title: A prospective study of intrafraction prostate motion in the prone vs. supine position.
abstract: 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.
authors.affiliation: Cancer Center of Irvine, Ste. 130, Irvine, CA 92618, USA.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Wilder
authors.forename: Lucy
authors.initials: L
authors.lastname: Chittenden
authors.forename: Albert V
authors.initials: AV
authors.lastname: Mesa
authors.forename: Jane
authors.initials: J
authors.lastname: Bunyapanasarn
authors.forename: Jeff
authors.initials: J
authors.lastname: Agustin
authors.forename: Jessica
authors.initials: J
authors.lastname: Lizarde
authors.forename: John
authors.initials: J
authors.lastname: Ravera
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Tokita
mesh_terms: 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
chemical_list: D006046:Gold