Vol 24, No 2 (2019)
Published online: 2019-03-01

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Improved error detection using a divided treatment plan in volume modulated arc therapy

Kazuo Tarutani12, Masao Tanooka13, Hiroshi Doi14, Masayuki Fujiwara1, Masaki Miyashita2, Kazufumi Kagawa2, Norihiko Kamikonya2, Koichiro Yamakado1
DOI: 10.1016/j.rpor.2018.12.002
Rep Pract Oncol Radiother 2019;24(2):133-141.

Abstract

Aim

We sought to improve error detection ability during volume modulated arc therapy (VMAT) by dividing and evaluating the treatment plan.

Background

VMAT involves moving a beam source delivering radiation to tumor tissue through an arc, which significantly decreases treatment time. Treatment planning for VMAT involves many parameters. Quality assurance before treatment is a major focus of research.

Materials and methods

We used an established VMAT prostate treatment plan and divided it into 12°×30° sections. In all the sections, only image data that generated errors in one segment and those that were integrally acquired were evaluated by a gamma analysis. This was done with five different patient plans.

Results

The integrated image data resulting from errors in each section was 100% (tolerance 0.5mm/0.5%) in the gamma analysis result in all image data. Division of the treatment plans produced a shift in the mean value of each gamma analysis in the cranial, left, and ventral directions of 94.59%, 98.83%, 96.58%, and the discrimination ability improved.

Conclusion

The error discrimination ability was improved by dividing and verifying the portal imaging.

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Reports of Practical Oncology and Radiotherapy