This standard specifies the classification, test conditions, instrumentation, test methods and technical indicator error determination of exposure time of medical diagnostic X-ray machines. This standard is applicable to testing the single exposure time of various types of medical diagnostic X-ray machines. GB/T 11757-1989 Test method for exposure time of medical diagnostic X-ray machines GB/T11757-1989 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for the measurement of exposure time ofmedical diagnostic X-ray equipmentSubject content and scope of application
GB 11757-89
This standard specifies the classification, test conditions, instruments, test methods and error determination of technical indicators of exposure time of medical diagnostic X-ray equipment.
This standard is applicable to the testing of single exposure time of various types of medical diagnostic X-ray equipment. 2 Terminology
2.1 No-load exposure time
Control time of the exposure system of the X-ray equipment under the condition that no X-rays are generated. 2.2 Load exposure time
Under the condition that X-rays are generated, the time represented by the number of voltage peaks and half-peaks of the high-voltage primary of a single-bee or double-bee high-voltage generator is regarded as the load exposure time. For three-phase and secondary controlled X-ray generating devices, it refers to the time interval when the voltage of the X-ray tube in its high-voltage circuit rises to 65% to 85% of its peak value and drops to the above value. 3 Test method
3.1 Test conditions
3.1.1 Environmental conditions
a. Ambient temperature is 15 to 35°C;
Relative humidity is 45% to 75%;
Atmospheric pressure is 86×103 to 106×10°Pa; there is no corrosive and explosive gas or dust.
3.1.2 Power supply conditions
The apparent internal resistance of the power supply of the X-ray machine under test shall comply with the provisions of the relevant product standards; the power supply voltage waveform is a sine wave, and its allowable fluctuation range is 95% to 105% of the rated value; the allowable range of the power supply frequency value is 49.5 to 50.5Hz. 3.1.3 Length of high-voltage cable
When testing the load exposure time, the length of the additional high-voltage cable for the test shall not be longer than 1.5m for each cable. 3.1.4 Thermal balance
When testing the load exposure time, the product under test shall be tested in a thermal equilibrium state. Unless otherwise specified, the product under test can be considered to be in a thermal equilibrium state after working for 0.5h under a load of 60% to 100% of the nominal output of the perspective. 3.2 Test instruments
Approved by the State Administration of Technical Supervision on October 20, 1989 and implemented on July 1, 1990
GB 11757--89
3.2.1 When testing the no-load exposure time, the following test instruments shall be used: 3.2.1.1 When the shortest time division of the product under test is ≥0.2s, an electric stopwatch may be used. 3.2.1.2 When the shortest time division of the product under test is <0.2s, the test instruments that can be used are: a digital timer that works in pulse trigger mode; a.
a digital timer that can measure the on-off interval; b.
an electronic oscilloscope that can measure the pulse width less than 0.1s. 3.2.2 When testing the load exposure time, a digital timer or an electronic oscilloscope with the function of distinguishing the pulse amplitude can be used. 3.3 Test requirements
3.3.1 Before testing, perform an inspection in accordance with the provisions of Article 4.1 and monitor its changes at any time. Perform an adjustment in accordance with the installation and operating instructions of the product under test. After the product can work normally, test the exposure time. 3.3.2 When testing the no-load exposure time, connect the test instrument to the open circuit point of the primary open circuit of the high-voltage generator. If the product under test is a secondary control type, the method of testing the control signal that ensures the generation of X-rays can be used instead of testing the no-load exposure time. 3.3.3 When testing the no-load exposure time, all time bins of the product under test must be tested. Measure each bin five times and take the average value. 3.3.4 When testing the load exposure time, connect the test instrument to the monitoring point specified in the instruction manual of the product under test. Set the load condition to 30% to 50% of the rated capacity of the X-ray tube. 3.3.5 When testing the load exposure time, five of the time bins of the product under test must be selected for testing, including the shortest time, 0.1s, 3.2s or the smaller of the longest time. Measure each bin three times and take the average value. 4
Calculation of test results and determination of errors
4.1 The exposure time error of the tested product is calculated as follows according to the average error percentage: PAE=$=×100%
Where: PAE—-
The average error percentage of the test result,bzxZ.net
t——-The predicted value of the time bin;
-The average value of each bin test.
4.2 During the test, the combined error of the test instrument and the test method should not exceed 30% of the allowable error of the test result. 4.3 The error of the test result includes the combined error of the measurement method. Additional notes:
This standard was proposed by the National Medical Electrical Standardization Technical Committee. This standard is under the jurisdiction of the Liaoning Provincial Medical Device Research Institute. This standard was drafted by Beijing Medical Radiation Machine. The main drafter of this standard is Mei Jinduo.
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