title: Comparison between real-time intra-operative ultrasound-based dosimetry and CT-based dosimetry for prostate brachytherapy using cesium-131.
abstract: The purpose of this study was to evaluate the correlation between real-time intra-operative ultrasound-based dosimetry (USD) and day 0 post-implant CT dosimetry (CTD) (131)Cs permanent prostate brachytherapy. Fifty-two consecutive patients who underwent prostate brachytherapy with (131)Cs were evaluated. Real time operating room planning was performed using VariSeed 7.1 software. Post-needle placement prostate volume was used for real-time planning. Targets for dosimetry were D(90) >110%, V(100) >90%, V(150) <50%, and V(200) <20%. The CT scan for post-operative dosimetry was obtained on day 0. The mean values for USD, CTD, and the linear correlation, respectively, were, for D(90): 114.0%, 105.61%, and 0.15; for V(100): 95.1%, 91.6%, and 0.22; for V(150): 51.5%, 46.4%, and 0.40; and for V(200): 15.8%, 17.9%, and 0.42. The differences between the mean values for USD and CTD for D(90) (p<0.01), V(100) (p<0.01), and V(150) (p<0.05) were statistically significant. For D(90), 30.8% of patients had a >15% difference between USD and CTD and 51.9% of patients had a >10% difference between these values. In contrast, the USD and CTD for V(100) were within 5% in 55.8% of patients and within 10% in 86.5% of patients. This study demonstrates a correlation between the mean intra-operative USD and post-implant day 0 CTD values only for V(200). Significant variation in D(90), V(150), and V(200) values existed for individual patients between USD and CTD. These results suggest that real-time intra-operative USD does not serve as a surrogate for post-operative CTD, and that post-operative CTD is still necessary.
authors.affiliation: Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. jacobsbl@upmc.edu
authors.forename: B L
authors.initials: BL
authors.lastname: Jacobs
authors.forename: E P
authors.initials: EP
authors.lastname: Gibbons
authors.forename: R P
authors.initials: RP
authors.lastname: Smith
authors.forename: S
authors.initials: S
authors.lastname: Beriwal
authors.forename: K
authors.initials: K
authors.lastname: Komanduri
authors.forename: R M
authors.initials: RM
authors.lastname: Benoit
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000379:methods*; D002588:Cesium Radioisotopes / Q000627:therapeutic use*; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy* / Q000601:surgery*; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D013997:Time Factors; D016896:Treatment Outcome; D014463:Ultrasonography / Q000379:methods*
chemical_list: D002588:Cesium Radioisotopes