Abstract：
BACKGROUND: Intracranial stereotactic radiosurgery (SRS) aims at achieving highly conformal dose distribution and, at the same time, attaining rapid dose falloff outside the treatment target. SRS is performed using different techniques including dynamic conformal arcs (DCA) and volumetric modulated arc therapy (VMAT).
OBJECTIVE: In this study, we compare dose conformity and falloff in DCA and VMAT plans for SRS with a single target.
METHODS: To compare dose conformity in SRS plans, we employ a novel conformity index C I d e x p $C{I}_{{d}_{exp}}$ , RTOG conformity index ( C I R T O G $C{I}_{RTOG}$ ), and Riet-Paddick conformity index ( C I R P $C{I}_{RP}$ ). In addition, we use indices R 50 % $R50\\% $ , V 10 G y ${V}_{10Gy}$ , and V 12 G y ${V}_{12Gy}$ to evaluate dose falloff. For each of the considered 118 cases of SRS, two plans were created using DCA and VMAT. A two-tailed Student\'s t-test was used to evaluate the difference between the employed indices for the DCA and VMAT plans.
RESULTS: The studied VMAT plans were characterized by higher dose conformity than the DCA plans. The differences between the conformity indices for the DCA plans and VMAT plans were statistically significant. The DCA plans had a smaller number of monitor units (MUs) and smaller indices R50%, V10 Gy, and V12 Gy than the VMAT plans. However, the differences between R50%, V10 Gy, and V12 Gy for the DCA and VMAT plans were not statistically significant.
CONCLUSIONS: Although the studied VMAT plans had higher dose conformity, they also had larger MUs than the DCA plans. In terms of dose falloff characterized by parameters R50%, V10 Gy, and V12 Gy, DCA serves as a reasonable alternative to VMAT in the case of a single brain metastasis.
OBJECTIVE: In this study, we compare dose conformity and falloff in DCA and VMAT plans for SRS with a single target.
METHODS: To compare dose conformity in SRS plans, we employ a novel conformity index C I d e x p $C{I}_{{d}_{exp}}$ , RTOG conformity index ( C I R T O G $C{I}_{RTOG}$ ), and Riet-Paddick conformity index ( C I R P $C{I}_{RP}$ ). In addition, we use indices R 50 % $R50\\% $ , V 10 G y ${V}_{10Gy}$ , and V 12 G y ${V}_{12Gy}$ to evaluate dose falloff. For each of the considered 118 cases of SRS, two plans were created using DCA and VMAT. A two-tailed Student\'s t-test was used to evaluate the difference between the employed indices for the DCA and VMAT plans.
RESULTS: The studied VMAT plans were characterized by higher dose conformity than the DCA plans. The differences between the conformity indices for the DCA plans and VMAT plans were statistically significant. The DCA plans had a smaller number of monitor units (MUs) and smaller indices R50%, V10 Gy, and V12 Gy than the VMAT plans. However, the differences between R50%, V10 Gy, and V12 Gy for the DCA and VMAT plans were not statistically significant.
CONCLUSIONS: Although the studied VMAT plans had higher dose conformity, they also had larger MUs than the DCA plans. In terms of dose falloff characterized by parameters R50%, V10 Gy, and V12 Gy, DCA serves as a reasonable alternative to VMAT in the case of a single brain metastasis.
摘要：
背景：颅内立体定向放射外科（SRS）旨在实现高度适形的剂量分布，同时,达到治疗目标之外的快速剂量下降。使用包括动态适形弧(DCA)和体积调制弧治疗(VMAT)的不同技术来执行SRS。
目的：在本研究中，我们比较了单目标SRS的DCA和VMAT计划的剂量一致性和衰减。
方法：为了比较SRS计划中的剂量一致性，我们采用了一个新的一致性指数CIdexp$C{I}_{{d}_{exp}}$，RTOG符合性指数(CIRTOG$C{I}_{RTOG}$),和Riet-Paddick一致性指数(CIRP$C{I}_{RP}$)。此外,我们使用指数R50%$R50\\%$，V10Gy${V}_{10Gy}$,和V12Gy${V}_{12Gy}$评估剂量下降。对于所考虑的118例SRS，使用DCA和VMAT创建了两个计划。使用双尾学生t检验来评估DCA和VMAT计划采用的指数之间的差异。
结果：研究的VMAT计划的特点是剂量一致性高于DCA计划。DCA计划和VMAT计划的符合性指数之间的差异具有统计学意义。DCA计划的监测单元(MU)数量较少，指数R50%较小，V10Gy,和V12Gy比VMAT计划。然而,R50%之间的差异，V10Gy,而V12Gy对于DCA和VMAT计划无统计学意义。
结论：尽管所研究的VMAT计划具有更高的剂量一致性，他们的MU也比DCA计划更大。就以参数R50%为特征的剂量下降而言，V10Gy,和V12Gy，在单个脑转移的情况下，DCA可作为VMAT的合理替代品。
目的：在本研究中，我们比较了单目标SRS的DCA和VMAT计划的剂量一致性和衰减。
方法：为了比较SRS计划中的剂量一致性，我们采用了一个新的一致性指数CIdexp$C{I}_{{d}_{exp}}$，RTOG符合性指数(CIRTOG$C{I}_{RTOG}$),和Riet-Paddick一致性指数(CIRP$C{I}_{RP}$)。此外,我们使用指数R50%$R50\\%$，V10Gy${V}_{10Gy}$,和V12Gy${V}_{12Gy}$评估剂量下降。对于所考虑的118例SRS，使用DCA和VMAT创建了两个计划。使用双尾学生t检验来评估DCA和VMAT计划采用的指数之间的差异。
结果：研究的VMAT计划的特点是剂量一致性高于DCA计划。DCA计划和VMAT计划的符合性指数之间的差异具有统计学意义。DCA计划的监测单元(MU)数量较少，指数R50%较小，V10Gy,和V12Gy比VMAT计划。然而,R50%之间的差异，V10Gy,而V12Gy对于DCA和VMAT计划无统计学意义。
结论：尽管所研究的VMAT计划具有更高的剂量一致性，他们的MU也比DCA计划更大。就以参数R50%为特征的剂量下降而言，V10Gy,和V12Gy，在单个脑转移的情况下，DCA可作为VMAT的合理替代品。
