Czech Metrology Institute  
Okružní 31,  638 00 
Brno 
1. ------IND- 2011 0013 CZ- EN- ------ 20110126 --- --- PROJET 
 
The Czech Metrology Institute (CMI), as the comp etent local body for stipulating metrological and 
technical requirements for a specified measuring device and for the stipulation of test methods for type 
approval and for verification of a specified measur ing device pursuant to Section 14(1) of Act No. 
505/1990 Coll., on Metrology, as amended, and pursuan t to the provisions of Section 172 et seq. of 
Act No. 500/2004 Coll., the Administrative Code, as amended (hereinafter the "AC"), has on 29 
November 2010 commenced ex officio proceedings pursuant to Section 46 of the AC, and based on 
supporting documents issues this: 
  
I. 
M E A S U R E  O F  A  G E N E R A L  N A T U R E 
number: 0111-OOP-C019-10 
reference no. 0313/012/10/Pos., 
publication date: 29 November 2010 
 
stipulating metrological and technical requirements for specified measuring devices, 
including test methods for verifying specified measuring devices: 
"measuring devices used to determine diagn ostic dosages during medical irradiation" 
 
1   Basic definitions 
For the purposes of this measure of a general natu re, terminology and defini tions contained in the 
VIM1) and the following apply: 
1.1   dosimeter: a device that uses an ionization chamber or semiconductor detectors to measure 
kerma in the air, absorbed dosage or corresponding X radiation input 
1.2   diagnostic dosimeter: a dosimeter intended for the determ ination of dosages applied during 
diagnostic irradiation 1.3   kerma in air 
K: ratio of d Etr/dm, where d Etr is the sum of initial kinetic energies of all charged 
ionizing particles released by uncharged ionizing particles in the air with mass d m 
The unit of the kerma in air is the Gray (Gy), where 1 Gy = J · kg-1. 
1.4   kerma input into air K&: the ratio d K/dt, where d K is the increase in kerma input in the air 
during the interval d t 
The unit of kerma input into air is Gy · s-1 (Gy · min-1; Gy · h-1). 
                                                      
