External Beam Radiation Therapy
External beam radiation therapy (EBRT) is the most widely used type of radiation therapy.
EBRT refers to the delivery of tightly targeted radiation beams from outside the body. A course of EBRT involves several daily treatments (fractions) over a few days to a few weeks. The radiation oncology team controls the radiation machine (called a linear accelerator or linac) to generate and direct the radiation beams. EBRT usually delivers X-rays (also called photons) but can also use electrons or other rarer particles such as protons. These have different properties which can be useful for different cancers or settings. The experience for the patient is similar to having an X-ray or CT scan – there is no sensation of being treated.
There are different types of EBRT techniques that can be applied. These include conventional EBRT, intensity modulated radiation therapy (IMRT), image guided radiation therapy (IGRT), volumetric modulated arc therapy (VMAT), stereotactic body radiation therapy (SBRT), and stereotactic radiosurgery (SRS).
The following steps are typical for most EBRT treatments:
Step 1: Initial consultation
Before treatment, your radiation oncologist will explain the radiation therapy process and answer any questions. Discussion will also take place with regards to treatment options and any potential short or long term side effects. An examination may be required, together with a review of any relevant X-rays, scans and test results. It is important that you bring these with you.
Your next appointment will be for a simulation CT scan, which may, or may not, be on the same day. The simulation CT scan is used to record the details of your anatomy and positioning so that the radiation can be delivered accurately to the target area.
Step 2: Treatment set up and immobilisation
An essential component of external beam radiation therapy is ensuring that treatment is set up correctly so that the dose of radiation therapy is delivered to the treatment area as accurately as possible.
This is done prior to treatment and usually involves the use of immobilisation equipment to stabilise the treatment area. The aim is to ensure that you are positioned in the same position for each treatment. The equipment used to position you for your simulation CT scan will be replicated each day during treatment. The type of immobilisation equipment used depends upon the area being treated.
As it is often necessary for the skin in the area needing treatment to be visible, you may be asked to change into a gown.
Step 3: Simulation CT scan
This CT simulation scanning procedure, whilst similar to other scans you may have had, is specifically setup to record all the necessary images, body shape and position details needed to ensure that daily treatments can be delivered accurately on repeat occasions throughout your treatment course.
The CT scan will be performed under the supervision of the attending radiation therapists. At its completion, all the required details and measurements relating to your position will be recorded and stored on file.
In most cases, tiny reference tattoo dots are placed on the skin for reproducibility of your treatment set up. These are not usually noticeable (they look like a tiny beauty spot) and will only be completed with your notified consent. In the instance where a tattoo is not suitable (i.e. on the face and neck), immobilisation masks or physical landmark references are used.
Step 4: Treatment planning
This step is performed without the patient present. The information gained from the CT scan in Step 3 is used by the radiation oncologist and radiation therapists to develop an accurate and customised treatment plan. Every plan is unique and tailored to the specific requirements of each patient. Once the treatment plan has been completed, verified and finally approved by the radiation oncologist, treatment is ready to commence.
Step 5:Treatment with external beam radiation
You will be positioned on the treatment couch by radiation therapists in exactly the same way as you were for the simulation CT scan.
The radiation therapists will leave the room and monitor you closely on closed circuit TV and audio intercom. During your treatment, the radiation therapists will move both the treatment machine and couch into precise positions. The machine will make a noise during treatment that is a bit like a buzzing or whirring sound.
Treatments usually take between 10 – 20 minutes, including the time it takes to position you. The first treatment may take slightly longer due to quality assurance and procedure verification processes.
The treatment itself is PAINLESS, just like having an X-ray taken.
Most treatments take place daily (Monday to Friday) over a period of 4-8 weeks.
We encourage you to bring along a family member or a friend. They may be present in the treatment room upon request but must leave when the machines are switched on.
Step 6: After treatment
You will be reviewed on a routine basis, usually weekly, after your treatment sessions by your radiation oncologist. This is to check on your progress and to discuss any questions or concerns you may have. Other appointments after treatment may also occur for follow-up review or for discussion and assistance from a nurse or other allied health care professional (dietitian, physiotherapist, etc).
Step 7: Follow up consultation
An appointment will be made for you to see your radiation oncologist at the completion of treatment.
As radiation therapy is designed to stop the growth of tumours, it may take weeks or months before the full benefit of treatment is assessable. Subsequent appointments for ongoing review may also be necessary. Imaging and diagnostic tests are often needed prior to these appointments and you will be informed should these are required.