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Stereotactic Radiosurgery and Radiotherapy 


Stereotactic Radiosurgery (SRS) and Stereotactic Radiotherapy (SRT) are both treatment methods of delivering radiation therapy to cancer tumors.  SRS or SRT may be used instead of or along with surgery.  SRS involves a single radiation treatment.  SRT uses a series of treatments over time.  Both methods spare healthy tissues because the radiation precisely targets the cancer.  The procedures are painless and usually performed on an outpatient basis.

SRS and SRT are used to destroy cancer cells with an external source of radiation.  Radiation kills and disrupts the growth of cancer cells.  Radiated cancer cells are not able to repair themselves or replicate.  Radiation damages all cells- both healthy and cancerous, in the exposed area.  SRS and SRT spare as many healthy cells as possible because it directs radiation precisely to a tumor. 

With SRS and SRT, sophisticated software controls the radiation treatment beams to match the exact shape of a tumor or lesion.  The beams may be moved to penetrate the cancer from different angles.  The state-of-the-art equipment is able to adjust for minor patient movements.  This precision delivery method quickly allows the cancer to receive the full dose of radiation, while the surrounding healthy tissue only receives a small percentage of radiation. 

SRS and SRT are used to treat tumors in delicate tissue areas, such as the brain and spinal cord.  SRS and SRT may also be used to treat lung, liver, prostate, and spine cancers.  It may be used to treat non-cancerous conditions in the brain, such as arteriovenous malformations, neuralgias, Parkinson’s Disease, pituitary adenomas, and intractable seizures.

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SRS is delivered in one high dose treatment.  SRT delivers radiation therapy in smaller amounts over several treatment sessions.  Both SRS and SRT deliver similar total doses of radiation, but SRT allows the healthy tissues time to recover between treatment sessions.  A protective contoured mask or form is fabricated prior to SRT. The mask and positioning devices may be worn during treatment.

SRS and SRT are usually outpatient procedures.  You should have another person drive you home from your treatment, as you may feel tired.  The treatment time is usually short, frequently under 20 minutes. The procedures are not painful.  Side effects may include headache or dizziness immediately following treatment.  Your doctor will let you know what to expect. Your doctor will monitor your treatment process with follow-up imaging scans.  It may take up to six months before the effect of SRS or SRT is visible on a follow-up image.

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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.

The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on April 13th, 2016. For information on iHealthSpot’s other services including medical website design, visit