open access

Vol 25, No 2 (2020)
Published online: 2020-03-01
Submitted: 2019-08-30
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Evaluation of the target dose coverage of stereotactic body radiotherapy for lung cancer using helical tomotherapy: A dynamic phantom study

Masahide Saito, Hidekazu Suzuki, Naoki Sano, Kazunari Ashizawa, Kazuya Yoshizawa, Yuki Shibata, Koji Ueda, Takafumi Komiyama, Kan Marino, Shinichi Aoki, Ryo Saito, Yoshiyasu Maehata, Hiroshi Onishi
DOI: 10.1016/j.rpor.2020.01.001
·
Rep Pract Oncol Radiother 2020;25(2):200-205.

open access

Vol 25, No 2 (2020)
Published online: 2020-03-01
Submitted: 2019-08-30

Abstract

Aim

To evaluate the target dose coverage for lung stereotactic body radiotherapy (SBRT) using helical tomotherapy (HT) with the internal tumor volume (ITV) margin settings adjusted according to the degree of tumor motion.

Background

Lung SBRT with HT may cause a dosimetric error when the target motion is large.

Materials and methods

Two lung SBRT plans were created using a tomotherapy planning station. Using these original plans, five plans with different ITV margins (4.0–20.0mm for superior-inferior [SI] dimension) were generated. To evaluate the effects of respiratory motion on HT, an original dynamic motion phantom was developed. The respiratory wave of a healthy volunteer was used for dynamic motion as the typical tumor respiratory motion. Five patterns of motion amplitude that corresponded to five ITV margin sizes and three breathing cycles of 7, 14, and 28 breaths per minute were used. We evaluated the target dose change between a static delivery and a dynamic delivery with each motion pattern.

Results

The target dose difference increased as the tumor size decreased and as the tumor motion increased. Although a target dose difference of <5 % was observed at ≤10mm of tumor motion for each condition, a maximum difference of -9.94 % ± 7.10 % was observed in cases of small tumors with 20mm of tumor motion under slow respiration.

Conclusions

Minimizing respiratory movement is recommended as much as possible for lung SBRT with HT, especially for cases involving small tumors.

Abstract

Aim

To evaluate the target dose coverage for lung stereotactic body radiotherapy (SBRT) using helical tomotherapy (HT) with the internal tumor volume (ITV) margin settings adjusted according to the degree of tumor motion.

Background

Lung SBRT with HT may cause a dosimetric error when the target motion is large.

Materials and methods

Two lung SBRT plans were created using a tomotherapy planning station. Using these original plans, five plans with different ITV margins (4.0–20.0mm for superior-inferior [SI] dimension) were generated. To evaluate the effects of respiratory motion on HT, an original dynamic motion phantom was developed. The respiratory wave of a healthy volunteer was used for dynamic motion as the typical tumor respiratory motion. Five patterns of motion amplitude that corresponded to five ITV margin sizes and three breathing cycles of 7, 14, and 28 breaths per minute were used. We evaluated the target dose change between a static delivery and a dynamic delivery with each motion pattern.

Results

The target dose difference increased as the tumor size decreased and as the tumor motion increased. Although a target dose difference of <5 % was observed at ≤10mm of tumor motion for each condition, a maximum difference of -9.94 % ± 7.10 % was observed in cases of small tumors with 20mm of tumor motion under slow respiration.

Conclusions

Minimizing respiratory movement is recommended as much as possible for lung SBRT with HT, especially for cases involving small tumors.

Get Citation

Keywords

Helical tomotherapy; SBRT; Lung cancer; Respiratory motion management

About this article
Title

Evaluation of the target dose coverage of stereotactic body radiotherapy for lung cancer using helical tomotherapy: A dynamic phantom study

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 25, No 2 (2020)

Pages

200-205

Published online

2020-03-01

DOI

10.1016/j.rpor.2020.01.001

Bibliographic record

Rep Pract Oncol Radiother 2020;25(2):200-205.

Keywords

Helical tomotherapy
SBRT
Lung cancer
Respiratory motion management

Authors

Masahide Saito
Hidekazu Suzuki
Naoki Sano
Kazunari Ashizawa
Kazuya Yoshizawa
Yuki Shibata
Koji Ueda
Takafumi Komiyama
Kan Marino
Shinichi Aoki
Ryo Saito
Yoshiyasu Maehata
Hiroshi Onishi

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