Early effect of external beam radiation therapy on the anal sphincter: a study using anal manometry and transrectal ultrasound.
Birnbaum EH, Dreznik Z, Myerson RJ, Lacey DL, Fry RD, Kodner IJ, Fleshman JW. Early effect of external beam radiation therapy on the anal sphincter: a study using anal manometry and transrectal ultrasound. Dis Colon Rectum. 1992 Aug; 35(8):757-61.