Abstract
Purpose
Interobserver differences in postimplant dosimetry based on computed tomography (CT) and CT/magnetic resonance imaging (MRI) fusion images were assessed to evaluate the efficacy of the fusion image. In addition, the part of the prostate contour responsible for the interobserver differences in CT was identified.
Materials and methods
In June 2008, 1-month postimplant CT data from two patients who underwent 125I prostate brachytherapy were sent to 90 institutions for postimplant dosimetry. Subsequently, MRI data from the same patients were sent for fusion-based postimplant dosimetry. The variance of the difference between MRIbased D90 and CT-based or fusion-based D90 was compared. Prostate volume on CT was plotted on the y-axis against the position of the most cranial and caudal slices in the prostate contour delineated at each institution to analyze interobserver differences.
Results
The prostate volume from CT was significantly greater than from the CT/MRI fusion image (P = 0.0014). Fusion-based variance was significantly greater than CT-based variance (P < 0.01). CT-based postimplant dosimetry showed that 88%-96% of the institutions had an apical and basal position within a range of 5 mm.
Conclusion
There were marked interobserver differences in CT/MRI fusion-based postimplant dosimetry.
Similar content being viewed by others
References
Prete J, Prestidge B, Bice W, Dubois D. Comparison of MRI- and T-based post implant dosimetric analysis of transperineal interstitial permanent prostate brachytherapy. Radiat Oncol Invest 1998;6:90–96.
Merrick G, Butler W, Dorsey A, Lief J. The dependence of prostate postimplant dosimetric quality on CT volume determination. Int J Radiat Oncol Biol Phys 1999;44:1111–1117.
Stock R, Stone N, Dahial M, Lo Y. What is the optimal dose for 125-I prostate implant? A dose-response analysis of biochemical control, posttreatment prostate biopsies, and longterm symptom. Brachytherapy 2002;1:83–89.
Papagikos M, deGuzman A, Rossi P, McCullough D, Clark P, Lee R. Dosimetric quantifiers for low-dose-rate prostate brachytherapy: is V100 superior to D90? Brachytherapy 2005;4: 252–258.
Dubois DF, Prestidge BR, Hotchkiss LA, Prete J, Bice W. Intraobserver variability of MR imaging- and CT-derived prostate volumes after transperineal interstitial permanent prostate brachytherapy. Radiology 1998;207:785–789.
Moerland M, Wijrdeman H, Beersma R, Bakker C, Battermann J. Evaluation of permanent I-125 prostate implants using radiography and magnetic resonance imaging. Int J Radiat Oncol Biol Phys 1997;37:927–933.
Polo A, Cattani F, Vavassori A, Origgi D, Villa G, Marsiglia H, et al. MR and image fusion for postimplant analysis in permanent prostate seed implants. Int J Radiat Oncol Biol Phys 2004;60:1572–1579.
McLaughlin P, Troyer S, Berri S, Narayana V, Meirowitz A, Roberson P, et al. Functional anatomy of the prostate: implications for treatment planning. Int J Radiat Oncol Biol Phys 2005;63:479–491.
Author information
Authors and Affiliations
Corresponding author
About this article
Cite this article
Aoki, M., Yorozu, A. & Dokiya, T. Evaluation of interobserver differences in postimplant dosimetry following prostate brachytherapy and the efficacy of CT/MRI fusion imaging. Jpn J Radiol 27, 342–347 (2009). https://doi.org/10.1007/s11604-009-0355-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11604-009-0355-y