PURPOSE: To evaluate differences in target motion during prostate irradiation in the prone versus supine position using electromagnetic tracking to measure prostate mobility. MATERIALS/ METHODS: Twenty patients received prostate radiotherapy in the supine position utilizing the Calypso Localization System® for prostate positioning and monitoring. For each patient, 10 treatment fractions were followed by a session in which the patient was repositioned prone, and prostate mobility was tracked. The fraction of time that the prostate was displaced by >3, 5, 7, and 10mm was calculated for each patient, for both positions (400 tracking sessions). RESULTS: Clear patterns of respiratory motion were seen in the prone tracks due to the influence of increased abdominal motion. Averaged over all patients, the prostate was displaced >3 and 5mm for 37.8% and 10.1% of the total tracking time in the prone position, respectively. In the supine position, the prostate was displaced >3 and 5mm for 12.6% and 2.9%, respectively. With both patient setups, inferior and posterior drifts of the prostate position were observed. Averaged over all prone tracking sessions, the prostate was displaced >3mm in the posterior and inferior directions for 11.7% and 9.5% of the total time, respectively. CONCLUSIONS: With real-time tracking of the prostate, it is possible to study the effects of different setup positions on the prostate mobility. The percentage of time the prostate moved >3 and 5mm was increased by a factor of three in the prone versus supine position. For larger displacements (>7 mm) no difference in prostate mobility was observed between prone and supine positions. To reduce rectal toxicity, radiotherapy in the prone position may be a suitable alternative provided respiratory motion is accounted for during treatment. Acute and late toxicity results remain to be evaluated for both patient positions.
PURPOSE: To evaluate differences in target motion during prostate irradiation in the prone versus supine position using electromagnetic tracking to measure prostate mobility. MATERIALS/ METHODS: Twenty patients received prostate radiotherapy in the supine position utilizing the Calypso Localization System® for prostate positioning and monitoring. For each patient, 10 treatment fractions were followed by a session in which the patient was repositioned prone, and prostate mobility was tracked. The fraction of time that the prostate was displaced by >3, 5, 7, and 10mm was calculated for each patient, for both positions (400 tracking sessions). RESULTS: Clear patterns of respiratory motion were seen in the prone tracks due to the influence of increased abdominal motion. Averaged over all patients, the prostate was displaced >3 and 5mm for 37.8% and 10.1% of the total tracking time in the prone position, respectively. In the supine position, the prostate was displaced >3 and 5mm for 12.6% and 2.9%, respectively. With both patient setups, inferior and posterior drifts of the prostate position were observed. Averaged over all prone tracking sessions, the prostate was displaced >3mm in the posterior and inferior directions for 11.7% and 9.5% of the total time, respectively. CONCLUSIONS: With real-time tracking of the prostate, it is possible to study the effects of different setup positions on the prostate mobility. The percentage of time the prostate moved >3 and 5mm was increased by a factor of three in the prone versus supine position. For larger displacements (>7 mm) no difference in prostate mobility was observed between prone and supine positions. To reduce rectal toxicity, radiotherapy in the prone position may be a suitable alternative provided respiratory motion is accounted for during treatment. Acute and late toxicity results remain to be evaluated for both patient positions.
Authors: Jeffrey R Olsen; Parag J Parikh; Michael Watts; Camille E Noel; Kenneth W Baker; Lakshmi Santanam; Jeff M Michalski Journal: Radiother Oncol Date: 2012-07-17 Impact factor: 6.280
Authors: Wei Zhao; Bin Han; Yong Yang; Mark Buyyounouski; Steven L Hancock; Hilary Bagshaw; Lei Xing Journal: Radiother Oncol Date: 2019-07-11 Impact factor: 6.280
Authors: Wendy Harris; Ellen Yorke; Henry Li; Christian Czmielewski; Mohit Chawla; Robert P Lee; Alexandra Hotca-Cho; Dominique McKnight; Andreas Rimner; D Michael Lovelock Journal: Med Phys Date: 2022-03-03 Impact factor: 4.071