Fenning M C, Brown D Q, Chapman J D
Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.
Med Phys. 1994 Jul;21(7):1149-56. doi: 10.1118/1.597342.
Both anaplastic and well-differentiated Dunning prostate adenocarcinomas were illuminated in anesthetized Fischer X Copenhagen rats by single-fiber and multiple-fiber illuminators. Each illuminator consisted of a 2-cm laterally diffusing optical fiber placed within a plastic brachytherapy needle which was implanted into a tumor. Light attenuation coefficients for various wavelengths were obtained from measures of the radial falloff of intensity with distance from single fibers. These coefficients served as input to a 2-dimensional (2-D) photodosimetry computer code which calculated relative light intensities in planes perpendicular to single-fiber and various multiple-fiber configurations. These calculations assumed uniform optical property of tissue throughout each tumor, uniform and equal illuminance from diffusing fibers, and precise needle implantation. Relative light intensities along specific tumor tracks were measured and compared with those predicted by the 2-D photodosimetry code. Agreement within +/- 14% was observed for all configurations studied. Variations in relative intensity in tumor planes perpendicular to a standard seven-fiber illuminator were determined as a function of the distance between the implanted needles. Light wavelengths of 700 nm and greater produced relatively uniform light fields (approximately +/- 20%) in the R3327-AT tumor with needle spacings of at least 1 cm. The addition of two fibers at the periphery of this illuminator (a nine-fiber illuminator) improved the uniformity of light delivery to the encompassed tumor volumes. The importance of precision photodosimetry for interstitial applications of photodynamic therapy is discussed.
在麻醉的Fischer×Copenhagen大鼠中，使用单光纤和多光纤照明器对间变性和高分化的邓宁前列腺腺癌进行照射。每个照明器由一根2厘米长的侧向散射光纤组成，该光纤置于植入肿瘤的塑料近距离治疗针内。通过测量单光纤强度随距离的径向衰减，获得了不同波长的光衰减系数。这些系数作为二维（2-D）光剂量学计算机代码的输入，该代码计算垂直于单光纤和各种多光纤配置平面内的相对光强度。这些计算假设每个肿瘤组织的光学特性均匀、散射光纤的照度均匀且相等，以及针植入精确。测量了沿特定肿瘤轨迹的相对光强度，并与二维光剂量学代码预测的光强度进行了比较。在所研究的所有配置中，观察到的一致性在±14%以内。确定了垂直于标准七光纤照明器的肿瘤平面内相对强度的变化与植入针之间距离的函数关系。对于R3327-AT肿瘤，针间距至少为1厘米时，700纳米及以上的光波长产生相对均匀的光场（约±20%）。在该照明器周边添加两根光纤（九光纤照明器）可改善向所包围肿瘤体积的光传输均匀性。讨论了精确光剂量学在光动力治疗间质应用中的重要性。
