Cancer is a disease in which abnormal cells divide without control and are able to invade other tissues. Malignant tumours can grow in any part of the body and can spread to other organs via the bloodstream or lymphatic system.
Cancer treatment involves surgery, chemotherapy, radiotherapy, or immunotherapy. This guide explains all the different types of radiation therapy.
Radiation Therapy
Radiation therapy is a type of cancer treatment that uses high-energy rays to kill cancer cells. It’s used to treat many types of cancer, including some types of lung cancer, breast cancer, and thyroid cancer.
Let us look at the types of Radiation Therapy in more detail:
External radiation therapy
Radiotherapy entails the treatment of lesions with ionising radiation. In the case of external beam radiotherapy, high energy x-rays or electrons are generated outside the body, usually by a linear accelerator machine, and these high energy beams are targeted at the tumour site where they deposit their energy within the body to destroy cancer or abnormal cells.
Intensity-modulated radiotherapy (IMRT)
IMRT is an advanced form of high accuracy radiotherapy that delivers a high dose of radiation to a tumour. Multiple beams are shaped to conform to the lesion outline. Each beam has a number of sub-beams or segments, and the intensity of each segment varies. In effect, IMRT allows control over both the shape of the radiation field as well as the dose that gets delivered to each sub-area of the field. This results in the delivery of the prescribed dose to an irregular tumour, at the same time sparing the normal structures and tissue around the tumour.
Image-guided radiation therapy (IGRT)
IGRT enables the creation of a three-dimensional image of the actual patient and the position of the lesion on a daily basis. This increases the accuracy of the treatment set-up and delivery. IGRT can also be used to adapt and modify the treatment plan to allow for anatomical changes during the course of radiotherapy. The increased precision in adapting to anatomical changes improves tumour control and reduces the side effects of treatment.
Gated radiotherapy
Gated radiation therapy is used to treat tumours in the regions of lungs, liver and stomach, where there is a possibility of organ movement during breathing. The treatment beam is then coordinated with the patient’s breathing rhythm. The CT images are acquired at a particular breathing phase and the linear accelerator is gated to irradiate the tumour during that phase. In effect, gating means that the equipment is used to restrict the radiation beam to only be on during a specific part of the breathing cycle.
Rapid arc
Rapid arc is a treatment that delivers with a single 360-degree rotation around the patient. This significantly shortens the treatment time, compared to normal treatment time, which improves patient comfort as the time they spend on the treatment couch is much shorter. During a 360◦ rotation, a precise sculpted 3-d distribution is delivered. This is made possible by a treatment planning algorithm that simultaneously changes three parameters during treatment, namely the rotation speed of the gantry, the shape of the treatment aperture by using a multi-leave collimator, and the dose delivery.
Stereotactic irradiation
Stereotactic irradiation is the external beam radiation technique that currently offers the highest level of precision. High dose radiation can be delivered to small lesions in the brain (intracranial) or the rest of the body (extra-cranial), with a position accuracy of 1 mm.
Brachytherapy
Unlike external beam therapy, brachytherapy involves placing radioactive material directly inside the body. Brachytherapy enables a physician to use a higher total dose of irradiation to treat a smaller area in a shorter time or treatment course than is needed in external beam radiation. Brachytherapy can be temporary or permanent.
Permanent brachytherapy, also called seed implants, involves the placing of radioactive seeds or pellets in or near a tumour, leaving them there permanently. After weeks the radioactivity level eventually diminishes to zero but the seeds remain in the body.
Radioisotope treatment
Different isotopes are absorbed by different organs, making targeted treatment of a specific organ possible. Radioisotopes may also be given as a pain reliever to patients suffering from metastasis.
Gamma Knife Icon radiosurgery
The Gamma Knife Icon is the sixth generation of the Leksell Gamma Knife system. The technology with its microsurgery capabilities is used in the treatment of selected malignant and benign brain, head and neck tumours, vascular malformations in the brain as well as functional disorders. Gamma Knife Icon is the most precise radiosurgery device on the market internationally, enabling the treatment of virtually any target in the brain with ultra-high precision. The technology delivers powerful doses of precision-targeted radiation that acts as a surgeon’s ‘scalpel’. This greatly reduces many of the risks associated with traditional cranial surgery as it consistently limits radiation doses to healthy tissue.
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