External beam radiotherapy

External Beam Radiotherapy (EBRT) is a method for delivering a beam or several beams of high-energy x-rays to a patient's cancer. The beams are generated outside the patient (hence the term "external") and can be aimed at the cancerous tissue from any direction. EBRT is commonly used to treat a wide variety of cancers and is one of the most prevalent forms of radiation therapy.

Overview

EBRT works by damaging the DNA of cancer cells, which interferes with their ability to reproduce, ultimately leading to the death of the cells. Healthy tissues surrounding the cancer can also be affected by EBRT, which can lead to side effects. However, advancements in technology have led to more precise targeting of tumors, minimizing damage to healthy tissues.

Types of External Beam Radiotherapy

There are several types of EBRT, each utilizing different technology to deliver radiation to the cancerous tissue:

• 3D Conformal Radiotherapy (3D-CRT): Uses imaging technology to create a three-dimensional model of the tumor, allowing for precise targeting of the radiation beams.
• Intensity-Modulated Radiation Therapy (IMRT): An advanced form of 3D-CRT that modulates the intensity of the radiation beams, allowing for even more precise targeting and sparing of healthy tissue.
• Stereotactic Body Radiotherapy (SBRT): Delivers very high doses of radiation to small, well-defined tumors in fewer sessions than traditional therapy, using detailed imaging to ensure accuracy.
• Proton Therapy: Uses protons instead of x-rays. Protons can be more precisely controlled, so they deposit their energy directly in the tumor and reduce exposure to surrounding healthy tissues.

Procedure

The EBRT process typically involves several steps:

1. Simulation: Before treatment begins, a simulation is conducted to determine the exact location, shape, and size of the area to be treated. This often involves imaging studies such as CT scans or MRIs. 2. Treatment Planning: A team of medical professionals, including a radiation oncologist, a medical physicist, and a dosimetrist, uses the simulation images to design a treatment plan that will deliver the maximum dose to the cancer while sparing healthy tissue. 3. Treatment Sessions: The patient will undergo a series of treatment sessions, or fractions, over a period of weeks. The number of sessions depends on the type and stage of cancer being treated.

Side Effects

While EBRT is non-invasive and painless, it can cause side effects, which vary depending on the treatment area. Common side effects include fatigue, skin irritation at the treatment site, and temporary changes in blood counts. More serious, long-term side effects can occur but are less common.

Advancements in EBRT

Technological advancements in EBRT continue to improve its efficacy and safety. Innovations such as image-guided radiation therapy (IGRT) and adaptive radiation therapy (ART) allow for more precise targeting of tumors and adjustment of treatment in response to changes in the tumor's size or position during the treatment course.

Conclusion

External Beam Radiotherapy is a cornerstone in the treatment of cancer, offering a non-invasive option that can be tailored to the specific needs of each patient. Ongoing research and technological developments promise to enhance its precision and reduce side effects, improving outcomes for cancer patients.