Radiosurgery replaces the surgeon’s scalpel with a single, high dose of radiation. Like the surgeon’s scalpel, the radiation eradicates the diseased area with a safe and effective approach. The patient wears a lightweight head frame that attaches to a helmet, through which radiation is precisely focused at a single target. Only the tissue being treated receives a very strong dose of radiation while the surrounding tissue remains unharmed. The painless, bloodless procedure is usually performed under local anesthesia with mild sedation. Although the entire procedure takes several hours, the actual treatment takes just 15 minutes to one hour, depending on the size of the lesion being treated. If there are multiple tumors or if the tumor spreads to another area, radiosurgery can be repeated. There is no risk of surgical complications like infection, hemorrhage or leakage of cerebral spinal fluid.
The patient is fitted with a stereotactic frame, which prevents movement during treatment and supports what is known as the collimator helmet. The patient then lies horizontally on the couch which moves into the collimator helmet, positioning the patient’s head for treatment. The machine then releases radiation on a predetermined position within the brain. Enough radiation is delivered to treat an abnormal area or tissue while leaving the surrounding healthy tissues intact and unharmed.
These machines allow non-invasive (without opening the skull) brain surgery to be performed with extreme precision while sparing healthy tissues surrounding the targeted treatment area. Also, because surgical incision is not required, the risks usually involved with open brain surgery, such as hemorrhage or infection, may be reduced. Hospitalization and recovery time are minimal. While individual patient outcomes may vary, patients may resume their normal lifestyle the very next day.
The risk of infection, hemorrhage and spinal fluid leakage associated with open skull surgery may be reduced.
The risk associated with general anesthesia is eliminated. Patients may be sedated during treatment and are able to communicate.
The scarring and potential disfigurement that results from open skull surgery is eliminated because radiosurgery is non-invasive.
The procedure usually only involves an overnight stay at the hospital . As opposed to open skull surgery, which requires hospitalization for an extended period of time, radiosurgery helps reduce the cost of treatment.
While individual patient outcomes may vary, patients may resume their normal activities, usually the day after treatment.
Stereotactic radiosurgery was first invented in 1950 through the joint efforts of Lars Leksell, a Swedish neurosurgeon, and Börje Larsson, a physicist at the Karolinska Hospital and Institute in Stockholm, Sweden. Dr. Leksell continued his extensive research and experimentation with stereotactic radiosurgery and finally created an instrument that could deliver such a precise dose of radiation.
Medical necessity can be determined by a neurosurgeon, radiation oncologist or other medical specialist after evaluating a prospective patient’s medical condition. Treatment options are then determined and discussed with the patient and family, so an informed decision may be made.
Radiosurgery has been used worldwide to treat benign, malignant, and metastatic tumors. It has also been used to eradicate arteriovenous malformations (AVM) and certain functional disorders such as trigeminal neuralgia, Parkinson’s disease, and essential tremor. Patients may be eligible for radiosurgery even if they have previously had open brain surgery, radiation therapy, chemotherapy, or in the case of AVM, embolization procedure. Results have proven to be superior or comparable to conventional neurosurgery, depending on the specific condition treated.
On the day of treatment, the patient will have a lightweight frame attached to the head. Local anesthesia is used before the frame is secured in place. The frame is used in conjunction with an imaging procedure to accurately locate the diseased area. With the frame in place, the patient has either an MRI or CT imaging study or, in the case of AVM, angiography, in order to precisely locate the diseased area to be treated. Data from the imaging study is transferred into the treatment planning computer. While the patient rests, the treatment team used advanced software to determine the treatment plan. This takes one or two hours to complete depending on the complexity and location of the disease. When the individual treatment plan is completed, the patient is placed on the couch and precisely positioned. The patient is then moved automatically, head first into the machine, and treatment begins. Treatment typically lasts from 15 minutes to an hour, during which time the patient feels nothing unusual. At the completion of the treatment the patient is automatically moved out of the machine, and the head frame is removed. The patient may remain in the hospital overnight for observation.
The effects of radiosurgery occur over a period of time that can range from days to several years, depending on the type of medical condition treated. Some abnormalities dissolve gradually, eventually disappearing. Others simply exhibit no further growth.
Cost studies have shown radiosurgery to be less expensive than conventional neurosurgery because it eliminates lengthy post-surgical hospital stays, expensive medication and sometimes months of rehabilitation. Importantly, there are virtually no post-surgical disability and convalescent costs with this procedure. Radiosurgery is reimbursed by most insurance companies, PPO’s, HMO’s, and Medicare.
Will my hair fall out with stereotactic radiosurgery? Or change colors?
The dose of radiation delivered with radiosurgery to the inside of the scalp (where the hair follicles are) determines whether or not you will lose hair. Your hair will never be lost over your entire scalp as may happen with conventional whole brain radiation. If a lesion being treated is very close to the inside of the skull, it is possible that enough radiation will be delivered to the scalp that a patch of hair may be lost. The hair should grow back and may become lighter and finer in texture. Hair loss is more likely to happen with fractionated stereotactic radiosurgery.
Because the radiation delivered by radiosurgery is so focused, it is unlikely that enough radiation would be delivered to the surface of the scalp to cause a radiation burn. At the current doses used, each beam of radiation is not sufficient to cause permanent damage to the skin.
Do the pins on the head frame go through my skull?
The four pins used to secure the frame onto the head penetrate only a small amount into the outer part of the skull. It would be extremely difficult to penetrate a normal adult skull with the pins. The exceptions would be a child or infant skull and a skull that had previous craniotomy defects or fractures. Any previous operations or trauma to the head should be reported to your neurosurgeon.
Necrosis is the technical term for the destruction of cells (in this case tumor cells.) It is therefore a desirable effect. If it is not accompanied by symptoms then it is not a problem. If symptoms occur, medications or surgery may be required to remove it. A determination for this is made my your neurosurgeon.
In the early post treatment period some tumors can swell, as a result of injury to their ability to regulate their water content. This swelling is self limited and reverses over several weeks to months. Such swelling may be misinterpreted as growth. Swelling is treated with a minor course of steroid drugs when it presents a problem.
Can stereotactic radiosurgery cause another tumor?
No, not in the last 30 years of its use. However the number of cases followed for 30 years are few and future observations will be more illuminating. Based on the existing experience with radiation however, the incidence of a radiation induced tumor is highly unlikely.
Full Question: I have a small acoustic neuroma and my friend’s wife has a larger one. We both had radiosurgery at different hospitals. When we were talking, she said she had less time in the machine than I did. Did I get too much radiation?
The treatment time is a factor of the dose given and the half-life of the cobalt60 in the treating machine. Apparently, the machine you were treated on had cobalt60 that was older and required more time to “emit” the dose required to you appropriately. The half-life of cobalt60 is 5.26 years. This means the same treatment given when the cobalt was fresh would take twice as long to give 5.26 years later.