Ostwald P M, Kron T, Hamilton C S, Denham J W
Department of Radiation Oncology, Newcastle Mater Misericordiae Hospital, Waratah, NSW, Australia.
Int J Radiat Oncol Biol Phys. 1995 Nov 1;33(4):943-50. doi: 10.1016/0360-3016(95)00274-4.
Carbon-loaded thermoluminescent dosimeters (TLDs) are designed for surface/skin dose measurements. Following 4 years in clinical use at the Mater Hospital, the accuracy and clinical usefulness of the carbon-loaded TLDs was assessed.
Teflon-based carbon-loaded lithium fluoride (LiF) disks with a diameter of 13 mm were used in the present study. The TLDs were compared with ion chamber readings and TLD extrapolation to determine the effective depth of the TLD measurement. In vivo measurements were made on patients receiving open-field treatments to the chest, abdomen, and groin. Skin entry dose or entry and exit dose were assessed in comparison with doses estimated from phantom measurements.
The effective depth of measurement in a 6 MV therapeutic x-ray beam was found to be about 0.10 mm using TLD extrapolation as a comparison. Entrance surface dose measurements made on a solid water phantom agreed well with ion chamber and TLD extrapolation measurements, and black TLDs provide a more accurate exit dose than the other methods. Under clinical conditions, the black TLDs have an accuracy of +/- 5% (+/- 2 SD). The dose predicted from black TLD readings correlate with observed skin reactions as assessed with reflectance spectroscopy.
In vivo dosimetry with carbon-loaded TLDs proved to be a useful tool in assessing the dose delivered to the basal cell layer in the skin of patients undergoing radiotherapy.
碳负载热释光剂量计（TLD）专为表面/皮肤剂量测量而设计。在 Mater 医院临床使用 4 年后，对碳负载 TLD 的准确性和临床实用性进行了评估。
本研究使用直径为 13 mm 的基于聚四氟乙烯的碳负载氟化锂（LiF）圆盘。将 TLD 与电离室读数和 TLD 外推法进行比较，以确定 TLD 测量的有效深度。对接受胸部、腹部和腹股沟野照射治疗的患者进行体内测量。将皮肤入射剂量或入射和出射剂量与从体模测量估计的剂量进行比较评估。
以 TLD 外推法作为比较，发现在 6 MV 治疗性 X 射线束中的有效测量深度约为 0.10 mm。在固体水体模上进行的入射表面剂量测量与电离室和 TLD 外推测量结果吻合良好，黑色 TLD 比其他方法能提供更准确的出射剂量。在临床条件下，黑色 TLD 的准确度为±5%（±2 标准差）。黑色 TLD 读数预测的剂量与用反射光谱法评估的观察到的皮肤反应相关。
事实证明，使用碳负载 TLD 进行体内剂量测定是评估接受放射治疗患者皮肤基底细胞层所接受剂量的有用工具。
