open access

Vol 25, No 5 (2020)
Original research articles
Published online: 2020-09-01
Submitted: 2020-04-25
Get Citation

Simplification of head and neck volumetric modulated arc therapy patient-specific quality assurance, using a Delta4 PT

Motoharu Sasaki, Wataru Sugimoto, Hitoshi Ikushima
DOI: 10.1016/j.rpor.2020.07.004
·
Rep Pract Oncol Radiother 2020;25(5):793-800.

open access

Vol 25, No 5 (2020)
Original research articles
Published online: 2020-09-01
Submitted: 2020-04-25

Abstract

Background/Aim

In many facilities, intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) use intensity-modulated beams, formed by a multi-leaf collimator (MLC). In IMRT and VMAT, MLC and linear accelerator errors (both geometric and dose), can significantly affect the doses administered to patients. Therefore, IMRT and VMAT treatment plans must include the use of patient-specific quality assurance (QA) before treatment to confirm dose accuracy.

Materials and methods

In this study, we compared and analyzed the results of dose verification using a multi-dimensional dose verification system Delta4 PT, an ionization chamber dosimeter, and gafchromic film, using data from 52 patients undergoing head and neck VMAT as the test material.

Result

Based on the results of the absolute dose verification for the ionization chamber dosimeter and Delta4 PT, taking an axial view, the upper limit of the 95% confidence interval was 3.13%, and the lower limit was −3.67%, indicating good agreement. These results mean that as long as absolute dose verification for the axial view does not deviate from this range, Delta4 PT can be used as an alternative to an ionization chamber dosimeter for absolute dose verification. When we then reviewed dose distribution verification, the pass rate for Delta4 PT was acceptable, and was less varied than that of gafchromic film.

Conclusion

This results in that provided the pass rate result for Delta4 PT does not fall below 96%, it can be used as a substitute for gafchromic film in dose distribution verification. These results indicate that patient-specific QA could be simplified.

Abstract

Background/Aim

In many facilities, intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) use intensity-modulated beams, formed by a multi-leaf collimator (MLC). In IMRT and VMAT, MLC and linear accelerator errors (both geometric and dose), can significantly affect the doses administered to patients. Therefore, IMRT and VMAT treatment plans must include the use of patient-specific quality assurance (QA) before treatment to confirm dose accuracy.

Materials and methods

In this study, we compared and analyzed the results of dose verification using a multi-dimensional dose verification system Delta4 PT, an ionization chamber dosimeter, and gafchromic film, using data from 52 patients undergoing head and neck VMAT as the test material.

Result

Based on the results of the absolute dose verification for the ionization chamber dosimeter and Delta4 PT, taking an axial view, the upper limit of the 95% confidence interval was 3.13%, and the lower limit was −3.67%, indicating good agreement. These results mean that as long as absolute dose verification for the axial view does not deviate from this range, Delta4 PT can be used as an alternative to an ionization chamber dosimeter for absolute dose verification. When we then reviewed dose distribution verification, the pass rate for Delta4 PT was acceptable, and was less varied than that of gafchromic film.

Conclusion

This results in that provided the pass rate result for Delta4 PT does not fall below 96%, it can be used as a substitute for gafchromic film in dose distribution verification. These results indicate that patient-specific QA could be simplified.

Get Citation

Keywords

Delta4 PT; Volumetric modulated radiation therapy; Head and neck; Patient-specific quality assurance

About this article
Title

Simplification of head and neck volumetric modulated arc therapy patient-specific quality assurance, using a Delta4 PT

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 25, No 5 (2020)

Pages

793-800

Published online

2020-09-01

DOI

10.1016/j.rpor.2020.07.004

Bibliographic record

Rep Pract Oncol Radiother 2020;25(5):793-800.

Keywords

Delta4 PT
Volumetric modulated radiation therapy
Head and neck
Patient-specific quality assurance

Authors

Motoharu Sasaki
Wataru Sugimoto
Hitoshi Ikushima

Important: This website uses cookies. More >>

The cookies allow us to identify your computer and find out details about your last visit. They remembering whether you've visited the site before, so that you remain logged in - or to help us work out how many new website visitors we get each month. Most internet browsers accept cookies automatically, but you can change the settings of your browser to erase cookies or prevent automatic acceptance if you prefer.

By "Via Medica sp. z o.o." sp.k., ul. Świętokrzyska 73, 80–180 Gdańsk, Poland
tel.:+48 58 320 94 94, fax:+48 58 320 94 60, e-mail: journals@viamedica.pl