GB/T 19629-2005 Medical electrical equipment - Ionization chambers and/or semiconductor detector dosimeters used in X-ray diagnostic imaging
Some standard content:
ICS 11.040.50
National Standard of the People's Republic of China
GB/T 19629--2005/IEC 61674:1997 Medical electrical equipment
, Ionization chambers and/or semiconductor detector dose meters used in X-ray diagnostic imaging (IEC 61674:1997.JDT)
Published on January 17, 2005
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Standardization Administration of China
Implemented on June 1, 2005
GB/T19629-—2005/IEC61674;1997 This standard adopts IEC61674:1997 "Ionization chamber and (or) semiconductor detector dosimeters used in medical electrical equipment X-ray diagnostic imaging". (First English version) This standard is translated from the international standard IEC61674 by translation method without any modification or addition or deletion. This standard is about diagnostic dosimeters (see 3.1 for definition). Ionization chamber dosimeters used in radiotherapy and dose-area products used in X-ray diagnosis are not discussed in this standard, but are covered by other special standards. Appendix A and Appendix B of this standard are informative appendices. This standard was proposed by the State Food and Drug Administration. This standard is under the jurisdiction of the National Technical Committee for Standardization of Radiotherapy, Nuclear Medicine and Radiation Dosimetry Equipment. This standard was drafted by the Beijing Medical Device Inspection Institute. The main drafters of this standard are Liu Decheng and Wang Peichen. GB/T19629-2005/IEC61674:1997
Among the artificial ionizing radiation exposures received by residents, the diagnostic radiation dose is the largest. Therefore, reducing the dose received by patients during medical radiation diagnosis or examination procedures has been a central issue in recent years. Only when the X-ray generating equipment is adjusted to have both good image quality and appropriate radiation output, the patient dose will be minimized. These adjustments require accurate measurement of air kerma, air kerma length and air kerma rate. The equipment included in this standard plays a key role in achieving the required accuracy. The dosimeters used for adjustment and control measurements must be of good quality and must therefore meet the various specific requirements specified in this standard. 1 Scope and purpose
GB/T 19629--2005/IEC61674:1997 Medical electrical equipment Ionization chamber and (or) semiconductor detector dosimeters for use in X-ray diagnostic imaging 1.1 This standard specifies the performance and some related structural requirements of diagnostic dosimeters (defined in 3.1). Diagnostic dosimeters are used to measure the air kerma, air kerma length or air kerma rate of the photon radiation field of radiation imaging equipment, including breast imaging equipment, X-ray fluoroscopy equipment and computed tomography (CT) equipment, where the excitation voltage for generating X-rays is not greater than 150 k.
This standard applies to ionization chamber and (or) semiconductor detector dosimeters for use in X-ray diagnostic imaging. 1.2 The purpose of this standard is to: 1) set requirements for satisfactory performance of diagnostic dosimeters, and 2) standardize methods for determining compliance with these performance requirements. This standard does not address safety requirements for dosimeters. The dosimeters covered by this standard are not intended for use in contact with patients; therefore, the electrical safety requirements for dosimeters intended for use in contact with patients are included in IEC 61010-1. 2 Normative references The clauses in the following documents become clauses of this standard through reference in this standard. For dated referenced documents, all subsequent amendments (excluding corrections) or revisions are not applicable to this standard; however, parties to agreements based on this standard are encouraged to investigate whether the latest versions of these documents can be used. For undated referenced documents, the latest versions apply to this standard. GB/T 17626.1—[1998 Electromagnetic compatibility test and measurement technology General introduction to immunity test (idt1EC61000-4-1:1992) GB/T 17626.2—1998 Electromagnetic compatibility test and measurement technology Electrostatic discharge immunity test (idl.IEC61000-4-2:1995
GB/T 17626. 3--1998
61000-4-3:1995)
