Radiotherapy | Radiation Therapy for Cancer | How Does It Work?

Radiotherapy | Radiation Therapy for Cancer | How Does It Work?


Radiation therapy or radiotherapy is a type of cancer treatment that uses powerful energy beams to kill cancer cells. Radiation therapy most often uses X-rays, but protons or other types of energy can also be used.

This is energy that moves in space. Radiation can be emitted naturally, such as from the sun, and in low doses, such as from soil and rock or it can also be produced artificially by devices. Low-dose radiation is used, among other things, for radiological examinations (X-rays), which provide images of the interior of the body.

When it comes to treating cancer, much higher doses of radiation are used to destroy cancer cells. Radiation therapy damages cancer cells many times. Not having time to regenerate between daily treatment sessions, cancer cells eventually die.

How radiation therapy works

Radiation therapy destroys cancer cells and damages their DNA, preventing them from growing and dividing. Radiation therapy can reduce the size of a tumor or destroy it completely. It is most effective against rapidly growing and dividing cells. Cancer cells tend to divide faster than most normal cells.

This makes them more vulnerable to the effects of radiation, or radiosensitive, than normal cells.

Although cancer cells and normal cells react differently to radiation, it is very difficult to destroy cancer cells without damaging some normal cells. Damage to normal cells causes side effects. Normal cells are often able to recover from radiation damage better than cancer cells. The goal of radiation therapy is to give a dose of radiation sufficient to destroy all cancer cells but not too high to prevent normal cells from recovering.

Radiotherapy process

The way radiotherapy sessions are conducted can vary depending on the type and stage of cancer, as well as the specific treatment plan developed by the healthcare team.

However, there are some general steps that are typically followed during a radiotherapy session:


Before beginning radiotherapy, the healthcare team will conduct a planning session to determine the appropriate dosage and target area for the radiation. This may involve taking scans, such as CT or MRI scans, to get a detailed picture of the cancerous area.


During the preparation stage, the patient may need to fast or drink a special contrast dye to help make the cancerous area more visible during the radiation treatment. The patient will also typically lie down on a table in the radiation therapy room, and the healthcare team will position them precisely using special marks on their skin or a special device that helps align the patient in the correct position.


Once the patient is properly positioned, the healthcare team will start the radiation treatment. The patient will be alone in the room during the treatment, but the healthcare team will be able to monitor them from outside through a window or a camera. The radiation machine will move around the patient, delivering the radiation to the targeted area.


After the radiation treatment, the healthcare team will continue to monitor the patient’s progress to assess the effectiveness of the treatment and ensure there are no complications. Follow-up appointments may be scheduled to monitor the patient’s recovery and make adjustments to the treatment plan as needed.

Overall, radiotherapy sessions are designed to be as safe and effective as possible while minimizing the risk of side effects or complications. It is important for patients to work closely with their healthcare team to understand what to expect during the treatment process and to ask any questions they may have.

How radiation therapy is used

Radiation therapy may only be given to treat cancer, or it may be combined with other treatments such as surgery and chemotherapy. It can be used before surgery to reduce the size of the tumor or after to destroy any remaining cancer cells to prevent the cancer from coming back. Radiation therapy can also help relieve symptoms, improve quality of life, and extend the life of people with advanced cancer, called palliative radiation therapy.

External beam radiation therapy is the most common type of radiation therapy used to treat cancer. A device emits a beam of radiation towards the cancerous tumor. There are different types of external beam radiation therapy.

In internal radiation therapy, radioactive substances are put into the body, such as directly into the tumor or inside a particular area, to destroy cancer cells. There are different types of internal radiation therapy.


The total radiation dose as well as the number of treatment sessions and their duration depend on the following factors:

  • type of cancer
  • how sensitive the tumor is to radiation therapy (radiosensitivity)
  • tumor size
  • tumor location
  • stage of cancer
  • amount of tissue to be irradiated
  • ability of normal tissue around the tumor to tolerate radiation
  • previous or future administration of other treatments
  • overall health

Many areas of the body can only tolerate a certain amount of radiation over a lifetime (maximum dose). The maximum dose of radiation depends on the area of ​​the body being treated. Doctors take the maximum dose into consideration when planning treatment. Once an area of ​​the body has received the maximum dose, it may not be able to receive further radiation therapy later. So having previously been treated with radiation therapy may limit the amount of radiation you could ever safely receive in the same area.

Types of Radiotherapy

There are 3 general types of radiation therapy:

1. External Radiation: External Beam Radiotherapy (EBRT)

This type of radiation can destroy almost all types of cancer and can be treated on an outpatient basis (no need for hospitalization). Can also be used to relieve pain and other disorders commonly experienced by cancer patients who have metastasized (spread).

Patients, sometimes given at the same time as surgery / surgery, if the cancer has not spread but cannot be completely removed, or if there is concern that it will grow again in the vicinity. The procedure is carried out after the main cancer tissue is removed, before the surgical wound is closed again where the cancer was irradiated. This method, called intraoperative radiation therapy (IORT), is mainly used in cancers of the colon, thyroid, pancreas, and uterus (including the ovaries, cervix, cervix, and surrounding areas).

External radiation is also given as a preventative (prophylactic cranial irradiation, PCI), for example in lung cancer patients the radiation is directed to the brain so that cancer cells do not spread to the brain.

External radiation therapy does not make the patient radioactive (emit radiation to the surroundings). So it is harmless to the people around him.

  • How it works: Radiation is delivered from an external machine directed precisely at the tumor site.
  • Example: Intensity-Modulated Radiation Therapy (IMRT) precisely adjusts the intensity of the radiation beams, minimizing damage to surrounding healthy tissues.
2. Internal or local radiation (Brachytherapy): Internal Beam Radiotherapy

The radiation source is in the form of an implant in the form of a cable, tape, capsule, catheter, or small pellet containing the radioactive isotope iodine, strontium 89, phosphorus, cesium, palladium, iridium, phosphate or cobalt, which is implanted right in the cancer tissue or nearby. This method is more effective in killing cancer cells while minimizing damage to healthy tissue around the radiation target.

Internal radiation is often used to treat cancers in the head and neck area, thyroid, prostate, cervix, uterus, breast, around the groin and in the urinary tract.

Some of these radioactive implants are implanted for only a few minutes (with high doses), some are for several days (with low doses), some are left in the body without being removed again.

The simplest example of Bachytheraphy is the use of Radioactive Patches / Patches to remove Keloids or Scars on the outer skin. Patch size and Radiation Level are predetermined and vary for people who have multiple Keloids and/or Scars on their bodies. Healing can reach 100% or at least almost disappear within the treatment period of 4-11 months.

  • How it works: Radioactive sources are placed directly inside or very close to the tumor.
  • Example: Prostate cancer patients may undergo brachytherapy where radioactive seeds are implanted within the prostate gland.
3. Systemic Radiation

In this type, radioactive material as a radiation source is swallowed like a drug or injected, which then follows the bloodstream throughout the body. This type is commonly used to treat thyroid cancer and non-Hodgkin’s lymphoma.

The remnants of unused radioactive material out of the body through saliva, sweat and urine. Within a certain period of time this liquid is radioactive, but after that it is no longer. That is why patients undergoing systemic radiation need to be hospitalized.

  • How it works: Radioactive substances are introduced into the bloodstream, targeting cancer cells throughout the body.
  • Example: Radioactive iodine therapy is used for thyroid cancer, where the thyroid absorbs the radioactive iodine, selectively destroying thyroid cells.
4. Proton Beam Therapy

This innovative form of radiotherapy uses protons, positively charged particles, to deliver radiation with exceptional precision. Protons deposit most of their energy at the end of their path, limiting damage to healthy tissues beyond the tumor.

  • How it works: Unlike traditional radiotherapy that employs X-rays, Proton Beam Therapy utilizes protons to target cancer cells.
  • Example: Brain tumors situated near vital structures can be treated with heightened accuracy, reducing the risk of damage to adjacent healthy tissues.
  • Example: Children with certain types of cancers, such as brain tumors or sarcomas, may benefit from reduced long-term side effects.

Taking care of yourself during radiotherapy

Radiation therapy will likely affect your daily life as well as that of your family. It is important that you take good care of yourself during treatment. You may experience the general side effects of radiation therapy as well as other effects depending on the part of your body that will be treated. Here are some general tips that may help you feel better during radiation therapy.

1. Get lots of rest

Radiation therapy can make you more tired than usual. Try to get enough sleep at night. Being active when you can can help you sleep better. Ask for help when you need it, and try to focus on the things that matter most. Plan a time to rest during the day. To feel more energetic, you can take a short nap, read, or listen to music.

2. Eat well

Your body needs nutrients to repair itself from the effects of radiation therapy. If the radiation therapy is directed to certain parts of your body, such as your abdomen or your head and neck, it may affect your ability to eat well. Your healthcare team may suggest dietary changes that will help you cope with the side effects of radiation therapy. Find out more about nutrition for people with cancer.

3. Report any side effects to your healthcare team

Talk to your healthcare team about any side effects you experience. Everyone can experience the side effects of treatment differently. Many side effects can be relieved by taking medications, making a change in diet, or becoming more physically active. Radiation therapy may need to be adjusted if the side effects are severe.

4. Tell your healthcare team about other medications you are taking

Other drugs, such as creams, ointments, vitamin or mineral supplements, as well as herbal remedies and natural health products, can affect the effectiveness of radiation therapy. They can also cause side effects or make some effects worse. Talk to your doctor about any medicine you are taking.

5. Take care of your skin

The skin can be very sensitive to radiation therapy. Be gentle with your skin and take care of it during radiation therapy. Talk to your radiation therapy team about any symptoms or problems you are having. She can give you advice on how to take care of your skin during treatment.

This allows you to take care of your skin during radiation therapy.
  • Gently wash your skin in lukewarm water with a mild soap and rinse it well. Do not rub it. Pat it dry. Do not use a blow dryer if you are receiving radiation therapy to the head.
  • Protect the treated area from friction, pressure and irritation by wearing loose, soft clothing where it comes in contact with the skin. Cotton and silk are less irritating to irradiated skin than rougher fabrics, such as wool and denim.
  • Before using any product, ask your radiation therapy team if it is suitable for the skin being treated. Powders, creams, perfumes, deodorants, body oils, ointments or lotions can irritate the skin or affect your response to radiation therapy.
  • Ask your radiation therapy team if you can shave the treated area. Use an electric razor rather than a razor with blades to avoid cutting yourself. Do not use aftershave or hair removal product on the treated area.
  • Do not wear a bra if your breast is in the treatment area. If that’s too uncomfortable, check with your radiation therapy team about the options, who may suggest that you wear a soft, comfortable non-wired bra.
  • Do not apply anything hot or cold to the treated area, such as a heating pad or an ice pack.
  • Don’t pinch or scratch your pimples.
  • Do not wash or rub any marks on the skin that is used to target radiation therapy until the last treatment session.
  • Rinse well after swimming in a swimming pool since chlorine can dry out the skin.
  • Protect the treated skin from the sun. The skin in the treated area is very sensitive to sunlight and can burn easily.
  • Cover the treated area with a hat or clothing before going outside. Ask your radiation therapy team if and when you can use sunscreen.
  • Tell your radiation therapy team if the treated area has been cut or scratched. You will be told how to treat cuts and scrapes and how to apply a bandage, if necessary, such as using a sensitive skin bandage or applying it to outside of the treated area.
6. Oral hygiene

Radiation therapy to the head and neck can increase the risk of tooth decay. It can also increase the risk of infection or bleeding during dental work. If you are going to receive radiation therapy to your head and neck, see a dentist before treatment. He will perform a complete oral examination and perform any necessary preventive dental work. They can also suggest ways to help prevent or manage mouth, teeth and jaw problems caused by radiation therapy or other treatments.

Does radiation therapy affect diet?

Some cancer treatments can cause difficulty eating and digesting normally as side effects. Common side effects include taste changes, dry mouth, sore mouth, thick saliva, nausea, vomiting, diarrhea, constipation, weight loss, loss of appetite and weight gain .

It is very important to follow dietary therapy during treatment. This therapy may include the following:

  • A diet based on cooked foods, as raw fruits and vegetables can contain harmful bacteria;
  • Food safety instructions to follow;
  • A diet adapted to the type of transplant and where the body is affected by cancer;
  • Parenteral nutrition during the first few weeks of the transplant, in order to obtain enough calories, fluids, protein, minerals and vitamins necessary for recovery.
Remember these tips:
  • Try to eat something an hour before treatment instead of starting radiation therapy on an empty stomach, unless your doctor has instructed you otherwise.
  • Make sure you drink regularly while eating, especially when the food does not taste like you, when it hurts when you swallow it, or when you have diarrhea.
  • Try to eat small, frequent meals rather than three large meals. If you have a better appetite at certain times of the day, eat your larger meals at these times.
  • Be sure to drink plenty of water and other fluids (not too hot).
  • Patients receiving a high dose of radiation therapy in preparation for a bone marrow transplant may experience many dietary problems and should consult a dietitian to arrange dietary follow-up. They may need to undergo food therapy.

Patient support

The entire treatment is difficult on the patient, both physically and emotionally. It is very important that they receive optimal nursing and medical care, as well as special attention and support.

While in hospital, it is possible to be assisted by a psychologist, social worker or spiritual advisor. The attending physician can advise patients on the possibilities of supervision and support that exist outside hospitals.

Types of Cancer Treatments and Medications: Comprehensive Overview of How They Work

Side effects of radiation therapy

Radiation therapy damages cancer cells, but it can also damage healthy cells in the treatment area. Damage to healthy cells causes side effects. The side effects depend on the part of the body that is receiving the radiation therapy. Different tissues and cells in the body tolerate radiation differently. The cells that are most affected are those that divide rapidly, such as skin cells, cells that line the mouth and digestive tract (gastrointestinal tract, or GI), and blood cells in the bone marrow.

Side effects can happen anytime during radiation therapy, right after, or a few days or even weeks later. Most usually go away a few weeks to 2 months after treatment. But there are some that are likely to persist since healthy cells take time to recover from radiation therapy. Sometimes side effects may appear months or years after treatment (late effects). If the radiation doses are high enough, some cells may not be able to repair themselves. Side effects may therefore last a long time or be permanent.

In general, the side effects of radiation therapy depend on the following:

  • the type of radiation therapy;
  • the part of the body being treated;
  • the amount (dose) of radiation and the method of administration;
  • overall health status.

General side effects of radiation therapy

Fatigue is one of the most common side effects of radiation therapy. It usually appears after a few weeks of radiation therapy and may get worse with treatment. It can be caused by a number of things. During radiation therapy, the body uses more energy to heal itself. Fatigue is more common when treating large areas of the body. Anemia can occur when radiation therapy is directed to areas of the body where there is bone marrow, such as the pelvis. Anemia can cause fatigue. Eating or sleeping disorders can increase fatigue. Changes to your schedule, such as daily trips to the hospital, can also cause fatigue. Fatigue usually goes away gradually after radiation therapy is finished, but some people continue to feel tired for weeks or months after this treatment.

Skin problems

Skin problems are common with external beam radiation therapy since the radiation travels through the skin to the area targeted by the treatment. The skin in the irradiated area may turn red, dry, or itchy. It may change color (become darker or take on a tanned appearance). Most skin reactions occur within the first 2 weeks of radiation therapy. They usually go away a few weeks after treatment, but some skin changes, such as browning of the skin or scar tissue formation, may be permanent. There are people who do not have a skin reaction.

