Lung and liver SBRT using helical tomotherapy — a dosimetric comparison of fixed jaw and dynamic jaw delivery

Rudofsky, Leonie; Aynsley, E.; Beck, Sebastian; Schubert, Kai; Habl, Gregor; Krause, Sonja; Debus, Jürgen; Sterzing, Florian

doi:10.1120/jacmp.v15i3.4664

Cited by 17 publications

(22 citation statements)

References 27 publications

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“…The TomoEDGE mode can reduce the longitudinal penumbra, and studies have reported an improvement in longitudinal dose distribution in a few clinical cases [ 3 , 4 , 9 , 11 ]. Based on our questionnaire results, 67% of all the cooperating facilities had TomoEDGE licenses, and >80% of these facilities used a dynamic FW (Fig.…”

Section: Discussionmentioning

confidence: 99%

Interfacility variation in treatment planning parameters in tomotherapy: field width, pitch, and modulation factor

Shimizu

Sasaki

Kubôta

et al. 2018

Journal of Radiation Research

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Several studies have reported changes in dose distribution and delivery time based on the value of specific planning parameters [field width (FW), pitch, and modulation factor (MF)] in tomotherapy. However, the variation in the parameters between different facilities is unknown. The purpose of this study was to determine standard values of the above parameters for cases of head and neck cancer (HNC) and prostate cancer (PC) in Japan. In this survey, a web-based questionnaire was sent to 48 facilities performing radiation therapy with tomotherapy in March 2016. The deadline for data submission was April 2016. In the questionnaire, the values of the planning parameters usually used were requested and 23 responses were received, representing a response rate of 48% (23/48). The FW selected was 2.5 cm in most facilities, and facilities with a tomoEDGE license used dynamic FW rather than fixed FW. Facilities changed the pitch based on FW, dose per fraction, or target offset more frequently in HNC than in PC. In contrast, >50% of the facilities used the magic number proposed by Kissick et al. Median preset MFs (range, min to max) in HNC and PC were 2.4 (1.8–2.8) and 2.0 (1.8–3.0), respectively, and MF values showed large variations between the facilities. Our results are likely to be useful to several facilities designing treatment plans in tomotherapy.

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Section: Discussionmentioning

confidence: 99%

Interfacility variation in treatment planning parameters in tomotherapy: field width, pitch, and modulation factor

Shimizu

Sasaki

Kubôta

et al. 2018

Journal of Radiation Research

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“…Patient selection, imaging protocols, and detailed treatment techniques have been reported previously ( 23 – 25 ). Risk-adapted fractionation schemes were used, meaning that dose and fractionation schemes were adjusted based on tumor size and location (peripheral vs. central).…”

Section: Methodsmentioning

confidence: 99%

Parenchymal and Functional Lung Changes after Stereotactic Body Radiotherapy for Early-Stage Non-Small Cell Lung Cancer—Experiences from a Single Institution

et al. 2017

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IntroductionThis study aimed to evaluate parenchymal and functional lung changes following stereotactic body radiotherapy (SBRT) for early-stage non-small cell lung cancer (NSCLC) patients and to correlate radiological and functional findings with patient and treatment characteristics as well as survival.Materials and methodsSeventy patients with early-stage NSCLC treated with SBRT from 2004 to 2015 with more than 1 year of CT follow-up scans were analyzed. Incidence, morphology, severity of acute and late lung abnormalities as well as pulmonary function changes were evaluated and correlated with outcome.ResultsMedian follow-up time was 32.2 months with 2-year overall survival (OS) of 83% and local progression-free survival of 88%, respectively. Regarding parenchymal changes, most patients only developed mild to moderate CT abnormalities. Mean ipsilateral lung dose (MLD) in biological effective dose and planning target volume size were significantly associated with maximum severity score of parenchymal changes (p = 0.014, p < 0.001). Furthermore, both maximum severity score and MLD were significantly connected with OS in univariate analysis (p = 0.043, p = 0.025). For functional lung changes, we detected significantly reduced total lung capacity, forced expiratory volume in 1 s, and forced vital capacity (FVC) parameters after SBRT (p ≤ 0.001). Multivariate analyses revealed SBRT with an MLD ≥ 9.72 Gy and FVC reduction ≥0.54 L as independent prognostic factors for inferior OS (p = 0.029, p = 0.004).ConclusionSBRT was generally tolerated well with only mild toxicity. For evaluating the possible prognostic impact of MLD and FVC reduction on survival detected in this analysis, larger prospective studies are truly needed.

