Does Gamma Knife or radiosurgery hurt?

The radiation itself is not felt and causes no pain during treatment. If a head frame is used, a local numbing injection is given at the pin sites, and the brief sting of that injection is usually the only discomfort. Some people feel pressure when the frame is placed. Mask-based treatment involves no pins at all.

How many sessions does SRS take?

Many tumors are treated in a single session. Some are treated across two to five sessions, an approach called fractionated stereotactic radiotherapy, which spreads the dose out to let healthy tissue recover between treatments. The number of sessions depends on the size, location, and type of tumor, and is decided during planning.

What is the difference between SRS and whole-brain radiation?

SRS focuses high-dose radiation on specific targets while sparing most of the brain. Whole-brain radiation treats the entire brain at a lower dose over several sessions. SRS is now standard for a limited number of metastases because it spares healthy tissue. Whole-brain radiation is still used in certain situations, such as widespread disease that cannot be managed with focused treatment alone.

What are the side effects of radiosurgery?

Short-term effects are usually mild and include tiredness, headache, nausea, and scalp tenderness at any pin sites. Over the following weeks the treated area can swell, sometimes requiring steroids. A delayed risk is radiation necrosis, in which treated tissue breaks down months later. Risks rise with larger treated volumes and prior radiation. Outcomes vary by tumor and cannot be promised.

Can SRS treat large tumors?

Generally no. SRS is best suited to smaller, well-defined tumors, often under about three centimeters. Large tumors are harder to treat safely because the dose must cover more tissue, and the risk of side effects rises with size. A large tumor pressing on the brain often needs surgery to relieve that pressure, since radiation works gradually rather than removing bulk.

Will I need to stay in the hospital?

In most cases, no. SRS is typically an outpatient procedure. Patients usually spend most of the treatment day at the center for imaging, planning, and delivery, then go home the same day. Most people resume usual activities within one to two days. A small number of situations may call for overnight observation.

How will we know if the treatment worked?

Response is tracked with follow-up imaging over the months after treatment, often starting around three and six months. SRS works gradually, so a tumor may shrink slowly or simply stop growing, and a stable scan can indicate the treatment is controlling the tumor. Because radiation necrosis can resemble regrowth on scans, follow-up is interpreted carefully over time.

Stereotactic Radiosurgery

Q: What do names like Gamma Knife and CyberKnife mean?

These are brand names for different SRS platforms. Gamma Knife uses fixed gamma-ray beams focused inside the brain. CyberKnife and similar systems use a moving linear accelerator that produces X-ray beams. Rutgers Cancer Institute and Robert Wood Johnson University Hospital in New Brunswick offer Gamma Knife radiosurgery for tumors in the brain.

Focused, high-dose radiation that treats tumors in the brain and spine precisely, without an incision, usually in a single session.

Overview

What Is Stereotactic Radiosurgery?

Stereotactic radiosurgery, or SRS, is a way to treat tumors with focused radiation rather than a scalpel. Despite the word surgery in the name, there is no incision, no opening in the skull, and nothing is physically removed. Many small radiation beams are aimed from different angles so they all meet at one precise point. Each beam passing through healthy tissue is weak. Where the beams converge on the tumor, the combined dose is high enough to damage the tumor cells and stop them from growing.

The radiation does not cut anything out. It alters the DNA inside the tumor cells so they lose the ability to divide and slowly die off. Because the dose drops sharply at the edge of the target, nearby healthy brain or spinal tissue receives far less radiation. This is what allows a high dose to be delivered to the tumor while limiting harm to the structures around it.

SRS is delivered by more than one specialist working together. A neurosurgeon and a radiation oncologist define the target and decide on the dose. A medical physicist and a dosimetrist build the treatment plan and confirm that the beams converge exactly where intended. The plan is checked carefully before anything is delivered, because the precision is the entire point of the approach.

Several platforms can deliver SRS. Gamma Knife uses many fixed beams of gamma rays that focus on a single point in the brain, while LINAC-based systems use a moving linear accelerator that produces X-ray beams. Rutgers Cancer Institute and Robert Wood Johnson University Hospital in New Brunswick offer Gamma Knife radiosurgery, which can be delivered with a head frame or, when appropriate, with a frameless mask-based approach.

Call our office at 732-235-6333 or send us a message.

The information on this page is general educational information and is not medical advice. It does not create a doctor-patient relationship or reflect a treatment recommendation for any individual. Treatment decisions require an individual evaluation by a qualified physician.

SRS is used for specific tumors and situations rather than as a general substitute for surgery. It tends to fit smaller, well-defined targets where precision matters and where open surgery would carry meaningful risk. Whether it is appropriate for a given tumor depends on the size, location, type, and how many lesions are present.

Brain metastases. SRS is a standard treatment for a limited number of brain metastases, and its use has expanded in recent years to include patients with more lesions than were once considered candidates. It can treat several metastases in a single session and reach lesions that are difficult or unsafe to remove surgically.

Meningiomas. SRS is often used for small meningiomas in locations where surgery would carry significant risk, for residual tumor left after a partial removal, and for meningiomas that have recurred after earlier surgery.

Ependymomas and other primary tumors. Focused radiation can be used for certain primary brain tumors, including residual or recurrent tumor after surgery, depending on the tumor type and location.

