Low-energy contact X-ray brachytherapy for rectal cancer

Low-energy contact X-ray brachytherapy (CXB) 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. The tube emits low-energy X-rays that only penetrate a few millimetres, which minimises damage to deeper tissues.

Low-energy CXB for rectal cancer is usually delivered in an outpatient setting. The person having the procedure is given an enema before treatment to clear the bowel. During the procedure they are in a knee-to-chest, prone jackknife (lying on their front, with hips flexed at a 90-degree angle so that their head and legs are lower than their hips) or supine (lying flat on their back) position. Local anaesthetic and glyceryl trinitrate are applied to the anal sphincter to numb the area and relax the sphincter muscles. A sigmoidoscope (a flexible tube with a camera and light that is used to look at the lower part of the large intestine, including the rectum) 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 placed into the applicator and treatment begins. . If the tumour does not respond to low-energy CXB or recurs after treatment, surgery may be performed.

Several different devices were used in the studies informing this guidance. All delivered a beam of 50-kV X-rays.