Internal radiotherapy involves having radioactive material placed inside the body. These can be either radioactive implants (such as metal wires, seeds, or tubes placed inside the body, within or close to a tumour) or radioactive liquids (given either as a drink, capsule or injection)
Brachytherapy is a form of radiation therapy where a sealed radioactive source is placed, inside, on or near the tumour. These sources produce gamma-rays, which have the same effect on cancer cells as X-rays. This treatment reduces damage to surrounding healthy tissue, thereby limiting side effects.
There are two main types of brachytherapy: low dose rate (LDR) and high dose rate (HDR).
Small radioactive ‘seeds’ are permanently implanted near or in the tumour. These stay permanently in place, releasing small amounts of radiation over several weeks or months. Most commonly this technique is used for treating localised prostate cancers. Men can get back to their usual activities within a day or two of having the ‘seeds’ inserted.
High dose rate brachytherapy is based on similar principles to that of low dose rate brachytherapy, but the delivery is a bit different. Firstly, the radioactive sources are removed from the patient at the end of each treatment session. Secondly, the radiation sources deliver a more intense but short-lived dose of radiation during each of several (usually 1–3) sessions. HDR brachytherapy is used for more high-risk but localised prostate cancers and gynaecological cancers, amongst others. HDR brachytherapy is often given in conjunction with External Beam Radiation Therapy (EBRT).
Brachytherapy can be used for certain prostate, breast, cervical and skin cancers, to find out more about this type of treatment please see the links below.
Radioisotope or Radionuclide therapy
This therapy uses radiopharmaceuticals to target specific tumours delivering radiation to tumorous lesions as part of a therapeutic strategy to cure or control the disease. It can be used either on selective targets or throughout the entire body. It is based on administering radioactive substances which are bound to a carrier to the diseased cells. Just like chemotherapy, this therapy is a systemic treatment, reaching cells throughout the body by travelling through the bloodstream. However, unlike chemotherapy, these radioactive substances specifically target diseased cells, thus reducing potential side effects.
This method delivers radiation directly into the diseased cells via a capsule, drink or injection into a vein. Diseased cells specifically absorb the radioactive substance via the carrier more than healthy cells which means they receive a higher dose of radiation. The radioactive part of the liquid is called an isotope. It is attached to a carrier which is designed to take the isotope into the tumour. There are different types of radioisotope used for different types of cancers e.g. phosphorous, radium, strontium and iodine.
The carrier substance are those that strongly bind with the tumour – also known as vehicles with a high tumour affinity. They can transport targeted doses of radiation directly to the tumours and its metastases, thereby sparing normal healthy tissue. The choice of the molecule that carries the radiation to the tumour is determined by its affinity – or binding power – to the tumour’s target structures, such as antigens or receptors. The ionizing radiation emitted by radionuclides linked to the carrier kill diseased cells by damaging their DNA, causing the tumours to shrink
For this type of treatment, it may be necessary to stay in hospital for a few days until most of the radioactivity has disappeared from your body. Please note these can be used for non-cancerous therapies also.
SIRT (also known as radio-embolisation)
SIRT is ‘Selective Internal Radiotherapy,’ also called ‘Radio-Embolisation’ (RE). It is a method of treating malignant liver tumours, whether those tumours originate from the liver itself, or have spread to the liver from elsewhere in the body (e.g. bowel cancer).
It is a special type of internal radiotherapy that uses high doses of radiation to target liver tumours inside the body. It delivers much higher doses of radiation over much longer periods of time than would be possible with external beam radiation.
Millions of little resin or glass ‘beads’ are injected into the arteries inside the liver. The microspheres are tiny and too small to see with the naked eye. Each microsphere is much smaller than the width of a human hair.
These microspheres contain a radioactive isotope which emits radiation that travels only a very short distance within the liver. Once injected, the microspheres lodge in the vessels that supply the tumour and emit radiation, which kills the tumour cells. This radiation will affect only a small area, meaning the liver tumour is directly targeted while doing little damage to the surrounding healthy liver. The microspheres also help to cut off the blood supply to the tumours, thus starving them of oxygen and essential nutrients. The radiation effect on the tumour lasts for about two weeks, after which only 3% of the initial useful radiation remains. After one month it has all gone, but the effects of the radiotherapy on the cancer last much longer.
IORT Intra-operative Radiotherapy
Intra-operative radiotherapy (IORT) is the application of therapeutic levels of radiation to a target area, such as a tumour, while the area is exposed during surgery. The treatment can be applied using low energy (0kv) x-rays, or with electrons (IOERT). These techniques are most commonly used in the treatment of breast cancer, but can be used for other tumours, e.g. cancer of the cervix.
Intra-operative Radiotherapy (IORT) is a single dose of radiotherapy which is delivered at the time of breast conserving cancer surgery and can eliminate the need for External Beam Radiotherapy (EBRT). Breast conserving surgery involves the removal of the tumour and a small area of surrounding tissue from the breast
In treating breast cancer, IORT is used in patients who have had a lumpectomy (removal of a tumour from the breast), rather than a mastectomy (removal of the entire breast). The IORT device delivers low-energy, high-dose radiation directly to the tumour bed (the cavity left after the tumour has been removed from the breast) in the operating room, right after the tumour has been removed. After the lumpectomy, a spherical applicator on the IORT device is placed directly into the tumour bed and delivers a smaller dose of radiation than standard radiation therapy. The delivery of the IORT is done via electron beams, x-rays or high-dose-rate brachytherapy after which the incision is closed.