Hair loss

Hair loss or hair loss (alopecia) or thinning occurs only in the area treated with radiation therapy. The extent of loss and regrowth varies from person to person and depends on the dose of radiation administered. Hair loss or hair loss can start after 2 to 3 weeks of radiation therapy. Small doses of radiation usually cause temporary loss, while permanent loss is more common with high doses. When the hair or hair grows back, usually 3 to 6 months after radiation therapy, it may be different in color or texture and it may be thinner or grow back in patches.

Loss of appetite

Loss of appetite may appear during the first weeks of radiation therapy and continue after treatment. Side effects such as pain in the mouth, dry mouth, difficulty swallowing, or nausea and vomiting can cause loss of appetite. Radiation therapy to the head and neck can temporarily cause changes in taste or smell, which can make food less appetizing. Some people are no longer interested in food at all and don’t eat, even though they know they have to. Eating well during and after radiation therapy is important for a person to recover from treatment..

Nausea and vomiting

Nausea and vomiting can be a common side effect of external beam radiation therapy, especially if the treatment area includes the stomach and abdomen. They can also occur as a general side effect regardless of the area being treated. These symptoms, called radiation sickness, usually go away only a few weeks after radiotherapy.

Low numbers of blood cells

There are low numbers of blood cells because the radiation affects the blood cells made in the bone marrow. This side effect is more common when chemotherapy is given at the same time as radiation therapy or if the treatment area includes the bones of the pelvis, where many blood cells are made. Usually, the drop in the number of blood cells is not severe enough to cause problems. The values ​​usually return to normal after a few days of treatment break.

Side effects of radiation therapy to the brain

Stereotaxic radiosurgery (SCR) directs a large dose of radiation to a small area of ​​the brain. Side effects depend on the area where the radiation therapy is given. Sometimes the whole brain is treated with radiation therapy, although the doses are often lower. Giving large doses of radiation therapy to the brain is more likely to cause long-term problems. In children, the younger they are, the more sensitive the brain cells are to the side effects of radiation.

Side effects of radiation therapy to the brain can be the following:
  • skin problems;
  • hair loss and hair loss;
  • swelling of the brain (intracranial hypertension);
  • epileptic seizures;
  • earache or difficulty hearing if the ear is in the treatment area;
  • headache;
  • nausea and vomiting;
  • loss of appetite;
  • cognitive problems, such as memory and speech problems;
  • extreme fatigue (sometimes called drowsiness syndrome);
  • damage to the nerves if radiation therapy causes damage to the cranial nerves, causing changes in vision, hearing problems, or weakness of the face, tongue, neck or shoulder;
  • hormonal disorders – low hormone levels may be a late effect of radiation therapy to the hypothalamus, pituitary or thyroid gland.

Side effects of radiation therapy to the head and neck

Radiation therapy can irritate the mucous membranes that line the mouth, throat and upper esophagus. It can also affect other structures in the treatment area.

Side effects of radiation therapy to the head and neck may be the following:
  • skin problems;
  • hair loss and hair loss;
  • pain in the mouth;
  • dry mouth;
  • taste changes;
  • difficulty swallowing;
  • earache or difficulty hearing if the ear is in the treatment area;
  • voice changes, such as a hoarse voice, if the larynx is in the treatment area;
  • changes in vision if radiation therapy damages blood vessels in the eye or the optic nerve;
  • dry eyes and loss of vision if the treatment area includes the eyes;
  • stiff jaw (trismus) if the treatment area includes the jawbone;
  • loss of appetite;
  • dental problems, such as cavities;
  • nausea and vomiting;
  • hormonal disorders – low hormone levels may be a late effect of radiation therapy to the hypothalamus, pituitary or thyroid gland;
  • damage to the nerves if radiation therapy causes damage to the cranial nerves, causing changes in vision, hearing problems, or weakness of the face, tongue, neck or shoulder;
  • bone death (osteoradionecrosis). It is a condition in which bones are weakened due to the loss of blood flow. With limited blood flow, bones begin to break down and eventually die.