Electromagnetic compatibility test and measurement technology Radio frequency electromagnetic field radiation disturbance test (tIFC Electromagnetic compatibility test and measurement technology Electrical fast transient pulse group immunity test (idtIECGB/T 17626. 4-.1998
61000-4-4:1995)
GB/T 17626.5--1999
Electromagnetic compatibility
Test and measurement technology
Surge (shock) immunity test (idtIEC61000-4-5: Radio frequency field induced conducted disturbance immunity (idt1ECGB/T17626.6-1998 Electromagnetic compatibility test and measurement technology 61000-4-6:1996)
GB/T 17626.11-1999 Electromagnetic compatibility test and measurement technology
Test (idt 1EC: 61000-4-11:1994) Voltage dips, short interruptions and voltage variations immunity 1EC.60417:1973 Graphical symbols for equipment January collection. Index single page compilation IEC60788, 1994 Radiology - Terminology JEC61187:1993 Electrical equipment and electronic test equipment - Documentation IFC61267:1994 Medical diagnostic X-ray equipment - Radiation conditions for characteristic measurements GB/T 19629-2005/IEC 61674:19973 Terms and definitions
In this standard, the word "shall" indicates that compliance with the requirements of the standard is mandatory; "may" indicates that it is allowed to meet the requirements of the standard in a special way. The definitions given in this standard are generally consistent with the following documents: -1EC60788:1984, Medical radiology terms: -ISO:1993 Basic and general terms in metrology; however, some definitions are given in a more stringent sense, and these special definitions should be regarded as applicable to this standard only. Standard. This standard adopts the following definitions.
(Diagnostic) dosimeter (dlagnostic) dosimeter is a device that uses an ionization chamber or a semiconductor detector to measure the air kinetic energy, air kerma length or air kerma rate of the radiation beam of an X-ray machine for diagnostic medical radiation examination. The diagnostic dosimeter contains the following components:
--one or several detector components, which may or may not be a part of the measuring component; -... measuring component,
* one or more stability test devices (optional). 3. 1. 1
Detector assembly detectorassemble
Radiation detector and all other components on which the radiation detector is permanently fixed, but does not include the measuring component. Note that the detector assembly usually includes!
--a rod (entity) on which the radiation detector and the radiation detector are permanently mounted (embedded), an electrical connector and a cable or preamplifier permanently connected to it. 3. 1. 1.1
Radiation detector radiatlondetector
An element that converts air kerma, air kerma length or air kerma rate into a measurable electrical signal can be an ionization chamber or a semiconductor detector:
1) Ionization chamber, an ionization detector consisting of a chamber filled with air. Voltage is applied to the electrodes of the ionization chamber to collect the charges associated with ions and electrons generated by ionizing radiation in the sensitive volume of the detector, but the electric field of the voltage in the air chamber cannot cause gas multiplication. The structure of the air chamber should enable the air in the measurement volume to communicate smoothly with the surrounding atmosphere, so as to make corrections to the response to changes in air density.
2) Ventilation chamber: An ionization chamber in which the air in the measurement volume can communicate smoothly with the open atmosphere. Note: A sealed chamber is not suitable because the wall of the sealed case is thick and the energy generated is too large, which does not meet the requirements; at the same time, the long-term stability of the sealed case is difficult to guarantee. 3) Semiconductor detector: It can be any of a) and b): a) A semiconductor device operating in short-circuit mode, which uses the generation and movement of excess self-generated charge carriers in the semiconductor to detect and measure the incident ionizing radiation: a scintillator operating in short-circuit mode, the scintillator is optically coupled to a semiconductor photodiode. In this component b)
, the incident ionizing radiation is first converted into light and then into an electrical signal. 3. 1,.2
measuring assembly
A device that converts the output of the detector component into a value suitable for displaying air kerma, air kerma length or air kerma rate.
stability check device GB/T19629--2005/1E61674:1997 This device can be separated from the diagnostic instrument or an integral part thereof, and can ensure that the response of the radiation detector and/or the measuring component is checked.
Note: The stability age detection device can be a purely electrical device or a radiation source only, or it can also contain both. 3.1.4
CT dosimeterCT dosimeter
A diagnostic dosimeter using an elongated ionization chamber or semiconductor detector, irradiating the detector in the transverse direction of the X-ray scan of the computed tomography machine, and measuring the integral of the air kerma along the long axis of the detector. The CT dosimeter contains the following components:
One or more detector components:
Measuring part.
CT detectorCT deteetor
A radiation detector used for CT dosimetry measurement. 3.2
Indicated value
The value of a quantity derived from the scale reading of the instrument and the scale factor indicated on the instrument control panel. 3.3
True value
The value of the physical quantity measured by the instrument.
Conventional true valueconventional true valueThe value used in place of the true value when calibrating or determining the performance of an instrument because the true value is unknown and unknowable in practice.
Note: Conventional true value is usually a value that is difficult to determine. The instrument being tested is compared with such a standard. 3.4.1
Standard
Definition, physical representation, instrument that maintains or reproduces the unit measurement value of a quantity (or a multiple of that unit value) in order to pass that value on to other instruments by comparison. 3.5
Measured value
The best determined value of the true value of a quantity derived from the indicated value of an instrument and all relevant positive factors. 3.5.1
Error of measurementThe difference between the measured value of a quantity and the true value of that quantity. 3.5.2
overall uncertainty
Total uncertainty
Uncertainty associated with the value of a quantity and expressing the limit within which it falls within the range of the estimated measurement error. 3.5.3
expanded uncertainty
Expanded uncertainty
Defines the quantity concerning the interval between the results of a measurement, within which the value of the measurand is assumed with a high degree of confidence to be within the limits of the quantity.
GB/T19629—2005/IEC61674;19973.6
correctlon factor
Correction factor
Dimensionless multiplication factor by which the indication of a particular instrument is corrected from that obtained under specified conditions to that obtained under recognized reference conditions.
influence quantity
Any external quantity (e.g. ambient temperature, radiation quality, etc.) that can affect the performance of an instrument. 3.8
instrument parameter
Any internal property of an instrument that can affect the performance of the instrument. 3.9
reference value
A particular value of an influencing quantity (or instrument parameter) selected for reference, which may be the correction factor associated with the influencing quantity (or instrument parameter) when the influencing quantity (or instrument parameter) exceeds this value. 13. 9. 1
Reference conditionsThe conditions under which all influencing quantities and instrument parameters take their reference values. 3.10
Standard test valuesThe value or range of values that an influencing quantity or instrument parameter is permitted to take when calibrating or testing other influencing quantities or instrument parameters that do not contain the influencing quantity or instrument parameter.
Standard test conditions
Standard test conditions
Standard test conditions
All influencing quantities and instrument parameters take their standard test values. 3.11
intrinsic error
intrinsic error
the difference between the indicated value (i.e., the indicated value corrected to a reference value) and the stated true value under standard test conditions. 3.11.1
relative intrinsic error
the value of the indicated error relative to the stated true value.
performance characteristic
a characteristic of the performance of an instrument (e.g., response, leakage current). 3.12.1
response
the quotient of the indicated value divided by the stated true value:
resolution of the displaythe smallest change in the scale reading from which a value can be estimated by further interpolation.一一For analog displays, resolution is the smallest part of a scale interval that can be determined by an observer under specified conditions;
For digital displays, resolution is the smallest meaningful increment of reading. 3.12.3
equilibrium timeequilibration time
GB/T19629—2005/IEC61674:1997The time taken for the scale reading to reach and remain within a specified deviation from its last stable value after a sudden change in an influencing quantity is applied to the instrument.
response timeresponisetme
The time taken for the scale reading to reach and remain within a specified deviation from its last stable value after a sudden change in the measured quantity. 3.12.5
stabilization timestabilizationtme
The time taken for a specified performance characteristic to reach and remain within a specified deviation from its last stable value after the dosimeter is powered on (and when the radiation detector is an ionization chamber, after the polarization voltage is applied). 3.12.6
leakage current
Any current in a signal circuit generated in a detector or measuring component, but never generated in a radiation detector by ionizing radiation.
variation
When an influencing quantity (or instrument parameter) adopts two specified values in succession, and other influencing quantities (and instrument parameters) remain unchanged at the standard test value (unless otherwise specified), the relative difference between the performance characteristic values 3 A/y. 3,14
limits of variation
The maximum variation of the performance characteristic value 3 allowed by this standard. If the variation limit is expressed as upper L%, the variation Ay/y expressed as a fraction of A must be within the range -L% to ~L%.
effective range (of indicated values) The range of indicated values when the instrument has the specified performance. The maximum (minimum) effective indicated value is the highest (lowest) value in this range. The concept of effective range can also be applied to scale readings and related quantities not directly indicated by the instrument, such as input signals. Note 1: The effective range of indicated values is the effective range in this standard. Note 2: For CT dosimeters, the effective range of air kerma length does not need to be specified as the maximum range of air kerma length values that may be measured by the dosimeter. Instead, it should be limited to the range of actual concern to the user, for example, 1mGy·m to 2mGy·m. 3.16bzxz.net
ratedrange(ofuse) The range of values of an influencing quantity or instrument parameter within which the instrument operates within specified limits of variation. The range is limited by the maximum and minimum rated values.
Note: The rated range of use is referred to as the rated range in this standard. 3.16.1
minimumratedrangeminimumratedrange The lowest range of influencing quantities or instrument parameters within which the instrument operates within specified limits of variation to comply with the requirements of this standard. 3.17
referencepoint(of a radiationdetector) The point in a radiation detector which, when calibrating the detector, coincides with the point at which the agreed true value is specified. 3.18
(Medical electrical) equipment (rnedicalefectrical) equipment is an electrical device that has a connection to a dedicated power supply network, performs diagnosis, treatment or monitoring on patients under medical supervision, has physical or electrical contact with patients, and (or) transmits energy to or obtains energy from patients, and (or) detects such energy transmitted or obtained. 3.18.1
Mains power supply system
Permanently installed power supply, which can also be used to power equipment outside the scope of this standard. 3.18.2
Patient patient
Living organism (human or animal) undergoing medical examination or treatment. 3.18.3
Accessible metal parts Metal parts of the equipment that can be touched without the use of tools. 3.18.4
tool
An instrument outside the human body used to tighten or loosen a fastener or to make adjustments. 3.19
unattenuatedbeam
An X-ray beam directed at a subject or phantom. 3.19.1
nnattenuatedbeanmquality
The quality of an X-ray beam directed at a subject or phantom in the absence of the subject or phantom, i.e., in free air. 3.20
attenuatedbeam
An X-ray beam directed at a subject or phantom.
attenuatedbeamqualityThe quality of an X-ray beam directed at a subject or phantom. 3.21
Rated length
The length along the axis of the CT detector within which the detector performance meets the requirements. 3.21.1
Effective length
The length between two points along the axis of the CT detector where the response drops to 50% of the maximum value (at the center). 3.22
Air kerma (lettersymbolK) dE. divided by dm. Where dE. is the sum of the initial kinetic energies of all charged particles released by non-charged particles in air of mass dm. The unit of air kerma is Gy (lGy1"·kg\\). 3.22. 1
Air kerma rate (symbol K) airkermarate (lettersymbol K) quotient of dK divided by d, where dK is the increment of air kerma in the time interval dt, and the unit of air kerma rate is Gy/s (Gy/min; Gy/h).
Air kerma length (symbol K·L) airkerrmaJength (lettersymbol K·L) For any straight line passing through the X-ray scanning cross section of the CT machine, the air kerma length is the integral of the product of the air kerma and the length element on this straight line. The unit of air kerma length is Gym (mGy·m). 3.23
(X-ray) tube voltage (X-ray) tubeyoltage The potential difference applied between the electron emitter and the anode of the X-ray tube. 3.24
coefficient of variation--the standard deviation of a group of readings, expressed as a percentage of the mean of the group of readings. 3.25
instructions
accompanying documents
GB/T19629—2005/IEC61674:1997 Documents that provide installation and equipment information with the equipment or accessories and contain information for assemblers, installers and users, especially those containing necessary information about safety.
instructions for useEorusersThe part of the accompanying documents that gives information necessary for the safe, proper use and operation of the equipment. 3.25.2
user
With regard to the IEC standard for medical electrical equipment, the organization or individual responsible for the use and maintenance of the equipment. 3.26
operator
The individual who uses the equipment alone, with or without the help of an assistant, and who controls some or all functions of the equipment on site. 3.27
Manufacturer
As an undefined term, it is listed in the IEC60788 standard in the clause Tm-85-03. 4 General requirements and test methods
4.1 Performance requirements
In Chapter 5 and Chapter G, the performance requirements of a complete dosimeter (i.e., including the detector component and the measuring component) are specified. For dosimeters with one or more measuring components, each combination of the measuring component and the detector component should meet the requirements of Section 4.4 and Chapters 5 and 6 for this combination.
4.2 Expected and standard test values
These values are given in Table 1:
4.3 General test conditions
4.3.1 Standard test conditions
During the test, the standard test conditions listed in Table 1 shall be met, with the exceptions: a) for the effect scenario to be studied;
b) where the relative humidity at the resting point exceeds the standard test conditions. In this case, the tester shall verify the validity of the test results.
4.3.2 Statistical fluctuations
In the case of low air kerma and air kerma rate, statistical fluctuations in the instrument readings due solely to the chance of radiation may account for a non-negligible contribution to the variation in the average readings determined during the test. Sufficient readings shall be taken to ensure that the average of such readings is determined with sufficient accuracy to show compliance or non-compliance with the test requirements. Table 2 gives the number of readings that should be taken, when these numbers are taken, the true difference between the two groups of readings will be determined with 95% confidence. The number of readings required as a function of the mean difference A and the coefficient of variation of each group of readings (assuming that the number of readings in each group is equal) is listed in the table. GB/T19629-2005/IEC61674:19974.3.3 Stabilization time
Before starting the verification test, the instrument should be turned on for at least the stabilization time required by the manufacturer. In addition, if the radiation detector is an ionization chamber, it should be allowed to reach thermal equilibrium with the environment and the time for applying the polarization voltage should be equal to or greater than the specified stabilization time.
4.3.4: Sections in the test
The verification test should be carried out with the instrument ready for use, that is, after the stabilization time and various necessary preliminary adjustments. During the test, adjustments can be repeated as long as they do not affect the effect to be verified. For example, zeroing is not allowed in tests measuring the current. 4.3.5 Battery Packs
Battery-powered instruments shall be powered by new batteries of the type specified by the manufacturer. 4.4 Performance-related construction requirements
4.4.1 Components
If a diagnostic dosimeter has several detector ranges or scales, or consists of several components, all ranges, scales and components shall be accurately and clearly indicated. This shall be verified by visual inspection.
4.4.2 Display
4.4.2.1 Units
The indicated units shall be the units of the measured quantity air kerma, air kerma length or air kerma rate, i.e. Gy, Gy·m or Gy/s respectively, followed by a prefix of S1, i.e. m or μ, which shall be verified by visual inspection.
4.4.2.2 Analogue display
The analogue display shall have a true linear scale and the ratio of the full scale values of two connected ranges shall not exceed 19:3. This shall be verified by visual inspection.
4.4.2.3 Digital display
Unnoticeable faults may produce erroneous mathematical displays (e.g., some segments of a segmented display not illuminating). The digital display shall have a reliable method of verifying the display function.
This shall be verified by visual inspection.
4.4.3 Battery voltage indication
Battery-powered dosimeters shall have a low voltage indication whenever the battery voltage is below the rated voltage. The verification method shall be a self-check.
4.4.4 Indication of insufficient polarization voltage
For dosimeters using ionization chambers, the dosimeter shall have a means of indicating if the polarization voltage does not meet the manufacturer's requirements for normal operation. This shall be verified by visual inspection.
