Prostate bed motion during intensity-modulated radiotherapy treatment.
Publication/Presentation Date
9-1-2012
Abstract
PURPOSE: Conformal radiation therapy in the postprostatectomy setting requires accurate setup and localization of the prostatic fossa. In this series, we report prostate bed localization and motion characteristics, using data collected from implanted radiofrequency transponders.
METHODS AND MATERIALS: The Calypso four-dimensional localization system uses three implanted radiofrequency transponders for daily target localization and real-time tracking throughout a course of radiation therapy. We reviewed the localization and tracking reports for 20 patients who received ultrasonography-guided placement of Calypso transponders within the prostate bed prior to a course of intensity-modulated radiation therapy at Fox Chase Cancer Center.
RESULTS: At localization, prostate bed displacement relative to bony anatomy exceeded 5 mm in 9% of fractions in the anterior-posterior (A-P) direction and 21% of fractions in the superior-inferior (S-I) direction. The three-dimensional vector length from skin marks to Calypso alignment exceeded 1 cm in 24% of all 652 fractions with available setup data. During treatment, the target exceeded the 5-mm tracking limit for at least 30 sec in 11% of all fractions, generally in the A-P or S-I direction. In the A-P direction, target motion was twice as likely to move posteriorly, toward the rectum, than anteriorly. Fifteen percent of all treatments were interrupted for repositioning, and 70% of patients were repositioned at least once during their treatment course.
CONCLUSION: Set-up errors and motion of the prostatic fossa during radiotherapy are nontrivial, leading to potential undertreatment of target and excess normal tissue toxicity if not taken into account during treatment planning. Localization and real-time tracking of the prostate bed via implanted Calypso transponders can be used to improve the accuracy of plan delivery.
Volume
84
Issue
1
First Page
130
Last Page
136
ISSN
1879-355X
Published In/Presented At
Klayton, T., Price, R., Buyyounouski, M. K., Sobczak, M., Greenberg, R., Li, J., Keller, L., Sopka, D., Kutikov, A., & Horwitz, E. M. (2012). Prostate bed motion during intensity-modulated radiotherapy treatment. International journal of radiation oncology, biology, physics, 84(1), 130–136. https://doi.org/10.1016/j.ijrobp.2011.11.041
Disciplines
Medicine and Health Sciences | Oncology
PubMedID
22330987
Department(s)
Department of Radiation Oncology
Document Type
Article