16 Mar, 2026
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16 Mar, 2026
Radiation therapy is a key component of cancer treatment. Radiation therapy controls cancer growth by damaging the DNA structure of cancer cells using high-energy radiation beams. There are various types of radiation therapy depending on where the radiation source is placed, precision, delivery system, number of sessions needed, and other factors.
This article will look at different types of radiation therapy, their procedures, and the malignancies they target.
There are two main types of radiation therapy based on the placement of the radiation source: external beam radiation therapy (EBRT) and internal radiation therapy (brachytherapy).
EBRT and brachytherapy are further classified into several types based on radiation dosage, session frequency, precision, and mechanism of action.
External beam radiation therapy (EBRT) sends high-energy radiation beams to the tumor from a linear accelerator (a radiation source) that is placed outside the body.
During radiation therapy planning, technologists evaluate the position, size, and shape of the tumor. This information is used to calculate the radiation dose, modify radiation beams to match the tumor's morphology, and reduce unnecessary radiation exposure to healthy tissue.
EBRT is administered in multiple sessions. It may be recommended as a stand-alone treatment or in combination with other cancer treatments to improve the overall effectiveness of the treatment.
Cancers Treated with EBRT:
Breast cancer, lung cancer, prostate cancer, head and neck cancers, brain tumors, and colorectal cancer.
3D conformal radiation therapy uses CT (computed tomography) to generate a three-dimensional image of the tumor. Radiation beams are more precise and cause less damage to healthy tissues close to the tumor than traditional radiation therapy because they are tailored to the tumor's exact dimensions and form.
Cancers Treated with 3DCRT:
Brain tumors, lung cancer, prostate cancer, and GI cancers
IMRT is a radiotherapy technique that targets tumors from multiple angles using high-energy radiation beams.
This technology allows radiation oncologists to accurately target cancer cells with higher radiation doses while limiting damage to surrounding tissues and vital organs.
Cancers Treated with IMRT:
Head and neck cancers, prostate cancer, gynecologic cancers, and CNS tumors
VMAT is a type of EBRT that continuously administers radiation beams as the equipment rotates around the patient, and it allows for adjustments to the radiation dosage, beam arrangement, and intensity in real time. This therapy is often opted for tumors with complex structures and close proximity to important organs.
Cancers Treated with VMAT:
Brain and CNS tumors, head and neck cancers, thoracic cancers, abdominal cancers, pelvic cancers, and spinal tumors.
IGRT is a radiotherapy treatment that uses imaging technology like CT scans before or during radiation administration to ensure the tumor is properly positioned.
By accounting for tumor displacement due to respiration, organ motion, or changes in the patient's location between sessions, IGRT helps improve the overall treatment precision.
Cancers Treated with IGRT:
Cancers of the prostate, lung, abdomen, and pelvis
Total body irradiation, a type of external beam radiation therapy, involves the controlled delivery of low doses of radiation throughout the body. It is commonly used as part of a conditioning regimen prior to bone marrow or stem cell transplantation to immunosuppress and eliminate remaining cancer cells.
Cancers Treated with TBI:
Leukemia, lymphoma, and multiple myeloma (as part of pre-stem cell or bone marrow transplant conditioning)
Radiation oncology has made considerable advances over the last two decades. The latest radiotherapy techniques available today have increased precision, requiring fewer therapy sessions or more targeted radiation administration.
These therapies are designed to treat cancers that are difficult to reach or are located near crucial organs. They protect healthy tissues while preventing tumor proliferation.
Stereotactic radiosurgery delivers extremely high radiation doses to specific brain locations during one or more treatment sessions. Despite being referred to as "surgery," no surgical incision is made. Furthermore, the approach limits radiation exposure to surrounding healthy brain tissue.
Cancers Treated with SRS:
Brain cancers, brain metastases, and certain benign brain disorders
SBRT delivers significant radiation doses to malignant tumors located outside the cranial cavity with stereotactic accuracy.
SBRT requires fewer treatments than conventional radiation therapy. It is most suited for treating small, well-defined tumors because it reduces radiation exposure to surrounding organs and tissues.
