A prospective study of intrafraction prostate motion in the prone vs. supine position.
OBJECTIVE
To prospectively analyze prostate intrafraction motion in the prone vs. supine position and to assess patient satisfaction with these two positions.


METHODS
Fifteen prostate cancer patients underwent implantation of five fiducial gold seeds in their prostate for localization. Patients were treated with high-dose-rate brachytherapy to 2,200 cGy followed by intensity-modulated radiation therapy (IMRT) to 5,040 cGy. Patients underwent computed tomography simulation and IMRT in the prone position. For the first five IMRT treatments, an electronic portal imaging system was used to acquire anteroposterior (AP) and lateral images pretreatment and posttreatment. We then repositioned each patient supine and repeated the process, resulting in 600 images.


RESULTS
Mean +/- standard deviation intrafraction prostate motion was 2.1 +/- 1.2 mm and 1.7 +/- 1.4 mm (AP, p = 0.47), 2.2 +/- 2.0 mm and 1.6 +/- 1.8 mm (superoinferior, p = 0.16), and 1.0 +/- 1.2 mm and 0.6 +/- 0.9 mm (left-right, p = 0.03) in the prone and supine positions, respectively. Eighty percent of patients stated that they were more comfortable in the supine position (p = 0.02).


CONCLUSIONS
Prone and supine positions resulted in a similar magnitude of AP and superoinferior intrafraction prostate motion (2 mm). Because there was no significant difference in the magnitude of AP and superoinferior prostate motion prone vs. supine and patients were more comfortable in the supine position, patients now undergo IMRT to the prostate and seminal vesicles at our center in the supine position.
Wilder
Richard B
RB
Cancer Center of Irvine, Ste. 130, Irvine, CA 92618, USA.
Chittenden
Lucy
L
Mesa
Albert V
AV
Bunyapanasarn
Jane
J
Agustin
Jeff
J
Lizarde
Jessica
J
Ravera
John
J
Tokita
Kenneth M
KM
D001918:Brachytherapy / Q000379:methods*; D006046:Gold; D006801:Humans; D008297:Male; D009068:Movement; D056888:Patient Positioning / Q000379:methods* / Q000523:psychology; D017060:Patient Satisfaction; D016684:Prone Position; D011446:Prospective Studies; D011467:Prostate / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000523:psychology / Q000532:radiotherapy*; D019736:Prostheses and Implants; D011859:Radiography; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012669:Seminal Vesicles / Q000000981:diagnostic imaging; D016683:Supine Position; D047368:Tumor Burden
D006046:Gold