title: Analysis of Geometric Shifts and Proper Setup-Margin in Prostate Cancer Patients Treated With Pelvic Intensity-Modulated Radiotherapy Using Endorectal Ballooning and Daily Enema for Prostate Immobilization.
abstract: We evaluate geometric shifts of daily setup for evaluating the appropriateness of treatment and determining proper margins for the planning target volume (PTV) in prostate cancer patients.We analyzed 1200 sets of pretreatment megavoltage-CT scans that were acquired from 40 patients with intermediate to high-risk prostate cancer. They received whole pelvic intensity-modulated radiotherapy (IMRT). They underwent daily endorectal ballooning and enema to limit intrapelvic organ movement. The mean and standard deviation (SD) of daily translational shifts in right-to-left (X), anterior-to-posterior (Y), and superior-to-inferior (Z) were evaluated for systemic and random error.The mean ± SD of systemic error (Σ) in X, Y, Z, and roll was 2.21 ± 3.42 mm, -0.67 ± 2.27 mm, 1.05 ± 2.87 mm, and -0.43 ± 0.89°, respectively. The mean ± SD of random error (δ) was 1.95 ± 1.60 mm in X, 1.02 ± 0.50 mm in Y, 1.01 ± 0.48 mm in Z, and 0.37 ± 0.15° in roll. The calculated proper PTV margins that cover >95% of the target on average were 8.20 (X), 5.25 (Y), and 6.45 (Z) mm. Mean systemic geometrical shifts of IMRT were not statistically different in all transitional and three-dimensional shifts from early to late weeks. There was no grade 3 or higher gastrointestinal or genitourianry toxicity.The whole pelvic IMRT technique is a feasible and effective modality that limits intrapelvic organ motion and reduces setup uncertainties. Proper margins for the PTV can be determined by using geometric shifts data.
authors.affiliation: From the Department of Radiation Oncology, St. Vincent Hospital, College of Medicine, The Catholic University of Korea, Suwon (SJ, JHL, MJC, SWL, DGK, SHK); and Department of Radiation Oncology, Kyungpook National University Hospital, Daegu, Korea (JWL).
authors.forename: Songmi
authors.initials: S
authors.lastname: Jeong
authors.forename: Jong Hoon
authors.initials: JH
authors.lastname: Lee
authors.forename: Mi Joo
authors.initials: MJ
authors.lastname: Chung
authors.forename: Sea Won
authors.initials: SW
authors.lastname: Lee
authors.forename: Jeong Won
authors.initials: JW
authors.lastname: Lee
authors.forename: Dae Gyu
authors.initials: DG
authors.lastname: Kang
authors.forename: Sung Hwan
authors.initials: SH
authors.lastname: Kim
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D015331:Cohort Studies; D004733:Enema; D005500:Follow-Up Studies; D006801:Humans; D007103:Immobilization / Q000379:methods; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D009364:Neoplasm Recurrence, Local / Q000473:pathology* / Q000503:physiopathology; D009367:Neoplasm Staging; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D012007:Rectum; D012189:Retrospective Studies; D018570:Risk Assessment; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D017430:Prostate-Specific Antigen