Multiple Breath-Hold Segmented Volumetric Modulated Arc Therapy Under Real-Time Fluoroscopic Image Guidance with Implanted Fiducial Markers: Preliminary Clinical Experience
TSUYOSHI TAKANAKA, MD, PhD, TOMOYASU KUMANO, MD, PhD, SHIGEYUKI TAKAMATSU, MD, Phd, TETSUYA MINAMI, MD, Phd, WATARU KODA, MD, Phd, TOSHIFUMI GABATA, MD, Phd, OSAMU MATSUI, MD, Phd, KIMIYA NOTO, RT, SHINICHI UEDA, RT and YUICHI KURATA, RT
Abstract: A technique for multiple breath-hold segmented volumetric modulated arc therapy (VMAT) has been proposed under real-time fluoroscopic image guidance with implanted fiducial markers. Fiducial markers were embedded as close as possible to a tumour and the patient was asked to breathe in slowly under fluoroscopy. Immediately after the marker positions on the fluoroscopic image moved inside the planned marker contours transferred from a digitally reconstructed radiographic image at each gantry start angle, the patient was asked to hold their breath and a segmented VMAT beam was delivered. During beam delivery, the breath-hold status was continuously monitored by viewing a pointer in a breath monitoring system, Abches (Apex Medical, Tokyo, Japan), with the aid of a video camera installed in the treatment room. As long as the pointer stayed still, the segmented VMAT delivery continued for a preset period of 15–30 s, depending on the breath-hold capability of each patient. As soon as each segmented delivery was completed, the beam interrupt button was pushed; subsequently, the patient was asked to breathe freely. Because the preset breath-hold period was determined in order for each patient to hold their breath without fail, an intermediate beam interrupt due to breath-hold failure during the segmented beam delivery was not observed. This procedure was repeated until all the segmented VMAT beams were delivered. A case of pancreatic cancer is reported here as a preliminary study. The proposed technique may be clinically advantageous for treating tumours that move with respiration, including pancreatic cancer, lung tumour and other abdominal cancers.