1)   International Vocabulary of Metrology - Basic and General Concepts and Associated Terms (VIM). Draft Measure of a General Nature No.  0111-OOP-C019-10 
1.5   response change: the ratio of the difference between the measured value and the reference value 
to the reference value at a reference point of the measuring device, expressed in percent  
1.6   response change limit: the maximum permissible change in operating characteristics expressed 
in percent 
1.7   variation coefficient v: the degree of relative data scatter as a ratio of the standard deviation to 
the arithmetic mean, in percent  
2   Metrological requirements 
2.1   Stipulated service conditions 
2.1.1   Service temperature range 
Measuring device response changes caused by ambient temperature changes over the range 15 °C to 
35 °C must not, after correction for air density, exceed ± 3.0 %. For ventilated ionization chambers, the 
measured value can be corrected for air density e ither manually or automatically with a measuring 
device prior to assessing this criterion. 
2.1.2   Influence of air pressure 
Measuring device response changes caused by air pressure changes over the range 80.0 kPa to 106.0 
kPa must not, after correction for air density, exceed ± 2.0 %. For ventilated ionization chambers, the 
measured value can be corrected for air density e ither manually or automatically with a measuring 
device prior to assessing this criterion. 
2.1.3  Reference conditions and standard test conditions 
Table 1 lists reference conditions  and standard test conditions. 
Table 1 – Reference conditions and standard test conditions 
Affecting value Reference conditions Standard test conditions 
Temperature 20 °C 15 °C to 25 °C 
Relative humidity 50 % 30 % to 70 % 
Air pressure 101.3 kPa air pressure 
Electromagnetic fields zero negligible a) 
Radiation quality 
 Un-weakened beam  Weakened beam  
70 kV, 2.5 mm Al 
70 kV, 23.5 mm Al  
reference value reference value 
a) Negligible means that the field is sufficiently small to not have a noticeable effect on dosimeter response, 
 e.g. as usually exists in a normal laboratory environment without special shielding. 
2.2   Measurement interval 
The measurement interval of a therapeutic dos imeter is stipulated by its manufacturer. 
2.3   Maximum permissible error Table 2 lists the maximum permissible errors of a therapeutic dosimeter for standard test conditions. 
Table 2 – Maximum permissible error  
Measurement range  Maximum permissible error 
2 Draft Measure of a General Nature No.  0111-OOP-C019-10 
In a weakened beam: 
 Kerma   K ≥ 1 μGy 
 Kerma input  K&< 1 μGy · s-1 
 Kerma input  K& ≥ 1 μGy · s-1  
± 5 % 
± (10 – 5 K&) % 
± 5 % 
In an un-weakened beam: 
 Kerma   K < 100 μGy 
 Kerma   K ≥ 100 μ Gy 
 Kerma input  K& < 100 μGy · s-1 
 Kerma input  K& ≥ 100 μGy · s-1  
± (10 – 0.05 K) % 
± 5 % 
± (10 – 0.05 K&) % 
± 5 % 
2.4   Response energy dependence 
Table 3 lists permitted response change limits fo r a diagnostic dosimeter caused by changes to 
radiation quality. 
Table 3 – Response energy dependence 
Range of the affecting quantity Quantity change limits 
In a weakened beam: 
 50 kV to 150 kV, W anode, total filtration (12.5 – 47.5) mm Al  ± 5 % for 70 kV, 2.5 mm Al 
In an un-weakened beam:  50 kV to 150 kV, W anode, total filtration 2.5 mm Al  ± 5 % for70 kV, 23.5 mm Al 
2.5   Dependence on radiation angle of incidence 
The permitted change in response of a diagnostic dosimeter caused by a change in the angle of 
incidence of radiation by ± 5° is ± 3.0 %. 
2.6   Measurement repeatability 
For repeated measurement with the same measuring device under invariant conditions, the variation 
coefficient must not exceed th e values listed in Table 4. 
3 Draft Measure of a General Nature No.  0111-OOP-C019-10 
Table 4 – Measurement repeatability 
Measurement range  Maximum permissible error 
In a weakened beam: 
 Kerma   K < 10 μGy 
 Kerma   K ≥ 10 μGy 
 Kerma input  K& < 1 μGy · s-1 
 Kerma input  K& ≥ 1 μGy · s-1  0.17⋅(16 – 
K) % 
1 % 
1.11⋅(4.7 – 2 K&) % 
3 % 
In an un-weakened beam: 
 Kerma   K < 1 000 μGy 
 Kerma   K ≥ 1 000 μGy 
 Kerma input  K& < 100 μGy · s-1 
 Kerma input  K& ≥ 100 μGy · s-1  0.17⋅(16 – 0.01
K) % 
1 % 
1.11⋅(4.7 – 0.02 K&) % 
3 % 
2.7   Stabilization time 
Fifteen minutes after the measuring instrument has been switched on, responses changes must not 
exceed ± 2 %. 
3   Technical requirements 
3.1   In general 
A dosimeter consists of the following parts: 
a) one or more chamber assemblies, 
b) a measurement assembly (possible including a separate display), 
c) one or more pieces of stability control equipment (optional). 
3.2   Chamber assembly The chamber assembly is composed of an ionization chamber and all other parts permanently attached 
to it, including electrical connecti ons and permanent cable connections. 
3.3   Analysis unit 
The analysis unit measures the voltage (or current) from the ionization chamber and converts it to a 
form suitable for displaying kerma or dosage values (or corresponding inputs). 
The analysis unit must have a display permitting the values of the measured quantity to be read in 
appropriate units of measurement. If the measuring device has several ranges or scales, or if it consists of several parts, each range, scale 
or part must be unmistakeab ly and uniquely identified. 
3.4   Stability control equipment 
Stability control equipment must enable control of the response stability of the chamber assembly or 
analysis unit. 
3.5   Power voltage 
Changes to measuring device response due to fluctu ations to operating power voltage of –5 % to 
+10 % of nominal voltage 
UN specified by the manufacturer of the measuring device must not exceed 
± 2 %. 
4 Draft Measure of a General Nature No.  0111-OOP-C019-10 
Changes to measuring device respons e due to battery voltage changes during its useful life must not 
exceed ± 2 %. 
Battery-powered dosimeters must display a low battery  indication if the voltage is outside the nominal 
value specified by the manufacturer. 
3.6   Electromagnetic compatibility (EMC) 
Measuring devices must not be affected by ambient electrical and electromagnetic fields, and must 
meet the requirements of applicable special legislation2). During interference tests, the change in the 
response of the measurement unit must not exceed 5 %. 
3.7   Protection from tampering 
Parts of the measuring device that are important to its metrological characteristics must be designed so 
that they can be secured in a way that provides proof of any unauthorized access. 
If the response of the measuring device can be adjust ed by correction to long-term response changes, 
correction of temperature and pressure on response, or  application of a corrective factor, the measuring 
device must then be designed to eliminate the possi bility of unintentional changes to any settings by 
users. 
Control switches and potentiometers must either  be inside the measuring unit and externally 
inaccessible without the use of a tool, or must be clearly marked and have a scale so that they can be 
set precisely in accordance with the resolution capability of the measur ing device, and then blocked to 
prevent accidental changes to settings. Corrective factors and calibration coefficients stored digitally 
must be prevented from being changed unless the user enters a security code (or password), or changes 
the position of a blocked or inaccessible switch. 
3.8   Safety 
The measuring device must be safe in accordance with the basic safety principles for equipment with 
ionizing radiation, and the requirements of relevant technical regulations under the conditions of usual 
use for purposes for which it is intended. 
4   Markings 
4.1   Markings on the measuring device 
The measuring device, which can consist of two functionally independent parts, must have the 
following data listed on each part: 
– the manufacturer, 
– measuring device type, 
– ionization chamber and analysis unit serial number, 
– type approval mark, 
– data on the safety of the ionizing radiation measuring device. 
The analysis unit must also be marked with power input information, i.e. nominal voltage and power 
frequency, or for battery-powered measuring devices, the battery type. 
The ionization chamber must have a mark i ndicating the position of the reference point. 
All markings and labels must be legible, perm anent, unambiguous and impossible to remove in a 
regular manner. 
                                                      
