Experimental Evaluation of the Influence of RPM Box Positioning Using AlignRT™ Postural Video™ in DIBH Treatments.
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Abstract
INTRODUCTION
DIBH (Deep Inspiration Breath Hold) is a widely used technique in clinical radiotherapy to reduce target motion and increase the distance between the target and organs at risk (OARs). With the introduction of a “tattoo-free” approach based on SGRT systems, challenges have emerged in ensuring reproducibility. To overcome this limitation, the inclusion of the RPM box within the patient’s body contour (“body” volume) has been proposed, allowing the visualization of its contours on the patient surface.
This study aimed to evaluate the reproducibility of the RPM box positioning and the impact of this approach on treatment time, accuracy, and patient comfort.
MATERIALS AND METHODS
This study was conducted at the Radiation Oncology Unit of the Campus Bio-Medico University Hospital Foundation. A total of 60 patients were analyzed: 30 treated with RPM box placement at the xiphoid process and 30 with placement guided by body contours obtained using AlignRT™ Postural Video™ (VisionRT Ltd., London, UK). All data were collected using the Offline Review mode of the ARIA RTM (Varian Medical Systems).
The longitudinal displacement of the RPM box was estimated using the median values. This parameter was determined by comparing all pre-treatment CBCT scans with the initial simulation CT and measuring the difference in the longitudinal displacement of the RPM box.
Subsequently, the number of repeated CBCT scans for each patient in both groups was noted. The treatment duration (in seconds) was analyzed and the number of effective breath-holds performed to complete both the CBCT acquisition and treatment delivery was evaluated.
RESULTS
The analysis demonstrated a significant improvement across all evaluated parameters, with the most notable differences observed in the longitudinal displacement of the RPM box and in the number of repeated CBCT scans. Regarding this displacement, it was observed that contouring the surrogate produced a significant 60% reduction. With the RPM box contoured, daily imaging repetitions decreased by 50%; the number of effective apneas required to complete verification decreased by 37%; the total duration of daily imaging decreased by 24% (31 s); and the number of effective apneas employed decreased by 32%.
CONCLUSIONS
The significant reduction in positioning errors, repeated imaging, and the number of required breath-holds translates into increased accuracy and efficiency of the overall therapeutic process, reducing patient effort and contributing to an improved “patient experience”.
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