Barton Rachael, Robinson Graham, Gutierrez Eric, Kirkbride Peter, McLean Michael
Palliative Radiation Oncology Program, Princess Margaret Hospital, University Health Network, University of Toronto, Toronto, Canada.
Int J Radiat Oncol Biol Phys. 2002 Mar 15;52(4):1083-91. doi: 10.1016/s0360-3016(01)02738-9.
To assess the effect of prescription parameters on the dose received by the spine during palliative radiotherapy.
In a survey, members of the Canadian Association of Radiation Oncologists were asked to define their prescription parameters for vertebral metastases. The depth of the spinal canal and vertebral body at 8 spinal levels was measured in 20 magnetic resonance imaging studies (MRIs). Survey results were applied to the measurements to assess the dose received at depth. The depth of spinal structures assessed at simulation and by diagnostic imaging was compared.
Prescriptions were most commonly to D(max) 3 cm or 5 cm using 60Co-6MV photons delivering 8-30 Gy in 1-10 fractions. Mean depths from MRI were: posterior spinal canal, 5.5 cm; anterior spinal canal, 6.9 cm; and anterior vertebral body, 9.6 cm. Application of the prescription parameters from the survey to these measurements showed a wide range in the dose at depth with variation in technique. Depths measured at simulation correlated well with diagnostic imaging.
The spinal canal and vertebral body lie >5 cm beneath the skin, and the dose received varies by up to 50% with changes in prescription depth. We suggest a suitable prescription point for vertebral metastases and a method for determining this at simulation.
评估姑息性放射治疗期间处方参数对脊柱所接受剂量的影响。
在一项调查中，加拿大放射肿瘤学家协会的成员被要求确定他们针对椎体转移瘤的处方参数。在20项磁共振成像研究（MRI）中测量了8个脊柱节段的椎管和椎体深度。将调查结果应用于测量值，以评估在深度处接受的剂量。比较了在模拟时和通过诊断成像评估的脊柱结构深度。
最常用的处方是使用60钴 - 6兆伏光子，给予D（max）3厘米或5厘米，分1 - 10次给予8 - 30戈瑞。MRI测得的平均深度为：脊髓后管5.5厘米；脊髓前管6.9厘米；椎体前部9.6厘米。将调查中的处方参数应用于这些测量结果显示，随着技术变化，深度处的剂量范围很广。在模拟时测量的深度与诊断成像相关性良好。
椎管和椎体位于皮肤下方>5厘米处，随着处方深度的变化，所接受的剂量变化高达50%。我们建议了一个适合椎体转移瘤的处方点以及在模拟时确定该点的方法。
