Multiple breath-hold segmented volumetric modulated arc therapy under real-time fluoroscopic image guidance with implanted fiducial markers: preliminary clinical experience

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.

Multiple Breath-hold Volumetric Modulated Arc Therapy Under Fluoroscopic Image Guidance with an Implanted Fiducial Marker: An Advanced Technique

“…Consequently, the delivery could be restarted at any gantry angle once the marker position moved within the tolerance lines. This is a much safer technique compared to our previous report [ 4 ], where an unexpected intermediate beam interrupt due to a breath-hold failure during a segmented VMAT delivery had not been well managed due to lack of the DRR for the failed gantry angle. In addition, the present technique does not need the breathing monitoring by way of thoracoabdominal surface coordinates during VMAT delivery, which was required in our previous method [ 4 ].…”

“…To solve this problem, a different fluoroscopic approach was proposed using implanted fiducial markers [ 4 ], where the diaphragm contour was replaced with contours of the fiducial markers. Although this technique worked well, a possible disadvantage may be that an unexpected intermediate beam interrupt due to a breath-hold failure during a segmented VMAT delivery cannot be well managed due to lack of the DRR for the failed gantry angle.…”

Intrafractional Diaphragm Variations During Breath-Hold Stereotactic Body Radiotherapy for a Liver Tumor Based on Real-Time Registration Between Kilovoltage Projection Streaming and Digitally Reconstructed Radiograph Images: A Case Report

“…This dynamic assessment allows for a more accurate estimation of the target position and the potential need for adaptive treatment strategies. Takanaka et al investigated a technique for multiple breath-hold split-VMAT using implanted fiducial markers and real-time fluoroscopic guidance [ 14 ]. Their method, demonstrated in a pancreatic cancer case, shows potential for treating tumors affected by respiration.…”

Initial validation of a diaphragm tracking system for multiple breath‐hold volumetric modulated arc therapy of abdominal tumors: A phantom study

“…1 Most of the breath-hold techniques are based on motion monitoring of body surface [2][3][4] or embedded metal markers. [5][6][7] Body surface may be a good surrogate for a near-surface target, but the accuracy was reduced for deep-seated tumors in some patients. 8 On the other hand, metal markers may cause migration and complications, and therefore risk assessment would be required for each patient.…”

“…The breath‐hold radiotherapy has been increasingly used to mitigate interfractional and intrafractional breathing impact on treatment planning and beam delivery, thereby reducing the dose to organs‐at‐risk (OARs) 1 . Most of the breath‐hold techniques are based on motion monitoring of body surface 2–4 or embedded metal markers 5–7 . Body surface may be a good surrogate for a near‐surface target, but the accuracy was reduced for deep‐seated tumors in some patients 8 .…”