2) Government Order No. 616/2006 Coll., on technical product requirements with respect to their 
electromagnetic compatibility. 
5 Draft Measure of a General Nature No.  0111-OOP-C019-10 
4.2   Verification marks 
The location of verification marks on the ionization ch amber and analysis unit is specified in the type 
approval certificate. 
If possible, marks are placed on the front panel of the display unit so that they do not cover any of the 
information listed on the measuring device. 
5   Type approval 
5.1   In general 
The approval process for a measuring device includes the following tests: 
a) external inspection, 
b) device accuracy test, 
c) response energy dependence test, 
d) radiation angle of incidence dependency test, 
e) repeatability test, 
f) stabilization time test, 
g) test of resistance to climatic influences, 
a) electromagnetic compatibility (EMC) tests. 
5.2   External inspection The following is assessed durin g an external inspection: 
a) that prescribed technical documentation is complete, including the user manual, 
b) that metrological and technical characteristics specified by the manufacturer in documentation 
conform to the requirements of this regulation listed in Articles 2 and 3, 
c) that the measuring device's functional wholes are complete and in accordance with the prescribed technical documentation, 
d) that the software (SW) version of the measuring device is the same as the version specified by 
the manufacturer. 
5.3   Functional tests 
5.3.1   Accuracy test 
The test is performed by irradiating the ionization chamber of the dosimeter in a collimated beam of X 
radiation with reproducible geometry and field size.  The measured value, dete rmined as the arithmetic 
mean of at least ten measurements, is compared with reference values of the measured quantity 
determined using a measurement standard. 
Measurement error must not exceed the limits of the maximum permissible error according to Article 
2.3. 
5.3.2   Response energy dependence test 
The test is performed by irradiating the ionization chamber of the dosimeter in a collimated beam of X 
radiation (at least three X radiation qualities) in th e required energy range with reproducible geometry 
and field size. The measured value, determined as th e arithmetic mean of at least ten measurements, is 
compared with reference values of the measured quantity determined using a measurement standard. 
6 Draft Measure of a General Nature No.  0111-OOP-C019-10 
The measured value must not exceed the limits of the maximum permissible change in accordance 
with Article 2.4. 
5.3.3   Test of dependence on radiation angle of incidence 
The test is performed by irradiating the ionization chamber of the dosimeter in a collimated beam of X 
radiation with reproducible geometry and field size, at a detector angle of ± 5° in two orthogonal 
directions to its reference position. The measure d value at individual positions, determined as the 
arithmetic mean of at least ten measurements, is compared with reference values of the measured 
quantity determined at the reference position. 
The measured value must not exceed the limits of the maximum permissible change in accordance 
with Article 2.5. 
5.3.4   Repeatability test 
The repeatability test consists of ten repeated measurements in the most sensitive measurement 
interval while irradiating the ionization chamber of the dosimeter in a collimated beam of X radiation 
with reproducible geometry and field size 
The calculated variation coefficient must meet the requirements of Article 2.6. 
5.3.5   Stabilization time test 
The test is performed by irradiating the ionization chamber of the dosimeter in a collimated beam of X 
radiation with reproducible geom etry and field size, by comparing measuring device data at 15 
minutes, 30 minutes, 45 minutes and one hour after the measuring device has been switched on. 
The response time change found must meet the requirements of Article 2.7. 
5.4  Tests of dosimeter resistance to external influences 
5.4.1    Tests of resistance to climatic effects 5.4.1.1    Test of resistance to service temperatures 
The test is performed while irradi ating the dosimeter's ionization cham ber with a constant input of a 
dosimetric quantity, and ascertaining the influence of ambient temperature on data from the measuring 
device. Measured quantities determined as the arith metic mean of at least ten measurements at 
temperatures of 15 °C, 20 °C and 35 °C are compared with the reference value of the measured 
quantity determined at reference temperature. 
The measured value must not exceed the permitted change limits in accordance with Article 2.1.1. 
5.4.1.2   Air pressure resistance test 
The test is performed while irradi ating the dosimeter's ionization cham ber with a constant input of a 
dosimetric quantity, and ascertaining the influence of air pressure on data from the measuring device. 
Measured quantities determined as the arithmetic mean of at least ten measurements at pressure values 
of 80 kPa and 106 kPa are compared with the reference value of the measured quantity determined at 
reference air pressure. 
The measured value must not exceed the perm itted limits in accordance with Article 2.1.2.. 
5.4.2   Electromagnetic compatibility (EMC) tests 
5.4.2.1   Resistance to electrostatic discharge 
Resistance to electrostatic discharge is tested in the most sensitive range by monitoring and recording 
displayed data or data outputs during measurement, wh ile discharging a test generator, preferably with 
a 6 kV contact discharge, or with an 8 kV air di scharge (for dosimeters with an insulated surface). 
