Feasibility of automated proton therapy plan adaptation for head and neck tumors using cone beam CT images.
Feasibility of automated proton therapy plan adaptation for head and neck tumors using cone beam CT images.
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DOI：
10.1186/s13014-016-0641-7
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发表时间：
2016-04-30
期刊：
影响因子：
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通讯作者：
Landry G
中科院分区：
文献类型：
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作者：
Kurz C;Nijhuis R;Reiner M;Ganswindt U;Thieke C;Belka C;Parodi K;Landry G
头部和颈部肿瘤的强度调节质子治疗(IMPT)可以从计划适应中受益，以纠正这些患者因体重减轻和肿瘤体积变化而引起的剂量扰动。随着锥束CT(CBCT)在质子治疗中的应用日益广泛，有可能利用强度校正后的CBCT图像进行计划调整。这是首次探索计划CT(PCT)与CBCT的可变形图像配准所校正和描绘的CBCT图像上的IMPT计划适配，从而产生虚拟CT(VCT)。使用Morphons算法将9例H&N癌患者的PCT和相应的轮廓变形为在对照重新计划CT扫描(RpCT)后±3天内获得的每周CBCT。使用VCT调整IMPT治疗计划，并在rpCT上重新计算调整后的计划和原始计划，以评估适应的影响的剂量/体积参数。关于方案预算编制，调整后的计划在目标数量D95和V95方面与原计划相当，但在这些数量上显示D2大幅减少。桨剂量基本相同或减少。特别是，调整后的计划并没有减少腮腺D均值，而是减少了光学系统的剂量。对于三名患者，脊髓或脑干获得了更高的最大剂量，尽管远低于耐受性。随后收紧这些桨对新的VCT适应计划的治疗计划限制，并没有降低目标覆盖率，并在VCT上产生了10%的等值计划。开发并研究了一种在CBCT图像上生成适应的IMPT计划的离线自动程序。当在对照rpCT上评估调整后的计划时，我们观察到目标体积中D2的减少是主要的改善。通过该手术，桨叶节省仅有部分改善。尽管VCT方法的准确性存在潜在的局限性，但调整后的计划的质量是可以提高的。本文的在线版本(doi：10.1186/s13014-0160641-7)包含补充材料，授权用户可以使用。
Intensity modulated proton therapy (IMPT) of head and neck (H&N) tumors may benefit from plan adaptation to correct for the dose perturbations caused by weight loss and tumor volume changes observed in these patients. As cone beam CT (CBCT) is increasingly considered in proton therapy, it may be possible to use available CBCT images following intensity correction for plan adaptation. This is the first study exploring IMPT plan adaptation on CBCT images corrected and delineated by deformable image registration of the planning CT (pCT) to the CBCT, yielding a virtual CT (vCT). A Morphons algorithm was used to deform the pCTs and corresponding delineations of 9 H&N cancer patients to a weekly CBCT acquired within ±3 days of a control replanning CT scan (rpCT). The IMPT treatment plans were adapted using the vCT and the adapted and original plans were recalculated on the rpCT for dose/volume parameter evaluation of the impact of adaptation. On the rpCT, the adapted plans were equivalent to the original plans in terms of target volumes D95 and V95, but showed a significant reduction of D2 in these volumes. OAR doses were mostly equivalent or reduced. In particular, the adapted plans did not reduce parotid gland Dmean, but the dose to the optical system. For three patients the spinal cord or brain stem received higher, though well below tolerance, maximum dose. Subsequent tightening of the treatment planning constraints for these OARs on new vCT-adapted plans did not degrade target coverage and yielded pCT equivalent plans on the vCT. An offline automated procedure to generate an adapted IMPT plan on CBCT images was developed and investigated. When evaluating the adapted plan on a control rpCT we observed reduced D2 in target volumes as major improvement. OAR sparing was only partially improved by the procedure. Despite potential limitations in the accuracy of the vCT approach, an improved quality of the adapted plans could be achieved. The online version of this article (doi:10.1186/s13014-016-0641-7) contains supplementary material, which is available to authorized users.