Abstract
Objective:To evaluate VMAT plans for conformity and homogeneity of radiation dose to the target in order to share our experience as a pioneering institute to use VMAT technology in Pakistan.Methods:Since December 2014 to January 2018, 530 patients of various anatomical sites were treated by VMAT technique at Neurospinal Cancer Care Institute (NCCI) Karachi Pakistan. ERGO++ planning system (Version 1.7.2) was used to develop VMAT plans with single or multiple arcs by the rotation of couch and gantry. The plans were evaluated by calculating Conformity Index (CI) and Homogeneity Index (HI) and critical organ (OARs) doses of individual tumor sites.Results:The average CI of various sites was 1.4 (range: 1.0–2.0) and average HI of various sites was 1.20 (range: 1.07–1.374), respective critical organ doses were adequately achieved.Conclusions:VMAT treatment planning technique showed good conformal and homogeneous target coverage with sparing of organs at risk and reduced treatment delivery time. With these features, safety of VMAT technique may allow its routine clinical use, though it is still under investigation in many areas.
Highlights
Significant advancement has occurred in the radiotherapy techniques and deliveries during the past few decades worldwide
Macchia et al.[1], published a detailed review of Volumetric Modulated Arc Therapy (VMAT) and its clinical use for various body sites in 2017, this study described that VMAT has been used mostly for brain tumors, head & neck, thoracic cancers, GU cancers, gradient Index (GI) cancers and stereotactic body radiotherapy (SBRT) for oligometastasis
The Synergy-S is controlled with the Elekta Integrity system version 1.1 which automatically selects the combination of dose rate, gantry speed and Multi-leaf Collimators (MLCs) speed during the VMAT technique
Summary
Significant advancement has occurred in the radiotherapy techniques and deliveries during the past few decades worldwide. In 1965, Takahashi was the first to describe arc therapy using dynamic field shaping using MLCs.[2] In the late 1990s, intensity-modulated radiation therapy (IMRT) was introduced and soon adopted in clinical practice. Pak J Med Sci March - April 2021 Vol 37 No 2 www.pjms.org.pk 355 term to define the different types of advanced radiotherapy treatment deliveries including the arc therapy.[3,4] Yu in 1995, was the first one to give the concept of Intensity modulation Arc Therapy (IMAT) in which continuous gantry rotation and dynamic MLC motion combine to produce modulation during the beam on time.[5] Several arcs were used with different gantry angles along with the segments as the approach of classical IMAT
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