Peters Gabrielle W, Tien Christopher J, Chiang Veronica, Yu James, Hansen James E, Aneja Sanjay
Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT, USA.
Department of Neurosurgery, Yale School of Medicine, New Haven, CT, USA.
J Radiosurg SBRT. 2021;7(3):207-212.
PURPOSE/OBJECTIVES: Treatment planning systems (TPS) for Gamma Knife stereotactic radiosurgery (GK-SRS) include TMR10 algorithms, which assumes tissue homogeneity equivalent to water, and collapsed-cone convolutional (CCC) algorithms, which accounts for tissue inhomogeneity. This study investigated dosimetric differences between TMR10 and CCC TPS for acoustic neuromas (ANs) treated with GK-SRS.
MATERIALS/METHODS: A retrospective review of 56 AN treated with GK-SRS was performed. All patients underwent MRI and CT imaging during their initial treatment and were planned using TMR10. Each plan was recalculated with CCC using electron density extracted from CT. Parameters of interest included D, D, D, cochlea D, mean cochlea dose, target size, and laterality (>20 mm from central axis).
Median target volume of patients was 1.5 cc (0.3 cc-2.8 cc) with median dose of 12 Gy prescribed to the 50% isodose line. Compared to CCC algorithms, the TMR10 calculated dose was higher: D was higher by an average 6.2% (p < 0.001), D was higher by an average 3.1% (p < 0.032), D was higher by an average of 11.3%. For lateralized targets, calculated D and D were higher by 7.1% (p < 0.001) and 10.6% (p < 0.001), respectively. For targets <1 cc, D and D were higher by 8.9% (p ≤ 0.009) and 12.1% (p ≤ 0.001), respectively. Cochlea D was higher, by an average of 20.1% (p < 0.001).
There was a statistically significant dosimetric differences observed between TMR10 and CCC algorithms for AN GK-SRS, particularly in small and lateralized ANs. It may be important to note these differences when relating GK-SRS with standard heterogeneity-corrected SRS regimens.
目的/目标：伽玛刀立体定向放射外科治疗（GK-SRS）的治疗计划系统（TPS）包括TMR10算法（该算法假定组织均匀性等同于水）和卷积叠锥（CCC）算法（该算法考虑了组织的不均匀性）。本研究调查了采用GK-SRS治疗听神经瘤（AN）时，TMR10和CCC TPS之间的剂量学差异。
材料/方法：对56例采用GK-SRS治疗的AN患者进行回顾性分析。所有患者在初始治疗期间均接受了MRI和CT成像，并使用TMR10进行治疗计划制定。利用从CT中提取的电子密度，使用CCC对每个计划重新进行计算。感兴趣的参数包括D、D、D、耳蜗D、平均耳蜗剂量、靶区大小和偏心度（距中心轴>20 mm）。
患者的中位靶区体积为1.5 cc（0.3 cc - 2.8 cc），规定给予50%等剂量线的中位剂量为12 Gy。与CCC算法相比，TMR10计算的剂量更高：D平均高6.2%（p < 0.001），D平均高3.1%（p < 0.032），D平均高11.3%。对于偏心靶区，计算得出的D和D分别高7.1%（p < 0.001）和10.6%（p < 0.001）。对于<1 cc的靶区，D和D分别高8.9%（p≤0.009）和12.1%（p≤0.001）。耳蜗D平均高20.1%（p < 0.001）。
在采用GK-SRS治疗AN时，TMR10和CCC算法之间存在统计学上显著的剂量学差异，尤其是在小型和偏心AN中。在将GK-SRS与标准的异质性校正SRS方案进行关联时，注意这些差异可能很重要。
