Bhagyalakshmi A T, Ramasubramanian Velayudham
School of Advanced Sciences, Vellore Institute of Technology, Vellore, Tamil Nadu, India.
Department of Radiation Oncology, American Oncology Institute at Baby Memorial Hospital, Kozhikode, Kerala, India.
J Med Phys. 2024 Oct-Dec;49(4):493-501. doi: 10.4103/jmp.jmp_97_24. Epub 2024 Dec 18.
This study evaluated the influence of high dose (HD) vertex numbers and its placement on equivalent uniform dose (EUD) and peak-to-valley dose ratio (PVDR) in lattice radiotherapy (LRT).
One hundred and eighty-eight RapidArc (RA) plans were created for a cohort of 15 patients.
RA plans were created with zero to eight HD vertices to analyze their relationship with EUD. Eight lattices were systematically and optimally placed (by avoiding proximity to organs at risks [OARs]) to study the impact of vertex placement. Variations in PVDR were assessed using PVDR1 (mean dose to HD vertices by the difference of mean doses to planning target volume [PTV] and HD vertices) and PVDR2 (D10/D90 of PTV in composite plans) across 38 RA plans with HD vertex doses of 9 Gy, 12 Gy, 15 Gy, and 18 Gy. PVDR3 (product of PVDR1 and PVDR2) was evaluated for its variation with peak dose.
Hypothesis testing between vertex placements was performed using a two-tailed Student's -test.
EUD values ranged from 32.88 Gy to 40.63 Gy. In addition, statistical analysis revealed significant associations ( = 0.0074) between the placement patterns of HD vertices, both in systematic and optimized arrangements. The PVDR and D10/D90 product values were 1.6, 1.8, 2.1, and 2.3 for peak doses of 9 Gy, 12 Gy, 15 Gy, and 18 Gy, respectively.
The addition of one HD vertex increased EUD, emphasizing the impact of individual vertex increments on outcomes. Systematic and optimized vertex placements enhance EUD, with optimized placement yielding better doses to PTV and OARs. PVDR3 offers superior dose reporting for LRT compared to PVDR1 and PVDR2.
本研究评估了高剂量（HD）射野节点数量及其位置对容积调强放疗（LRT）中均匀等效剂量（EUD）和峰谷剂量比（PVDR）的影响。
为15例患者创建了188个容积旋转调强放疗（RA）计划。
创建含0至8个HD射野节点的RA计划，以分析其与EUD的关系。系统且优化地放置8个射野节点格（通过避免靠近危及器官[OAR]），以研究节点位置的影响。在38个HD射野节点剂量分别为9 Gy、12 Gy、15 Gy和18 Gy的RA计划中，使用PVDR1（通过计划靶区[PTV]与HD射野节点的平均剂量之差得出的HD射野节点平均剂量）和PVDR2（复合计划中PTV的D10/D90）评估PVDR的变化。评估PVDR3（PVDR1与PVDR2的乘积）随峰值剂量的变化情况。
使用双尾学生t检验对射野节点位置进行假设检验。
EUD值范围为32.88 Gy至40.63 Gy。此外，统计分析显示，无论是系统排列还是优化排列，HD射野节点的放置模式之间均存在显著关联（P = 0.0074）。对于9 Gy、12 Gy、15 Gy和18 Gy的峰值剂量，PVDR和D10/D90乘积值分别为1.6、1.8、2.1和2.3。
增加一个HD射野节点会提高EUD，强调了单个节点增加对治疗结果的影响。系统且优化的节点放置可提高EUD，优化放置能为PTV和OAR提供更好的剂量。与PVDR1和PVDR2相比，PVDR3为LRT提供了更优的剂量报告。