Spine metastases. Focused radiation directed at the spine, sometimes called spine SBRT, can treat tumors in the vertebrae with high precision while limiting dose to the spinal cord.

Tumors near critical structures. Lesions close to nerves, vessels, or areas controlling speech and movement may be better suited to focused radiation than to open surgery.

When it's not the right tool. Large tumors generally fall outside its range, both because the dose is harder to deliver safely across a big volume and because the risk of side effects rises with size. A tumor causing significant pressure on the brain often needs surgery to physically relieve that pressure, since radiation works gradually and does not remove bulk quickly. Tumors that need a tissue diagnosis usually require a biopsy or surgery first.

The decision between radiosurgery, surgery, and other options is made by weighing all of these factors together, usually with neurosurgery and radiation oncology in the same conversation.

The Process

What to Expect

The process is built around precision, so most of the effort happens before any radiation is delivered. Here is the general sequence.

Consultation and review
A neurosurgeon and a radiation oncologist review imaging and the broader treatment plan to confirm that SRS fits the tumor and the situation. They discuss the goals, the alternatives, and the expected risks.
Planning imaging and simulation
Detailed imaging, usually MRI and sometimes CT, maps the exact size, shape, and position of the target. This imaging is used to build the treatment plan.
Immobilization
Because the target must hold still, the head is stabilized either with a lightweight frame fixed to the skull using local numbing at the pin sites, or with a custom-fitted mask molded to the face. Frames are common for single-session treatment; masks are common when treatment is spread across several sessions.
Treatment planning
The physicist and dosimetrist design how the beams will converge, set the dose, and confirm the plan protects the surrounding tissue. This step can take time, and patients often wait while it is finalized.
Treatment delivery
During delivery the patient lies still while the machine positions the beams. Nothing is felt during the radiation itself. Treatment of a single target often takes under an hour, longer when multiple lesions are treated.
After treatment
Any frame or mask is removed. Most people go home the same day, often with someone to drive them, and resume usual activities within a day or two.
Follow-up imaging
Scans are scheduled over the following months to see how the tumor responds and to watch for any changes. Imaging at roughly three and six months is common, with longer intervals after that.

The days right after treatment

Most people feel close to normal soon after SRS and return to usual activities within one to two days. Common short-term effects are mild and include tiredness, headache, or scalp tenderness at the pin sites if a frame was used. Some people have nausea. These effects are usually temporary. Because there is no incision, there is no surgical wound to heal and no shaving of the head.

How tumors respond over time

SRS does not make a tumor disappear right away. It stops the tumor cells from dividing, and the tumor changes slowly over weeks to months. Some metastases begin to shrink within a couple of months. Benign tumors such as meningiomas may take a year or two to show their full response, and for many of these the goal is to stop growth rather than to see the tumor vanish. Follow-up imaging is how the response is tracked, and a tumor that looks stable on scans can indicate the treatment is controlling it.

Risks, including radiation necrosis

SRS carries real risks even though it is non-invasive. In the weeks after treatment, the treated area can swell, which may briefly worsen symptoms or require steroids. The risk that draws the most attention is radiation necrosis, a delayed reaction in which treated tissue breaks down and inflammation develops at the site. It usually appears months after treatment, most often between about three and eighteen months, and can cause headaches, nausea, seizures, or new neurologic symptoms.

Reported rates vary widely and rise with larger treated volumes and with prior radiation to the same area. On imaging, radiation necrosis can look similar to tumor regrowth, which sometimes makes follow-up scans harder to interpret. These risks are weighed against the benefits for each specific tumor, and outcomes are never guaranteed.

Related Conditions

Conditions Treated with Stereotactic Radiosurgery

Focused radiation is a core treatment option across several of the conditions Dr. Sherman treats. Each condition page covers symptoms, diagnosis, and the full range of treatment options.

Technology

Using XR Technology To Advance Medical Care

Dr. Sherman integrates VR and AR visualization into surgical planning and patient education, giving patients a clearer picture of their diagnosis and the approach to treatment.

Common Questions About Stereotactic Radiosurgery

No. Despite the name, SRS does not involve any incision, no opening in the skull, and nothing is physically removed. It uses many focused radiation beams that meet at the tumor to deliver a high, precise dose. The word surgery refers to the precision of the targeting, not to cutting. There is no wound to heal afterward.

Next Step

Considering Radiosurgery or Seeking a Second Opinion?

Dr. Sherman is accepting new patients at Rutgers Cancer Institute in New Brunswick, New Jersey. Whether you are weighing stereotactic radiosurgery against surgery or looking for another perspective on a treatment plan, a consultation is the first step toward understanding your options.

Schedule a Consultation 732-235-6333

Stereotactic Radiosurgery

What Is Stereotactic Radiosurgery?

Who It's For

What to Expect

Consultation and review

Planning imaging and simulation

Immobilization

Treatment planning

Treatment delivery

After treatment

Follow-up imaging

Recovery & Risks

Conditions Treated with Stereotactic Radiosurgery

Using XR Technology To Advance Medical Care

Common Questions About Stereotactic Radiosurgery

Considering Radiosurgery or Seeking a Second Opinion?