Ramani R, Lightstone A W, Mason D L, O'Brien P F
Toronto-Bayview Regional Cancer Centre, North York, Ontario, Canada.
Med Phys. 1994 Mar;21(3):389-92. doi: 10.1118/1.597385.
Standard silver-based films are usually too sensitive to be used as direct indicators of dose in dynamic radiosurgery because of optical saturation. This paper describes the use of a new radiochromic film to measure 6-MV radiosurgery doses and dose distributions in a head phantom. Dose calibration of the radiochromic film was performed in the range of 2.3-50.2 Gy using light of 632- and 530-nm wavelengths. Radiosurgery dose distributions were measured using the radiochromic film in a head phantom undergoing the same treatment as a patient, and were compared with the planned distributions. For an example case (nominal 2.0-cm-diam cone), film measurement verified the calculated dose distribution in one plane. The simple measurement technique described led to experimental uncertainties of +/- 0.1 cm for the 90% and 50% isodose lines, +/- 0.3 cm for the 20% line, and +/- 0.5 cm for the 10% line. Isocenter dose was measured with an uncertainty of +/- 3%. Refinements to the technique should allow more precise measurements. It is concluded that the radiochromic film, with some limitations, is a convenient and useful tool for dynamic radiosurgery quality assurance.
由于光学饱和，标准的银基胶片通常过于敏感，无法用作动态放射外科中剂量的直接指标。本文描述了使用一种新型放射变色胶片来测量头部模型中的6兆伏放射外科剂量和剂量分布。使用波长为632纳米和530纳米的光，在2.3 - 50.2戈瑞的范围内对放射变色胶片进行剂量校准。使用放射变色胶片在与患者接受相同治疗的头部模型中测量放射外科剂量分布，并与计划分布进行比较。对于一个示例病例（标称直径2.0厘米的圆锥体），胶片测量验证了一个平面内计算出的剂量分布。所描述的简单测量技术导致90%和50%等剂量线的实验不确定度为±0.1厘米，20%等剂量线为±0.3厘米，10%等剂量线为±0.5厘米。等中心剂量测量的不确定度为±3%。对该技术的改进应能实现更精确的测量。得出的结论是，尽管存在一些局限性，放射变色胶片仍是动态放射外科质量保证的一种方便且有用的工具。
