology of the patients, only theactivity values (in MBq) were requested. Examinations involving patients who are minors (under 18 years of age),pregnant patients, and pulmonary shunt tests were excluded from the study.
There was a high degree of participation from nuclear medicine professionals: 94 institutions sent data, including
60% public or similar institutions (cancer centres included) (see figure 19 below). 72 institutions use technetium
aerosols; 30 institutions use krypton; and one institution only performs examinations without ventilation. Someinstitutions use both krypton and technetium aerosols.
Cancer centres
7%

Private sector
39%

Public sector
54%

Figure 19: Breakdown of the types of institutions that responded to the survey

ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDICINE – IRSN49

In order to have enough data for the survey, IRSN called in particular upon institutions using krypton, and thevast majority of these are public institutions (93%). This explains the slight over-representation of public
institutions in this survey.
Results
Data analysis was performed to compare the MAA activities administered according to the type of procedure(see figure 20 below).
An analysis was also carried out, specifically for examinations without ventilation, in institutions also performing
certain tests with ventilation, by separating out the users of krypton or technetium aerosols (see figure 21
below). The institutions using both Kr and Tc aerosols have been considered as users of Kr because in this casethey use Kr more than Tc and for many of them Tc is only used as a “back-up”. The greater dispersion of resultsfor examinations without ventilation than for examinations with ventilation required more extensive analysis
for this category.
600

Injected MAA activity (MBq)

500
400
300
200
100
0

Ventilation with Tc Ventilation with Kr Perfusion only
(N = 30)(N = 72)(N = 28)
Type of procedure performed

Figure 20: Distribution of administered median activities by type of procedure performed: ventilation with Tc,
ventilation with Kr, or with no ventilation.

Injected MAA activity (MBq)

600
500
400
300
200
100
0

Perfusion only
Kr users)(N = 12)

Perfusion only
(Tc users)(N = 15)Type of procedure performed

Figure 21: Distribution of administered median activities by type of procedure performed for examinations
without ventilation for the usual users of Kr, and without ventilation for the usual users of Tc aerosols (institutions
using both Kr and Tc aerosols were considered users of Kr)

50

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINE

Table 15: Summary of results of analysis of the distribution of administered median activities by type of procedure
performed for examinations with ventilation with Tc, ventilation with Kr, or without ventilation, without
ventilation for the usual users of Kr, and without ventilation for the usual users of Tc aerosols (institutions using
both Kr and Tc aerosols were considered as users of Kr)
Examinations
Examinations
Examinations without
without ventilation
without ventilation ventilation for Kr users
for Tc Users

Examinations withventilation with Tc

Examinations withventilation with Kr

Number of institutions

72

30

28

12

15

Number of patients

4556

2294

924

358

526

228.1

150.7

153.5

151.5

185.6

Indicator

50
percentile
administeredactivities (MBq)thof

The analysis of the data collected, presented in figure 20 above, shows that the 50th percentiles of theadministered activities per institution, for examinations with ventilation with krypton or without ventilation, arevery close to each other (2% difference) and in the region of 155 MBq, and much lower than the DRL in force (225
MBq). The median of the activities for examinations with ventilation with technetium is the region of 230 MBq,
therefore slightly higher than the DRL in force, and higher than the 50th percentile of the data collected in 2019–2021 (194 MBq), for which the different types of procedures are not separated (see table 15 above).
These results therefore confirm the anticipated difference in terms of MAA administered activity between
examinations with ventilation with technetium on the one hand, and examinations with ventilation with krypton
or without ventilation on the other.
Separate analysis of the data from examinations without ventilation between the usual users of krypton and theusers of technetium aerosols, shown in figure 21 above, shows that the latter inject, overall, higher activities(median of 186 MBq versus 152 MBq). Therefore, there seems to be room for optimisation for some of the usersof technetium aerosols, who are accustomed to using higher MAA activities when performing examinations
without ventilation.
Recommendations for updating the DRL in relation to lung scans
Based on the results of the survey, IRSN therefore recommends replacing the DRL in force with two new DRL
values:-230 MBq for examinations with ventilation with 99m technetium,
155 MBq for examinations with ventilation with 81m krypton or without ventilation.

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51

SUMMARY – NUCLEAR MEDICINE
Analysis of dose assessments in nuclear medicine shows:
•
•
•
•
•
•

stabilised participation of departments since 2014, at around 90%
a very low quantity of data for certain examinations (dynamic renal scans with DTPA and brain perfusion SPECT
with ECD and HMPAO);
median values of the administered activities less than the DRL in force in adults by 1 to 22%;an overall decrease of 4% in nuclear medicine dose indicators compared to 2016–2018, which confirms thepreviously observed decrease of 3% compared to 2013–2015;
for CT acquisitions of PET examinations, results lower than the DRLs in terms of CTDIvol and DLP;
too little data in paediatrics.

