Report on planning comparison of VMAT, IMRT and helical tomotherapy for the ESCALOX-trial pre-study

Abstract

Background The ESCALOX trial was designed as a multicenter, randomized prospective dose escalation study for head and neck cancer. Therefore, feasibility of treatment planning via different treatment planning systems (TPS) and radiotherapy (RT) techniques is essential. We hypothesized the comparability of dose distributions for simultaneous integrated boost (SIB) volumes respecting the constraints by different TPS and RT techniques. Methods CT data sets of the first six patients (all male, mean age: 61.3 years) of the pre-study (up to 77 Gy) were used for comparison of IMRT, VMAT, and helical tomotherapy (HT). Oropharynx was the primary tumor location. Normalization of the three step SIB (77 Gy, 70 Gy, 56 Gy) was D95% = 77 Gy. Coverage (CVF), healthy tissue conformity index (HTCI), conformation number (CN), and dose homogeneity (HI) were compared for PTVs and conformation index (COIN) for parotids. Results All RT techniques achieved good coverage. For SIB77Gy, CVF was best for IMRT and VMAT, HT achieved highest CN followed by VMAT and IMRT. HT reached good HTCI value, and HI compared to both other techniques. For SIB70Gy, CVF was best by IMRT. HTCI favored HT, consequently CN as well. HI was slightly better for HT. For SIB56Gy, CVF resulted comparably. Conformity favors VMAT as seen by HTCI and CN. Dmean of ipsilateral and contralateral parotids favor HT. Conclusion Different TPS for dose escalation reliably achieved high plan quality. Despite the very good results of HT planning for coverage, conformity, and homogeneity, the TPS also achieved acceptable results for IMRT and VMAT. Trial registration ClinicalTrials.gov Identifier: NCT 01212354, EudraCT-No.: 2010-021139-15. ARO: ARO 14-01

Dosimetric justification for the use of volumetric modulated arc therapy in head and neck cancer—A systematic review of the literature

“…Although a number of studies enrolled a limited number of patients, they all succeeded to show the differences regarding PTV coverage. 7 , 11 , 12 While Clemente et al and Stieler et al achieved lower values for CI for VMAT plans, thus demonstrating the superiority of VMAT over IMRT, Pigorsch et al obtained equal coverage factors (CVF) for IMRT and VMAT for PTV77 and PTV56. 7 , 11 , 12 …”

“… 7 , 11 , 12 While Clemente et al and Stieler et al achieved lower values for CI for VMAT plans, thus demonstrating the superiority of VMAT over IMRT, Pigorsch et al obtained equal coverage factors (CVF) for IMRT and VMAT for PTV77 and PTV56. 7 , 11 , 12 …”

“…The values of MU of the selected studies that were presented in the previous section can be found in Table 2. The study led by Pigorsch was 7 In all the studies, the number of monitor units was lower for VMAT plans compared to IMRT. The maximum reduction was obtained by Broggi et al, of around 73% for rapid arc.…”

“…Every step from the QA must be followed, otherwise the clinical outcome of head and neck cancer patients is compromised. 7 …”

A nomogram for predicting late radiation-induced xerostomia among locoregionally advanced nasopharyngeal carcinoma in intensity modulated radiation therapy era

“…Since IMRT is characterized by typically arranging less than 9 fixed-field beam angles, VMAT instead has numerous beam directions from the arc trajectory. Thanks to there being no beam modulation by the MLCs, VMAT achieves less high-dose areas, more homogeneous dose distribution, and better spare to the salivary glands while treatment beams are sequenced one after another in IMRT treatment plan [ 22 ]. Some researchers found that the isodose distribution in IMRT approaches to VMAT as increasing numbers of beams are utilized [ 23 ].…”