Shielding of medical imaging X-ray facilities: a simple and practical method
Tóm tắt
The most widely accepted method for shielding design of X-ray facilities is that contained in the National Council on Radiation Protection and Measurements Report 147 whereby the computation of the barrier thickness for primary, secondary and leakage radiations is based on the knowledge of the distances from the radiation sources, the assumptions of the clinical workload, and usage and occupancy of adjacent areas. The shielding methodology used in this report is complex. With this methodology, the shielding designers need to make assumptions regarding the use of the X-ray room and the adjoining areas. Different shielding designers may make different assumptions resulting in different shielding requirements for a particular X-ray room. A more simple and practical method is to base the shielding design on the shielding principle used to shield X-ray tube housing to limit the leakage radiation from the X-ray tube. In this case, the shielding requirements of the X-ray room would depend only on the maximum radiation output of the X-ray equipment regardless of workload, usage or occupancy of the adjacent areas of the room. This shielding methodology, which has been used in South Australia since 1985, has proven to be practical and, to my knowledge, has not led to excess shielding of X-ray installations.
Tài liệu tham khảo
Australian/New Zealand Standard (AS/NZS) 3200.1.3:1996) (1996) Approval and test specification—medical electrical equipment. Part 1.3: General requirements for safety –collateral standard: requirements for radiation protection in diagnostic X-ray equipment (The Standard has been reproduced from the International Electrotechnical Commission (IEC) 601-1-3:1994, medical electrical equipment, Part 1: General requirements for safety – 3. Collateral standard: general requirements for radiation protection in diagnostic X-ray equipment)
National Council on Radiation Protection and Measurements (NCRP) (2005) Structural shielding design for medical X-ray imaging facilities. NCRP Report No. 147. Bethesda, Maryland
National Council on Radiation Protection and Measurements (NCRP) (1976) Structural shielding design and evaluation for medical use of X rays and gamma rays of energies up to 10 MeV. NCRP Report No. 49. Bethesda, Maryland
Archer BR, Thornby JI, Bushong SC (1983) Diagnostic X-ray shielding design based on an empirical model of photon attenuation. Health Phys 44(5):507–517
The Ionizing Radiation Regulations (1985) Regulations made under the Radiation Protection and Control Act, 1982. The South Australian Government Gazette, 4 April pp 993–1107
Bibbo G (1988) Shielding requirements for diagnostic and therapeutic X-ray apparatus in South Australia: regulatory requirements, specification and assessment of X-ray rooms. Presented at the seventh international congress of the International Radiation Protection Association, Sydney, Australia, 10–17 April
Radiation Protection and Control (Ionising Radiation) Regulations (2015) https://www.legislation.sa.gov.au/LZ/C/R/Radiation%20Protection%20and%20Control%20(Ionising%20Radiation)%20Regulations%202000.aspx. Accessed 30 Sept 2016
Simpkin DJ (1996) Evaluation of NCRP Report 49 assumptions on workloads and use factors in diagnostic radiology facilities. Med Phys 23:577–584
Fog LS, Cormack J (2010) Mathematical modelling of the radiation dose received from photons passing over and through shielding walls in a PET/CT suite. Health Phys 99:769–779
Wallace H, Martin CJ, Sutton DG, Peet D, Williams JR (2012) Establishment of scatter factors for use in shielding calculations and risk assessment for computed tomography facilities J. Radiol Prot 32:39–50
Martin CJ, Sutton DG, Magee J, McVey S, Williams JR, Peet D (2012) Derivation of factors for estimating the scatter of diagnostic X-rays from walls and ceiling slabs. J Radiol Prot 32:373–396. doi:10.1088/0952-4746/32/4/373
Simpkin DJ, Dixon RL (1998) Secondary shielding barriers for diagnostic X-ray facilities: scatter and leakage revisited. Health Phys 74(3):350–365
Simpkin DJ (1995) Transmission data for shielding diagnostic X-ray facilities. Health Phys 68(5):704–709