title: Dosimetric differences between intraoperative and postoperative plans using Cs-131 in transrectal ultrasound-guided brachytherapy for prostatic carcinoma.
abstract: The aim of the study was to investigate the differences between intraoperative and postoperative dosimetry for transrectal ultrasound-guided transperineal prostate implants using cesium-131 ((131)Cs). Between 2006 and 2010, 166 patients implanted with (131)Cs had both intraoperative and postoperative dosimetry studies. All cases were monotherapy and doses of 115 were prescribed to the prostate. The dosimetric properties (D90, V150, and V100 for the prostate) of the studies were compared. Two conformity indices were also calculated and compared. Finally, the prostate was automatically sectioned into 6 sectors (anterior and posterior sectors at the base, midgland, and apex) and the intraoperative and postoperative dosimetry was compared in each individual sector. Postoperative dosimetry showed statistically significant changes (p < 0.01) in every dosimetric value except V150. In each significant case, the postoperative plans showed lower dose coverage. The conformity indexes also showed a bimodal frequency distribution with the index indicating poorer dose conformity in the postoperative plans. Sector analysis revealed less dose coverage postoperatively in the base and apex sectors with an increase in dose to the posterior midgland sector. Postoperative dosimetry overall and in specific sectors of the prostate differs significantly from intraoperative planning. Care must be taken during the intraoperative planning stage to ensure complete dose coverage of the prostate with the understanding that the final postoperative dosimetry will show less dose coverage.
authors.affiliation: Department of Radiation Oncology, Geisinger Medical Center, Danville, PA. Electronic address: aojones@geisinger.edu.
authors.forename: Andrew
authors.initials: A
authors.lastname: Jones
authors.affiliation: Department of Radiation Oncology, Geisinger Medical Center, Danville, PA.
authors.forename: Jared
authors.initials: J
authors.lastname: Treas
authors.affiliation: Department of Radiation Oncology, Geisinger Medical Center, Danville, PA.
authors.forename: Brian
authors.initials: B
authors.lastname: Yavoich
authors.affiliation: Department of Radiation Oncology, Geisinger Medical Center, Danville, PA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Dean
authors.affiliation: Department of Urology, Geisinger Medical Center, Danville, PA.
authors.forename: John
authors.initials: J
authors.lastname: Danella
authors.affiliation: Department of Radiation Oncology, Geisinger Medical Center, Danville, PA.
authors.forename: Omar
authors.initials: O
authors.lastname: Yumen
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D002588:Cesium Radioisotopes / Q000627:therapeutic use; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D008297:Male; D011182:Postoperative Care / Q000379:methods*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional / Q000379:methods*
chemical_list: D002588:Cesium Radioisotopes; D019275:Radiopharmaceuticals
keywords: Brachytherapy; Cs-131; Dosimetry; Prostate