Low‐cost Kinect Version 2 imaging system for breath hold monitoring and gating: Proof of concept study for breast cancer VMAT radiotherapy

David M Edmunds,Richard Symonds‐Tayler,Fatemeh Tahavori,Kk Tang,Anna Kirby,Ellen Donovan,Lone Gothard,Poonam Madhale,Kevin Wells,Komel Khabra,Helen Mcnair,David Roberts

doi:10.1002/acm2.12286

Abstract

Voluntary inspiration breath hold (VIBH) for left breast cancer patients has been shown to be a safe and effective method of reducing radiation dose to the heart. Currently, VIBH protocol compliance is monitored visually. In this work, we establish whether it is possible to gate the delivery of radiation from an Elekta linac using the Microsoft Kinect version 2 (Kinect v2) depth sensor to measure a patient breathing signal. This would allow contactless monitoring during VMAT treatment, as an alternative to equipment–assisted methods such as active breathing control (ABC). Breathing traces were acquired from six left breast radiotherapy patients during VIBH. We developed a gating interface to an Elekta linac, using the depth signal from a Kinect v2 to control radiation delivery to a programmable motion platform following patient breathing patterns. Radiation dose to a moving phantom with gating was verified using point dose measurements and a Delta4 verification phantom. 60 breathing traces were obtained with an acquisition success rate of 100%. Point dose measurements for gated deliveries to a moving phantom agreed to within 0.5% of ungated delivery to a static phantom using both a conventional and VMAT treatment plan. Dose measurements with the verification phantom showed that there was a median dose difference of better than 0.5% and a mean (3% 3 mm) gamma index of 92.6% for gated deliveries when using static phantom data as a reference. It is possible to use a Kinect v2 device to monitor voluntary breath hold protocol compliance in a cohort of left breast radiotherapy patients. Furthermore, it is possible to use the signal from a Kinect v2 to gate an Elekta linac to deliver radiation only during the peak inhale VIBH phase.

Highlights

Breast cancer is the most common malignancy in women in the UK, with more than 40,000 new cases diagnosed each year.[1]
We developed a gating interface to an Elekta linac, using the depth signal from a Kinect v2 to control the delivery of radiation to a programmable motion platform
The study was designed to test the hypothesis that repeated voluntary inspiration breath-hold (VIBH) can be monitored with a non contact device (Kinect v2 system) in a cohort of patients in the supine treatment position on an angled breast board, on a radiotherapy treatment unit during the procedure for both standard two field whole breast and Volumetric Modulated Arc Therapy (VMAT) radiotherapy

Summary

Introduction

Breast cancer is the most common malignancy in women in the UK, with more than 40,000 new cases diagnosed each year.[1] Surgery followed by radiotherapy improves local control and survival such that rates of local tumor relapse in the breast are approximately 3% at 5 yr.[2,3] breast radiotherapy is associated with a 1% increase in nonbreast-cancer-related deaths at 15 yr, 90% of which are cardiovascular in origin.[4,5] Given the increasing incidence of breast cancer, and the large numbers of survivors in the population, it is imperative that the improvements in breast cancer mortality are not compromised by nonbreast-cancer deaths. One approach to achieving this is deep inspiration breath-hold, using either equipment-assisted or voluntary inspiration breath-hold (VIBH) techniques.[6,7]

Methods

Results

Conclusion