Daily electronic portal imaging of implanted gold seed fiducials in patients undergoing radiotherapy after radical prostatectomy

Journal Article · Thu Feb 01 04:00:00 EST 2007 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2006.09.042· OSTI ID:20944709

Schiffner, Daniel C ^[1]; Gottschalk, Alexander R ^[2]; Lometti, Michael M.S. ^[1]; Pouliot, Jean ^[1]; Speight, Joycelyn ^[1]; Hsu, I -Chow ^[1]; Shinohara, Katsuto ^[3]; Roach, Mack ^[1]

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1. Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA (United States)
2. Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA (United States) and Department of Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA (United States)
3. Department of Urology, University of California, San Francisco, San Francisco, CA (United States)

Purpose: The aim of this study was to measure interfraction prostate bed motion, setup error, and total positioning error in 10 consecutive patients undergoing postprostatectomy radiotherapy. Methods and Materials: Daily image-guided target localization and alignment using electronic portal imaging of gold seed fiducials implanted into the prostate bed under transrectal ultrasound guidance was used in 10 patients undergoing adjuvant or salvage radiotherapy after prostatectomy. Prostate bed motion, setup error, and total positioning error were measured by analysis of gold seed fiducial location on the daily electronic portal images compared with the digitally reconstructed radiographs from the treatment-planning CT. Results: Mean ({+-} standard deviation) prostate bed motion was 0.3 {+-} 0.9 mm, 0.4 {+-} 2.4 mm, and -1.1 {+-} 2.1 mm in the left-right (LR), superior-inferior (SI), and anterior-posterior (AP) axes, respectively. Mean set-up error was 0.1 {+-} 4.5 mm, 1.1 {+-} 3.9 mm, and -0.2 {+-} 5.1 mm in the LR, SI, and AP axes, respectively. Mean total positioning error was 0.2 {+-} 4.5 mm, 1.2 {+-} 5.1 mm, and -0.3 {+-} 4.5 mm in the LR, SI, and AP axes, respectively. Total positioning errors >5 mm occurred in 14.1%, 38.7%, and 28.2% of all fractions in the LR, SI, and AP axes, respectively. There was no significant migration of the gold marker seeds. Conclusions: This study validates the use of daily image-guided target localization and alignment using electronic portal imaging of implanted gold seed fiducials as a valuable method to correct for interfraction target motion and to improve precision in the delivery of postprostatectomy radiotherapy.

• OSTI ID: 20944709
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 2 Vol. 67; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
ACCURACY
ALIGNMENT
GOLD
IMAGES
IMPLANTS
PATIENTS
POSITIONING
PROSTATE
RADIOTHERAPY