Stereotactic Radiosurgery (SRS) is a precise medical treatment that delivers concentrated radiation to targeted areas. This specialized therapy offers a highly accurate approach for various conditions. This article will explore the nature of SRS, its principles, common medical applications, and the patient experience during treatment.
Defining SRS Radiation
Stereotactic Radiosurgery (SRS) is a sophisticated radiation therapy that does not involve surgical incisions. It precisely delivers high doses of radiation to a small, well-defined target area. This method differs from conventional radiation therapy due to its accuracy and the intensity of radiation delivered in a limited number of sessions, typically one to five.
The core concept of SRS is to damage the DNA of abnormal cells, such as those in tumors, preventing them from reproducing and growing. Over time, the targeted tissue becomes inactive and may shrink. This non-invasive technique aims for results comparable to open surgery, but with reduced risks and faster recovery.
Principles of SRS Delivery
The precision of SRS relies on advanced technologies and meticulous planning. Treatment begins with detailed imaging, such as CT, MRI, or PET scans, to precisely map the target area and surrounding healthy tissues. For conditions like arteriovenous malformations (AVMs), cerebral angiograms may also enhance targeting accuracy. These images allow a multidisciplinary team, including radiation oncologists and neurosurgeons, to develop a customized treatment plan.
Sophisticated software then uses these images to design multiple, convergent radiation beams. Each individual beam has a low dose, but where they intersect at the target, they deliver a highly concentrated dose. Patient immobilization is crucial for maintaining sub-millimeter accuracy during treatment, often involving custom head frames or masks. This focused delivery minimizes radiation exposure to healthy tissues, reducing potential side effects compared to traditional radiation therapy.
Medical Applications of SRS
SRS is primarily used for conditions where precision is paramount and traditional surgery is too risky or challenging. It treats various brain tumors, including benign and malignant types, primary tumors, and metastatic brain tumors. Its ability to target small, difficult-to-reach lesions makes it suitable for these applications.
Beyond tumors, SRS effectively treats arteriovenous malformations (AVMs), which are abnormal tangles of blood vessels in the brain that can disrupt blood flow and lead to bleeding. The radiation causes these vessels to thicken and close off. Another application is for trigeminal neuralgia, where SRS targets the nerve root to disrupt pain signals. Furthermore, SRS principles extend to stereotactic body radiation therapy (SBRT) for lesions in other body areas, including spinal, lung, liver, prostate, and pancreatic lesions.
The Patient Experience with SRS
Patients undergoing SRS typically have an outpatient procedure, returning home the same day. The process begins with an initial consultation and imaging scans for meticulous treatment planning. During planning, a custom immobilization device, such as a head frame or mask, is created to ensure the patient remains still during treatment.
On the day of treatment, the patient is positioned on a treatment table, and the immobilization device is secured. The treatment is generally painless, though patients may hear machine noises or feel the table move as radiation beams are delivered. A session can last from 15 minutes to four hours, depending on the target’s size and complexity. Medical staff monitor the patient throughout the procedure from an adjacent room, communicating via an intercom. After treatment, patients are observed briefly before discharge. While immediate side effects are often minimal, some may experience temporary fatigue, headaches, or nausea in the days following.