Dosimetric advantage of volumetric modulated arc therapy in the treatment of intraocular cancer

Zhenxiang Deng,Ce Han,Xiaomin Zheng,Lanxiao Shen,Xiance Jin,Congying Xie,Yongqiang Zhou,Jinling Yi

doi:10.1186/s13014-017-0819-7

Zhenxiang Deng, Ce Han + Show 6 more

Open Access

https://doi.org/10.1186/s13014-017-0819-7

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Journal: Radiation Oncology	Publication Date: May 10, 2017
Citations: 12	License type: open-access

Affiliation: Wenzhou Medical University

Abstract

ObjectiveThe purpose of this study is to investigate the dosimetric advantages of volumetric modulated arc therapy (VMAT) in the treatment of intraocular cancer by comparing it directly with three-dimensional conformal radiotherapy (CRT) and intensity-modulated radiotherapy (IMRT).MethodsCRT plan, 7f-IMRT plan, and one-arc VMAT plan were generated for 14 intraocular cancer patients. Dosimetric and biological quality indices for target volume and organs at risks (OARs) were evaluated and compared.ResultsThe target coverage presented by V95 for CRT, IMRT and VMAT were 95.02% ± 0.67%, 95.51% ± 2.25%, and 95.92% ± 3.05%, respectively. The homogeneity index (HI) for CRT, IMRT and VMAT were 0.15 ± 0.05, 0.23 ± 0.05, and 0.23 ± 0.06, respectively. IMRT and VMAT greatly decreased the dose to ipsilateral lens compared with CRT with a D1 of 2972.66 ± 1407.12 cGy, 3317.82 ± 915.28 cGy and 4809.54 ± 524.60 cGy for IMRT, VMAT and CRT, respectively. Similar results were observed for ipsilateral eyeballs. IMRT and VMAT also spared better on brainstem, optical nerves and optical chiasm compared CRT. However, CRT achieved lower dose to the eyeballs compared with IMRT and VMAT. VMAT and IMRT showed mixed results on target coverage and OAR sparing. The average MUs and delivery time of IMRT and VMAT were 531.25 ± 81.21 vs. 400.99 ± 61.49 and 5.05 ± 0.53 vs.1.71 ± 0.69 min, respectively.ConclusionsAlthough no clear distinction on PTV coverage among CRT, IMRT and VMAT plans was observed in the treatment of intraocular cancer, VMAT and IMRT achieved better homogeneity and conformity for target volume, and delivered fewer doses to ipsilateral lens and eyeballs compared with CRT. However, VMAT and IMRT increased the low dose volume to the contralateral OARs. Although VMAT and IMRT showed mixed results on target coverage and OAR sparing, VMAT decreased MU and delivery time significantly compared with IMRT. VMAT is a promising and feasible external beam radiotherapy technique in the treatment of intraocular cancer patients.

Highlights

Intraocular cancer, which includes primary and secondary intraocular cancers, presents a therapeutic challenge due to the sensitive tissues involved and the necessity to destroy the tumor while minimizing visual loss
The purpose of this study is to investigate the dosimetric advantages of volumetric modulated arc therapy (VMAT) in the treatment of intraocular cancer by comparing it with conformal radiotherapy (CRT) and intensity-modulated radiotherapy (IMRT)
The high dose volumes of IMRT and VMAT matched better to the target volume compared with CRT

Summary

Introduction

Intraocular cancer, which includes primary and secondary intraocular cancers, presents a therapeutic challenge due to the sensitive tissues involved and the necessity to destroy the tumor while minimizing visual loss. Primary intraocular cancers start inside the eyeball. Melanoma is the most common primary intraocular cancer. Retinoblastoma (a cancer arising from cells in the retina) is the most common primary intraocular cancer, and medulloepithelioma is the most common [1]. Secondary intraocular cancers start somewhere else and spread to the eye, which are more common than primary intraocular cancers. The most common cancers that spread to the eye are breast and lung cancers [2]

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