4.4.5 Overrange
Note: When verifying that the overrange meets the requirements, it is not necessary to use reference conditions. 4.4.5.1 On all air kerma rate ranges, air kerma rate up to 1 Gy/s, the dosimeter shall clearly indicate the overrange when the full scale reading is exceeded and shall maintain this indication. Verification method:
When the full scale reading is equal to or less than 10 mGy/s, a verification test shall be performed for each permitted combination of air kerma rate range and detector components. Expose the relevant radiation detector with any suitable X-ray beam having an air kerma rate just below the specified full scale reading and then: a) slowly and continuously increase the air kerma rate until the display shows an over-range; b) gradually increase the air kerma rate in tenths of 10 mGy/s until it exceeds 10 mGy/s, checking that the display indicates an over-range at each discrete increase in air kerma rate. CB/119629--2005/1EC61674:1997 When the full-scale reading is greater than 10mGy/s, a verification test should be carried out for each permitted combination of air kerma rate range and detector components, as described above, or an electrical test should be carried out on the detector components to verify that the dosimeter clearly indicates the over-range condition for ion currents corresponding to air kerma rates up to 1(mGy/s, or to 10 times the full-scale reading. 4.4.5.2 On all air kerma and air kerma length ranges, the dosimeter should clearly indicate the over-range condition when the full-scale reading is exceeded. Verification test method: Air kerma and A verification test is performed on each range of the air kerma length. During the test, the relevant radiation detector is irradiated until the displayed reading is just below the specified full-scale value and then irradiation is continued, with increases approximately equal to the resolution of the air kerma or air kerma length range used, in discrete steps, until the display indicates an overrange. An equivalent electrical test may be performed on the measuring components.
4.4.5.3 On all air kerma and air kerma length ranges, the dosimeter shall clearly indicate an overrange when the rated range of the air kerma rate is exceeded unless the dosimeter is capable of measuring air kerma at least at the following air kerma rates: 1 Gy/s conventional diagnostic attenuated beam
—10 mGy/s conventional diagnostic attenuated beam
100 mGy/s unattenuated beam for breast imaging;
500 mGy/s Computer gradient image unattenuated beam: Verification test method:
Verification tests should be carried out for each range of air kerma and air kerma length. During the test, the air kerma rate of the irradiated relevant radiation detector shall exceed 10% of the rated range, and the check dosimeter clearly indicates the over-range condition. 4.4.6 Recovery or other inoperative indication
When the dosimeter is in the inoperative time, that is, after the recovery procedure, this state should be indicated and verified by visual inspection.
4.4.7 Multi-detector measurement components
For measurement components using multiple detectors and only one display, it can display air kerma or air kerma. The measuring unit shall show a signal from only one detector at any given time. This shall be verified by daylight inspection.
