title: Radiation safety of receptive anal intercourse with prostate cancer patients treated with low-dose-rate brachytherapy.
abstract: Prostate low-dose-rate (LDR) brachytherapy involves implantation of radioactive seeds permanently into the prostate gland. During receptive anal intercourse, the penis of the partner may come in close proximity to the implanted prostate gland. We estimate the potential intrarectal dose rates and suggest guidance on radiation precautions.
  
  
  
  One hundred two patients were included in the study. After implantation, with patients under anesthesia in the dorsal lithotomy position, a new set of ultrasound (US) images and a CT scan were obtained. The images were fused, radioactive seeds and US probe locations were determined on the CT, and prostate, bladder, and rectal contours were drawn on the US. Dose rates (cGy/h) were calculated for the portion of the US probe spanning the prostate for several dose-volume histogram parameters.
  
  
  
  Twenty patients were treated with (125)I and 82 patients with (103)Pd. Average dose rates at Day 0 to the portion of the US probe spanning the prostate were 2.1 ± 1.3 cGy/h and 2.5 ± 0.8 cGy/h for patients treated with (125)I and (103)Pd, respectively. After 60 days, average calculated probe dose drops to 1.0 ± 0.6 cGy/h and 0.2 ± 0.1 cGy/h for (125)I and (103)Pd, respectively.
  
  
  
  During the immediate weeks after prostate seed implant, the estimated intrarectal dose rates are higher in (103)Pd compared to (125)I. As (103)Pd decays faster than (125)I, 2 months after the implant, radiation exposure from (103)Pd becomes lower than (125)I. Receptive anal intercourse time should be kept as low as possible during 2 and 6 months after low-dose-rate brachytherapy of the prostate with (103)Pd and (125)I, respectively.
authors.affiliation: Departments of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY.
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Nasser
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY.
authors.forename: Gil'ad N
authors.initials: GN
authors.lastname: Cohen
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY.
authors.forename: Lawrence T
authors.initials: LT
authors.lastname: Dauer
authors.affiliation: Departments of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY. Electronic address: zelefskm@mskcc.org.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Zelefsky
mesh_terms: D001918:Brachytherapy; D018451:Homosexuality, Male; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D058958:Organs at Risk / Q000000981:diagnostic imaging; D010165:Palladium / Q000627:therapeutic use*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011829:Radiation Dosage; D011868:Radioisotopes / Q000627:therapeutic use; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012189:Retrospective Studies; D012449:Safety; D012725:Sexual Behavior; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography; D001743:Urinary Bladder / Q000000981:diagnostic imaging
chemical_list: D007457:Iodine Radioisotopes; D011868:Radioisotopes; D010165:Palladium
keywords: Anal sex; Homosexual; Prostate brachytherapy; Radiation precautions