Radiotherapy: Radiation to destroy malignant cells
Medical technology is rapidly advancing. In modern times, we have the ability to treat cancer and other conditions with radiotherapy. During radiotherapy, beams of radiation target and destroy malignant cells in a localized area. The types of radiation, its side effects, and safety measures are integral components of radiotherapy treatment.
What is Radiotherapy?
Radiotherapy, also known as radiation therapy, applies high energy x-rays, gamma rays, electron beams, or protons to destroy cells in a localized area. It is ideal for treating cancer and non-cancerous growths, as well as to reduce inflammatory processes in the body. The patient receiving treatment lies beneath a machine that delivers radiation to the targeted cells.
There are two types of radiation—ionizing radiation and non-ionizing radiation. Ionizing radiation has a powerful effect on atomic structure, which is the smallest unit of matter. It is strong enough to remove an electron from the nucleus of an atom. Non-ionizing radiation, however, is weaker. While ionizing radiation can still cause damage, it cannot deconstruct an atom. Cell phones, TV, computers, radio waves, and microwaves are examples. It uses ionizing radiation.
Radiotherapy as Cancer Treatment
Cancer is the uncontrolled growth of abnormal cells in the body. These cells clump together to form a tumor, which is a mass of tissue. It is a common treatment for this condition.
The goal is to eradicate or damage cancer cells by targeting beams of radiation at the tumor site. As the DNA is damaged, cells stop multiplying and spreading (metastasizing) to surrounding tissues. Tumors then shrink and the progression of the disease is slowed. Radiotherapy for cancer treatment occurs over a series of weeks, but cancer cells continue to die for months after the therapy is discontinued. It is often practiced in conjunction with chemotherapy, surgery, or immunosuppressive agents.
Other Conditions Treated by Radiotherapy
Cancer and malignant tumors are not the only condition physicians treat with radiotherapy. It is an important part of treatment for a variety of pain disorders, hyperproliferative disorders, and degenerative joint conditions. Below are the most prevalent non-cancerous conditions treated with radiotherapy.
Benign tumors are non-cancerous growths in the body. They differ from cancer in the fact that they do not metastasize or spread to surrounding tissues. Still, benign tumors cause many of the same symptoms as cancerous tumors. Radiotherapy for benign tumors directs radiation at the source of the tumor to shrink its size and reduces symptoms.
Trigeminal neuralgia is a chronic pain condition of the trigeminal nerve. The trigeminal nerve carries sensations from the face to the brain. In trigeminal neuralgia, this nerve is overstimulated to cause intense episodes of pain by seemingly insignificant tasks such as brushing your teeth, a slight touch, or applying makeup. It targets the trigeminal nerve, damaging it to prevent pain signals.
Arteriovenous malformations are non-cancerous congenital entanglements of the blood vessels that connect the arteries and veins in the brain or spinal cord. It is often a successful treatment for arteriovenous malformations. The beams of radiation focus on the abnormal tangle of vessels to restore blood flow and prevent bleeding, seizures, headaches, and stroke symptoms.
The thyroid is a butterfly-shaped gland that secretes hormones. Radiotherapy targets cancer of the thyroid gland, but it also treats chronic thyroid disease. An oral pill form of radiation called radioactive iodine is a long-term solution because it destroys the entire gland.
Certain blood disorders involve radiotherapy in their treatment. Aplastic anemia occurs when the bone marrow fails to produce blood cells. Similarly, myelodysplastic syndrome results in deformed and underdeveloped blood cells. Both are blood disorders in which radiotherapy is used to deplete the diseased bone marrow before a stem cell transplant in severe cases.
External Beam Radiotherapy
External beam radiotherapy is the most prevalent form of radiation therapy. Radiation beams are delivered outside of the body through a linear accelerator—a specialized machine that sends radiation to a targeted site. No sources of radiation are inside the patient’s body. External beam radiotherapy has three types.
Three-dimensional Conformal Radiotherapy (3D-CRT)
3D conformal radiotherapy treats tumors near vital organs. Through detailed 3D images of cancer, higher doses of radiation target the site without compromising healthy tissue.
Intensity Modulated Radiotherapy (IMRT)
Intensity-modulated radiotherapy applies the concepts of 3D conformal radiotherapy, but with increased efficiency. Its radiation beams are at varying intensities. To spare healthy tissues, intensity-modulated radiotherapy reduces the tissue dose to tumor dose ratio. Since radiation beams are administered in multiple small volumes, treatment time is longer.
