Radiation Protection Requirements For Medical X-ray Therapy
The International Atomic Energy Agency (IAEA) Technical Report No. 277 (TRS277) divides the energy range of low and medium energy X-rays into: 10-100kV for low-energy X-rays and 100-300kV for medium-energy X-rays. In China, there are usually three types of therapeutic X-rays used in clinical practice, namely contact treatment 10-60kV (0-1.0mmAl filter); shallow treatment 80-120kV (1-1.4mmAl filter) and deep treatment 150-400kV ( 0.5mmCu composite filter). Due to the low radiation energy of X-ray tube treatment equipment, it is easy to cause loopholes in protection design and supervision. As a standard for medical X-ray radiotherapy protection and equipment testing, this standard is not only a technical basis for testing and evaluation, but also a technical support document for administrative licensing and supervision of radiological health.
The performance of such magic machines meet the requirements of clinical treatment and protection, and relevant type tests and other work should replace the "Health Protection Standards for Medical X-ray Therapy" (GBZ 131-2002). Compared with GBZ 131-2002, the main technical content changes include:
(1) The location requirements for the setting of the treatment room have been deleted. The original standard proposed that the X-ray treatment room should generally be set up at one end of the ground floor of the building. According to the survey of the setting conditions of this type of radiotherapy unit, the medical X-ray treatment room can be set up in a suitable location in the hospital, which can be the second floor. The space above and above is not necessarily set on the ground floor or one end;
(2) The dose control requirements for the shielding protection of the treatment room have been added: "The surrounding dose equivalent rate at a distance of 0.3 m from the outer surface of the shielding body of the treatment room and the annual effective dose received by the personnel at the place of interest shall meet the requirements of GBZ/T 201.1." . In the revision, it is clarified that this standard is related to GBZ/T201.1 in terms of dose control;
(3) The relevant description of the inspection by the management department has been deleted. Since supervision and testing are basically separated, the testing of radiological diagnosis and treatment equipment, including acceptance testing and status testing, can only be undertaken by qualified technical service organizations;
(4) The type test and inspection requirements of the therapeutic machine manufacturer have been deleted. The revision of this standard is, in principle, to make it more conducive to testing institutions and medical institutions to carry out radiological health protection, to make it easier for radiological health supervision departments to grasp the substance of the standard, and to better carry out the protection and quality control of radiological diagnosis and treatment equipment. The manufacturer of the treatment machine mainly controls the quality of the products delivered to ensure that the dosimetry indicators and various technical performances of the equipment meet the requirements of clinical treatment and protection. The relevant type tests and other work are carried out before the equipment leaves the factory. This standard mainly focuses on X Protection during use of radiotherapy machine;
(5) Update the "Detection Method" to "Detection Conditions and Method Requirements", describing the basic requirements of leakage radiation, radiation output, output repeatability, and linear output detection conditions and methods;
(6) An appendix has been added to list the main items and technical requirements to be tested by medical X-ray therapy machines, and supplement the lead equivalent of the shielding body required for the attenuation of X-ray useful beams 106 and 104 under the conditions of rated tube voltage of 50~400kV, so as to facilitate Reference for related personnel.
