Czech Metrology Institute  
Okružní 31,  638 00 
Brno  
 
1. ------IND- 2011 0012 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 de vice and for stipulating the test methods for type 
approval and for verifying of specified measuri ng devices pursuant to Section 14(1) of Act No. 
505/1990 Coll., on Metrology, as amended, and pursuant to provisions of Section 172 et seq. of Act 
No. 500/2004 Coll., the Administrative Code, as amended (hereinafter the "AC"), commenced on 29 
November 2010 ex officio proceedings pursuant to Section 46 of the AC, and based on supporting 
documents issues this: 
  
I. 
G E N E R A L  M E A S U R E  
number: 0111-OOP-C020-10 
reference no. 0313/013/10/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 determin e therapeutic dosages during medical 
irradiation" 
 
 
1   Basic definitions 
For the purposes of this general measure, the term inology and definitions contained in the VIM1), as 
well as the following, shall apply: 
1.1   dosimeter: a device that uses an ionization chamber to  measure kerma in the air, absorbed 
dosage or corresponding photon radiation input 1.2   therapeutic dosimeter: a dosimeter intended for the determ ination of dosages applied during 
therapeutic 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 
                                                      
1)   International Vocabulary of Metrology - Basic and General Concepts and Associated Terms (VIM). Draft Measure of a General Nature No. 0111-OOP-C020-10 
The unit of kerma input into air is Gy · s-1 (Gy · min-1; Gy · h-1). 
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 per cent  
1.6   response change limit: the maximum permissible change in operating characteristics expressed 
in per cent 
1.7   variation coefficient v : the degree of relative data scatter as a ratio of the standard deviation to 
the arithmetic mean, in per cent 
2   Metrological requirements 
2.1   Stipulated service conditions 2.1.1   Service temperature range 
Measuring device response changes caused by ambien t temperature changes over the range 15°C to 
35°C must not, after correction for air density, exceed ± 1.0%. 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 ± 1.0%. 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 
 X radiation in open geometry 
 X and γ radiation in open 
geometry  
1.8 mm Cu HVL or 100 keV 
60Co  
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. 
2 Draft Measure of a General Nature No. 0111-OOP-C020-10 
Table 2 – Maximum permissible error 
Measurement range  Maximum permissible error 
 Kerma  
 Kerma input ± 1.5% ± 1.8% 
2.4    Response energy dependence 
Table 3 lists permitted response change limits fo r a therapeutic dosimeter caused by changes to 
radiation quality. 
Table 3 – Response energy dependence 
Range of the affecting quantity Quantity change limits 
Mantle chambers 
X and γ  radiation in air 
 2 mm Al to 3 mm Cu HVL (30 keV to 140 keV)  
± 2% for 1.8 mm Cu 
X and γ  radiation in air 
 1.8 mm Cu HVL to 60Co (100 keV to 1.33 MeV)  ± 4% for 
60Co 
X and γ  radiation in phantom 
 0.42 mm Cu HVL to 60Co (60 keV to 1.33 MeV)  ± 4% for 
60Co, or  
± 2% response energy dependence 
listed by manufacturer 
High-energy X and γ radiation in phantom 
 60Co to 25 MV  
± 2% for 60Co 
Plane-parallel chambers 
X radiation  0.05 mm Al to 2 mm Al HVL (8 keV to 30 keV)  ± 2% for 0.36 mm Al 
2.5    Dependence on radiation angle of incidence 
Table 4 lists permitted response change limits fo r a therapeutic dosimeter caused by changes to 
radiation angle of incidence. 
Table 4 – Dependence on radiation angle of incidence 
Measurement range or range of affecting quantity Quantity change limits 
± 5° angle 
± 360° rotation (does not apply to plane-parallel chambers) ± 1.0% ± 0.5% 
2.6   Measurement repeatability 
For repeated measurement with the same measuring device under invariant conditions, the variation 
coefficient must not exceed ± 0.5%. 
2.7   Stabilization time 
Fifteen minutes after the measuring instrument has been switched on, responses changes must not 
exceed ± 0.5%. 
3 Draft Measure of a General Nature No. 0111-OOP-C020-10 
3   Technical requirements 
3.1   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 –12% to 
+10% of nominal voltage 
UN specified by the manufacturer of the measuring device must not exceed 
± 0.5%. 
Changes to measuring device respons e due to battery voltage changes during its useful life must not 
exceed ± 0.5%. 
Battery-powered dosimeters must have 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 1%. 
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 
                                                      