RECOMMENDATIONS – NUCLEAR MEDICINEFor nuclear medicine, IRSN makes the following recommendations:
•

•

•

52

revise, based on the study conducted by IRSN, the DRL relating to lung perfusion scans by replacing the DRL
in force with two new DRL values:- 230 MBq for examinations with ventilation with 99m technetium,- 155 MBq for examinations with ventilation with 81m krypton or without ventilation;in paediatrics:- study the relevance of revising the weight categories in order to align with European
recommendations and thus allow comparisons to be made,- continue to encourage healthcare professionals to submit data by reminding them that it is possible
to collect data over a period of more than one year;
based on stakeholder consultation:- consider removing DRLs for examinations that have become too infrequent, as illustrated by the
results of this report:orenal scans with DTPA,obrain scans with ECD and HMPAO;- define a single DRL in terms of activity per body weight (MBq/kg) for the examinations that lendthemselves to it, rather than a combination of activity and activity per body weight as is currently
the case,- reflect on the implementation of DRLs for new examinations, particularly in PET, such as:obrain PET with 18F-FDG,o
PET with 18F-Choline,o
PET with 18F-DOPA (brain, full body),o
PET with gallium 68 (somatostatin receptors, PSMA);- while prioritising the investigations to be carried out according to the frequency of implementation;- in a second phase, consider the implementation of DRLs for new scanner examinations, such as, forexample:odual-isotope (iodine-123 and 99mTc-MIBI) scans of the parathyroid glands,obrain scans with DaTSCAN;- consider the implementation of DRLs for CT acquisitions of the trunk and the full body associatedwith bone scans.

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINEDRLs: SUMMARY, RECOMMENDATIONSAND PERSPECTIVES
7.

DRLs: SUMMARY, RECOMME NDAT IONS AND PERSPECT IVES

7.1 SUMMARY:
From the analysis of the data collected from 2019 to 2021, IRSN highlights the following salient points:









participation of structures still limited in conventional radiology to around 50%, and stabilised around 90% incomputed tomography and nuclear medicine;strong mobilisation of healthcare professionals in the implementation of the new DRLs in interventional
radiology;
an increase in the quantity of data submitted in paediatrics but still insufficient to enable a robust analysis ofpractices in this field;
DRL quantities below the DRLs in force in all adults examinations fields. The 75th percentile values (50thpercentile for nuclear medicine) for 2021 are below the DRLs in force by:o 20% to 30% in conventional radiology,
o 30% to 54% in interventional radiology,
o 14% to 60% in computed tomography,o 1 to 22% in nuclear medicine,an overall drop in DRL quantities compared to 2016–2018 of:o 19% in conventional radiology,
o 8% in computed tomography,
o 4% in nuclear medicine,heterogeneities in the results that may illustrate a diversity of practices and/or indications, on the one hand inconventional paediatric radiology for UGI and retrograde cystography examinations, and on the other in adultinterventional radiology for vertebroplasty.

7.2 RECOMMENDATIONS AND PERSPECTIVES
Based on the analysis of the dose assessments sent to IRSN during the 2019–2021 period, the results of additional
analyses carried out by IRSN in collaboration with healthcare professionals, and consultation with these professionals,
as well as expert opinions produced at the request of ASN, IRSN makes the following recommendations:







in paediatrics, in all areas:o continue efforts to submit data, reminding practitioners that it is possible to collect data over a periodof more than one year,
o study the relevance of revising weight categories in order to align with European recommendations
and thus allow comparisons to be made;revise DRL values in all areas, prioritising computed tomography;
monitor the evolution of the results of certain procedures and, if necessary, ultimately review the definitionof these DRLs based on feedback since 2019, in particular:o UGI and retrograde cystography in conventional paediatric radiology;o vertebroplasty in adult interventional radiology;change the definition of certain DRLs and the data collected:
o in interventional radiology:
 add the air KERMA at the reference point as an extra DRL quantity in addition to the DAP and
the radioscopy time; consider increasing the quantity of patient data to be requested for each assessment
submitted. To do this, it will be necessary to study the relevance of a mass data transmission
from DACS without patient weights and sizes, with the aim of obtaining average data more
representative of clinical practice;o in nuclear medicine: revise the DRL relative to lung perfusions scans by replacing the DRL in force with two new
DRL values: 230 MBq for examinations with ventilation with 99m technetium and 155 MBq
for examinations with ventilation with 81m krypton or without ventilation;
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53