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“…[19][20][21][22] Similar results were observed when compared to linacbased intensity modulated radiation therapy (IMRT), VMAT plans, helical TomoTherapy, or optimized robotic CyberKnife plans (showing significant increases in SBRT treatment times). [23][24][25][26] However, for a single dose of lung SBRT treatments, highly modulated IMRT/ VMAT plans are susceptible to delivery uncertainties due to smallfield dosimetry error 27 and interplay effects 28 users can control the field aperture shape and create a 3D plan using dynamic conformal arc (DCA) therapy before VMAT optimization.…”

Section: Introductionmentioning

confidence: 99%

A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT

Pokhrel

Visak

Sanford

2020

J Applied Clin Med Phys

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Purpose: Volumetric modulated arc therapy (VMAT) is gaining popularity for stereotactic treatment of lung lesions for medically inoperable patients. Due to multiple beamlets in delivery of highly modulated VMAT plans, there are dose delivery uncertainties associated with small-field dosimetry error and interplay effects with small lesions. We describe and compare a clinically useful dynamic conformal arc (DCA)-based VMAT (d-VMAT) technique for lung SBRT using flattening filter free (FFF) beams to minimize these effects. Materials and Methods: Ten solitary early-stage I-II non-small-cell lung cancer (NSCLC) patients were treated with a single dose of 30 Gy using 3-6 non-coplanar VMAT arcs (clinical VMAT) with 6X-FFF beams in our clinic. These clinically treated plans were re-optimized using a novel d-VMAT planning technique. For comparison, d-VMAT plans were recalculated using DCA with user-controlled field aperture shape before VMAT optimization. Identical beam geometry, dose calculation algorithm, grid size, and planning objectives were used. The clinical VMAT and d-VMAT plans were compared via RTOG-0915 protocol compliances for conformity, gradient indices, and dose to organs at risk (OAR). Additionally, treatment delivery efficiency and accuracy were recorded. Results: All plans met RTOG-0915 requirements. Comparing with clinical VMAT, d-VMAT plans gave similar target coverage with better target conformity, tighter radiosurgical dose distribution with lower gradient indices, and dose to OAR. Lower total number of monitor units and small beam modulation factor reduced beam-on time by 1.75 min (P < 0.001), on average (maximum up to 2.52 min). Beam delivery accuracy was improved by 2%, on average (P < 0.05) and maximum up to 6% in some cases for d-VMAT plans. Conclusion: This simple d-VMAT technique provided excellent plan quality, reduced intermediate dose-spillage, and dose to OAR while providing faster treatment delivery by significantly reducing beam-on time. This novel treatment planning approach will improve patient compliance along with potentially reducing intrafraction motion error. Moreover, with less MLC modulation through the target, d-VMAT could potentially minimize small-field dosimetry errors and MLC interplay effects. If

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Lung and liver SBRT using helical tomotherapy — a dosimetric comparison of fixed jaw and dynamic jaw delivery

Cited by 17 publications

References 27 publications

Interfacility variation in treatment planning parameters in tomotherapy: field width, pitch, and modulation factor

Interfacility variation in treatment planning parameters in tomotherapy: field width, pitch, and modulation factor

Parenchymal and Functional Lung Changes after Stereotactic Body Radiotherapy for Early-Stage Non-Small Cell Lung Cancer—Experiences from a Single Institution

A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT

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