title: Alpha/beta value and importance of dose per fraction for the late rectal and recto-sigmoid complications.
abstract: A total of 203 patients with cancer of cervix stage IIIB, treated by radiation alone were analysed retrospectively for the incidence of late rectal and recto-sigmoid complications. The patients were treated with a combination of external irradiation and a single intracavitary insertion during January 1979 to December 1983. The external irradiation was randomised to deliver by four different fractionation regimens having dose per fraction of 2 Gy, 3 Gy, 4 Gy and 5.4 Gy. The doses for various fractionation regimens were matched using the time dose factors (TDF) model. 39 cases of late radiation induced rectal and recto-sigmoid complications were observed. The complication rate increased significantly (p < 0.05) with the size of dose per fraction. Using this clinical data an alpha/beta value of 3.87 +/- 0.74 Gy was estimated for late rectal and recto-sigmoid complications.
authors.affiliation: Department of Medical Physics, Tata Memorial Hospital, Bombay, India.
authors.forename: S M
authors.initials: SM
authors.lastname: Deore
authors.forename: S K
authors.initials: SK
authors.lastname: Shrivastava
authors.forename: S J
authors.initials: SJ
authors.lastname: Supe
authors.forename: P S
authors.initials: PS
authors.lastname: Viswanathan
authors.forename: K A
authors.initials: KA
authors.lastname: Dinshaw
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000453:epidemiology / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology / Q000532:radiotherapy*; D012809:Colon, Sigmoid / Q000528:radiation effects*; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D008875:Middle Aged; D011832:Radiation Injuries; D011878:Radiotherapy / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D012007:Rectum / Q000528:radiation effects*; D012189:Retrospective Studies; D013997:Time Factors; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology / Q000532:radiotherapy*