Intensity-modulated radiotherapy using implanted fiducial markers with daily portal imaging: assessment of prostate organ motion.
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.
Chen
Jergin
J
Department of Radiation Oncology, LDS Hospital, Salt Lake City, UT 84143, USA. jergin.chen@hci.utah.edu
Lee
R Jeffrey
RJ
Handrahan
Diana
D
Sause
William T
WT
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