Stereotactic Radiosurgery Procedure

Overview

Stereotactic radiosurgery (SRS) uses advanced imaging and specialized machines to deliver focused radiation to specific tissues. This approach precisely targets the treatment area, limiting exposure to surrounding healthy areas. Doctors commonly use SRS for tumors or other problems in the brain, spine, neck, lungs, liver, and some soft tissues throughout the body.

SRS does not require a physical incision. Instead, doctors use 3D images such as CT or MRI scans to pinpoint the area needing treatment. Multiple small beams of radiation come from different angles and converge at the target. Surrounding tissues receive a low dose, but the spot where all the beams meet receives the maximum radiation.

Different types of equipment deliver this treatment. Some, like linear accelerator (LINAC) machines—including devices known as CyberKnife or TrueBeam—use X-rays. Doctors can use these for single treatments or spread them over several short sessions (fractionated therapy). Other systems, such as the Gamma Knife, use a high number of small gamma ray beams. The Gamma Knife treats small to medium-sized problems in the brain and is less commonly found.

The newest technology uses protons instead of regular X-rays or gamma rays. Proton beam therapy, available in limited centers, uses charged particles to focus the treatment and often provides high precision with less damage to nearby tissues. Below is a summary table of the main technologies:

Technology	Type of Radiation	Common Uses	Typical Sessions	Notable Systems
Linear Accelerator	X-rays	Brain, body, spine tumors	1–5 sessions	CyberKnife, TrueBeam
Gamma Knife	Gamma rays	Brain lesions and tumors	Single session	Gamma Knife system
Proton Beam Therapy	Protons	Brain, body (mainly research centers)	1 or multiple	Various

All these technologies aim to deliver a concentrated radiation dose to abnormal tissue, such as a tumor or a blood vessel malformation. SRS treatment generally follows these steps:

Imaging: High-resolution scans help map the exact location.
Planning: Doctors plan the dose and path of each beam.
Treatment: The patient is positioned, and the machine directs the beams, which may happen in one visit or a few over several days.

Key features of this method:

No surgical cuts
High precision
Lower risk of side effects compared to other forms of traditional surgery or radiation therapy
Applicable for both cancerous and noncancerous conditions

By using multiple focused beams, SRS damages the DNA of targeted cells so they lose the ability to grow. Over time, treated tumors shrink or stop growing, and blood vessels in the area may close off, limiting the tumor’s blood supply.

Stereotactic body radiotherapy (SBRT), also known as stereotactic ablative radiotherapy (SABR), applies the same principles but targets tumors outside the brain, often treating them over a few days. Each method aims for maximum accuracy to protect nearby tissues and organs.

Main Methods

Several key methods deliver stereotactic body radiotherapy:

Gamma Knife: Uses focused gamma rays mainly for brain treatments.
CyberKnife: Delivers radiation from many angles with a robotic system.
Linear Accelerator (Linac): Uses X-rays to treat various areas, not just the brain.

Each option uses different equipment and technology. Some are better for certain body areas or types of tumors.

Reasons for Stereotactic Radiosurgery

Stereotactic radiosurgery offers a powerful alternative when traditional surgery is too risky, invasive, or not possible due to the tumor’s location or a patient’s overall health. It is often chosen to:

Treat hard-to-reach or inoperable tumors without harming surrounding tissues.
Manage conditions in sensitive areas like the brain or spinal cord, where precision is critical.
Avoid extended recovery times and complications linked to open surgery.
Address tumors or lesions in patients who are not surgical candidates due to age or other medical conditions.
Control or shrink tumors in people seeking noninvasive or outpatient treatment options.

This approach is especially helpful for patients who need targeted treatment but want to minimize disruption to daily life, reduce hospital stays, and lower the risk of post-operative complications.

Possible Complications

Stereotactic radiosurgery carries fewer risks than standard surgery because it does not require cutting into the body. Most side effects are mild and appear soon after treatment. Common issues include:

Tiredness: Many people feel low energy or fatigue for a few weeks.
Brain Swelling: Swelling near the treatment area can lead to headaches, nausea, or vomiting. Doctors may use corticosteroids to manage swelling if it happens.
Scalp and Hair Changes: The scalp may become red, sore, or sensitive. Some people notice small areas of hair loss near where the device was attached, but this is often temporary.
Neurological Symptoms: In rare cases, problems such as seizures or numbness may happen. Most symptoms fade with time, but some may appear months after treatment.

Side Effect	How Often	Notes
Fatigue	Common	Usually lasts a few weeks
Nausea	Sometimes	Often linked to swelling near the brain
Hair Loss	Sometimes	Temporary, near the treatment site
Changes in Vision	Rare	May occur if areas near the optic nerves are treated

Steps for Getting Ready

Eating, Drinking, and Taking Medicine

Patients should stop eating and drinking after midnight before treatment. They should talk to their doctor to find out which medicines to take the night before or the morning of the procedure. Some regular medications might need to be paused or adjusted, so clear instructions from a doctor are necessary.

What to Wear and Bring

Wear comfortable, loose clothes. Do not wear personal items that could get in the way, such as jewelry, eyeglasses, contacts, makeup, nail polish, dentures, wigs, or hairpieces during brain or spine treatments. Bring only essential items for safety and convenience.

Safety Around Medicine Use and Allergies

Inform your doctor if you use diabetes medicine, have allergies to iodine or shellfish, or have implants like pacemakers or stents. Bring a list or the medicine itself to the center. Always ask the care team about any medicine routines required on the day of the procedure.

