Low‑energy contact X‑ray brachytherapy (CXB; the Papillon technique) aims to improve local control or cure rectal cancer. The procedure involves inserting an X‑ray tube through the anus and placing it in close contact with the tumour, to kill cancer cells and reduce the size of the tumour.
Low‑energy CXB for rectal cancer is usually delivered in a day‑care setting. The patient is given an enema before treatment, to clear the bowel. With the patient in a knee‑to‑chest, prone jack‑knife or supine position, local anaesthesia and glyceryl trinitrate are applied to the anal sphincter to numb the area and relax the sphincter muscles. A sigmoidoscope is inserted to check the size and position of the tumour. A rigid endorectal treatment applicator is then inserted and placed in contact with the tumour. A contact X‑ray tube is introduced into the applicator and treatment begins. The tube emits low‑energy X‑rays that only penetrate a few millimetres. This minimises damage to deeper tissues that are not involved in the cancer. If the tumour does not respond to low‑energy CXB, or recurs after treatment, surgery may be performed.