Strand S E, Strandh M
Radiation Physics Department, Lund University, Sweden.
Cancer. 1994 Feb 1;73(3 Suppl):985-8. doi: 10.1002/1097-0142(19940201)73:3+<985::aid-cncr2820731335>3.0.co;2-8.
For systemic radiation therapy, i.e., radioimmunotherapy, there is a demand for direct methods of measuring the absorbed dose in vivo. One such method is the use of mini-thermoluminescent dosimeters (TLDs). This paper reports an investigation of the sensitivity of tissue implanted mini-TLDs (calcium sulfate:Dy, 0.2 x 0.4 x 5.0 mm).
After being irradiated with cobalt-60, the mini-TLDs were left for as long as 9 days in air, gel, and muscle tissue.
There was an extensive signal loss, which increased with time, except in air. After 9 days in gel or muscle tissue at room temperature, the signal was decreased to one third of its original value. The dosimeters needed to be kept in constant darkness. There was a strong pH dependence, with a loss of sensitivity of 63% at a pH below 5, which got smaller at higher pH values and reached 10% at pH = 10.
When using mini-TLDs in vivo, one must calibrate the dosimeters in similar milieus, unless the position of the dosimeters in tissue after implantation can be monitored for temperature, pH, and liquid flow.
对于全身放射治疗，即放射免疫治疗，需要直接在体内测量吸收剂量的方法。一种这样的方法是使用微型热释光剂量计（TLD）。本文报告了对植入组织的微型TLD（硫酸钙：镝，0.2×0.4×5.0毫米）灵敏度的研究。
用钴-60照射后，微型TLD在空气、凝胶和肌肉组织中放置长达9天。
除了在空气中，存在广泛的信号损失，且随时间增加。在室温下于凝胶或肌肉组织中放置9天后，信号降至其原始值的三分之一。剂量计需要保存在持续黑暗中。存在很强的pH依赖性，在pH低于5时灵敏度损失63%，在较高pH值时损失变小，在pH = 10时达到10%。
在体内使用微型TLD时，必须在类似环境中对剂量计进行校准，除非植入后能监测剂量计在组织中的温度、pH和液体流动情况。
