Radiation therapy can vary in length from one day to several weeks. Over the course of treatment, the radiation oncology team will provide care and support to help you through your treatment.
RCTS Radiation Oncology operates four linear accelerators (treatment machines). A linear accelerator produces high-energy x-rays and electron beams capable of treating a variety of cancers. X-rays (photons) are commonly used to treat tumours below the skin’s surface, while electrons can be used to treat areas closer to the skin. For some cancers on the surface of the skin, a superficial x-ray machine is used.
MegaVoltage Radiation Therapy Techniques
There are variations on the way in which radiation therapy treatment can be delivered. Factors such as the type, size, shape and position of the cancer will determine the best radiation therapy treatment for each individual.
The aim with all radiation therapy treatment is to deliver a dose of radiation that will be effective in killing the cancerous cells while minimising the dose received by the surrounding healthy tissue.
Teams used in Radiation Therapy
3D Conformal Radiation Therapy
Three dimensional conformal radiation therapy is a technique where the radiation beams are tailored to the shape of the area requiring treatment, thus limiting unnecessary radiation to the surrounding healthy tissue. This treatment is computer-planned using the planning computed tomography (CT) scan. Radiation therapy treatment will often be given from several different angles. The treatment machine moves around the patient, stopping at specific angles to deliver the treatment beam and then moving on to the next angle.
Intensity modulated radiation therapy (IMRT) is a complex treatment technique that allows healthy tissue to be spared whilst delivering an optimal radiation dose to the tumour. IMRT uses several small beams (beamlets) within a beam. A conventional beam puts out a reasonably even dose of radiation across the beam. When many beamlets make up the beam, there is greater capability to control the dose across the beam, and therefore modulate / vary the intensity across the radiation beam. IMRT allows the radiation dose to closely match the three-dimensional shape of the tumour and provides greater control in avoiding parts of the body that do not require treatment. Varying the intensity of the radiation also gives the ability to deliver larger radiation doses to concentrated areas within the tumour, making this a very precise treatment.
Modulated Arc Therapy mARC
Modulated Arc Therapy (also known as Volumetric Modulated Arc Therapy VMAT) is a form of IMRT that uses single or multiple radiation beams that move around that patient while delivering the treatment. A beam that is delivered with the machine moving is often referred to as an arc. This technique produces excellent dose uniformity and greatly reduces the treatment time.
Stereotactic Body Radiation Therapy
Stereotactic body radiation therapy (SBRT) is used to treat small localized tumours to high doses in a small number of treatments, usually between 1 and 5 treatments. It can be used to treat tumours in the brain and other areas of the body. An arc technique is frequently used, either with 3D conformal radiation therapy or IMRT. A rigid immobilization apparatus is required. Additional equipment may also be used to monitor the tumour position, which may move due to respiratory motion. Spatial localization is of key importance to assist in a more precise and focused dose delivery.
Image Guided Radiation Therapy is the verification process used to confirm the accuracy of the set up. In this process, X-ray / CT images are taken just prior to treatment and compared to the planning CT images to identify any variations in the positioning / set up. Adjustments are then made, if necessary. This is a very streamlined process with X-Ray and Cone Beam CT integrated into the treatment machine. Digital X-ray / CT images captured by the machine are viewed at the treatment console. Any adjustments to the position of the treatment couch are made remotely from the treatment console, making this a very efficient process. IGRT is important in ensuring a highly accurate treatment delivery.
Superficial Radiation Therapy
Superficial radiation therapy is for the treatment of cancers that are on or close to the skin’s surface. Treatment is given on the superficial x-ray (SXR) machine. This machine uses x-rays of a lower energy than the linear accelerator machines, which means the treatment does not go as deep into the body.
If you are having superficial treatment, your radiation oncologist will mark the area that is to be treated on the skin.
A radiation therapist will deliver the treatment, often over a number of days. The SXR machine sits against the skin and delivers x-rays for around 15 seconds to two minutes. Treatment may cause skin in the treated area to become red and sore over time. A scab may also form or the area may begin to weep. Please tell the radiation therapist if you experience any of these side effects. The skin reaction may continue for some time after your treatment has finished, but should begin to heal after that.
It is very important that you are gentle with the skin in the treatment area, both during and immediately after your treatment. An information booklet about caring for your skin while receiving superficial radiation therapy will be given to you at your first treatment.