4.4.8 Stability check radioactive source
The half-life of the radionuclide of the stability check source (if fitted) shall be greater than 5 years. 4.5 Uncertainty of measurement
To confirm that an instrument complies with a specified variation limit, the total uncertainty of the variable measurement shall be less than one fifth of the variation limit when measuring a variable
If the above requirements are not met and it is assumed that the total uncertainty of the measurement is less than one half of the variation limit, the total uncertainty of the measurement made in the verification test shall be the sum of the total uncertainty and the permissible variation limit to assess the instrument under test. If the total uncertainty exceeds one fifth of the variation limit, this shall be stated. NOTE: In this standard, the total uncertainty may be taken as an expanded uncertainty with a 9% margin. 5 Performance characteristic limits
5.1 Relative inherent error
The relative inherent error I of measuring air kerma K, air kerma length K·L and air kerma rate K under standard test conditions (as defined in Table 1) shall not exceed the values given in Tables 3 and 4. Verification test method:
Irradiate the radiation detector with a radiation beam that reproduces the geometric conditions and fields. When measuring the air kerma length, the radiation detector should be positioned on the central axis of the radiation beam: the irradiated length on the detector must correspond to 50% of the minimum rated length, and the air kerma length should not exceed 50% of the minimum rated length.1 On all air kerma rate ranges up to 1 Gy/s, when the air kerma rate exceeds the full scale reading, the dosimeter shall clearly indicate the over-range and shall maintain this indication. Verification method:
When the full scale reading is equal to or less than 10 mGy/s, the verification test shall be carried out for each permitted combination of air kerma rate range and detector components. Irradiate the relevant radiation detector with any suitable X-ray beam, with the air kerma rate of the beam just below the specified full scale reading, and then: a) increase the air kerma rate slowly and continuously until the display shows an over-range; b) increase the air kerma rate in steps of tenths of 10 mGy/s until it exceeds 10 mGy/s, checking that the display indicates an over-range at each discrete increase in air kerma rate. CB/119629--2005/1EC61674:1997 When the full-scale reading is greater than 10mGy/s, a verification test should be carried out for each permitted combination of air kerma rate range and detector components, as described above, or an electrical test should be carried out on the detector components to verify that the dosimeter clearly indicates the over-range condition for ion currents corresponding to air kerma rates up to 1(mGy/s, or to 10 times the full-scale reading. 4.4.5.2 On all air kerma and air kerma length ranges, the dosimeter should clearly indicate the over-range condition when the full-scale reading is exceeded. Verification test method: Air kerma and A verification test is performed on each range of the air kerma length. During the test, the relevant radiation detector is irradiated until the displayed reading is just below the specified full-scale value and then irradiation is continued, with increases approximately equal to the resolution of the air kerma or air kerma length range used, in discrete steps, until the display indicates an overrange. An equivalent electrical test may be performed on the measuring components.
4.4.5.3 On all air kerma and air kerma length ranges, the dosimeter shall clearly indicate an overrange when the rated range of the air kerma rate is exceeded unless the dosimeter is capable of measuring air kerma at least at the following air kerma rates: 1 Gy/s conventional diagnostic attenuated beam
—10 mGy/s conventional diagnostic attenuated beam
100 mGy/s unattenuated beam for breast imaging;
500 mGy/s Computer gradient image unattenuated beam: Verification test method:
Verification tests should be carried out for each range of air kerma and air kerma length. During the test, the air kerma rate of the irradiated relevant radiation detector shall exceed 10% of the rated range, and the check dosimeter clearly indicates the over-range condition. 4.4.6 Recovery or other inoperative indication
When the dosimeter is in the inoperative time, that is, after the recovery procedure, this state should be indicated and verified by visual inspection.
4.4.7 Multi-detector measurement components
For measurement components using multiple detectors and only one display, it can display air kerma or air kerma. The measuring unit shall show a signal from only one detector at any given time. This shall be verified by daylight inspection.
4.4.8 Stability check radioactive source
The half-life of the radionuclide of the stability check source (if fitted) shall be greater than 5 years. 4.5 Uncertainty of measurement
To confirm that an instrument complies with a specified variation limit, the total uncertainty of the variable measurement shall be less than one fifth of the variation limit when measuring a variable
If the above requirements are not met and it is assumed that the total uncertainty of the measurement is less than one half of the variation limit, the total uncertainty of the measurement made in the verification test shall be the sum of the total uncertainty and the permissible variation limit to assess the instrument under test. If the total uncertainty exceeds one fifth of the variation limit, this shall be stated. NOTE: In this standard, the total uncertainty may be taken as an expanded uncertainty with a 9% margin. 5 Performance characteristic limits