What You Might Experience

Most people have stereotactic radiosurgery as an outpatient, so they go home the same day. The process usually takes most of the day. Patients often bring someone with them for support and transportation afterward.

Before treatment starts, a healthcare provider may place an intravenous (IV) line in a vein, usually in the arm. This IV keeps the patient hydrated if they cannot eat or drink during the procedure.

Preparing the Head or Body

When treating the brain, the team uses different methods to keep the head still. Sometimes, they attach a lightweight frame to the scalp with four small pins, placed at points on the forehead and back of the head. They inject a numbing medicine where each pin will go.

No shaving of the hair is necessary, but they might use a special shampoo to clean the area. Some newer systems use a soft plastic mask molded to the patient’s face, which can be more comfortable, especially when more than one treatment session is needed.

For tumors or other spots outside the brain, a different method holds the body still. Sometimes, the team places a marker near the tumor for some types of technology, but this is not always needed.

Scanning and Planning

Once the head frame or mask is in place, the team performs imaging tests such as CT scans, MRI scans, or sometimes both. These tests help locate the tumor, blood vessels, or target nerve very precisely. Sometimes, they inject a special dye to see blood flow more clearly.

For problems with blood vessels in the brain, the team may perform a cerebral angiogram. In this test, a thin tube goes through a blood vessel (often in the groin) up to the brain to inject the dye.

The medical team uses all these images with special computer software to plan exactly where the focused radiation should go, how much to give, and from what angles. The planning can take one to two hours. While the team works, the patient can usually rest in another room but must keep the frame or mask on. With some technologies, patients might go home and return later for the actual treatment.

Simulation

To ensure the right areas are treated, the team may conduct a simulation step. The medical staff check the best way to position the body and use an immobilization device to keep everything still. If the patient feels worry or fear about being in a tight space, they should share this with their doctor. A table below summarizes the main steps before the procedure:

Step	Purpose	Tools Used
IV line	Hydration	Needle, tubing
Head frame/mask	Keeps head still	Pins or plastic mask
Body immobilization	Stops body from moving	Custom device
Imaging scans	Locate and target problem area	CT, MRI, angiogram
Planning	Decide on radiation dose and location	Computer software
Simulation	Check best body or head position	Immobilization device

What Happens During Treatment

Adults usually remain awake for the procedure and may receive medication to help relax. Children often receive anesthesia so they sleep during the scan and treatment. For brain treatments, the patient lies on a table that moves into the machine. If a head frame is used, the team attaches it firmly to the table.

If a mask is used, it fits snugly over the face. Treatment time depends on the area being treated and can range from less than an hour to up to four hours. Treatments with a mask tend to be shorter and might involve more than one visit. Two main types of machines are common:

Gamma Knife: The table moves the patient into a machine that stays still during the process.
LINAC: This machine moves around the head or body to focus beams from different directions.

Patients do not feel the radiation. They can talk with the healthcare team through a microphone if they need anything or have questions. The medical team monitors the patient from another room for safety and precision. Most patients rest quietly and may listen to music during the session. Here is a quick list of what happens during treatment:

The patient is positioned on the table.
The head frame or mask is secured.
The machine delivers focused beams of radiation.
The team watches, ready to help if needed.
The patient can talk to staff using a microphone.

Key Points

Radiation does not cause pain or discomfort during treatment.
Staying still is important for accuracy.
The length of the treatment depends on size, shape, and number of target spots.

What to Expect When Treatment Is Finished

Once the session ends, the team removes any head frame or mask. If a frame with pins was used, you may notice a little bleeding or soreness at the pin sites. Any discomfort is usually mild and temporary.

Some people might feel a headache, nausea, or the urge to vomit after treatment. If you experience this, your provider can give medication to help with these symptoms. The staff usually removes the IV line at this point.

After treatment, you can eat and drink as normal. Most people feel well enough to go home a short time after the procedure, though how each person feels can vary. The person who came with you can help get you home safely. Some important things to remember after stereotactic radiosurgery:

You may feel tired or have a mild headache.
The pin sites, if any, might be slightly sore or swollen for a day or two.
Most people do not need a hospital stay.
You can often resume normal activities quickly, but following the healthcare team’s instructions is important.

Here is a checklist table for after the procedure:

What Happens Next	What to Watch For	Help Available
Head frame/mask removed	Tenderness at pin sites	Pain medicine
IV line removed	Mild bleeding at pin sites	Bandages, nurse assistance
Allowed to eat/drink	Nausea or headache	Anti-nausea or pain medicine
Possible rest needed	Fatigue	Instructions for home care

Tips for Recovery:

Keep any pin site areas clean and dry per instructions.
Report any lasting headaches, worsening symptoms, or fever.
Attend all follow-up appointments to monitor progress.

Your care team will give specific instructions about when to return for check-ups and what signs might mean you need extra help.

Outcomes

The results of stereotactic radiosurgery differ based on the specific health issue being addressed. Changes often appear over varying periods, depending on the type of condition treated:

Benign Tumors (Such as Vestibular Schwannoma): The main aim is to stop any new growth. Tumor shrinkage can take between 18 months and two years.
Malignant Tumors: These cancerous tumors often respond quicker, sometimes shrinking within just a few months.
Arteriovenous Malformations (AVMs): The procedure works by thickening and sealing off abnormal blood vessels, which may take two years or longer.
Trigeminal Neuralgia: Many patients start to notice pain relief within weeks, but full results can take several months to appear.