What is Radiation Oncology (Cancer): Medicine, Therapy, Treatment | Narayana Health
Radiation Oncology

Radiation Oncology

Our State-of-the-Art Radiotherapy Department provides a Wide Spectrum of Conventional as well as High Precision Radiation Oncology and Radiotherapy Techniques.

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Radiation Oncology

What is Radiation Oncology?

Radiation oncology is a medical discipline that deals with the use of radiation to treat cancer. In India, every day it is estimated that 1,300 Indians die due to cancer. People of all ages face the risk of cancer, and pollution and modern lifestyle has increased cancer incidence. Radiotherapy is one of the common treatments for cancer and a qualified radiation oncologist is the one who administers this treatment.

Radiation therapy or radiotherapy uses different types of radiation like X-rays and high energy beams to target cancer cells and kill them. Radiotherapy for cancer may be used as a stand alone treatment or may be used along with other treatment options like chemotherapy and surgery.

A radiation oncologist is a specialist who has undergone a course and knows how to use the power of radiation to treat cancer. All hospitals that provide cancer treatment would have a radiation oncologist to manage the treatment of different types of cancers that call for the use of radiation oncology.

Why NH?

The Department of Radiation Oncology at Narayana Health's group hospitals provides patient-centric, state-of-the-art Radiotherapy treatment of international standards. Narayana Health is equipped with a wide spectrum of conventional as well as high precision Radiation Oncology facilities and radiotherapy techniques such as-

  • IGRT
  • IMRT
  • SRS
  • SRT
  • VMAT
  • Brachytherapy


  • High-quality, experienced, compassionate multidisciplinary care.
  • Personalized treatment plans that consider our patient’s health, age, cancer type and ability to tolerate potential side effects.
  • Leading-edge technology that delivers radiation with maximum precision, reducing treatment time.

Radiation therapy – overview

Radiation therapy is a cancer treatment that uses high energy beams to kill cancer cells. X-rays, proton beams, and other forms of energy are used in this treatment. A trained radiation oncologist would administer this treatment.

The problem with cancer is that it spreads fast and it spreads across the body affecting various organs. When radiation is directed on the cancer cells, it breaks the DNA inside the cell. This ensures the cell does not grow and divide, as a result, the cancer cell dies. It must be noted that radiation cannot distinguish between healthy and cancerous cells. All cells in the area targeted would die. This is the reason why cancer treatments like radiotherapy and chemotherapy cause side effects. Healthy cells would grow again, whereas cancer cells are unlikely to grow back.

Radiation therapy is a targeted treatment. While chemotherapy uses drugs that can expose the entire body to side effects, radiotherapy is focused only on a particular area. This minimizes death of healthy cells and reduces side effects.

Almost 50% of all cancer patients would need radiation therapy to treat cancer. It can be given along with chemotherapy. When cancer cells cannot be removed completely through surgery, radiation therapy is also used. The decision on using this treatment is taken by the treating oncologist along with the radiation oncologist. It’s decided based on the extent of cancer, type of cancer, and the overall health of the patient.

One more issue to note is that radiation therapy cannot reach all parts of the body. Its goals may not be to destroy all cancer cells, but to reduce the size of cancer cells, when the tumor has grown large. This helps remove the reduced tumor during surgery. In some cases, radiation is used after surgery to ensure cancer cells do not grow back.


There are two types of radiation therapy. They are:

1.External beam radiation:

As the name suggests, here the radiation beams are directed externally, i.e, from a source outside the body. The equipment used to deliver the radiation will be directed at the target area (that is decided by the radiation oncologist in advance). The area to be targeted, the type of radiation to be used, and the extent of radiation are decided based on the individual case history. Some of the equipment used for external beam radiation are:

  • X-ray machines.
  • Proton beam machines.
  • Cobalt-60 machines.
  • Neutron beam machines.
  • Linear accelerator.
  • Gamma knife.

External radiation is painless. It is usually an outpatient treatment and the patient can leave once the session is complete. Multiple sessions would be needed to complete treatment.

The radiation used may be high energy, if the cancer cells are deep. When cancer cells are located on the surface, then low energy beams are used. This kind of an application of radiotherapy needs expertise, which is why a radiation oncologist supervises the entire process.

A form of external beam radiation is stereotactic therapy. This works on the principle of using a very high beam of energy that is focused on a very small area on the body. It also involves targeting a tumor from multiple angles. The advantage of this therapy is that the tumor is completely targeted from all sides in a concentrated way. This ensures the tumor is destroyed. At the same time, it avoids targeting healthy cells and thus minimizes the side effects of radiotherapy.

The gamma knife is a tool used in external radiation therapy. It can be used to treat brain tumors without making any surgical incision. It uses Cobalt-60 radiation that delivers targeted radiation of the affected cells to destroy it. No healthy cells are damaged.

2.Internal Radiation Therapy:

This is also known as brachytherapy. Unlike external therapy, radiation is not delivered in the form of beams. Instead, the radiation source is placed internally near the tumor where it delivers radiation at close range and destroys the tumor. It is very helpful in treating cancers of the neck, cervix, vagina, eye, and rectum. Wires that are radioactive may be placed inside the body using the applicator. This would ensure the affected area gets radiation internally to destroy cancer cells.

The applicator is a metal or plastic device inserted internally and is suitable for use in body cavities. The applicator is left in the body until the treatment is complete, after which the radiation oncologist removes it from the body. Internal radiation may also be delivered through intravenous mode. Small molecules would have radioactive particles attached to it and these are delivered intravenously. When internal radiation is used, the oncologist needs to monitor the patient regularly to find out if any radioactive particles are remaining after completion of treatment.