Side effects of radiation therapy to the chest

Radiation therapy given to treat lymphoma or cancer of the lung, esophagus, spinal cord or breast is often directed to structures within the chest. Radiation therapy to the upper chest can irritate the throat and esophagus.

Side effects of radiotherapy to the chest may be the following:
  • skin problems;
  • hair loss and hair loss;
  • sore throat;
  • difficulty swallowing;
  • stomach pains;
  • hoarse voice if the larynx is in the treatment area;
  • nausea and vomiting if the treatment area is near the stomach;
  • taste changes;
  • loss of appetite;
  • cough;
  • radiation lung;
  • tenderness or swelling of the breast;
  • scar tissue in the lungs (pulmonary fibrosis);
  • heart problems such as irregular heartbeat, congestive heart failure or coronary artery disease.

Side effects of radiation therapy to the abdomen

Radiation therapy given to the upper abdomen can irritate the esophagus and stomach. Radiation therapy given to the lower abdomen is more likely to irritate the small and large intestines. People are more likely to experience side effects if a large part of their abdomen is treated.

Side effects of radiation therapy to the abdomen can be the following:
  • skin problems;
  • hair loss and hair loss;
  • nausea and vomiting;
  • difficulty digesting;
  • bloating;
  • loss of appetite;
  • diarrhea;
  • stomach ulcers;
  • radiation enteritis;
  • kidney problems.

Side effects of radiotherapy to the pelvis

Radiation therapy given to the pelvis can irritate the large and small intestines and cause digestive problems. It can also irritate the bladder and affect the reproductive organs.

Side effects of radiotherapy to the pelvis can be the following:
  • skin problems;
  • hair loss and hair loss;
  • diarrhea;
  • nausea and vomiting;
  • bleeding from the rectum;
  • inflammation of the rectum or anus;
  • pain when you have a bowel movement;
  • loss of bowel control (incontinence);
  • radiation enteritis;
  • bladder infection (cystitis);
  • burning sensation or pain when urinating;
  • blood in the urine;
  • urgent need to urinate;
  • loss of bladder control (urinary incontinence);
  • fertility disorders;
  • sexual disorders in women;
  • sexual problems in men, including erectile dysfunction.

Late side effects

Sometimes side effects appear long after treatment. These are late effects. They can vary depending on where on the body that received the radiation therapy. Here are some possible late effects:

  • fertility problems (if you have received radiation therapy to the pelvis);
  • heart problems (if you have received radiation therapy to the chest);
  • lung problems (if you have received radiation therapy to the chest);
  • changes in skin color;
  • mental or emotional problems (if you have had radiation therapy to the head and neck or brain);
  • secondary cancers.

Conclusion: A Beacon of Hope in the Fight Against Cancer

Radiotherapy has emerged as a cornerstone of cancer treatment, offering a precise and effective approach to eradicating malignant cells. With its continuous advancements and the development of new techniques, radiotherapy holds immense promise for further improving cancer outcomes and extending lives. As we continue to unravel the mysteries of cancer biology and refine our therapeutic strategies, radiotherapy will remain a powerful weapon in our arsenal, offering hope and healing to those battling this formidable disease

List of all Cancers

The word “cancer” is a generic term for a large group of diseases that can affect any part of the body. We also speak of malignant tumors or neoplasms. One of the hallmarks of cancer is the rapid multiplication of abnormal growing cells, which can invade nearby parts of the body and then migrate to other organs. This is called metastasis, which is the main cause of death from cancer. Types of cancer (in alphabetical order of the area concerned):

Types of Cancer | List all of Cancers | Adult, Children, Head and neck, Digestive and Types of Blood Cancer

Information: Cleverly Smart is not a substitute for a doctor. Always consult a doctor to treat your health condition.

Sources: PinterPandai, National Cancer Institute, Mayo Clinic

Photo credit: Jakembradford / Wikimedia Commons

Photo description: radiation therapy for Hodgkin’s Lymphoma in HD Versa.

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