7 Draft Measure of a General Nature No.  0111-OOP-C019-10 
Discharges are applied to various external parts of the dosimeter that users c ould touch while using the 
measuring device. 
During this test, the measured value must not excee d the permitted limits in accordance with Article 
3.6. 
5.4.2.2   Resistance to radiated high-frequency electromagnetic fields 
Resistance to a radiated high-frequency electromagnetic field is tested in the most sensitive range by 
monitoring and recording displayed data or data outputs during measurement, while measuring in the 
presence and absence of a high-frequency electromagnetic field in the 80 MHz to 1 GHz frequency range, and for battery powered devices also at 27 MHz, at a test field intensity of 3 V · m
-1. 
Interference is applied in all three axes. 
During this test, the measured value must not excee d the permitted limits in accordance with Article 
3.6. 
5.4.2.3   Resistance to electrical bursts (transients) 
Resistance to rapid transient electrical bursts (trans ients) is tested in the most sensitive range by 
monitoring and recording displayed data or data outputs during measurement, while measuring in the 
absence and presence of interference by a test voltage of  2 kV applied through a coupling circuit to the 
power source. 
During this test, the measured value must not excee d the permitted limits in accordance with Article 
3.6. 
5.4.2.4   Resistance to electrical surges 
Resistance to electrical surges is tested on devices powered by mains power by monitoring and 
recording displayed data or data outputs during measurement in the most sensitive range in the 
absence and presence of interference caused by surges. 
During this test, the measured value must not excee d the permitted limits in accordance with Article 
3.6. 
5.4.2.5   Resistance to interference caused by power lines, induced by high-frequency fields 
Resistance to interference caused by power lines, indu ced by high-frequency fields, is tested with the 
device switched on, by monitoring and recording di splayed data or data outputs during measurement, 
while measuring in the absence and presence of inte rference over a frequency range of 150 kHz to 80 
MHz. Amplitude modulation 80 % AM/1 kHz, voltage level 10 V. 
During this test, the measured value must not excee d the permitted limits in accordance with Article 
3.6. 
5.4.2.6   Resistance to voltage dips, short interruptions and slow voltage variations 
Resistance to short mains voltage dips, short interr uptions and slow voltage variations is tested on 
devices powered by mains power, in the most sens itive range by monitoring and recording displayed 
data or data outputs during measurement, while me asuring in the absence and presence of interference 
caused by a voltage dip of 40% and short interruptions of 25 cycles. 
During this test, the measured value must not excee d the permitted limits in accordance with Article 
3.6. 
5.4.3   Test of resistance to limit power voltage values 
Resistance to limit power voltage values is tested while irradiating the dosimeter's ionization chamber 
with a constant input of dosimetric quantity. For measuring devices powered from the mains, the 
measured value is determined as the arithmetic mean of at least ten measurements at limit power 
8 Draft Measure of a General Nature No.  0111-OOP-C019-10 
voltages of UN – 15 % and UN + 10 %. For battery-powered measuring devices, the measured value is 
determined with a set of fresh batteries and a set of  used batteries that are sufficiently discharged to 
elicit a low battery signal on the display. 
Measurement errors must not exceed the maximum permissible error in accordance with Article 3.5 at 
limit power voltages. 
6   Initial verification 
6.1   In general 
The following is performed during initial verification: 
a) visual inspection, 
b) device accuracy test, 
c) response energy dependence test. 
6.2   Visual inspection The following is assessed during vi sual inspection of a dosimeter: 
a) that the measuring device is the same as the approved type, 
b) that the measuring device is complete according to the type approval certificate, 
c) that individual parts of the measuri ng device are undamaged and functional, 
d) that the SW version matches the ve rsion approved during type approval. 
6.3   Functional tests 
6.3.1   Device accuracy test 
A device accuracy test is performed in accordance with Article 5.3.1. 
6.3.2   Response energy dependence test 
A response energy dependence test is perfo rmed in accordance with Article 5.3.2. 
7   Subsequent verification 
Subsequent verification is performed using the same procedure as initial verification pursuant to 
Section 6. 
9 Draft Measure of a General Nature No.  0111-OOP-C019-10 
8   Notified standards 
To specify metrological and technical requirements for measuring devices and to specify verification 
test methods stemming from this measure of a genera l nature, the CMI shall give notification of Czech 
technical standards, other technical standards or technical documents of international or foreign 
organizations or other technical documents containing detailed technical requirements (hereinafter 
"notified standards"). The CMI shall publish a list of  these notified standards, with their assignation to 
relevant measures, along with the measure of a general nature, in a manner available to the public (on the website www.cmi.cz). 
Compliance with notified standards or parts thereof is considered to be, to the extent and under the 
conditions stipulated by the measure of a genera l nature, to be compliant with the requirements 
stipulated by this measure to which these standards or parts thereof apply. 
  
