X-ray brachytherapy is a form of short-range radiation therapy used locally for the treatment of tumors. The technique involves a minimally invasive procedure to insert an X-ray tube at the target site followed by application of the radiation to destroy the cancer cells selectively.
It may be used to treat cancers located in various parts of the body such as skin, breast, uterus, lung, rectum, gallbladder, and prostate over a relatively shorter duration compared to traditional radiation treatments.
Conventional Radiation Techniques
Oncologists employ various approaches to treat cancer depending on the type and severity of the condition. Apart from the traditional chemotherapeutic options, radiotherapy has become an increasingly popular choice over the last few decades because of the advantages it offers.
Radiotherapy may be categorized into two types: (1) External beam radiotherapy and (2) Brachytherapy
External beam radiotherapy is also referred to as teletherapy wherein high-intensity radiation beams are applied to the area of the tumor from outside the body. While the external beam radiotherapy is a relatively simpler and non-invasive technique, it affects a larger area of the body, including the normal cells around the tumor area. Moreover, in several cases, it has not been found to achieve the desired efficacy, and hence the surgical removal of the tumor is often needed at the later stage.
Brachytherapy (also known as internal radiation therapy) involves the application of a radionuclide (such as Palladium, Cesium, Iridium, or Iodine) to a particular target tumor area internally in controlled doses. Brachytherapy may therefore be a more promising option, as it focuses on only a few millimeters of target area. This, in turn, minimizes the collateral damage to adjacent cells, and maximizes the efficacy as the dose remains concentrated on a particular locus.
However, because of the toxic manifestations and long-term side effects of using radioactive materials inside the body, brachytherapy using radioactive nuclides remains questionable.
Application of X-Ray Brachytherapy
In regular brachytherapy, radio-oncologists typically employ X-rays, ultrasound, MRI or CT scan in order to position the radioactive substance to the exact location of interest. The use of X-rays in this technique had so far been limited to the imaging purpose only.
Moving one step ahead, researchers have extended the use of X-rays from imaging to therapeutic purpose, giving rise to the technique termed as ‘X-ray brachytherapy’. Unlike the temporary or permanent radioisotope implants used in the regular brachytherapy, X-ray brachytherapy utilizes low-energy X-ray beams for a specific duration of time to the target area internally.
The procedure involves preparations such as pre-treatment MRI or CT scan, ECG, and other tests similar to those done before radionuclide brachytherapy. The target area is sterilized first, followed by the application of anesthesia, either local or general, depending on the tumor site and the physician’s judgment.
A miniature X-ray tube of around 2-3 mm diameter is inserted through a small invasion. The length of the X-ray tube is preselected based on the depth/accessibility of the tumor site. With the help of a suitable imaging technique, the radio-oncologist remotely places the catheter exactly at the site of the tumor. This is followed by the application of an X-ray beam to the tumor at a recommended dose (Gy/min) for a given duration (a few minutes or hours).
Patients are often hospitalized overnight or for a couple of days for multiple sessions of X-ray brachytherapy. Some oncologists prefer to apply very low-intensity X-rays continuously for an extended period of time (e.g. for a day or two) instead of applying multiple aliquots of smaller durations. This is to avoid having to insert and place the X-ray tube multiple times inside the body.
The dose, duration, and number of brachytherapy sessions vary depending on the tumor stage and severity. Customization of the brachytherapy regimens by an experienced radio-oncologist is required to serve the best interests of the patient.