Dosimetric comparison between helical tomotherapy, volume modulated arc-therapy and Fixed-Field intensity modulated radiation therapy in postoperative adjuvant radiotherapy for cervical cancer

Yu, Deyang; Wang, Lei; Hu, Xueyuan; Li, Xin; Bai, Yang; Yang, Shanshan

doi:10.21203/rs.3.rs-58107/v1

Cited by 1 publication

(8 citation statements)

References 24 publications

(24 reference statements)

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“…Also, our results showing that VMAT can deliver dose in a shorter time than HT is in agreement with the other studies. 10,11,13,15 Furthermore, our finding that plan computation times for VMAT are longer than those for HT is consistent with the literature 48 and is explained because, mathematically speaking, HT is an easier optimization problem than VMAT. 42,43 Finally, a previous study on 3 patients suggested that the distance between Pareto fronts for different treatment techniques was related to the relative PTV-rectum-overlap volume.…”

Section: Discussionsupporting

confidence: 90%

“…This finding is in agreement with studies that were in favor of VMAT for simple geometries 15,16 and showed that HT was superior for complex geometries. 12,13 The reason why older studies were never in favor of VMAT, even for simple geometries, is the following: 10,11,14,[44][45][46] VMAT is a difficult, non-convex optimization problem that requires sophisticated optimization algorithms to avoid getting trapped in a local optimum far away from the global optimum. 42,43,47 With the development of new algorithms and faster computers, one may expect VMAT to get better over years.This is not the case for HT,because it is an easier convex optimization problem.…”

Section: Discussionmentioning

confidence: 99%

“…8,9 In the literature, many studies have compared different set-ups, some of which specifically compared VMAT and HT treatment techniques for prostate 10,11 and other cancer sites. 12,13 However, in each case, the studies compared one VMAT and one HT treatment plan, with some dose metrics favoring VMAT and others favoring HT. The decision as to which plan was better thus depended on individual physician preference.…”

Section: Introductionmentioning

confidence: 99%

“…Studies comparing different setups using the more objective method of Pareto front comparisons are scarcer. [9][10][11][12][13][14] Two studies specifically compared VMAT and HT using Pareto fronts in one prostate 15 and one breast cancer patient. 16 However, to the authors' knowledge, there are no studies comparing VMAT and HT using Pareto fronts for prostate cancer in more than one patient.…”

Section: Introductionmentioning

confidence: 99%

“…As a Pareto front represents the set of best possible treatment plans for a given set‐up, that is, for a given treatment technique applying given machine parameters, it can be used to make a fair comparison between those set‐ups 8,9 . In the literature, many studies have compared different set‐ups, some of which specifically compared VMAT and HT treatment techniques for prostate 10,11 and other cancer sites 12,13 . However, in each case, the studies compared one VMAT and one HT treatment plan, with some dose metrics favoring VMAT and others favoring HT.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of volumetric modulated arc therapy and helical tomotherapy for prostate cancer using Pareto fronts

Wüthrich,

Wang,

Zeverino

et al. 2023

Medical Physics

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BackgroundStudies comparing different radiotherapy treatment techniques—such as volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT)—typically compare one treatment plan per technique. Often, some dose metrics favor one plan and others favor the other, so the final plan decision involves subjective preferences. Pareto front comparisons provide a more objective framework for comparing different treatment techniques. A Pareto front is the set of all treatment plans where improvement in one criterion is possible only by worsening another criterion. However, different Pareto fronts can be obtained depending on the chosen machine settings.PurposeTo compare VMAT and HT using Pareto fronts and blind expert evaluation, to explain the observed differences, and to illustrate limitations of using Pareto fronts.MethodsWe generated Pareto fronts for twenty‐four prostate cancer patients treated at our clinic for VMAT and HT techniques using an in‐house script that controlled a commercial treatment planning system. We varied the PTV under‐coverage (100% ‐ V95%) and the rectum mean dose, and fixed the mean doses to the bladder and femoral heads. In order to ensure a fair comparison, those fixed mean doses were the same for the two treatment techniques and the sets of objective functions were chosen so that the conformity indexes of the two treatment techniques were also the same. We used the same machine settings as are used in our clinic. Then, we compared the VMAT and HT Pareto fronts using a specific metric (clinical distance measure) and validated the comparison using a blinded expert evaluation of treatment plans on these fronts for all patients in the cohort. Furthermore, we investigated the observed differences between VMAT and HT and pointed out limitations of using Pareto fronts.ResultsBoth clinical distance and blind treatment plan comparison showed that VMAT Pareto fronts were better than HT fronts. VMAT fronts for 10 and 6 MV beam energy were almost identical. HT fronts improved with different machine settings, but were still inferior to VMAT fronts.ConclusionsThat VMAT Pareto fronts are better than HT fronts may be explained by the fact that the linear accelerator can rapidly vary the dose rate. This is an advantage in simple geometries that might vanish in more complex geometries. Furthermore, one should be cautious when speaking about Pareto optimal plans as the best possible plans, as their calculation depends on many parameters.

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