II. 
J U S T I F I C A T I O N  
The CMI issues, towards the implementation of Section 24c of Act No. 505/1990 Coll., on metrology, 
as amended, this measure of a ge neral nature, stipulating metrologi cal and technical requirements for 
specified measuring devices and test methods for verification of these specified measuring devices. 
In Decree No. 345/2002 Coll., specifying measuring devices for mandatory verification and measuring 
devices subject to type approval, as amended, the annex "List of Specified Measuring Device Types" 
classifies "measuring devices used to determine di agnostic and therapeutic dosages during medical 
irradiation" under item 8.3 as measuring devices subject to type approval and verification. 
The CMI thus issues, towards the implementation of Section 24c of Act No. 505/1990 Coll., on 
metrology, as amended, for the measuring device type specified as "measuring devices used to 
determine diagnostic dosages during medical irradiation" , this measure of a general nature, stipulating 
metrological and technical requirements for  measuring devices used to determine diagnostic dosages 
during medical irradiation and test methods for type approval and verification of these specified 
measuring devices. 
III. 
N O T I C E 
 
An appeal cannot be made against a measure of a general nature (Section 173 (2) of Act No. 500/2004 
Coll., of the Administrative Code, as amended (hereinafter the "Administrative Code"). 
Pursuant to the provisions of Section 172 (5) of the Administrative Code, an appeal cannot be made 
against a decision on objections. 
The conformity of a measure of a general natu re with legislation can be assessed in review 
proceedings pursuant to Section 94 to 96 of th e Administrative Code. A participant may submit a 
request for a review to the administrative body that issued this measure of a general nature. If the 
administrative body does not find reasons for co mmencing review proceedings, it shall notify the 
applicant of this fact within thirty days, al ong with its reasons. A decision on commencement of 
review proceedings can, according to Section 174 (2) of the Administrative Code, be issued within 
three years of the effective date of the measure of a general nature. 
 
IV. 
10 Draft Measure of a General Nature No.  0111-OOP-C019-10 
11 E F F E C T I V E  D A T E 
This measure of a general nature takes effect on th e fifteenth day following the day of its publication 
(Section 24d of Act No. 505/1990 Coll., on metrology, as amended). 
This measure of a general nature sha ll be published for a period of 15 days.