Dominique C, Schwartz L H, Lescrainier J, Keraudy K, Belkacemi Y, Foulquier J N, Ozsahin M, Lefkopoulos D, Pene F
Department of Radiation Oncology, Hôpital Tenon, Paris, France.
Int J Radiat Oncol Biol Phys. 1995 Nov 1;33(4):951-7. doi: 10.1016/0360-3016(95)00208-2.
A modified teletherapy unit to achieve total body irradiation with a vertical beam in a conventional treatment room.
A standard 60C teletherapy unit has been modified to achieve total body irradiation with a vertical beam in a conventional treatment room. Patients are treated in prone and supine positions. Removal of the adjustable collimator assembly of this standard machine provides a circular field of 196 cm in diameter at 167 cm from the source. Second, the machine has been elevated by about 50 cm on a metallic base to enlarge irradiation field to obtain 248 cm in diameter at 210 cm from the source, and to encompass tall patients under better conditions. A special lead conical beam flattening filter, 10-mm thick at the center, was designed to compensate the spatial inhomogeneity of the beam. An instantaneous dose rate of 6.10(-2) Gy/min is attained at the L4 level (midplane) in an average 20-cm thick patient with a source activity of 5099 RHM (air kerma rate of 44.8 Gy.h-1.m2). Between February 2, 1984 and December 27, 1990, 244 total body irradiations were performed either by single dose (n = 69, 10 Gy were given to midplane at L4 level in about 6 to 8 h, 8 Gy to the lungs), or by fractionated dose (n = 175, 12 Gy were given in 6 fractions over 3 consecutive days to midplane at L4 level, 9 Gy to the lungs).
The dose distribution is similar than the ones obtained by a linear accelerator with patients lying on their sides.
Patients were treated in a comfortable and highly reproductible position. Organ shielding was easily achievable. This could be a less expensive and reasonable alternative to linear accelerator.
一种改进的远距离治疗设备，用于在传统治疗室中以垂直光束进行全身照射。
对一台标准的60C远距离治疗设备进行了改进，以便在传统治疗室中以垂直光束进行全身照射。患者采用俯卧位和仰卧位进行治疗。拆除该标准设备的可调准直器组件后，在距源167 cm处可提供直径为196 cm的圆形照射野。其次，该设备在金属底座上被抬高了约50 cm，以扩大照射野，在距源210 cm处获得直径为248 cm的照射野，并在更好的条件下覆盖身材较高的患者。设计了一种特殊的铅锥形束平坦化滤波器，中心厚度为10 mm，以补偿光束的空间不均匀性。对于一名平均厚度为20 cm的患者，在L4水平（中平面）处，源活度为5099 RHM（空气比释动能率为44.8 Gy·h⁻¹·m²）时，瞬时剂量率达到6.10⁻² Gy/min。在1984年2月2日至1990年12月27日期间，共进行了244次全身照射，照射方式分为单次剂量照射（n = 69，在约6至8小时内给予L4水平中平面10 Gy，肺部给予8 Gy）或分次剂量照射（n = 175，在连续3天内分6次给予L4水平中平面12 Gy，肺部给予9 Gy）。
剂量分布与患者侧卧时使用直线加速器获得的剂量分布相似。
患者在舒适且高度可重复的体位下接受治疗。器官屏蔽易于实现。这可能是一种比直线加速器成本更低且合理的替代方案。
