TOTAL BODY IRRADIATION DOSIMETRY OF A LOW DOSE RATE 60CoGAMMA FIELD

Fizika B (Zagreb)

MLADEN VRTAR¹ 

关键词: in-vivo dosimetry;    silicon detector;    total body irradiation;   

DOI  :  

学科分类：物理（综合）

来源: Fizika B: a journal of experimental and theoretical physics

【 摘 要 】

An in-vivo dosimetry procedure for direct patient dose reading can help to definedeviations of the actually delivered dose from the prescribed one. It is routinelyperformed by the use of external measurements, i.e. entrance and and exit dose readings atcertain locations in the body. This article presents a method for the absorbed dosedetermination of the patient situated in a large ⁶⁰Co gamma field, as in totalbody irradiation (TBI), during in-vivo irradiation and the radiation field analysis atextended distance (in low dose rate conditions) prior to the actual in vivo treatment. Thenew approach consists of: (1) adjusting the real patient's anatomical data (anteriorposterior thickness at a number of points) to the theoretical model of an anthropomorphicphantom of a shape of an elliptical cylinder, and (2) using a n-type silicon fielddetector with increased sensitivity for the purpose of radiation-field analysis prior tothe actual in vivo TBI treatment. Namely, the standard p type field detector, ascommercially available for routine radiation field analysis at short distances and highdose rates, was not suitable for radiation field analysis under TBI conditions, becausethe signal was too weak. Dependence of the calibration factor of the silicon detector,exposed to different dose rates in standard and large field irradiation conditions, wasinvestigated. The detector was found to be suitable for TBI measurements. This wasconfirmed, among others, in a depth dose curve's behaviour as compared to the resultsobtained by the standard p-type silicon detector at extended distances.

【 授权许可】

Unknown