Intensity modulated arc therapy implementation in a three phase adaptive 18F-FDG-PET voxel intensity-based planning strategy for head-and-neck cancer. Issue 1 (December 2016)

• Record Type: Journal Article
• Authors: Berwouts, Dieter; Olteanu, Luiza; Speleers, Bruno; Duprez, Frédéric; Madani, Indira; Vercauteren, Tom; De Neve, Wilfried; De Gersem, Werner
• Is Part Of: Radiation oncology. Volume 11:Issue 1(2016)
• Page Start: 1
• Page End: 9
• Publication Date: 2016-12
• Subjects: Adaptive intensity modulated arc therapy -- Dose-painting -- Intensity modulated radiotherapy -- Head-and-neck cancer; Cancer -- Radiotherapy -- Periodicals; 616.9940642
• DOI: 10.1186/s13014-016-0629-3
• Languages: English
• ISSNs: 1748-717X

Abstract

Abstract Background This study investigates the implementation of a new intensity modulated arc therapy (IMAT) class solution in comparison to a 6-static beam step-and-shoot intensity modulated radiotherapy (s-IMRT) for three-phase adaptive18 F-FDG-PET-voxel-based dose-painting-by-numbers (DPBN) for head-and-neck cancer. Methods We developed18 F-FDG-PET-voxel intensity-based IMAT employing multiple arcs and compared it to clinically used s-IMRT DPBN. Three IMAT plans using18 F-FDG-PET/CT acquired before treatment (phase I), after 8 fractions (phase II) and CT acquired after 18 fractions (phase III) were generated for each of 10 patients treated with 3 s-IMRT plans based on the same image sets. Based on deformable image registration (ABAS, version 0.41, Elekta CMS Software, Maryland Heights, MO), doses of the 3 plans were summed on the pretreatment CT using validated in-house developed software. Dosimetric indices in targets and organs-at-risk (OARs), biologic conformity of treatment plans set at ≤5 %, treatment quality and efficiency were compared between IMAT and s-IMRT for the whole group and for individual patients. Results Doses to most organs-at-risk (OARs) were significantly better in IMAT plans, while target levels were similar for both types of plans. On average, IMAT ipsilateral and contralateral parotid mean doses were 14.0 % (p = 0.001) and 12.7 % (p < 0.001) lower, respectively. Pharyngeal constrictors D50% levels were similar or reduced with up to 54.9 % for IMAT compared to s-IMRT for individual patient cases. IMAT significantly improved biologic conformity by 2.1 % for treatment phases I and II. 3D phantom measurements reported an agreement of ≥95 % for 3 % and 3 mm criteria for both treatment modalities. IMAT delivery time was significantly shortened on average by 41.1 %. Conclusions IMAT implementation significantly improved the biologic conformity as compared to s-IMRT in adaptive dose-escalated DPBN treatments. The better OAR sparing and faster delivery highly improved the treatment efficiency.