What is total body irradiation (TBI)?
- Radiotherapy treatment to the whole body using high energy x-rays (called ionising radiation).
- Delivered using a machine called a linear accelerator (pictured) that directs the radiation beam to treat your whole body.
Why is TBI treatment used?
TBI is used in conjunction with high dose chemotherapy as part of the preparation for a blood stem cell or bone marrow transplant and is used to:
- destroy remaining cancer cells.
- to treat body areas where chemotherapy alone doesn't kill the disease (e.g. testicles and fluid around your brain and spine).
What happens during planning for TBI treatment?
Prior to your treatment starting, you will have to attend a simulation/planning session. During this session, the radiation therapists will explain the TBI process to you, take some measurements and you may have a CT (computed tomography) scan. At some centres, these measurements will be taken with you lying on your back on a bed with perspex walls (see photo). Other centres may have you lying on your side or even sitting for treatment. You will receive your treatment in the same position each time.
The measurements and/or CT scan will be used by the radiation therapists and physicists to calculate your treatment, and determine how long the treatment machine needs to stay on for. This session will take approximately 1 hour.
What happens prior to TBI treatment?
You will be admitted to hospital before your treatment begins. On the day of treatment, you will be placed in the same position as the planning session. To ensure you receive the radiation dose prescribed by your radiation oncologist, the physicists will place some very small measuring devices the size of a small sticker on your skin called TLDs (thermoluminescent dosimeters). These are placed on various points on your body using tape and are painless. At some centres, an additional radiation measuring device called an ion chamber may also be placed between your legs to check the dose being delivered.
Radiation therapists and physicists will use different materials; like rice bags/water/wax blocks/bolus(jelly-like sheets) or perspex on and around your body (particularly in thinner areas such as ankles, legs and lower limbs). This is to ensure that the radiation dose is distributed evenly.
Once the measuring devices have been attached and the rice bags/water/wax blocks/ bolus (jelly)/perspex are positioned you are ready for your treatment.
What will happen during TBI treatment?
Once inside the treatment room, the lights may be dimmed while the treatment bed is raised to the correct treatment height and moved into position. The machine will not touch you and when your treatment setup is complete, the radiation therapists and physicists will leave the room. During the treatment you will be monitored via a video camera and microphone. You can speak with the treatment staff at any time but it is important that you stay very still during the treatment.
When the treatment machine is turned on, you will hear a buzzing noise but you will not see or feel anything. Some patients report a metallic taste in their mouth and smell an odour; both of these things are normal.
During your treatment, the radiation therapists may turn the machine off and come into the room to make an adjustment or turn the bed around. It is important to remain still until the therapists advise you are able to move.
Photo courtesy of St Vincent's Hospital
Radiation Oncology Department
How long does treatment last?
You will be in the treatment room for approximately 45-60 minutes each time. The duration of your treatment may vary slightly between treatments and the radiation beam will not be on the whole time you are in the room. It takes approximately 10 minutes to setup the treatment bed and check that everything is in the correct position before turning the beam on.
How many treatments will I have?
The number of treatments varies between patients. TBI treatment is given twice daily, at least 6 hours apart over two or three days, for a total of 4-6 sessions. In some cases, your treatment may be given in a single session. Your radiation oncologist will decide the number of treatments most suitable for you.