Department of Radiation Oncology, IRCCS 'Sacro Cuore don Calabria', Negrar (VR), Italy.
Department of Radiation Oncology, IRCCS 'Sacro Cuore don Calabria', Negrar (VR), Italy.
Radiother Oncol. 2019 Mar;132:70-78. doi: 10.1016/j.radonc.2018.11.014. Epub 2018 Dec 21.
Three mono-isocenter techniques with multiple non-coplanar arcs are nowadays clinically available for linac-based stereotactic radiosurgery (SRS) of multiple brain metastases (BM): HyperArc (HA), Multiple Brain Mets (MBM), and Monaco-HDRS. Two of them, HA and MBM, are here compared in terms of plan-quality, and dosimetric consistency between planning and delivering.
For 20 patients with multiple BM (2-10), treated by mono-isocenter volumetric modulated arc therapy (VMAT) HA plans, mono-isocenter MBM dynamic conformal arc plans were generated. Prescription dose (Dp) was 18-25 Gy, for single-fraction, and 21-27 Gy, for three-fractions. Mean overall Planning Target Volume (PTV), expanded by 2 mm from each lesion, was 9.6 cm (0.5-27.9 cm). Dose normalization of 100%Dp at 98%PTV was adopted. Plan-quality was compared by the Paddick conformity (CI) and gradient (GI) index, for the target, mean dose and V volume, for the healthy brain, and number of monitor units (MU). Further, verification dosimetry by radiochromic films was performed for each plan, thus comparing also, by γ-analysis, the consistency between in-phantom computed and measured dose distributions.
CI significantly improved for HA plans, changing on average from 0.75 (MBM) to 0.94 (HA) (p < .001). No significant differences between HA and MBM plans were computed for GI (p = .216), and for mean dose (p = .436) and V (p = .062) to the healthy brain; although V increased on average from 23.7 cm (HA) to 37.3 cm (MBM). No significant difference resulted for MU (p = .107), whereas γ (1 mm, 3%) and γ (2 mm, 2%) passing-rates significantly improved for HA plans (p = .006; p = .023).
HA plans assured a higher CI, while no significant difference resulted for any of the other planning metrics. Although on average slightly higher for HA plans, the dosimetric consistency between planned and delivered was satisfactory from both techniques. Hence, our judgement of near equal plan-quality from HA and MBM SRS-techniques.
目前，临床上有三种使用多个非共面弧的单等中心技术用于立体定向放射外科（SRS）治疗多发脑转移瘤（BM）：HyperArc（HA）、Multiple Brain Mets（MBM）和 Monaco-HDRS。本文比较了其中的两种，HA 和 MBM，比较它们在计划质量和计划与治疗之间的剂量一致性。
对 20 例 2-10 个脑转移瘤患者，采用单等中心容积旋转调强放疗（VMAT）HA 计划进行治疗，生成单等中心 MBM 动态适形弧计划。处方剂量（Dp）为单次 18-25Gy，3 次分割为 21-27Gy。每个病灶从每个病灶向外扩展 2mm 后，平均总计划靶区（PTV）为 9.6cm（0.5-27.9cm）。采用 100%Dp 在 98%PTV 处归一化剂量。通过目标、平均剂量和健康脑的 V 体积的 Paddick 适形度（CI）和梯度（GI）指数，对计划质量进行比较，并通过放射色胶片进行验证剂量测量，从而通过γ分析比较计算剂量分布与实测剂量分布之间的一致性。
HA 计划的 CI 显著改善，平均从 0.75（MBM）变为 0.94（HA）（p<0.001）。HA 计划和 MBM 计划的 GI（p=0.216）、对健康脑的平均剂量（p=0.436）和 V（p=0.062）无显著差异；尽管健康脑的 V 平均从 23.7cm（HA）增加到 37.3cm（MBM）。MU 无显著差异（p=0.107），而 HA 计划的γ（1mm，3%）和γ（2mm，2%）通过率显著提高（p=0.006；p=0.023）。
HA 计划可获得更高的 CI，但其他计划指标无显著差异。尽管 HA 计划的平均剂量略高，但两种技术之间的计划与治疗剂量一致性令人满意。因此，我们认为 HA 和 MBM SRS 技术的计划质量相当。
