STEREOTACTIC RADIO THERAPY (SRT): Procedure, Causes and Recovery

Stereotactic radiotherapy (SRT) is a type of technique used to precisely target radiation beams at the tumour. This is one of the latest innovations in the field of radiation therapy. Since this treatment requires special equipment, machine, and expertise, this treatment is not widely available across all cancer treatment hospitals.

SRT involves treatment of a tumour with the help of a special machine known as a linear accelerator (LINAC). This machine is used to deliver external radiation therapy in the case of normal radiation therapy and intensity-modulated radiation therapy (IMRT).

SRT treatment involves of small daily doses of radiation, which are also known as fractions. The patient may be advised to undergo anywhere between 3 to 30 fractions in a day, depending on the extent of cancer and the size of the area that is being targeted. SRT is mostly used for the treatment of smaller lesions and tumours and is less than 3 cms in size.

Stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) are types of SRT. SRS is also known as Gamma Knife surgery. It involves exposing the tumour to a very high dose of radiation in one to five fractions. Gamma Knife surgery is usually used for the treatment of a tumour in the central nervous system (CNS).

On the other hand, SBRT is a special procedure used for the treatment of tumours located outside the central nervous system. In this approach, radiation is delivered through different directions or positions of the body. It can be used for the treatment of small tumours in the lungs, pelvis, prostate, pancreas and other organs as well.

SRT is mostly used for the treatment of the following conditions:

Secondary brain tumours
Small lesion or brain tumour that has a well-defined edge
Glioma that may have returned after months or years of treatment

Gamma Knife surgery is different from CyberKnife radiation. The latter is used for the treatment of cancerous and non-cancerous tumours as well as other medical conditions. CyberKnife treatment is actually a frameless robotic radiosurgery system that delivers a high dose of radiation to the targeted location.

The planning that takes places before the actual stereotactic radiotherapy is similar to what happens before a typical radiotherapy session. Your surgeon will have a thorough look at the different scans to identify the exact targeted location and the size and intensity of the beam to be used. Every effort is made to target just the tumour area without affecting the nearby cells. This ensures that you experience minimal side effects due to exposure of normal tissues to radiation.

Talk to your specialist about the risks involved with the procedure and the side effects you are likely to experience after afterwards. Try to understand what exactly you can do to minimize them.

Additionally, take the following precautions:

Do not eat anything after midnight before the surgery.
Do not wear any jewellery on the day of radiation treatment.
Remove dentures, eyeglasses, and contact lenses before the procedure.
Inform the specialist if you have a pacemaker, stent, or an artificial heart valve.

Just before the surgery, the radiographer will fit the head frame or the mask in case it is being used for other parts of the body. This is done to restrict the movement so that the targeted location stays in place. You may receive a local anaesthetic before the placement of mask or head frame.

You are placed on the radiotherapy table as soon as the frame is in place. A typical session lasts for just 10 minutes or more, depending on how much radiation is scheduled to be delivered.

In the case of stereotactic radiosurgery or Gamma Knife surgery, several tiny beams of radiation are aimed at a tumour precisely. It can also be used for the treatment of specific conditions such as Parkinson’s disease, trigeminal neuralgia, and epilepsy. This lets the specialist focus a single dose of large radiation at a time to eliminate the tumour cells. In the case of stereotactic body radiation therapy, several beams of radiation are targeted at the cancerous tumour from different directions.

Most of the patients are able to resume their normal life and work within two or three days of the procedure. The patients are usually discharged on the same day of the procedure. However, a few of them may be required to stay overnight is medically advised or needed.