The Process Behind Radiation Oncology

Radiation oncology is administered by a team of trained professionals under the supervision of a radiation oncologist. The oncologist is a doctor who is overall in-charge of managing the treatment. The doctor decides on the type of radiation therapy to be used, dosage, and other such parameters. The radiation physicist is a technician who actually operates the equipment and delivers radiation to the patient.

A dosimetrist is the person responsible for calculating the dosage of radiation and monitoring it to ensure the right dose is given. The radiation therapist helps the patient through the therapy ensuring the patient is in the right position to receive radiation. A nurse would also be available for assisting the doctor. Radiation oncology also uses the assistance of a dietitian to help the patient plan a healthy diet during and after treatment.

There are different types of radiation. The type used in radiation oncology is known as ionizing radiation. This is because the radiation forms ions, or charged particles in the cells, in which it enters. These ions would be formed by taking out electrons from atoms. This causes changes in the DNA and kills the cells. From these ionizing radiations, x-rays and gamma rays are called photon radiation. When electrons, protons, beta particles, or carbon ions are used, the radiation is called particle radiation. The type of radiation depends on the cancer type and stage.

Radiation Oncology

What is the scope of radiation oncology?

Radiation oncology has a wide scope and includes the use of radiation for the treatment of cancer. It uses radiotherapy in conjunction with chemotherapy to ensure treatment.

Does radiation therapy cause cancer?

A fear most people have is that radiation therapy can itself cause cancer. It is true that increased exposure to radiation increases the risk of cancer. This is something the oncologist considered while planning the treatment. Adequate safety precautions are used to prevent unnecessary exposure to radiation. There is a risk of a second cancer developing due to the treatment but the benefits radiotherapy offers is more than this risk. The radiation oncologist would help a patient make an informed decision.

Can radiation therapy affect fertility?

A concern patients would have is whether radiation would affect fertility and their ability to become parents in the future. In females, if the radiation is used to treat ovary cancers, and there is a high risk of causing sterility. Radiation used on other parts of the body is unlikely to affect the reproductive system. However, pregnant women must not undergo radiation therapy as it can harm the baby. In males, if radiation is directed on the testicles then the man can become sterile, else it is unlikely to cause any problems.

What are the side effects of radiation therapy?

Radiation therapy is usually targeted at cancer cells but it is possible that healthy cells may be affected causing side effects. It can heat up the area targeted causing irritation to the skin; a sunburn like reaction may be observed. This can be treated through lotions, nausea is possible when radiation is used on the abdomen. Difficulty swallowing is a side effect when radiotherapy is used on the mouth and neck. Its side effects depend on the area, and they are not as severe as chemotherapy.

What is radiation oncology like?

Radiation oncology is a medical speciality that uses high-energy radiation to damage the DNA of cancer cells and prevent them from dividing and growing. Radiation therapy or radiotherapy is the term used to describe the actual treatment provided to the cancer patient by the radiation oncology team. The treatment may be delivered using linear accelerators or by placing radioactive sources inside the patient either temporarily or permanently.

What are the techniques involved in radiation therapy?

Some of the techniques used in radiation therapy to ensure effective treatment are as follows.

  • Intensity-modulated radiation therapy or IMRT precisely directs the dose to the tumours, making it safe to deliver high doses of radiation.
  • Stereotactic radiosurgery uses three-dimensional imaging to find out the exact location of a tumour and then converge highly focused gamma rays or x-rays on it.
  • The Gamma Knife is a treatment option that focuses on multiple beams of radiation on a small area using radioactive cobalt sources.
  • Image-guided radiation therapy or IGRT may also be used along with IMRT to focus the radiation on the exact planned area.
  • In radioembolization, microspheres of radioactive isotopes are used to block blood supply to the tumour and starve it.

What are the side effects of radiation therapy?

Radiation therapy is a local treatment and is directed only on the area where the tumour is located. Common side effects of radiation therapy include:

  • Skin problems: After radiation therapy, some people tend to experience dryness, itching, blistering, or peeling. These problems usually go away on their own after a few weeks of treatment. However, the treatment plan may be altered if the skin problems become serious.
  • Fatigue: The level of fatigue one feels depends on their treatment plan. For example, they are likely to feel more exhausted if radiation therapy is given in combination with chemotherapy.
  • Long-term side effects: Although most side effects subside after treatment, some can come back or develop later. Second cancer is one example of such late effects. It might develop due to the original cancer treatment, and the risk is quite small compared to the benefit of treating existing cancer.

How is radiation therapy used in cancer care?

Radiation oncologists may either use the brachytherapy method or external beam radiation therapy for the treatment of cancer. In brachytherapy, radioactive sources are placed in the patient, whereas the external beam radiation therapy uses a linear accelerator machine to produce x-rays or gamma rays. Proton therapy is another way of cancer care, which uses cyclotrons or synchrotrons to produce charged atoms to destroy tumours.

Radiation therapy given before other primary treatment is called neoadjuvant treatment. If it is given after the primary surgery, it is called adjuvant treatment.

How radiation is used with other cancer treatments?

In some individuals, radiation is the only possible course of treatment. However, for most cases, radiation therapy is given in conjunction with other cancer treatments like chemotherapy, immunotherapy and surgery. It may also be given before, during or after other treatments to improve the chances of success of treatment. The timing of giving radiation therapy is decided based on the type of cancer being treated as well as on the goal of treating cancer or alleviating the symptoms.

Radiation therapy can be given:

  • Before surgery to reduce the size of the cancerous tumour so that it is easier to remove it by surgical methods.
  • During surgery to act directly on the cancerous tumour without having to go through the skin. This method of giving radiation therapy is called intraoperative radiation. This allows doctors to prevent the radiation from affecting the surrounding normal tissues.
  • After surgery to kill the remaining cancer cells.