define a single DRL in terms of activity per body weight (MBq/kg) for the examinations that
lend themselves to it.
o in computed tomography: upgrade DRLs to take clinical indications into account;define new DRLs, in particular:
o in conventional radiology:
 in mammography, define a DRL in digital mammography based on clinical doses and no longer
on the doses measured during quality control, and introduce a DRL in breast tomosynthesis
taking into account the notice published by IRSN in December 2021 (16); in dental CBCT, introduce a DRL for certain indications taking into account the notice
published by IRSN in January 2023 (17);o in interventional radiology: consider, in consultation with healthcare professionals, creating a DRL for
two rhythmology procedures considered to be the most irradiating procedures, and interventional
cardiology procedures performed in operating theatres or hybrid rooms, and not in dedicatedradiology rooms;
o in nuclear medicine: consider, in consultation with healthcare professionals, the implementation of DRLs for new
examinations, particularly in PET, as well as, in a second phase, for new scanningexaminations; consider the implementation of DRLs for computed tomography acquisitions of the trunk andthe full body associated with bone scans;consider removing DRLs for some infrequent examinations, such as renal scans with DTPA and brain scanswith ECD and HMPAO in nuclear medicine or lateral thoracic spine examinations in conventional radiology.

Finally, as highlighted in IRSN notice 2020–001699 on image-guided radiotherapy, the implementation of a DRL type
optimisation approach and the definition of dose index reference values for computed tomography acquisitions carriedout as part of radiotherapy preparation could be considered.

7.3 CONCLUSIONSThis seventh analysis report on French diagnostic reference level data makes it possible to take stock of theimplementation of the new modalities introduced by ASN resolution 2019-DC-0667, in particular in paediatrics andinterventional radiology.
The results in terms of participation illustrate the degree of support from professionals in the field of interventional
radiology for the DRL system.
The number of assessments submitted in paediatrics is increasing in all areas but remains insufficient for a robust
analysis of practices. Continued efforts are required in this area.
Finally, the reduction in DRL quantities, which are below the DRLs in force for adults in all areas, illustrates a general
downward trend in exposures and justifies a revision of DRL values. The implementation of this revision could be an
opportunity to consider updating the list of examinations in consultation with the healthcare professionals concerned.

9

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IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINEGLOSSARY8.

GLOSSARY

Abbreviations
AD

Achievable dose

ADF

Association dentaire française (French dental association)

AFTMN

Association française des techniciens en médecine nucléaire (French association of nuclear
medicine technicians)

AMM

Marketing authorisation (Autorisation de Mise sur le Marché)

ANSM

Agence nationale de sécurité du médicament et des produits de santé (French National
Agency for Medicines and Health Products Safety)

AP

Anterior posterior

ASN

Autorité de Sûreté Nucléaire (French Nuclear Safety Authority)

ASP

Abdomen AP (“abdomen sans préparation”)

AVM

Arteriovenous malformations

BMI

Body mass index

CA

Chest-abdomen

CAP

Chest-abdomen-pelvis

CBCT

Cone-beam computed tomography

CCAM

Classification Commune des Actes Médicaux (common classification of medical
procedures)

CDF

Chirurgiens-dentistes de France (Dental surgeons in France)

CLCC

Cancer centre (Centre de Lutte Contre le Cancer)

CNPCV

Conseil National Professionnel Cardiovasculaire (French national cardiovascularprofessional council)

CPD

Continuing professional development

CQE

External quality control

CRD

Commission radioprotection dentaire (French dental radiation protection commission)

CTcomputed tomography

CTDIvol

Volume computed tomography dose index

DACS

Dose Archiving and Communication System

DAP

Dose area product

De

Dose à l'entrée (entrance dose)

DGOS

Direction générale de l’offre de soins (Directorate general for healthcare services)

DLP

Dose length product

DOCS

Dépistage organisé du cancer du sein (Organised breast cancer screening)

DOPA

Dihydroxyphenylalanine

DRL

Diagnostic reference level

DTPA

Diethylene triamine pentaacetic acid

EANM

European Association of Nuclear Medicine

EC

European Commission

ECD

Ethyl cysteine dimer
ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDICINE – IRSN

55

FDD

Focus-to-detector distance

FDG

Fluorodeoxyglucose

FNMR

Fédération Nationale des Médecins Radiologues (French National Federation ofRadiologists)

FSD

Focus-to-skin distance

FSDL

Fédération des syndicats dentaires libéraux (French federation of private dentist unions)

G4

Conseil professionnel de la radiologie française (French professional radiology council)

GACIGroupe athérome coronaire et cardiologie interventionnelle de la Société française decardiologie (French cardiology society, coronary atheroma and interventional cardiology
group)HMPAO

