Discussion on quality control of radiation health protection

Discussion on quality control of radiation health protection

Radiation equipment in radiation work units is often different from that in the workplace, and some of them are more complicated. How to control the quality of radiation health protection?

1 inspector's quality control

On-site inspectors are the main body of radiation health protection inspection and the key point of inspection quality control. The professional and technical quality and ability of radiation health protection inspectors are the most fundamental factors to ensure the quality of testing work. Therefore, the staff engaged in testing must pass the training and assessment of radiation health technical service ability and hold relevant certificates. We should understand and master the national technical specifications and standards for radiation protection testing, national radiation hygiene and laboratory quality management and other relevant laws and regulations. Have the basic knowledge of health inspection and other related knowledge, and have correct and skilled operation skills of radiological protection inspection. Correctly grasp the performance, usage and precautions of radiation protection testing instruments and equipment, and be familiar with laboratory quality management systems such as quality manuals and program documents. At the same time, adhere to the principles of science, justice, confidentiality and seeking truth from facts in the process of on-site inspection, and do not resort to deceit or other irregularities.

2 establish and improve the quality management control system

Establishing and effectively implementing a relatively perfect laboratory quality management control system is the fundamental guarantee for the quality of radiation health protection testing. It is the legal obligation of radiation health technical service institutions to provide scientific and accurate health test data for radiation work units. Therefore, radiation health technical service institutions should formulate corresponding quality management manuals [8], procedural documents, work instructions and operating procedures for testing instruments and equipment according to the requirements of Laboratory Qualification Accreditation Criteria. For example, the recording program of on-site inspection, the control program of on-site inspection, the verification program during equipment, the inspection and calibration program of equipment (traceability of values), the inspection instrument in and out of the warehouse, the customer service program, the error correction program, and the operating rules or detailed rules of each inspection instrument are formulated.

3 quality control of on-site testing instruments and equipment

It is very important for on-site inspectors to be familiar with and master the working conditions of testing instruments and equipment, such as environmental meteorological conditions, application scope, testing scope, sensitivity, stability, accuracy, error, measurement standards and benchmarks. To ensure the accuracy of the test results. For each testing instrument and equipment, an equipment use ledger shall be established, a verification and calibration plan for the instrument and equipment shall be formulated, and the equipment shall be regularly sent to a quality and technical verification institution with corresponding qualifications for verification or calibration. Designate special personnel to keep it, and be responsible for the maintenance of instruments and equipment, and keep the use records of warehousing. Testers should regularly check the operation of instruments and equipment and make records. Before use, testing instruments and equipment should be calibrated or verified during use to ensure the traceability and reliability of testing results. After the testing instruments and equipment are used, they should be sent back to the instrument room for preservation and registration. For newly purchased testing instruments and equipment, the inspector shall confirm the quality and performance of the instruments and equipment according to the requirements of the instruction manual.

4. Quality control of on-site inspection process

The radiation equipment of radiation work unit is often different from the work site, and some of them are more complicated, which directly affects the test results. Therefore, the quality control of on-site inspection process is extremely important. Before each inspection, on-site inspectors should be trained, including inspection purpose, planning, specific guidance and requirements of inspection techniques and methods, record filling and job responsibilities. , to ensure the quality of inspection work. On-site inspectors should focus on the following aspects of quality control during testing.

4. 1 detection method selection

Choosing the correct detection method is the premise of doing a good job of detection, and it is also the fundamental guarantee for the representativeness, authenticity, accuracy and reliability of detection data. Therefore, the correct detection method should be selected according to the radiation generated by the radiation working device, environmental conditions and the applicability of the detection method. The principle of method selection is to give priority to the standard detection methods specified by national, international standards and industry standards [9].

