Statistical Determination of the Gating Windows for Respiratory-Gated Radiotherapy Using a Visible Guiding System.

Se An Oh,Sung Kyu Kim,Ji Woon Yea,Qinghui Zhang

doi:10.1371/journal.pone.0156357

Se An Oh, Sung Kyu Kim + Show 2 more

Open Access

https://doi.org/10.1371/journal.pone.0156357

Copy DOI

Journal: PloS one	Publication Date: May 26, 2016
Citations: 19	License type: CC BY 4.0

Affiliation: Yeungnam University Medical Center, Yeungnam University

Abstract

Respiratory-gated radiation therapy (RGRT) is used to minimize the radiation dose to normal tissue in lung-cancer patients. Although determining the gating window in the respiratory phase of patients is important in RGRT, it is not easy. Our aim was to determine the optimal gating window when using a visible guiding system for RGRT. Between April and October 2014, the breathing signals of 23 lung-cancer patients were recorded with a real-time position management (RPM) respiratory gating system (Varian, USA). We performed statistical analysis with breathing signals to find the optimal gating window for guided breathing in RGRT. When we compared breathing signals before and after the breathing training, 19 of the 23 patients showed statistically significant differences (p < 0.05). The standard deviation of the respiration signals after breathing training was lowest for phases of 30%–70%. The results showed that the optimal gating window in RGRT is 40% (30%–70%) with respect to repeatability for breathing after respiration training with the visible guiding system. RGRT was performed with the RPM system to confirm the usefulness of the visible guiding system. The RPM system and our visible guiding system improve the respiratory regularity, which in turn should improve the accuracy and efficiency of RGRT.

Highlights

The aim of radiation therapy is to provide a sufficient radiation dose to the tumors of cancer patients while minimizing the radiation dose to normal tissues [1]
The results showed that the optimal gating window in Respiratory-gated radiation therapy (RGRT) is 40% (30%– 70%) with respect to repeatability for breathing after respiration training with the visible guiding system
If the margin added to the target volume is too small, the uncertainty of the radiation dose to the target volume increases and leads to undesired treatment outcomes, the radiation dose into the lung is decreased to reduce the chance of radiation pneumonitis

Summary

Introduction

The aim of radiation therapy is to provide a sufficient radiation dose to the tumors of cancer patients while minimizing the radiation dose to normal tissues [1]. Reports from the Radiation Therapy Oncology Group (RTOG) [7,8,9,10] include guidelines for stereotactic body radiation therapy (SBRT) treatment of lung cancer and cover patient selection, techniques, dose fractions, dose verification at treatments, localization, simulations, immobilization, calculation algorithms, prescription dose constraints for treatment planning, and critical organ dose–volume limits. Adding large margins to the target volume helps deliver a sufficient radiation dose to the tumor, the radiation dose to the lung increases, which increases the chance of radiation pneumonitis [11, 12]. If the margin added to the target volume is too small, the uncertainty of the radiation dose to the target volume increases and leads to undesired treatment outcomes, the radiation dose into the lung is decreased to reduce the chance of radiation pneumonitis

Objectives

Methods

Results

Discussion

Conclusion