Fig L M, Shapiro B, Taren J
University of Michigan Hospital, Ann Arbor.
Stereotact Funct Neurosurg. 1992;59(1-4):166-8. doi: 10.1159/000098935.
To suppress cyst formation in 42 brain tumors, 32P has been stereotactically instilled in doses calculated to deliver 20,000-40,000 rad to the cyst wall, assuming uniform dispersal of the radioisotope. However, samples of cyst fluid obtained at varying intervals after injection showed lower than expected activity levels, suggesting early 'plating' of 32P. To accommodate this phenomenon, a surface-area-dependent dosimetric calculation is compared with a volume-dependent calculation which assumes uniform dispersal. These two approaches represent lower and upper extremes. It appears that in small cysts there is less difference in the required administered dose, but in larger cysts potentially very large differences exist and caution should be exercised if uniform suspension is assumed.
为了抑制42例脑肿瘤中的囊肿形成，已通过立体定向方式注入32P，其剂量经计算可向囊肿壁输送20,000 - 40,000拉德，假定放射性同位素均匀散布。然而，注射后不同时间间隔获取的囊肿液样本显示活性水平低于预期，提示32P早期“沉积”。为适应这一现象，将基于表面积的剂量计算与假定均匀散布的基于体积的计算进行了比较。这两种方法分别代表了下限和上限极端情况。似乎在小囊肿中，所需给药剂量的差异较小，但在大囊肿中可能存在非常大的差异，若假定为均匀悬浮则应谨慎行事。