4.2 Selection of detection points

Only by selecting representative inspection points that can reflect the real situation of radiation health protection can the evaluation of radiation health protection be carried out scientifically. According to the requirements of GBZ 138-2002 Monitoring Standard for Medical X-ray Diagnosis and Health Protection, when detecting the specific kinetic energy of the air on the surface of the useful beam, if it is an ordinary fluorescent screen X-ray machine, the detector should be placed in the center of the useful beam; When testing the sensitivity of the perspective screen, the detector should be placed on the light incident surface of the screen and tested under the conditions of minimum screen distance and maximum exposure field. GBZ165-2012 "Radiological Health Protection Requirements for X-ray Computed Tomography" stipulates that when testing the walls, floors and protective doors of the CT computer room, the testing point should be set at a distance of 30cm from the walls or protective doors of the computer room and a height of 130cm from the ground. The detection point above the ceiling is 100cm away from the ceiling floor, and the detection point below the computer room floor is 170cm away from the downstairs floor. At the same time, the standard also requires that when measuring CT dose index, the corresponding test module should be selected according to the regulations and placed on the patient's bracket, which is located in the center of the scanning rotation axis.

4.3 Selection of testing categories and testing items Radiation health protection now

On-site inspection work is determined according to the purpose and requirements of inspection, which is divided into radiation workplace protection inspection and radiation work equipment quality control inspection. GBZ 13 1-2002 Health Protection Standard for Medical X-ray Therapy [10], GB1631-2012 Clinical Nuclear Medicine Patient Protection and Quality Control Standard [12] Acceptance inspection of national health standards such as radiation protection requirements is a quality control inspection to identify whether the performance index of radiation working equipment meets the agreed value after installation or major maintenance; Condition detection is the periodic quality control detection of radiation working equipment in operation to evaluate whether its performance index reaches the agreed value; Stability testing is a kind of quality control testing, which is used to determine whether the change of equipment performance in use relative to the initial state meets the control standard [13]. What kind of test to carry out depends on the job requirements or specific circumstances. Such as GBZ 16 1-2004 "medical care? The Protection and Safety Standard for Beam Teletherapy stipulates that [14] in any of the following circumstances shall be accepted: newly purchased or imported? Teletherapy equipment; Replace the radioactive source? Teletherapy equipment; After the overhaul? Teletherapy equipment; Idle or inactive for more than 6 months before reactivating? Teletherapy equipment; New construction, renovation, expansion and continuation? Teletherapy room, etc. Test items are indicators of evaluation and are related to test categories. GB17589-2011The inspection items specified in the Quality Assurance Inspection Standard for X-ray Computerized Tomography Devices are11; When performing state detection, the detection item is10; When carrying out the stability test, only seven test items are needed. Only by comprehensively testing the items required by national standards can radiation protection evaluation be carried out scientifically and normatively.

4.4 Quality control of on-site inspection

Before the on-site inspection of radiation health protection, inspectors must read the instructions of the inspection instrument in detail and be familiar with the performance and application scope of the instrument. When testing, it should be checked whether the environmental conditions of on-site testing meet the conditions of use of instruments and equipment. GBZ 138-2002 "Medical X-ray Diagnostic Health Protection Monitoring Specification" stipulates that the instruments used for stray radiation protection detection should have the following main performance: minimum range, 0? Gy？ h- 1~ 10？ Gy？ h- 1； Energy response: 10 kev ~ 60 kev? 40%; Reading reaction time

5 Quality control of original records of on-site inspection

Making on-site inspection records is one of the important contents of radiological protection inspection, and the on-site inspection records should be filled in according to the requirements of on-site inspection record procedure. Records shall be in a uniform format in accordance with quality control regulations. The contents of the form must be true, scientific and accurate, with complete information, no omissions, clear handwriting and standardized writing. Draw the inspection site plan accurately, and mark the inspection points and directions. And record the environmental gas conditions such as temperature, humidity and air pressure in detail. When it is necessary to change the record, it shall be carried out in accordance with the prescribed requirements. And do a good job of filing and preservation according to the requirements of record preservation.

6 Quality control of test results

The data obtained by detection is related to the sensitivity and resolution of the detection instrument. If the measurement result is lower than the detection limit, it shall be recorded as lower than the detection limit, and the detection limit of this method shall be recorded at the same time. Generally, one bit should be reserved when judging the data below the resolution of the detection instrument and the calculated data, and it is not appropriate to make too detailed judgment. In the detection and analysis, if obvious errors or deviations are found, the corresponding data should be eliminated or re-tested to ensure that the detection results conform to the objective reality. Collate and analyze the test data obtained, and compare them with the national health standards, make an evaluation report on radiation health protection for the inspected units, and put forward suggestions for improvement.

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