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A treatment planning study comparing IMRT techniques and cyber knife for stereotactic body radiotherapy of low-risk prostate carcinoma.

ABSTRACT: PURPOSE:Comparing radiation treatment plans by using the same safety margins and dose objectives for all techniques, to ascertain the optimal radiation technique for the stereotactic body radiotherapy (SBRT) of low-risk prostate cancer. MATERIAL AND METHODS:Treatment plans for 27 randomly selected patients were compared using intensity-modulated (IMRT) techniques as Sliding Window (SW), volumetric modulated arc therapy (VMAT), and helical tomotherapy (HT), as well as Cyber Knife (CK) system. The target dose was calculated to 36.25?Gy delivered in five fractions over 1?week. Dosimetric indices for target volume and organs at risk (OAR) as well as normal tissue complication probability (NTCP) of late rectal and urinary bladder toxicities were analyzed. RESULTS:The CK provided lower homogeneity in the target volume, but higher values for most of the conformity indices compared to the IMRT approaches. The SW demonstrated superior rectum sparing at medium-to-high dose range (V18?Gy - V32.6?Gy) compared to other techniques (p

SUBMITTER: Scobioala S

PROVIDER: S-EPMC6689170 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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A treatment planning study comparing IMRT techniques and cyber knife for stereotactic body radiotherapy of low-risk prostate carcinoma.

Scobioala Sergiu S Kittel Christopher C Elsayad Khaled K Kroeger Kai K Oertel Michael M Samhouri Laith L Haverkamp Uwe U Eich Hans Theodor HT

Radiation oncology (London, England) 20190809 1

<h4>Purpose</h4>Comparing radiation treatment plans by using the same safety margins and dose objectives for all techniques, to ascertain the optimal radiation technique for the stereotactic body radiotherapy (SBRT) of low-risk prostate cancer.<h4>Material and methods</h4>Treatment plans for 27 randomly selected patients were compared using intensity-modulated (IMRT) techniques as Sliding Window (SW), volumetric modulated arc therapy (VMAT), and helical tomotherapy (HT), as well as Cyber Knife ( ...[more]

PMID: 31399115

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Project description:Prostate cancer is the most common non-cutaneous cancer in males. There are a number of options for patients with localized early stage disease, including active surveillance for low-risk disease, surgery, brachytherapy, and external beam radiotherapy. Increasingly, external beam radiotherapy, in the form of dose-escalated and moderately hypofractionated regimens, is being utilized in prostate cancer, with randomized evidence to support their use. Stereotactic body radiotherapy, which is a form of extreme hypofractionation, delivered with high precision and conformality typically over 1 to 5 fractions, offers a more contemporary approach with several advantages including being non-invasive, cost-effective, convenient for patients, and potentially improving patient access. In fact, one study has estimated that if half of the patients currently eligible for conventional fractionated radiotherapy in the United States were treated instead with stereotactic body radiotherapy, this would result in a total cost savings of US$250 million per year. There is also a strong radiobiological rationale to support its use, with prostate cancer believed to have a low α/β ratio and therefore being preferentially sensitive to larger fraction sizes. To date, there are no published randomized trials reporting on the comparative efficacy of stereotactic body radiotherapy compared to alternative treatment modalities, although multiple randomized trials are currently accruing. Yet, early results from the randomized phase III study of HYPOfractionated RadioTherapy of intermediate risk localized Prostate Cancer (HYPO-RT-PC) trial, as well as multiple single-arm phase I/II trials, indicate low rates of late adverse effects with this approach. In patients with low- to intermediate-risk disease, excellent biochemical relapse-free survival outcomes have been reported, albeit with relatively short median follow-up times. These promising early results, coupled with the enormous potential cost savings and implications for resource availability, suggest that stereotactic body radiotherapy will take center stage in the treatment of prostate cancer in the years to come.

Project description:INTRODUCTION:Stereotactic body radiation therapy (SBRT) was found effective in treating laryngeal cancer with only five treatment fractions by a recent clinical trial (NCT01984502, ClinicalTrials.gov). Nevertheless, this trial used the Cyberknife system, which is not widely accessible enough to benefit all patients affected by laryngeal cancer. Our study investigates the feasibility of larynx SBRT treatment planning on a conventional gantry-based LINAC and compares its plan quality with that from the Cyberknife. MATERIALS & METHODS:Ten larynx SBRT cases were originally treated by Cyberknife using fixed cones in our institution, with plans created and optimized using the Monte-Carlo algorithm in the MultiPlan treatment planning system. These cases were retrospectively planned in the Eclipse planning system for a LINAC with the same prescription dose. We used volumetric modulated arc therapy (VMAT) for larynx SBRT planning in Eclipse and incorporated non-coplanar arcs to approach the Cyberknife's large solid angle delivery space. We used both anisotropic analytical algorithm (AAA) and Acuros XB (AXB) algorithm for dose calculation and compared their accuracy by measurements on an in-house larynx phantom. We compared the LINAC VMAT plans (VMAT-AAA and VMAT-AXB) with the original Cyberknife plans using dosimetric endpoints such as the conformity index, gradient indices (R50, R20), OAR maximum/mean doses, and the monitor units. RESULTS:Phantom measurement showed that both the AAA and the AXB algorithms provided adequate dose calculation accuracy (94.7% gamma pass rate on 2%/2 mm criteria for AAA vs. 97.3% for AXB), though AXB provided better accuracy in the air cavity. The LINAC-based VMAT plans achieved similar dosimetric endpoints as the Cyberknife planning, and all plans met the larynx SBRT dosimetric constraints. Cyberknife plans achieved an average conformity index of 1.13, compared to 1.20 of VMAT-AXB and 1.19 of VMAT-AAA. The VMAT plans spared the thyroid gland better with average Dmean of 2.4 Gy (VMAT-AXB) and 2.7 Gy (VMAT-AAA), as compared to 4.3 Gy for Cyberknife plans. The VMAT-AAA plans had a slightly lower contralateral arytenoid Dmax (average: 15.2 Gy) than Cyberknife plans (average: 17.9 Gy) with statistical significance, while the contralateral arytenoid Dmax was similar between VMAT-AXB and Cyberknife plans with no statistically significant difference. Cyberknife plans offered slightly better R50 (average: 5.0) than VMAT-AXB (5.9) and VMAT-AAA (5.7) plans. The VMAT plans substantially reduced the plan MUs to less than 1/3 of the Cyberknife plans, and the differences were statistically significant. The other metrics were similar between VMAT and Cyberknife plans with no statistically significant differences. CONCLUSIONS:Gantry-based LINACs can achieve similar plan quality to Cyberknife systems. Treatment outcome with both methods remains to be investigated.

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Dataset Information

A treatment planning study comparing IMRT techniques and cyber knife for stereotactic body radiotherapy of low-risk prostate carcinoma.

Publications

A treatment planning study comparing IMRT techniques and cyber knife for stereotactic body radiotherapy of low-risk prostate carcinoma.

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