An introduction to the quality control of radiation hygiene protection
Radiation work unit radiation equipment and work site conditions are often different, some more complex, how the quality control of radiation hygiene protection?
1 detector quality control
On-site detector is the main body of radiation health protection detection work, but also the detection of the key point of quality control. Radiological health protection detection of professional and technical quality and ability to detect the most fundamental factors to ensure the quality of detection work. Therefore, the staff engaged in testing must pass the training and assessment of radiation hygiene technical service capacity, licensed to work. Should understand and master the national technical specifications for radiation health protection testing, standards and national radiation health and laboratory quality management and other relevant laws and regulations. With health testing and inspection and other related basic knowledge, with correct and skillful radiation health protection testing operation skills. Correctly grasp the performance of radiation hygiene protection testing instruments and equipment, the use of methods, precautions, familiar with the quality manual and program documents and other laboratory quality management system. At the same time, in the process of on-site testing work to adhere to the principles of science, impartiality, confidentiality, seeking truth from facts, and shall not be falsified and other disciplinary actions.
2 establish a sound quality management control system
The establishment and effective implementation of a more complete laboratory quality management control system is the fundamental guarantee of the quality of radiation health protection testing. Radiation work units to provide scientific and accurate health testing data is the statutory obligation of radiation health technology service organizations. Therefore, radiation health technology service organizations should be based on the "Laboratory Accreditation Review Guidelines" requirements for the development of the corresponding quality management manual [8], procedural documents, operating instructions and operating procedures for testing instruments and equipment. Such as the development of "on-site testing record procedures", "on-site testing control procedures", "equipment during the verification program", "equipment testing, calibration (traceability) program", "testing instrument access procedures", "customer service procedures", "corrective action procedures" and each testing instrument operating procedures or rules.
3 on-site quality control of testing instruments and equipment
On-site inspectors are familiar with and master the working conditions of the testing instruments and equipment, such as the use of environmental and meteorological conditions, use of the range, detection range, sensitivity, stability, accuracy, error, measurement standards and standards for the accuracy of the test results is critical. Each testing instrument and equipment should establish an equipment use ledger, develop instrument and equipment testing, calibration program, and regularly send the appropriate qualifications of quality and technical certification bodies to test or calibrate. Set up a person to keep, responsible for instrument and equipment maintenance and maintenance, in and out of the warehouse use records. Testing personnel should regularly check the operation of instruments and equipment and make records. Before the use of testing instruments and equipment should be calibrated or period verification of instrumentation to ensure the traceability and reliability of test results. After the use of testing instruments and equipment, should be returned to the instrument room to save, and make a good use of registration. The newly purchased testing instruments and equipment, acceptance of personnel should be required by the instruction manual to confirm the quality of the instrumentation, performance and so on.
4 on-site quality control of the detection process
Radiological work unit radiation equipment and work site conditions are often different, some more complex, directly affecting the detection results. Therefore, the quality control of the on-site testing process is extremely important. Each time before the test should be on-site inspection staff for training, including the purpose of testing, planning and organization, testing technology and methods of specific guidance and requirements, record filling and work responsibilities, etc., in order to ensure the quality of testing work. On-site inspectors should focus on the following aspects of quality control when testing.
4.1 Selection of detection methods
Selection of the correct detection method is a prerequisite for good detection work, but also the detection of data representative of the data, authenticity, accuracy and reliability of the fundamental guarantee. Therefore, according to the radiation generated by the radiological work equipment, environmental conditions, the applicability of detection methods to choose the correct detection method. The principle of method selection is to prioritize the use of national standard testing methods, international standards, industry standards and other provisions of the testing method [9].
4.2 Selection of testing points
Select representative, reflecting the real state of radiation health protection testing points to detect the test data obtained in order to scientifically evaluate radiation health protection. According to GBZ138-2002 "medical X-ray diagnostic health protection monitoring norms" requirements, in the useful beam incident body surface air specific kinetic energy rate detection, if the ordinary fluorescent screen X-ray machine, the detector should be placed in the center of the useful beam; in the fluoroscopic fluorescent screen sensitivity detection, should be in the smallest distance between the table screen, the irradiation field to the maximum, the detector will be placed in the screen fluorescent ray incident surface position for detection. GBZ165-2012 "X-ray Computed Tomography Radiation Protection Requirements" stipulates that, in the CT room four walls, floors, protective doors for protection detection, the detection point is located in the distance from the wall or protective door of the room for 30cm, the height from the ground is 130cm. the detection point above the ceiling is 100cm from the ceiling floor, and the detection point below the floor is 170cm from the floor below. At the same time, the standard also requires that in the CT dose index measurement, should be in accordance with the provisions of the selection of the corresponding test module, placed in the examinee bracket, located in the center of the scanning axis of rotation.
