Acuros XB和各向异性分析算法对使用直肠内气囊的前列腺癌容积调强弧形治疗计划的剂量学影响。

Dosimetric effects of the acuros XB and anisotropic analytical algorithm on volumetric modulated arc therapy planning for prostate cancer using an endorectal balloon.

作者信息

Koo Taeryool, Chung Jin-Beom, Eom Keun-Yong, Seok Jin-Yong, Kim In-Ah, Kim Jae-Sung

机构信息

Department of Radiation Oncology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Korea.

Department of Radiation Oncology, Seoul National University Bundang Hospital, 82 Gumi-ro, 173beon-gil, Bundang-gu, Seongnam-si, 463-707, Korea.

出版信息

Radiat Oncol. 2015 Feb 22;10:48. doi: 10.1186/s13014-015-0346-3.

BACKGROUND

To compare the dosimetric effects of Acuros XB (AXB) and Anisotropic Analytical Algorithm (AAA) on volumetric modulated arc therapy (VMAT) planning for postoperative prostate cancer patients irradiated using an endorectal balloon (ERB).

METHODS

We measured central axis doses with film in a phantom containing an air cavity, and compared measurements with calculations of the AAA and AXB. For clinical study, 10 patients who had undergone whole pelvic radiotherapy (WPRT) followed by prostatic bed-only radiotherapy (PBRT) using VMAT were enrolled. An ERB was used for PBRT but not for WPRT. To compare dosimetric parameters, the cumulative dose-volume histograms, mean, maximum, and minimum doses were measured for the planning target volume. Homogeneity of plans were confirmed using V95%, V107% (VX%, percentage volumes receiving at least X% of prescribed doses) and conformity indices (homogeneity index [HI], conformity index [CI], and conformation number [CN]). We compared volumes of the organ-at-risk receiving 10% to 100% (10-tier at 10% interval) of prescribed doses (V10% - V100%).

RESULTS

In the phantom study, the AAA showed larger disagreement with the measurements, and overestimated the dose in the air cavity, comparing with the AXB. For WPRT planning, the AAA predicted a lower maximum dose and V107% than the AXB. For PBRT planning, the AAA estimated a higher minimum dose, lower maximum dose, and smaller V107%, and larger V95% than the AXB. Regarding the conformity indices, the AAA was estimated to be more homogenous than the AXB for PBRT planning (HI, 0.088 vs. 0.120, p = 0.005; CI, 1.052 vs. 1.038, p = 0.022; and CN, 0.920 vs. 0.900, p = 0.007) but not for WPRT planning. Among V10% to V100% of the rectum, the PBRT exhibited significant discrepancies in V30%, V40%, V70%, V80%, and V90%; while the WPRT did in V20% and V30%.

CONCLUSIONS

The phantom study demonstrated that the AXB calculates more accurately in the air cavity than the AAA. In the clinical setting, the AXB exhibited different dosimetric distributions in the VMAT plans for PBRT containing an ERB. The AXB should be considered for prostate cancer patients irradiated with an ERB for better applying of heterogeneous condition.

背景

比较Acuros XB（AXB）和各向异性分析算法（AAA）对使用直肠内气囊（ERB）进行术后前列腺癌患者容积调强弧形放疗（VMAT）计划的剂量学影响。

方法

我们在含有气腔的体模中用胶片测量中心轴剂量，并将测量结果与AAA和AXB的计算结果进行比较。对于临床研究，纳入10例接受全盆腔放疗（WPRT）后使用VMAT进行仅前列腺床放疗（PBRT）的患者。PBRT使用ERB，而WPRT不使用。为了比较剂量学参数，测量计划靶体积的累积剂量-体积直方图、平均剂量、最大剂量和最小剂量。使用V95%、V107%（VX%，接受至少X%处方剂量的体积百分比）和适形指数（均匀性指数[HI]、适形指数[CI]和适形数[CN]）确认计划的均匀性。我们比较了接受10%至100%（以10%间隔分为10层）处方剂量（V10% - V100%）的危及器官体积。

结果

在体模研究中，与AXB相比，AAA与测量值的差异更大，并且高估了气腔中的剂量。对于WPRT计划，AAA预测的最大剂量和V107%低于AXB。对于PBRT计划，AAA估计的最小剂量更高，最大剂量更低，V107%更小，V95%比AXB更大。关于适形指数，对于PBRT计划，AAA估计比AXB更均匀（HI，0.088对0.120，p = 0.005；CI，1.052对1.038，p = 0.022；CN，0.920对0.900，p = 0.007），但对于WPRT计划并非如此。在直肠的V10%至V100%中，PBRT在V30%、V40%、V70%、V80%和V90%方面存在显著差异；而WPRT在V20%和V30%方面存在差异。