Cancers Treated with SBRT:
Liver cancers, spinal tumors, adrenal tumors, and early-stage lung cancer
Adaptive radiation therapy is a type of external beam radiation therapy that changes the radiation protocol throughout treatment to accommodate changes in tumor size, shape, and position caused by tumor shrinkage or weight loss.
ART can protect the healthy tissues around the tumor while improving treatment safety and precision.
Cancers Treated with Adaptive Radiation Therapy:
Head and neck cancers, certain cancers of the pelvic region, and thoracic cancers
Unlike conventional X-ray–based radiation therapy, proton therapy uses protons to deliver radiation. Protons deposit the majority of their energy at a defined depth within the body (known as the Bragg peak). This allows for reduced radiation exposure to surrounding healthy tissues and minimal dose beyond the tumor.
Cancers Treated with Proton Therapy:
Brain tumors, spinal tumors, head and neck malignancies, and cancers in children
Intraoperative radiation therapy involves delivering a high dosage of radiation straight to the tumor bed after surgery.
Radiation can be precisely targeted to high-risk locations while minimizing exposure to neighboring organs by physically relocating or protecting healthy tissues.
Cancers Treated with IORT:
Breast cancer, colorectal cancer, and specific pancreatic cancer cases
During internal radiation therapy, a radioactive source is placed inside the body under the supervision of a radiation oncologist. The radiation emitted damages the DNA of cancer cells, impairing their ability to grow and divide.
Because of its narrow range, radiation can successfully target cancer cells in large doses while protecting surrounding healthy tissues and organs.
Cancers Treated with IBRT:
Cervical cancer, endometrial cancer, thyroid cancer, and prostate cancer
Brachytherapy involves placing radioactive sources in human tissues or cavities near the tumor for a short or long time. This allows for more accurate radiation treatment, improving tumor management while reducing radiation exposure to surrounding tissues. Brachytherapy is considered most effective for early-stage small tumors.
Brachytherapy is divided into two types based on its dosage: low-dose rate (LDR) and high-dose rate (HDR).
HDR brachytherapy is the temporary implantation of a radiation source in the body to provide targeted treatment for the tumor.
In contrast, LDR brachytherapy uses low-intensity radiation to treat cancer, with the radiation source remaining within the body or being withdrawn after a set period of time.
Cancers Treated with Brachytherapy:
Cervical, uterine, vaginal, and prostate cancers, as well as some head and neck cancers
Radioactive compounds diffuse throughout the body following intravenous or oral delivery. This approach helps in managing radioactively sensitive tumors by selectively attaching to certain cancer cells and dispersing radiation throughout the body.
Cancers Treated with Systemic Radiation Therapy:
Thyroid carcinoma, certain lymphomas, and metastatic cancers
| Feature | External Radiation Therapy | Internal Radiation Therapy |
|---|---|---|
| Radiation source | Outside the body | Inside or near the tumor, often in the form of seed implants |
| Treatment schedule | Multiple sessions over days or weeks | Single or limited sessions |
| Radiation remains in the body | No | Temporary or limited |
| Precision | High with modern imaging | Highly localized |
| Typical use | Solid tumors | Localized or systemic cancers |
At HCG Cancer Hospitals, we have a dedicated radiation oncology department, which is run by experienced radiation oncologists who deliver precise radiation treatments using high-end technologies and treatment programs that are based on what works best for each patient's type of cancer, stage, and overall health.
Across the network of 20+ comprehensive cancer hospitals, HCG houses highly advanced linear accelerators like CyberKnife, Ethos Adaptive Radiation Therapy, Halcyon Linear Accelerator, TrueBeam, Radixact X9 TomoTherapy, Elekta Versa HD, Elekta Harmony Pro, and more.
Radiation therapy at HCG is combined with other cancer treatments like surgery or systemic therapy to improve the overall effectiveness of the treatment. Patients are encouraged to talk to their care team about their treatment objectives, worries, and hopes so that they can get care that is right for them
