Podgorsak E B, Olivier A, Pla M, Lefebvre P Y, Hazel J
Dept. of Radiation Oncology, McGill University, Montreal Gen. Hosp., Quebec, Canada.
Int J Radiat Oncol Biol Phys. 1988 Jan;14(1):115-26. doi: 10.1016/0360-3016(88)90059-4.
Two radiosurgical procedures using a stereotactic frame and a linear accelerator X ray beam with a circular field diameter between 0.5 and 3 cm are presented. One technique is based on a single plane rotation (single plane radiosurgery) whereas the other uses simultaneous and continuous motions of both the gantry (approximately 360 degrees) and couch (approximately 180 degrees) during the radiosurgical procedure (dynamic radiosurgery). The dose, typically a few thousand cGy, is prescribed to the 90% isodose line which just covers the target volume. The dose fall-off outside the spherical target volume is considerably sharper for the dynamic rotation than for the single plane rotation, and is comparable to the dose fall-off obtained with the two presently known dedicated radiosurgical techniques: one based on focused cobalt beams and the other on proton beams. The dose fall-off in the dynamic radiosurgery discussed here is also comparable to that of previously described linear accelerator based multiple converging are techniques, making the dynamic radiosurgery an attractive alternative to presently known radiosurgical procedures. The radiation beam parameters are discussed and the stereotactic frame described. The dose distributions for both radiosurgical techniques are calculated in a single plane and then corrected for the attenuation effects in the stereotactic frame (approximately 2%) and for the effects of the dynamic rotation (approximately 2%). The skin doses are 0.7% and 2%, and the lens doses, if the beam passes through the eyes, are 2.5% and 3.5% for the dynamic rotation and single plane rotation, respectively. The scatter and leakage dose for the radiosurgical procedures is typically 0.2% to the patient's thyroid, 0.06% to the breast, and 0.02% to the gonads.
介绍了两种使用立体定向框架和线性加速器X射线束的放射外科手术，其圆形射野直径在0.5至3厘米之间。一种技术基于单平面旋转（单平面放射外科），而另一种在放射外科手术过程中使用机架（约360度）和治疗床（约180度）同时连续运动（动态放射外科）。剂量通常为几千cGy，规定在刚好覆盖靶体积的90%等剂量线上。球形靶体积外的剂量下降，动态旋转比单平面旋转明显更陡，并且与目前已知的两种专用放射外科技术所获得的剂量下降相当：一种基于聚焦钴束，另一种基于质子束。这里讨论的动态放射外科中的剂量下降也与先前描述的基于线性加速器的多汇聚弧技术相当，使得动态放射外科成为目前已知放射外科手术的一种有吸引力的替代方法。讨论了辐射束参数并描述了立体定向框架。计算了两种放射外科技术在单个平面内的剂量分布，然后针对立体定向框架中的衰减效应（约2%）和动态旋转的效应（约2%）进行校正。动态旋转和单平面旋转的皮肤剂量分别为0.7%和2%，如果束穿过眼睛，晶状体剂量分别为2.5%和3.5%。放射外科手术的散射和泄漏剂量通常对患者甲状腺为0.2%，对乳腺为0.06%，对性腺为0.02%。