5.1 Relative inherent error
The relative inherent error I of measuring air kerma K, air kerma length K·L and air kerma rate K under standard test conditions (as defined in Table 1) shall not exceed the values given in Tables 3 and 4. Verification test method:
Irradiate the radiation detector with a radiation beam that reproduces the geometric conditions and fields. When measuring the air kerma length, the radiation detector should be positioned on the central axis of the radiation beam: the irradiated length on the detector must correspond to 50% of the minimum rated length, and the air kerma length should not exceed 50% of the minimum rated length.1 On all air kerma rate ranges up to 1 Gy/s, when the air kerma rate exceeds the full scale reading, the dosimeter shall clearly indicate the over-range and shall maintain this indication. Verification method:
When the full scale reading is equal to or less than 10 mGy/s, the verification test shall be carried out for each permitted combination of air kerma rate range and detector components. Irradiate the relevant radiation detector with any suitable X-ray beam, with the air kerma rate of the beam just below the specified full scale reading, and then: a) increase the air kerma rate slowly and continuously until the display shows an over-range; b) increase the air kerma rate in steps of tenths of 10 mGy/s until it exceeds 10 mGy/s, checking that the display indicates an over-range at each discrete increase in air kerma rate. CB/119629--2005/1EC61674:1997 When the full-scale reading is greater than 10mGy/s, a verification test should be carried out for each permitted combination of air kerma rate range and detector components, as described above, or an electrical test should be carried out on the detector components to verify that the dosimeter clearly indicates the over-range condition for ion currents corresponding to air kerma rates up to 1(mGy/s, or to 10 times the full-scale reading. 4.4.5.2 On all air kerma and air kerma length ranges, the dosimeter should clearly indicate the over-range condition when the full-scale reading is exceeded. Verification test method: Air kerma and A verification test is performed on each range of the air kerma length. During the test, the relevant radiation detector is irradiated until the displayed reading is just below the specified full-scale value and then irradiation is continued, with increases approximately equal to the resolution of the air kerma or air kerma length range used, in discrete steps, until the display indicates an overrange. An equivalent electrical test may be performed on the measuring components.
4.4.5.3 On all air kerma and air kerma length ranges, the dosimeter shall clearly indicate an overrange when the rated range of the air kerma rate is exceeded unless the dosimeter is capable of measuring air kerma at least at the following air kerma rates: 1 Gy/s conventional diagnostic attenuated beam
—10 mGy/s conventional diagnostic attenuated beam
100 mGy/s unattenuated beam for breast imaging;
500 mGy/s Computer gradient image unattenuated beam: Verification test method:
Verification tests should be carried out for each range of air kerma and air kerma length. During the test, the air kerma rate of the irradiated relevant radiation detector shall exceed 10% of the rated range, and the check dosimeter clearly indicates the over-range condition. 4.4.6 Recovery or other inoperative indication
When the dosimeter is in the inoperative time, that is, after the recovery procedure, this state should be indicated and verified by visual inspection.
4.4.7 Multi-detector measurement components
For measurement components using multiple detectors and only one display, it can display air kerma or air kerma. The measuring unit shall show a signal from only one detector at any given time. This shall be verified by daylight inspection.
4.4.8 Stability check radioactive source
The half-life of the radionuclide of the stability check source (if fitted) shall be greater than 5 years. 4.5 Uncertainty of measurement
To confirm that an instrument complies with a specified variation limit, the total uncertainty of the variable measurement shall be less than one fifth of the variation limit when measuring a variable
If the above requirements are not met and it is assumed that the total uncertainty of the measurement is less than one half of the variation limit, the total uncertainty of the measurement made in the verification test shall be the sum of the total uncertainty and the permissible variation limit to assess the instrument under test. If the total uncertainty exceeds one fifth of the variation limit, this shall be stated. NOTE: In this standard, the total uncertainty may be taken as an expanded uncertainty with a 9% margin. 5 Performance characteristic limits
5.1 Relative inherent error
The relative inherent error I of measuring air kerma K, air kerma length K·L and air kerma rate K under standard test conditions (as defined in Table 1) shall not exceed the values given in Tables 3 and 4. Verification test method:
Irradiate the radiation detector with a radiation beam that reproduces the geometric conditions and fields. When measuring the air kerma length, the radiation detector should be positioned on the central axis of the radiation beam: the irradiated length on the detector must correspond to 50% of the minimum rated length, and the air kerma length should not exceed 50% of the minimum rated length.
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