Stereotactic radiosurgery (SRS) is a non-invasive, non-surgical procedure which uses radiation therapy to treat the small tumors present in the brain. Stereotactic radiosurgery is better than the other radiation therapy procedures are it uses precise radiation which is only delivered to the site containing the tumor, thereby protecting the neighbouring tissues and organs from the intense radiation. If SRS is used to treat tumors present throughout the entire body then it’s called stereotactic body radiotherapy (SBRT).
The main objective of SRS is to give out intense doses of radiation that will break down the tumor and achieve permanent local control.
Both SRS and SBRT use the following technologies for their function:
● 3-D imaging and localization techniques that will give the exact coordinates of the tumor residing in the body
● SRS setup which will immobilize the patient so that he/she maintains a fixed position during therapy
● Delivery of high radiation gamma-ray or x-ray beams to particularly converge and project on the tumor
● Image-guided radiation therapy, or simply IGRT is one of the many types of radiotherapies that are used to treat cancer cells present in the body. The IGRT is a conformational therapy which specifically targets the cancer cells, thereby preventing exposure and damage to the healthy tissues present in the body
SRS and SBRT are considered as good alternatives to the conventional invasive surgeries to remove the tumors and abnormalities that are:
● are present next to vital organs
● can show movement within the body and spread easily
SRS is used to a great range of tumors ranging from benign to malignant. Brain tumors with complications, that can't be treated with surgical methods can also be treated by SRS. The many types of brain tumors that can be treated with SRS include:
● benign and malignant
● primary and metastatic
● single and multiple
● tumors that may remain even after surgery
● intracranial, orbital and base-of-skull tumors
● arteriovenous malformations (AVMs)
● trigeminal neuralgia (a nerve disorder in the face)
SBRT can also treat primary, or metastatic tumors present in the :
● head and neck
SRS has the same fundamentals of the other radiation treatment. It may not remove the tumor; instead, it targets the tumor cells and destroys their DNA. When the DNA of these tumor cells is destroyed, the cells are not able to reproduce. After the stereotactic radiotherapy, the benign tumors will take about 1.5-2 years to shrink. On the other hand, malignant and metastatic tumors only take a couple of months to shrink.
Arteriovenous malformations (AVMs), however, may take a period of several years before they begin to thicken and close off. After the SRS, the tumors may still be present but they will be inactive and stable, and won't spread to cause further damage. The main aim of all cancer therapies is to stop the tumor from growing. However, in certain cases, like acoustic neuromas, the tumor may first enlarge after the SRS due to an inflammation which stabilizes, later.
Stereotactic Radiosurgery Equipments
The stereotactic radiosurgery mainly uses 3 kinds of equipment, which have different forms of radiations.
● The GammaKnife is the special equipment with a focus of as many as 200 small packet beams which collectively form the radiation and are delivered to the site of tumor. Each little beam may not have a considerable effect on the tumor, however, when collectively irradiated, they constitute a strong dose of radiation is delivered to the site where all the beams meet.
● Linear accelerator (LINAC) machines, emit high-energy x-rays, known as photons which are delivered to the tumor in an intense beam. The linear accelerator can treat tumors in stereotactic radiosurgery in a single session or during multiple sessions, also known as fractionated stereotactic radiotherapy.
● Proton beam or heavy-charged-particle radiosurgery
Although the stereotactic radiosurgery is a non-invasive procedure for treating tumor. No incisions are involved, therefore the risks are lesser than the invasive cancer surgeries. However, there may handful side effects and complications of the stereotactic radiosurgery which may include:
● Tiredness and fatigue after a first few weeks of stereotactic radiosurgery
● Swelling in the brain, at the site where the radiations were delivered to destroy the tumor. Swelling may lead to a headache, nausea and vomiting.
● Scalp and hair problems. Your scalp may feel itchy and can also get red at the place where the device was hooked during the stereotactic radiosurgery.