| 刘晓莉,邓宇,Nicki Schlegel,黄志杰,Michael F. Moyers.点扫描式粒子治疗患者验证分析的初步研究[J].中华放射医学与防护杂志,2017,37(10):789-793 |
| 点扫描式粒子治疗患者验证分析的初步研究 |
| A preliminary study of spot scanning particle therapy patient-specific quality assurance |
| 投稿时间：2017-04-24 |
| DOI：10.3760/cma.j.issn.0254-5098.2017.10.013 |
| 中文关键词: 剂量验证 调强点扫描 粒子射束 |
| 英文关键词:Dose verification Modulated spot scanning Particle beam |
| 基金项目: |
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| 中文摘要: |
| 目的 通过对以调强点扫描质子和碳离子技术治疗患者的验证计划测量结果分析，评估现行的计划验证方式的完善性。方法 通过分析质子和碳离子验证计划的1 734个射束照射记录，验证测量通过的标准是验证计划测量值与计算值之间的剂量差异≤3%或距离一致性（distance-to-agreement，DTA）差异≤3 mm，同时满足所有电离室的剂量偏差平均值≤3%，电离室矩阵中24个电离室中有至少22个通过此标准为验证计划通过，测量结果按照不同的测量水箱、测量房间和电离室矩阵测量深度等测量信息分类。结果 测量结果分类分析显示，验证测量通过率和测量参数存在部分相关性，质子和碳离子总的计划通过率分别为97.7% 和91.9%。对于质子射束，验证测量通过率在任意深度都较高，但对于碳离子的验证测量，验证测量通过率会随着测量深度的增加而降低。多数电离室性能稳定，不同水箱，不同治疗机房间验证通过率无明显差异。结论 用三维水箱测量到的点剂量和治疗计划系统（TPS）计算的剂量值之间有较好的一致性。当电离室矩阵在水中的测量深度>150 mm时，碳离子通过率会略差，可能由于在高剂量跌落的区域，水箱内电离室矩阵摆位的不确定性（左右和深度方向）造成，也可能是TPS散射模型对碳离子在深度>150 mm处剂量贡献评估存在不足造成，此现象仍需要做进一步研究。 |
| 英文摘要: |
| Objective To evaluate the procedures for patient-specific quality assurance (QA) measurements using modulated spot scanning beam for proton and carbon ion treatment.Method Records of 1 734 beam measurements were analyzed by using a passing criteria, namely, dose difference between the measured and calculated doses ≤ 3% or distance-to-agreement (DTA) between them ≤ 3 mm, and meanwhile mean dose deviation in all chambers ≤ 3% and at least 22 of 24 chamber array having passed this criteria. The results of measurement were categoried by water phantom, treatment room, measurement depth in chamber array, etc.Results Stratification of result showed some correlation between measurement parameters and passing rates. The total passing rates were 97.7% and 91.9% for proton and carbon ion beams, respectively. The passing rates were high at all measurement depths for proton beam, but decreased for carbon ion beam with increased depth. Chambers were mostly stable, leading to no significant difference in passing rate between different water phantoms and between different treatment rooms.Conclusions A good agreement was shown between the doses measured by water phantoms with those by the treatment planning system (TPS). When the chamber position was deeper than 150 mm in carbon ion measurements, a lower passing rate was observed. This could be caused by uncertainty of ion chamber array setup (lateral and in depth) in highly modulated beams or by incorrect modelling of scattering by the TPS. These deviations need the further investigation. |
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