2) Government Order No. 616/2006 Coll., on technical product requirements with respect to their 
electromagnetic compatibility. 
4 Draft Measure of a General Nature No. 0111-OOP-C020-10 
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 w ith basic safety principles for equipment with 
ionizing radiation, and requirements  of relevant technical regulations  under 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. 
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, 
5 Draft Measure of a General Nature No. 0111-OOP-C020-10 
f) stabilization time test, 
g) test of resistance to climactic influences, 
h) 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 requirements of this re gulation listed in Articles 2 and 3, 
c) that the measuring device's functional wholes are complete and in accordance with 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 
gamma rays with reproducible geometry and fiel d size. The measured value, determined as the 
arithmetic mean of at least 10 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 
and gamma rays (at least five X radiation and 
60Co gamma radiation qualities) in the required energy 
range with reproducible geometry and field size. The measured value, determined as the arithmetic 
mean of at least 10 measurements, is compared with reference values of the measured quantity 
determined using a measurement standard. 
The measured value must not exceed the limits of  the maximum permissible change according to 
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 
gamma rays with reproducible geometry and field size,  at four various rotati on angles of the ionization 
chamber around its axis, or at a chamber angle of 5°  from its reference position. The measured value at 
individual positions, determined as the arithmetic mean of at least 10 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 according to 
Article 2.5. 
5.3.4   Repeatability test 
The repeatability test consists of 10 repeated measu rements in the most sens itive measurement interval 
using a current source. The calculated variation coefficient must meet the requirements of Article 2.6. 
6 Draft Measure of a General Nature No. 0111-OOP-C020-10 
5.3.5   Stabilization time test 
The test is performed in the normally used measureme nt interval using a current source, by comparing 
measuring device data at 15 minutes, 1 hour and 6 hours 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 climactic 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 10 measurements at the 
lowest and highest temperature from the range specified in Article 2.1.1. are compared with the 
reference value of the measured quantity determined at reference temperature. 
The measured value must not exceed permitted ch ange limits according to 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 10 measurements while ambient 
pressure changes by +10% or o –10% compared to reference air pressure are compared with the 
reference value of the measured quantit y determined at reference air pressure. 
The measured value must not exceed perm itted limits according to 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 a 8 kV air discharge (for dosimeters with an insulated surface). 
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 exceed permitted limits according to 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 exceed permitted limits according to 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 exceed permitted limits according to Article 3.6. 
7 Draft Measure of a General Nature No. 0111-OOP-C020-10 
5.4.2.4   Resistance to electrical surges 
Resistance to electrical surges is tested on devices powered by mains power, in the most sensitive 
range by monitoring and recording displayed da ta or data outputs during measurement, while 
measuring in the absence and presence of interfere nce by a test voltage of ± 2 kV between power 
conductors. 
During this test, the measured value must not exceed permitted limits according to 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, induced by high-frequenc y 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 exceed permitted limits according to 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 exceed permitted limits according to 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 mains, the 
measured value is determined as the arithmetic me an of at least 10 measurements at limit power 
voltages of UN – 12% 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 pe rmissible error according to 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. 
8 Draft Measure of a General Nature No. 0111-OOP-C020-10 
6.3   Functional tests 
6.3.1   Device accuracy test 
A device accuracy test is performed according to Article 5.3.1. 
6.3.2   Response energy dependence test 
A response energy dependence test is performed according to 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-C020-10 
8   Notified standards 
To specify metrological and technical requirements for measuring devices and to specify verification 
test methods stemming from this general measure, th e CMI notifies Czech technical standards, other 
technical standards or technical documents of international or foreign organizations or other technical 
documents containing detailed tec hnical requirements (hereinafter "notified standards"). The CMI 
shall publish a list of these notified standards, with their assignation to relevant measures, along with the general measure, 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 a general measure, to be  compliance with those 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, in view of the implementation of Section 24c of Act No. 505/1990 Coll., on 
metrology, as amended, this general measure, stipul ating metrological 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, in view of the implementa tion 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 therapeutic dosages during medical irra diation", this general measure, stipulating 
metrological and technical requirements for  measuring devices used to determine therapeutic dosages 
during medical irradiation and test methods for type approval and verification of these specified 
measuring devices. 
III. 
N O T I C E 
 A general measure cannot be appealed (Section 173 (2) of Act No. 500/2004 Coll., the Administrative 
Code, as amended (hereinafter the "Administrative Code"). Pursuant to provisions of Section 172 (5) of the Administrative Code, a decision on objections cannot 
be appealed in any manner. The conformity of a general measure to legislation can be assessed in review proceedings pursuant to 
Section 94 to 96 of the Administrative Code. A partic ipant may submit a request for a review to the 
administrative body that issued this general measure. If the administrative body does not find reasons 
for commencing review proceedings, it shall notify the a pplicant within thirty days of this fact along 
with its reasons. A decision on commencement of re view proceedings can, according to Section 174 
(2) of the Administrative Code, be issued within th ree years of the entry into force of the general 
measure. 
 
IV. 
E N T R Y  I N T O  F O R C E 
10 Draft Measure of a General Nature No. 0111-OOP-C020-10 
11 This general measure enters into force on the fifteenth day following its promulgation (Section 24d of 
Act No. 505/1990 Coll., on metrology, as amended). 
This general measure shall be published for a period of 15 days.