Stereotactic external-beam radiation therapy

Stereotactic External-Beam Radiation Therapy

Stereotactic external-beam radiation therapy (SBRT) is a form of radiation therapy that precisely delivers a high dose of radiation to a tumor while minimizing exposure to surrounding healthy tissues. This technique is commonly used in the treatment of small, well-defined tumors and is particularly effective in treating cancers of the lung, liver, spine, and brain.

Overview

SBRT is a non-invasive treatment that uses advanced imaging techniques to accurately target tumors. The procedure involves the use of a linear accelerator to deliver radiation beams from multiple angles, converging on the tumor with high precision. This allows for a higher dose of radiation to be delivered in fewer treatment sessions compared to conventional radiation therapy.

History

The concept of stereotactic radiation therapy was first developed in the 1950s by Swedish neurosurgeon Lars Leksell, who introduced the Gamma Knife for treating brain lesions. The development of linear accelerators in the 1980s and 1990s allowed for the expansion of stereotactic techniques to extracranial sites, leading to the evolution of SBRT.

Procedure

The SBRT procedure typically involves the following steps:

1. Patient Positioning and Immobilization: Patients are positioned on a treatment table and immobilized using custom molds or frames to ensure precise targeting.

2. Imaging and Planning: High-resolution imaging techniques such as CT or MRI are used to visualize the tumor and surrounding anatomy. These images are used to create a detailed treatment plan.

3. Radiation Delivery: The linear accelerator delivers radiation beams from various angles, focusing on the tumor. The treatment is usually completed in 1 to 5 sessions.

4. Follow-up: Patients are monitored for response to treatment and potential side effects.

Applications

SBRT is used to treat various types of cancer, including:

- Lung Cancer: Particularly effective for early-stage non-small cell lung cancer (NSCLC) in patients who are not surgical candidates. - Liver Cancer: Used for hepatocellular carcinoma and liver metastases. - Spinal Tumors: Provides pain relief and local control of metastatic spinal lesions. - Prostate Cancer: An emerging application with promising results in localized prostate cancer.

Advantages

- Precision: High precision reduces damage to healthy tissues. - Convenience: Fewer treatment sessions compared to conventional therapy. - Effectiveness: High doses per session can lead to better tumor control.

Risks and Side Effects

While SBRT is generally well-tolerated, potential side effects may include:

- Fatigue - Skin irritation - Nausea - Damage to nearby organs, depending on the tumor location

Also see

- Radiation therapy - Gamma Knife - Linear accelerator - Intensity-modulated radiation therapy