title: Health physics aspects in treatment rooms after 18-MV X-ray irradiations.
abstract: Delayed activation products contribute to the exposure of the staff operating high-energy accelerators. Induced activity was studied in a treatment room following 18-MV X-ray irradiations using a hand-held system that allows both dose rate measurements and spectroscopic analysis. The major activation products and the corresponding nuclear reactions were identified. At the majority of the studied locations, β(+) emitters were the main short-term dose contributors. The time variation of the absorbed dose rate in a treatment room during the first 20-min post-irradiation was represented by the sum of two exponential components with half-lives of 1-2 min and either 4 or 10 min, depending on the location in the room. Components with a half-life of hours or days contribute <1 % to the initial dose rate. The activation of some accessories, such as iron filters and portal imagers, deserve special attention. The collection of such data with the proposed method allows the development of optimised working protocols at each treatment room.
authors: Medical Physics Department, University of Ioannina and Ioannina University Hospital, 45510 Ioannina, Greece. jkalef@cc.uoi.gr
authors: John A
authors: JA
authors: Kalef-Ezra
mesh_terms: D006207:Half-Life; D006283:Health Physics; D006801:Humans; D016273:Occupational Exposure / Q000517:prevention & control*; D010315:Particle Accelerators / Q000295:instrumentation*; D019047:Phantoms, Imaging; D011834:Radiation Monitoring; D011835:Radiation Protection; D011882:Radiotherapy, High-Energy / Q000009:adverse effects*; D018570:Risk Assessment; D014965:X-Rays