The effect of titanium stabilization rods on spinal cord radiation dose.
The effect of titanium stabilization rods on spinal cord radiation dose.
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DOI：
10.1016/s0958-3947(02)00083-3
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发表时间：
2002-01-01
期刊：
影响因子：
--
通讯作者：
Komaki, Ritsuko
中科院分区：
文献类型：
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作者：
Liebross, Robert H;Starkschall, George;Komaki, Ritsuko
本研究的目的是探讨钛棒脊柱稳定系统对周围组织，特别是脊髓的剂量学效应。在含有钛棒脊柱稳定系统的水模中对6 mv和18 mv的光子光束进行了离子室剂量测定。在带和不带杆状体的幻体内得到等剂量曲线。为了评估治疗计划系统重现稳定系统对传递到周围组织的辐射剂量影响的能力，在计算机断层扫描数-密度转换表中进行适当修改后计算剂量分布，以考虑钛棒密度的增加。将得到的非均质校正平面与未校正平面进行比较。在水影中对应脊髓深度的7cm处，与无棒时产生的曲线相比，仅在棒下的6 mv光子束衰减了4%，在有螺钉的棒下衰减了13%。对于18mv的光束，衰减幅度分别为3%和11%。使用前后（18 mv）和前后（6 mv）光子束，对棒进行和不进行非均匀性校正，校正后的等剂量计划显示，与未校正计划相比，在棒前方4 cm处的光束衰减约为2%。然而，脊髓剂量在两种方案之间无显著差异。在本研究中测试的钛棒脊柱稳定系统导致远端递送到棒的剂量减少，但对递送到脊髓的剂量没有显著影响。
The purpose of this study was to investigate the dosimetric effect of a titanium-rod spinal stabilization system on surrounding tissue, especially the spinal cord. Ion chamber dosimetry was performed for 6- and 18-MV photon beams in a water phantom containing a titanium-rod spinal stabilization system. Isodose curves were obtained in the phantom with and without rods. To assess the ability of a treatment planning system to reproduce the effects of the stabilization system on the radiation dose delivered to surrounding tissue, dose distributions were calculated after appropriate modifications were made in the computed tomography number-to-density conversion table to account for the increased density of the titanium rods. The resultant heterogeneity-corrected plans were compared with uncorrected plans. At a 7-cm depth in the water phantom, corresponding to the depth of the spinal cord, the beam was attenuated by 4% under the rods alone and by 13% rods under the rods with screws for the 6-MV photon beam as compared with curves generated in the absence of rods. The beam was attenuated by 3% and 11%, respectively, for the 18-MV beam. Using anteroposterior (18-MV) and posteroanterior (6-MV) photon beams, with and without heterogeneity correction for the rods, the corrected isodose plan showed an approximately 2% beam attenuation 4 cm anterior to the rods as compared with the uncorrected plan. No significant difference in the spinal cord dose was observed between the 2 plans, however. The titanium-rod spinal stabilization system tested in this study caused a decrease in the dose delivered distal to the rods but did not significantly affect the dose delivered to the spinal cord.