Optical density dependence on postirradiation temperature and time for MD-55-2 type radiochromic film
Optical density dependence on postirradiation temperature and time for MD-55-2 type radiochromic film
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DOI：
10.1118/1.598538
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发表时间：
1999-03-01
期刊：
影响因子：
3.8
通讯作者：
Gluckman, GR
中科院分区：
文献类型：
--
作者：
Reinstein, LE;Gluckman, GR
几年来，各种形式的GAFChromic胶片（GC）已被用作射线照相介质，用于测量近距离放射治疗源和小辐射野的剂量分布。一种新的双层膜，称为MD-55-2，现在提供，是有用的临床剂量范围。本文研究了这种新型辐射变色胶片在光密度测量中的辐射后贮存效应和温度的可逆效应。发现用He-Ne激光密度计（632.8 nm）测量的光密度的可逆变化在18-30 ℃的范围内变化小于1%，但是用光源福尔斯落在左手侧（即，较短的波长）的GC膜的主要吸收峰的依赖性被发现高达2%/摄氏度。发现膜不可逆地变暗（辐射后）的速率取决于储存温度。在典型的临床条件下（20-25摄氏度），他变暗的初始速率可以变化多达1.5倍。此外，储存温度被发现会影响光学吸光度的渐近值。对于30-35 ℃的储存温度，吸光度的极限值比储存在较低温度下的样品高约4%，这些样品已经被照射到相同的剂量。(C)1999年美国医学物理学家协会。【S0094-2405（99）00103-0】。
Various forms of GAFChromic film (GC) have been used for several years as radiographic media for measuring dose distributions of brachytherapy sources and small radiation fields. A new double layer film, referred to as MD-55-2 is now offered and is useful for clinical dose ranges. In this paper we study the effect of postirradiation storage and the reversible effects of temperature during optical density measurements for this new radiochromic film. The reversible change in optical density measured with a He-Ne laser densitometer (632.8 nm) was found to vary by less than 1% over the range 18-30 degrees C, but with densitometers whose light source falls on the left-hand side (i.e., shorter wavelengths) of the GC film's major absorbance peak the dependence was found to be as high as 2%/degrees C. The rate at which the film darkens irreversibly (postirradiation) was found to depend on the storage temperature. In typical clinical conditions (20-25 degrees C), the initial rate at which the him darkens can vary by as much as a factor of 1.5. Furthermore, the storage temperature was found to affect the asymptotic value for the optical absorbance. For storage temperatures of 30-35 degrees C, the limiting values of the absorbance were approximately 4% higher than samples stored at lower temperatures, which had been irradiated to the same dose. (C) 1999 American Association of Physicists in Medicine. [S0094-2405(99)00103-0].