Radiotherapy is the use of ionising radiation (photons, electrons, protons), aiming at curing or relieving neoplastic diseases, and at the same time protecting adjacent healthy tissues.
The radiation is called ionising because it forms ions (electrically charged particles) and deposits energy on the tissue cells through which it runs. This energy can destroy the cancer cells or cause genetic changes that lead to cell death.
Although radiation harms healthy cells as well, constant advancements in the techniques applied increasingly limit this phenomenon, allowing the administration of higher doses in the area of the tumour with substantially better results in controlling the disease.
Radiotherapy is administered with the aim of either curing the patient or relieving the symptoms caused by cancer. It may be the only treatment or it may be one component of a treatment regimen – e.g. combined with surgery, chemotherapy, hormonal therapy and/or immunotherapy. When administered before surgery, the purpose is to shrink the tumour pre-operatively, while post-operative administration aims to destroy any remaining cancer cells.
The administration of radiotherapy can range from only once, to once a day for approximately two months, with each session lasting from a few minutes to about half an hour. It is usually administered five times a week or, in certain cases, more often, depending on the disease.
Almost one in two patients receives radiotherapy at some point during the course of the disease, while 40% of those who beat cancer have managed to do so thanks to this treatment.
Types of radiotherapy
There are two ways to radiate a cancerous tumour. The first one is externally (external beam radiotherapy), where the high-energy beams generated by the machines are directed at the tumour. The second way is internally (brachytherapy), with the placement of radioactive sources into the tumour.
It is mostly used in palliative care. The shape of the radiation beam is usually square or parallelogram and, apart from the tumour, it inevitably affects a substantial amount of healthy tissue. Radiation must be low-dose, which may be inadequate to cure the cancer, but it is enough to alleviate its symptoms. It is delivered using cobalt devices or low energy linear accelerators.
Also called 3D-CRT. It allows a much more precise radiation of the tumour compared to conventional radiation (2D). As a result, the radiation of healthy tissues around the tumour is substantially limited. It is suitable for all kind of tumours.
Intensity modulated (IMRT, VMAT). This is an advanced technique using computer-guided linear accelerators to give radiation the shape of the tumour, therefore limiting even more the radiation of healthy tissues.
The results of volumetric treatment to date, show that it helps achieve a drastic reduction of the unpleasant side effects of radiation, good local control of the tumour and increased cure rates.
Delivered with the use of a CT scanner incorporated in the linear accelerator. The imaging allows the monitoring of the position of the tumour and the patient during treatment, ensuring even greater precision of the radiation. For the Centre, this is an important instrument for providing volumetric treatments.
This is a technique that allows great precision in the radiation of tumours. It is commonly used for small, well defined tumours (especially of the brain, the spinal cord, the lung, etc.) which often cannot be removed with surgery. It is delivered using specialised linear accelerators. It will soon be available at the Centre.
It is delivered with the placement or radiation sources inside the body or very close to the tumour.
In brachytherapy, the placement of a radioactive source inside the affected organ and into the tumour allows the delivery of high-dose radiation exclusively in the region of the tumour, with the least possible effects on adjacent healthy organs.
Brachytherapy can be used as monotherapy or as complementary therapy after or before external beam radiotherapy. It can be permanent (radioactive seeds) or temporary (e.g. Ir-192).
At the Centre, brachytherapy is mostly used for gynaecological tumours (intraventricular).