Hexa-methyl propylene amine oxime

IAEA

International Atomic Energy Agency

ICRP

International Commission on Radiological Protection

IRSN

Institut de Radioprotection et de Sûreté Nucléaire (French institute for radiation protection
and nuclear safety)

LVEF

Left ventricular ejection fraction

MAA

Macroaggregated albumin

MGD

Mean Glandular DoseMRPRadiopharmaceutical(s)ONCD

Ordre national des chirurgiens-dentistes (French national order of dental surgeons)

OPT

Orthopantomography

PA

Posterior anterior

PET

Positron Emission Tomography

PIR

Image-guided interventional procedures

PSMA

Prostate-specific membrane antigen

SFIPP

Société Francophone d'Imagerie Pédiatrique et Prenatale (French-language society for
paediatric and prenatal imaging)

SFMN

Société Française de Médecine Nucléaire et imagerie moléculaire (French society for
nuclear medicine and molecular imaging)

SFPM

Société Française de Physique Médicale (French society for medical physics)

SFR

Société Française de Radiologie (French society for radiology)

SoFRa

Société française de radiopharmacie (French society for radiopharmacy)

TAVI

Transcatheter aortic valve implantation

UD

Union dentaire (French dental union)

UGI

Upper gastrointestinal series

WHO

World Health Organisation

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Titles of nuclear medicine examination types
Bone scan 99mTc

Bone scan with 99mTc MDP/HMDP/DPD

Lung perfusion scan

Lung perfusion scan with 99mTc-macroaggregates

Thyroid 99mTc

Thyroid scan with 99mTc

Thyroid 123I

Thyroid scan with 123I

Myocardial perfusion
SPECT with 99mTc

Myocardial perfusion SPECT scans with stress test and/or pharmacological stimulation with
99m
Tc- MIBI/tetrofosmin (1st/2nd injections)Myocardial perfusion
SPECT with 201 Tl

Myocardial perfusion SPECT scans with stress test and/or pharmacological stimulation with
201
Tl-Chloride (1st/2nd injections)

LVEF

Equilibrium radionuclide ventriculographies (left ventricular ejection fraction measurement)with 99mTc-serum albumin/red blood cells

Dynamic renal scan

Dynamic renal scan with 99mTc-DTPA/99mTc-MAG3

Brain perfusion SPECT

Brain perfusion SPECT with 99mTc-HMPAO/99mTc-ECD

FDG-PET

Tumour FDG PET with 18F-fluorodeoxyglucose

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ANNEXES
Annexes to this report are available on the original report in French: rapport IRSN 2023 – 00333, Analyse des données
relatives à la mise à jour des niveaux de référence diagnostiques en radiologie et médecine nucléaire. Via :https://www.irsn.fr/sites/default/files/2023-06/Rapport-IRSN-2023-00333-NRD.pdf

58

IRSN – ANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDECINEREFERENCES
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(13) Décision du 8 décembre 2008 fixant les modalités du contrôle de qualité des installations de radiologie dentaire.
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(14) IEC 2010. Medical electrical equipment: Part 2-43 - Particular requirements for the safety of X-ray equipment forinterventional procedures. Report 60601. 2nd ed. Geneva, Switzerland: International Electrotechnical Commission,2010(15) ANSM, 2020. Décision du 15 janvier 2020 fixant les modalités du contrôle de qualité des installations demammographie numérique.

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(17) European Commission 2018, Directorate-General for Energy, European guidelines on diagnostic reference levels
for paediatric imaging, Publications Office, 2018, https://data.europa.eu/doi/10.2833/486256

(18) IRSN, 2020. Expertise portant sur la qualité d’image et la dose délivrée en mammographie numérique CR. Avis IRSN
n°2020-00071

(19) IRSN, 2021. Révision de la décision ASN sur les niveaux de référence diagnostiques (NRD) en imagerie médicale –Mammographie numérique 2D CR, DR et tomosynthèse. Avis IRSN n°2021-00193
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Pôle Santé et Environnement
Direction de la Santé
E-mailcontact@irsn.fr
Report Number
Report IRSN 2023-00577
IRSN – All rights reserved
August 2023
Cover photo:
Julien Frandon, radiologist, and Hélène Mohammad, intern, during an embolisation of the prostatic artery in an interventional
radiology room in the medical imaging department of the CHU in Nîmes. Sophie Brändström/Signatures/Médiathèque IRSNANALYSIS OF DATA FOR UPDATING DIAGNOSTIC REFERENCE LEVELS IN RADIOLOGY AND NUCLEAR MEDICINE – IRSN

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