Characterization of Respiration-Induced Motion in Prone Versus Supine Patient Positioning for Thoracic Radiation Therapy

Abstract

Variations in the breathing characteristics, both on short term (intrafraction) and long term (interfraction) time scales, may adversely affect the radiation therapy process at all stages when treating lung tumors. Prone position has been shown to improve consistency (ie, reduced intrafraction variability) and reproducibility (ie, reduced interfraction variability) of the respiratory pattern with respect to breathing amplitude and period as a result of natural abdominal compression, with no active involvement required from the patient. The next natural step in investigating breathing-induced changes is to evaluate motion amplitude changes between prone and supine targets or organs at risk, which is the purpose of the present study. Methods and Materials: Patients with lung cancer received repeat helical 4-dimensional computed tomography scans, one prone and one supine, during the same radiation therapy simulation session. In the maximum-inhale and maximum-exhale phases, all thoracic structures were delineated by an expert radiation oncologist. Geometric centroid trajectories of delineated structures were compared between patient orientations. Motion amplitude was measured as the magnitude of difference in structure centroid position between inhale and exhale. Results: Amplitude of organ motion was larger when the patient was in the prone position compared with supine for all structures except the lower left lobe and left lung as a whole. Across all 12 patients, significant differences in mean motion amplitude between orientations were identified for the right lung (3.0 mm, P Z .01), T2 (0.5 mm, P Z .01) and T12 (2.1 mm, P < .001) vertebrae, the middle third of the esophagus (4.0 mm, P Z .03), and the lung tumor (1.7 mm, P Z .02). Conclusions: Respiration-induced thoracic organ motion was quantified in the prone position and compared with that of the supine position for 12 patients with thoracic lesions. The prone position induced larger organ motion compared with supine, particularly for the lung tumor, likely requiring increases in planning margins compared with supine.

Radiotherapy based management during Covid-19 pandemic – A systematic review of presented consensus and guidelines

“…It can be more useful to apply BBD (Belly Board device) for pelvic malignancies whenever the small bowel dose could be a restrictive factor for target dose escalation in clinical routine ( Estabrook et al, 2016 ). For lung cancer, the supine position is superior to prone orientation by mitigating the target margins ( Guy et al, 2020 ). Nevertheless, using spirometry analysis for respiratory gating of lung cancers was also abandoned and replaced by 4D scanners usage to high-risk components management; it avoids the risk of contamination spread from breathing filters and droplet precautions ( Table 4 ) ( Beddok et al, 2020 ).…”

An adaptive planning strategy in carbon ion therapy of pancreatic cancer involving beam angle selection

“…When the CTV and OARs are close, the PTV margin may be reduced. Moreover, Guy et al reported an increase in respiratory motion based on the body position [31] , and Fontana et al reported that setup motion in the prone position was significantly greater than that in the supine position [32] . Therefore, irradiation with several beams in the supine position is considered a better irradiation method.…”

Comparison between supine and prone patient setup for lumbosacral spinal stereotactic body radiosurgery with CyberKnife

“…XSPT combines the spine image registration algorithm with dynamic compensation of respiratory motion, which can realize spinal radiosurgery in the prone position. Although prone position can overcome the above problems, the stability of the position and the reliability of tracking can be reduced due to the influence of respiration ( 9 , 10 ). Therefore, whether the prone position can be used for spinal tumor treatment needs to be further discussed.…”