TITLE:
A Half-Arc Multiple Deep-Inspiration Breath-Hold Volumetric Modulated Arc Therapy for a Lung Tumor with 10 MV Flattening-Filter-Free Beams and an Image Sensor Measuring a Distance Map to Thorax Surface: An Initial Clinical Experience
AUTHORS:
Keiichi Nakagawa, Kanabu Nawa, Masatoshi Hashimoto, Shuri Aoki, Yoshihiro Kaneko, Hideomi Yamashita, Akihiro Haga
KEYWORDS:
Deep Inspiration Breath-Hold, DIBH, FFF, VMAT, Kinect, Lung
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.6 No.1,
January
13,
2017
ABSTRACT: A
technique for multiple deep-inspiration breath-hold (DIBH) volumetric modulated
arc therapy (VMAT) for a lung tumor has been proposed with 10 MV
flattening-filter-free beams and an image sensor measuring a distance map to
thorax surface. Planning CT images were acquired under a DIBH condition and a
clinical target volume (CTV) was contoured. This procedure was repeated five
times and an internal target volume (ITV) among the multiple DIBHs was created
by integrating the five CTVs. A planning target volume (PTV) was defined by
adding an isotropic margin of 5 mm to the ITV. Immediately before treatment, a
30-second half-arc cone-beam computer tomography (CBCT) imaging was performed
under another DIBH condition, and the couch was repositioned so that tumor may
be located inside the PTV contours. An infrared distance measurement device
having laser diodes and an image sensor was attached to the couch, and a
distance map to the patient thorax surface was recorded as a reference during
still another DIBH condition. A half-arc segmented VMAT beams with two beam
interrupts were delivered to the patient under multiple DIBHs, where the
delivery time of each of the three segmented beams was 30 seconds. During the
beam delivery, the distance map was monitored in real time to confirm that the
distance to the thorax surface remained unchanged. In-treatment CBCT images
suggested that the tumor position at the time of tumor registration was
accurately reproduced during the DIBH VMAT delivery.