Radiation Oncology

External Beam Radiation Therapy

It is the most common type of radiotherapy, which is delivered from external equipment. Depending on the type and spread of cancer, external beam radiation therapy can be used to target specific or large areas of the body. The various types of external beam radiotherapy are as follows :

• Three-Dimensional Conformal Radiation Therapy (3D-CRT)

  The oncology team uses detailed 3-dimensional images of tumors created by computerized tomography (CT) or magnetic resonance imaging (MRI). It helps the oncologists safely administer high-intensity radiotherapy from different directions to cover the size and shape of the tumor and reduce the damage to nearby healthy tissues.

• Intensity-Modulated Radiation Therapy (IMRT)

  Three-dimensional images of the tumor are taken and entered into the advanced software that is used to program the linear accelerator (radiation machine) to deliver precise doses of radiation depending on the size and shape of the tumor. Unlike other radiation where a single beam intensity is administered, IMRT uses different radiation intensities. Stronger doses are delivered to certain areas of the tumor while causing less damage to nearby healthy tissue, thereby reducing the side effects of the radiation oncology treatment.

• Proton Beam Therapy

  This therapy uses high-energy protons to destroy cancerous cells. Proton beam therapy allows greater control over radiation as protons travel only a certain distance which limits the exposure to healthy tissues around the tumor.

• Image-Guided Radiation Therapy (IGRT)

  IGRT uses frequent imaging scans (CT or MRI), which allows the radiation oncology doctors to adjust the patient's position, focus the radiation beam precisely on the tumor, and limit the exposure of normal tissues. Due to its precision, effectiveness, and tumor monitoring and control, IGRT is used to treat tumors near vital organs like the heart, lungs, liver, and kidneys.

• Stereotactic Radiation Therapy (SRT)

  SRT delivers a large but precise dose of radiotherapy to a small tumor area. It is often used to treat inaccessible growths like brain tumors. After the scan locates the exact location of cancer, radiation is sent from different angles to target it precisely. It is often called stereotactic radiosurgery because of its highly specific action, almost like surgery. When stereotactic radiotherapy is used outside the brain to treat small, isolated forms of cancer, it is called stereotactic body radiotherapy (SBRT). It is used for certain types of lung and liver tumors. When small doses of stereotactic radiotherapy are administered for several days to weeks, it is called fractionated stereotactic radiotherapy. It is best used to treat meningioma in sensitive areas like the brain stem or optic (eye) nerves.

• Gated Treatment Delivery

  Respiratory gating uses advanced computer software that guides the radiation beam's delivery as the patient breathes. It is used in specific tumors located in the lungs, chest, or abdomen that move during the natural process of respiration. The gating mechanism helps the radiologist to use the window period when the tumor is within a specific targeted treatment field. It improves the accuracy and effectiveness of radiotherapy and minimizes the impact on healthy tissues.

• Volumetric Modulated Arc Therapy (VMAT)

  VMAT is a type of radiotherapy where the linear accelerator delivers the 3-dimensional dose of radiation in a single rotation. Unlike other delivery machines that rotate several times and start and stop periodically throughout the process, VMAT is efficient and faster. A planning session is required before the treatment to ensure precise delivery by properly aligning the linear accelerator with the tumor.

• Deep Inspiration Breath Hold (DIBH)

  Respiratory deep inspiration breath hold is a type of radiation therapy technique that is delivered only at specific points during a patient's breathing cycle of inspiration and expiration. It minimizes the movement of body organs like the heart, stomach, pancreas, and liver, thereby limiting their exposure.