Stereotactic Radiation Therapy

What is stereotactic radiation therapy?

Stereotactic radiation therapy, or stereotactic radiotherapy, is a form of radiotherapy that uses highly intense but precise doses of radiation to target cancer cells from multiple angles.

How it works

Stereotactic radiotherapy works like other forms of radiotherapy by destroying or damaging the targeted cells' DNA. This stops the abnormal cells' growth, causing these tumours to become inactive and shrink.

During the procedure, radiation beams are aimed at the tumour from many different points to allow for accurate delivery of radiation. Except for the spot where all the beams intersect, each beam has minimal effect on the areas it passes through. This reduces possible damage to healthy tissues surrounding the tumour.

Tumours in locations that move with breathing, such as the lung or liver, may also be safely targeted with this technique. At IHH Healthcare Singapore, specialised equipment is available to allow doctors to monitor the breathing motion, and to deliver the radiation only when the patient is in the correct position.

What is the difference between stereotactic radiotherapy and conventional radiotherapy?

The difference between stereotactic radiotherapy and conventional radiotherapy is in the intensity and duration of the radiation treatment.

In conventional radiotherapy, small doses of radiation are delivered over many sessions, lasting several weeks. It is usually used to treat large tumours, or post-operatively to prevent recurrence.

In stereotactic radiotherapy, bigger doses of radiation are delivered in precise doses. The treatment is typically done over 5 or fewer sessions, usually over 1 – 2 weeks. It is usually used for small, well-defined tumours and generally results in less collateral damage to the surrounding tissues.

A single dose of very high intensity radiation delivered to a small area in the brain is called a stereotactic radiosurgery.

Stereotactic radiotherapy applied to areas other than the brain is called stereotactic body radiotherapy or stereotactic ablative radiotherapy.

Why do you need stereotactic radiation therapy?

Stereotactic radiotherapy may be a treatment option for:

• Cancers involving small, well-defined tumours. This includes the lungs, liver, lymph nodes, neck, pancreas, prostate, or spine.
• Patients who cannot undergo surgery to remove the tumour.
• Cancers that have relapsed and where conventional treatments are no longer viable.

Who should not undergo stereotactic radiation therapy?

Stereotactic radiotherapy is not recommended if you are pregnant or breastfeeding.

What are the risks and complications of stereotactic radiation therapy?

Stereotactic radiotherapy results in fewer collateral damage compared to conventional radiotherapy. Depending on the site of the radiation, you may still experience these temporary side effects:

• Feeling tired
• Feeling weak
• Sore skin
• Loss of hair

There can be rare serious side effects depending on the location of treatment. Your radiation oncologist will counsel you of these side effects if they are applicable in your case.

How do you prepare for stereotactic radiation therapy?

Depending on the condition and body area being treated, your doctor will advise you on preparation requirements that may involve:

• Abstaining from food or drink after midnight the night before the procedure
• Checking with your doctor on when you should take your regular medications, especially metformin, a drug used to treat diabetes
• Wearing comfortable, loose-fitting clothing

Note: Inform your doctor if you have an implanted medical device in your body, such as a pacemaker, artificial heart valve or stent.

What can you expect in a stereotactic radiation therapy?

Stereotactic radiotherapy is usually an outpatient treatment.

Estimated duration

One session lasts 20 – 60 minutes.

Before the procedure

You will undergoing a procedure called a CT simulation. It is a CT scan performed at the radiation oncology department, where the area of your body to be treated will be mapped out.

In certain cases, your doctor may also make a customised plastic head mask, or a back or arm support moulded to your body shape.

Your doctor may also make some very small skin marks for reference. These marks help to position you accurately over the course of your treatment. They do not indicate the precise treatment location.

During the procedure

You will need to lie still during the treatment. You may hear some noises but will not feel anything, like taking an X-ray. The machine which delivers the radiation beams will not touch you, but will move around you to deliver the beams from different angles.

After the procedure

You can expect to go home on the same day.

Inform your doctor if you experience symptoms such as pain or nausea. Your doctor will prescribe appropriate medications to ease your symptoms.

Care and recovery after a stereotactic radiation therapy?

You will be able to eat and drink after the procedure and can resume your normal activities within 1 – 2 days.