The SRS Treatment Process
Stereotactic radiosurgery is a carefully controlled process that consists of a series of steps: consultation, positioning, imaging, treatment planning, treatment delivery, and follow-up care.
Your initial visit will be with the physician leading your treatment team. This may be a radiation oncologist or a neurosurgeon. The physician will review your medical history and reports, make a recommendation about any further tests that may be required, discuss the options available to you, and work with you to choose an optimal course of treatment. If it is SRS, the entire treatment process will be completed in one day; if it is SRT, you will be scheduled for a series of appointments.
In order to achieve the precision of a stereotactic treatment, it’s important to be accurately positioned and carefully immobilized during treatment. The doctor will fit you with an immobilization device to ensure that you remain in the same position—as comfortable as possible—without moving during the procedure.
There are different methods for positioning and immobilization, depending on the area to be treated. Some single-session treatments to the brain require a minimally invasive headframe. The frame is fixed to the head using pins or screws, which are put in place under local anesthetic. The frame is then attached to the treatment couch.
A frameless system may be used in other instances, especially for SRT treatments delivered over several days. Frameless systems range from a lightweight mesh mask, individually formed to fit to your face and head, to a bite block. With the bite-block system, a bite tray similar to a dental mold is closely fitted to your upper jaw and then secured to the treatment couch.
For stereotactic treatments to regions of the body other than the head, various types of body frames or cushioning systems are available for patient positioning. Your physician will discuss with you the various options to determine which will work best, given your specific circumstances.
If you have been fitted with a headframe for SRS, you will need to remain at the clinic for the entire treatment process. With other types of positioning systems, you may have the option of going home after imaging, then returning for actual treatment on another day.
A CT scan is performed, to generate images of the area to be treated. This scan—along with any other CT, PET, MRI, and X-ray images you may have had—provides information required not only to create a treatment plan but to ensure that you are positioned correctly at the time of treatment.
With the information gathered during the positioning and imaging steps, a dedicated medical team will design the best treatment plan for your situation. They will use a sophisticated software program to generate a customized plan for your treatment.
SRS treatments usually take about an hour. In some cases the treatment time can be longer. Most of the time is used to ensure that you are accurately positioned for your treatment. You may see laser lights in the room; these help the therapist make sure you are level and straight on the treatment couch. You may see and hear the robotic arms of the imager as they extend from the linear accelerator and move into position. Usually, two or more images are taken from different angles, or a complete rotation of the accelerator may be used to generate a three-dimensional image. The therapist will use these images to guide adjustment of the treatment couch. You may also notice a camera on the ceiling; this is part of an optical guidance system that monitors and corrects for any movement during the treatment. In some cases, a camera may also be used to monitor your breathing.
You will be alone in the room during the treatment, but the therapist can see and hear you at all times through intercom and closed circuit television systems. The therapist will control the accelerator, imagers, and treatment table from outside the room.
The linear accelerator emits a buzz as it produces the radiation beams. Although its effect on tumors is quite dramatic, the radiation itself is invisible. You will not feel it, either, just as you do not feel chest X rays or CT scans. You may also hear the quiet whir of the beam-shaping device and see the leaves move. The accelerator will move around you to deliver beams from different angles, according to your treatment plan. Sometimes the couch will move as well. This is all normal and part of the treatment process.
After you complete your treatment, your doctor will monitor your progress with a series of followup visits. Blood tests, diagnostic X rays, and even additional CT and MRI scans may be requested at these appointments. These appointments are your opportunities to discuss any problems and review how to stay healthy after treatment. Ask about nutrition, exercise, and other basics for maintaining a healthy lifestyle. You can also find out about support groups for survivors of cancer or neurological conditions.