4.3 Detection category and selection of test items Radiological health protection present
Field testing is based on the purpose and requirements of the test to determine, can be divided into radiation workplace protection testing and radiation work equipment quality control testing.GBZ131-2002 "medical X-ray therapy health protection standards" [10], GB16361-2012 "clinical GB16361-2012 Clinical Nuclear Medicine Patient Protection and Quality Control Standards [11], GB16362-2010 Teletherapy Patient Radiation Protection and Quality Assurance Requirements [12] and other national health standards will be radiological work equipment quality control testing is divided into three categories: acceptance testing, state testing and stability testing. Acceptance testing is the radiological work equipment after installation or major maintenance, in order to identify its performance indicators are in line with the agreed value of quality control testing; state testing is the operation of the radiological work equipment, in order to evaluate its performance indicators are in line with the agreed value of regular quality control testing; stability testing is to determine the performance of the equipment in use relative to an initial state of change in line with the control standards and quality control testing. Stability testing is a quality control test to determine whether changes in the performance of equipment in use relative to an initial state comply with control standards [13]. What type of testing is carried out according to the requirements of the work or specific circumstances. Such as GBZ161-2004 "medical? Beam teletherapy protection and safety standards" stipulates that where one of the following circumstances [14], acceptance testing should be carried out: the new acquisition or introduction of? Teletherapy equipment; replacement of radioactive sources `? Teletherapy equipment; after major repairs? Teletherapy equipment; idle or out of service for more than 6 months and reactivated? Teletherapy equipment; new construction, remodeling, expansion and renewal of ? Teletherapy rooms, etc. The test items are evaluation indicators, related to the test category.GB17589-2011 "X-ray computed tomography device quality assurance testing specifications" provides that for acceptance testing, the test items are 11 items; for status testing, the test items are 10 items; for stability testing, the test items are only 7 items. Only according to the national standard requirements of the project to carry out a comprehensive test, in order to scientific and standardized radiological health protection evaluation.
4.4 Quality control of on-site testing
Before conducting on-site testing of radiation hygiene protection, the inspector must read the instructions for the use of testing instruments in detail, and familiarize themselves with the performance of the instrument and its scope of application. When the test, should check the site to detect whether the environmental conditions to meet the conditions of use of the instrument and equipment. Such as GBZ138-2002 "medical X-ray diagnostic health protection monitoring norms" provides that the instrument used for stray radiation protection detection should have the following main properties: the minimum range, 0?Gy?h-1 ~ 10?Gy?h-1; energy response: 10KeV ~ 60KeV?40%; readings response time <15s; should be measured cumulative dose file. And according to the instrument and equipment operating instructions for operation. If you find that the instrument or equipment is damaged or malfunctioning, it should be immediately deactivated and repaired in a timely manner. After repair by the calibration or verification of qualified before use, to ensure that do not use unqualified testing instruments and equipment.
5 on-site testing of the original records of quality control
Do a good job on-site testing records is one of the important elements of radiation health protection testing, should be carefully filled in according to the "on-site testing records program" requirements on-site testing records. Records in line with the quality control provisions of the unified format of the record table, form content must be filled out to achieve real, scientific, accurate, complete information, not missing, missing items, and clear handwriting, writing standards. Accurately draw a plan of the testing site, labeling the testing points and directions, etc.. And detailed records of the test site environmental temperature, humidity, air pressure and other environmental gas conditions. Need to change the record, should be in accordance with the requirements of the regulations. And according to the record keeping requirements to do a good job of filing and preservation.
6 quality control of the test results
The data obtained from the test is related to the sensitivity and resolution of the detection instrument. If the measurement results below the detection limit of the data, should be recorded as below the detection limit, and at the same time record the detection limit of the method. In the judgment of the data below the resolution of the detection instrument and the judgment of the calculated data is generally retained one, should not be too detailed judgment. In the detection and analysis, if any obvious error or deviation is found, the corresponding data should be eliminated or re-tested to ensure that the test results are in line with the objective reality. The test data obtained to organize and analyze, and compared with the national health standards, the unit to be tested to make radiation health protection testing and evaluation report, and put forward recommendations for improvement.
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