title: Intensity-modulated radiotherapy using implanted fiducial markers with daily portal imaging: assessment of prostate organ motion.
abstract: OBJECTIVE
  To assess our single institutional experience with daily localization, using fiducials for prostate radiotherapy.
  
  
  METHODS
  From January 2004 to September 2005, 33 patients were treated with 1,097 intensity-modulated radiation treatments, using three implanted fiducials. Daily portal images were obtained before treatments. Shifts were made for deviations > or =3 mm in the left-right (LR), superior-inferior (SI), and anterior-posterior (AP) dimensions.
  
  
  RESULTS
  Of 1,097 treatments, 987 (90%) required shifts. Shifts were made in the LR, SI, and AP dimensions in 51%, 67%, and 58% of treatments, respectively. In the LR dimension, the median distance shifted was 5 mm. Of 739 shifts in the SI dimension, 73% were in the superior direction for a median distance of 6 mm, and 27% were shifted inferiorly for a median distance of 5 mm. The majority of shifts in the AP dimension were in the anterior direction (87%). Median distances shifted in the anterior and posterior directions were 5 mm and 4 mm, respectively. The median percentage of treatments requiring shifts per patient was 93% (range, 57-100%). Median deviations in the LR, SI, and AP dimensions were 3 mm, 4 mm, and 3 mm, respectively. Deviations in the SI and AP dimensions were more often in the superior rather than inferior (60% vs. 29%) and in the anterior rather than posterior (70% vs. 16%) directions.
  
  
  CONCLUSIONS
  Interfraction prostate motion is significant. Daily portal imaging with implanted fiducials improves localization of the prostate, and is necessary for the reduction of treatment margins.
authors: Department of Radiation Oncology, LDS Hospital, Salt Lake City, UT 84143, USA. jergin.chen@hci.utah.edu
authors: Jergin
authors: J
authors: Chen
authors: R Jeffrey
authors: RJ
authors: Lee
authors: Diana
authors: D
authors: Handrahan
authors: William T
authors: WT
authors: Sause
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008875:Middle Aged; D009068:Movement; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000532:radiotherapy*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods