Department of Radiation Oncology, Boston, MA, USA.
Radiother Oncol. 2010 Apr;95(1):3-22. doi: 10.1016/j.radonc.2010.01.015. Epub 2010 Feb 23.
Relative to X-ray beams, proton [(1)H] and carbon ion [(12)C] beams provide superior distributions due primarily to their finite range. The principal differences are LET, low for (1)H and high for (12)C, and a narrower penumbra of (12)C beams. Were (12)C to yield a higher TCP for a defined NTCP than (1)H therapy, would LET, fractionation or penumbra width be the basis?
Critical factors of physics, radiation biology of (1)H and (12)C ion beams, neutron therapy and selected reports of TCP and NTCP from (1)H and (12)C irradiation of nine tumor categories are reviewed.
Outcome results are based on low dose per fraction (1)H and high dose per fraction (12)C therapy. Assessment of the role of LET and dose distribution vs dose fractionation is not now feasible. Available data indicate that TCP increases with BED with (1)H and (12)C TCPs overlaps. Frequencies of GIII NTCPs were higher after (1)H than (12)C treatment.
Assessment of the efficacy of (1)H vs(12)C therapy is not feasible, principally due to the dose fractionation differences. Further, there is no accepted policy for defining the CTV-GTV margin nor definition of TCP. Overlaps of (1)H and (12)C ion TCPs at defined BED ranges indicate that TCPs are determined in large measure by dose, BED. Late GIII NTCP was higher in (1)H than (12)C patients, indicating LET as a significant factor. We recommend trials of (1)H vs(12)C with one variable, i.e. LET. The resultant TCP vs NTCP relationship will indicate which beam yields higher TCP for a specified NTCP at a defined dose fractionation.
与 X 射线相比，质子[(1)H]和碳离子[(12)C]束提供了更好的分布，主要是由于它们的有限射程。主要区别在于 LET，质子低，碳离子高，碳离子束的半影较窄。如果对于定义的 NTCP，(12)C 比(1)H 治疗产生更高的 TCP，那么 LET、分割或半影宽度将是基础吗？
回顾了(1)H 和(12)C 离子束的物理、辐射生物学、中子治疗以及九种肿瘤类别中(1)H 和(12)C 照射的 TCP 和 NTCP 的选定报告的关键因素。
结果基于(1)H 的低剂量分割和(12)C 的高剂量分割。目前尚不可能评估 LET 和剂量分布与剂量分割的作用。现有数据表明，随着(1)H 和(12)C 的 TCP 重叠，BED 与 TCP 呈正相关。(1)H 治疗后 GIII NTCP 的频率高于(12)C 治疗。
由于剂量分割差异，评估(1)H 与(12)C 治疗的疗效是不可行的。此外，对于 CTV-GTV 边界的定义或 TCP 的定义没有公认的政策。在定义的 BED 范围内，(1)H 和(12)C 离子 TCP 的重叠表明 TCP 在很大程度上由剂量、BED 决定。(1)H 患者的晚期 GIII NTCP 高于(12)C 患者，表明 LET 是一个重要因素。我们建议进行(1)H 与(12)C 的试验，其中一个变量是 LET。TCP 与 NTCP 的关系将表明在给定的剂量分割下，哪种射线产生更高的 TCP 以达到特定的 NTCP。
