Operational radiation safety considerations during superficial x-ray treatment for veterinary applications
Date
2021
Authors
Singh, Ashutosh, author
Leary, Del, advisor
Johnson, Thomas, advisor
Wotman, Kathryn, committee member
Journal Title
Journal ISSN
Volume Title
Abstract
This study was conducted to determine whether the scatter x-ray emission during a superficial radiation treatment (SRT) using the SRT-100™ result in a significant occupational dose to veterinary personnel present in the room during treatment. Measurements were taken for 50, 70, and 100 kV x-ray for 9 different SRT-100 applicators. The exposure rates at the surface of solid water phantom (SWP) phantom ranged from 3.9 mR/hr for applicator #2 to 396 mR/hr for CB18 for 50 kV, from 41 mR/hr to 2,880 mR/hr for 70 kV, and from 235 mR/hr to 7,500 mR/hr, for 100 kV, respectively. A heat map of scatter x-ray around the x-ray source was generated for 50, 70, and 100 kV at 25 cm and 75 cm above the SWP surface plane. The highest measured exposure rate was at 0.5 m from the applicator and was 76.8 mR/hr at 25 cm above SWP and 33.6 mR/hr at 75 cm above the SWP for 50 kV. Exposure rate values at same locations were 192 mR/hr and 96 mR/hr for 70 kV, and 389 mR/hr and 194 mR/hr for 100 kV, respectively. A horse phantom was utilized to generate a spatial dose profile at 1m for 50, 70, and 100 kV and it was discovered that backscatter emission has an angular response. Residence time for veterinary staff to exceed 10% of quarterly dose limits were calculated for 50, 70, and 100 kV and distances ranging from 0.5m to 2.5 m. These values ranged from a minimum of 24 min for 100 kV at 0.5m to a maximum of 7,813 min for 50 kV at 2.5 m. Minimum distance from the applicator for exposure rates below 2 mR/hr were calculated to be 1.78, 2.52, and 3.45 m, for 50, 70, and 100 kV, respectively.