Proton Beam Therapy
Instead of x-rays, proton beam therapy positively charged particles (protons) to destroy cancer cells. It is a relatively new form of treatment requiring updated equipment. A benefit of proton beam therapy is its high energy. It allows protons to deposit the radiation dose at the site of the tumor. Proton beam therapy confines the radiation to the tumor and not to healthy tissues.
Image-guided Radiotherapy (IGRT)
It decreases damage to healthy tissue due to its precise targeting. The doctor takes images of the patient throughout treatment to compare them to the images taken in the planning stage of radiotherapy.
It is suited for patients with small tumor sites. Large doses of radiation target the area(s). The doses of radiation are so large that patients only need a single treatment.
Internal Radiotherapy (Brachytherapy)
Internal radiotherapy or brachytherapy deposits radiation inside of the patient’s body. The radiology team places radioactive material into cancer or group of cells being treated. Internal radiotherapy is accomplished through permanent or temporary internal implants.
Permanent implants consist of radioactive steel seeds about the size of a grain of rice. The seeds deliver the majority of the radiation dose to the location of the implant, but small amounts of radiation exit the patient’s body. Even once inactive, the seeds remain internally. Contrarily, temporary internal radiotherapy lasts minutes to days. The radiation is administered via needles, applicators, or catheters.
Radioisotope therapy is liquid radiation that the patient ingests by mouth (i.e. a drink or capsule) or injected intravenously into the veins. The radioactive material (radionuclides) are combined with cell-targeting molecules that destroy harmful cells. This type is helpful because the cancer cells receive a higher dose of radiation. Bodily fluids stay radioactive for a period of time after treatment. Thyroid cancer, bone cancer, and prostate cancer are a few malignancies treated with radioisotope therapy.
Side Effects of Radiotherapy: General Symptoms
The side effects are extensive. Symptoms vary depending on the location of the radiation. Regardless of location, patients receiving radiotherapy are susceptible to the following basic side effects.
2 to 3 weeks after the beginning of treatment, many receiving radiotherapy experience hair loss. Large doses of radiation might cause permanent hair loss.
The skin might appear darker or take on a different texture. Broken blood vessels cause red, spidery patterns on the skin called telangiectasia.
Low Blood Counts
The bone marrow that produces blood cells in the body slows down. This increases infection risk and may require a blood transfusion to increase counts.
The treatment to all areas of the body has the potential to affect the gastrointestinal tract. Patients experience radiation sickness which includes nausea, vomiting, a lack of appetite, and alterations in the taste of food.
Swelling results from the blockage of the drainage channels to the arms or legs.
Side Effects of Radiotherapy: Abdomen
Radiotherapy of the abdomen exposes radiation to the esophagus, stomach, small intestine, and colon. Along with the general symptoms, radiotherapy of the abdomen may lead to:
- Bloating or gas
- Loss of appetite
- Stomach ulcers
- Kidney problems
- Damage to the lining of the intestines (radiation enteritis)
Side Effects of Radiotherapy: Pelvis
Radiotherapy to the pelvis shares many of the same side effects of the abdomen. It significantly impacts the lower gastrointestinal tract, the bladder, and the sex organs. Side effects are:
- Digestive changes (i.e. nausea, vomiting, diarrhea)
- Rectal bleeding
- Painful bowel movements
- Inflammation of the rectum and/or anus
- Bowel and bladder incontinence
- Radiation enteritis
- Urinary tract infections
- Sexual problems (i.e. infertility, erectile dysfunction in men, irregular menstruation in women)
- Painful, burning urination
Side Effects of Radiotherapy: Chest
Radiotherapy to the chest is a routine treatment for breast cancer, cancers of the lung, spine, esophagus, and lymphoma. The throat and esophagus become irritated when radiation targets the chest. Possible side effects are:
- Throat soreness
- Hoarse voice
- Swelling of the breast
- Inflammation of the lung (radiation pneumonitis)
- Scar tissue in the lungs (pulmonary fibrosis)
- Difficulty swallowing
- Taste changes
- Irregular heartbeat
- Cardiac disease (i.e. coronary artery disease, congestive heart failure)
Side Effects of Radiotherapy: Head and Neck
Radiotherapy to the head and neck shrinks cancer cells in those locations. Some brain cancers are also responsive to radiotherapy. The side effect profile is considerable, as radiation irritates the mucous membranes in the mouth, throat, and upper esophagus:
- Mouth soreness
- Dry mouth
- Difficulty swallowing
- Taste changes
- Hearing loss
- Stiff jaw (trismus)
- Tooth decay
- Hormone imbalance (i.e. from radiotherapy to the thyroid, pituitary gland, etc.)
- Cognitive problems (i.e. memory loss, poor speech, etc.)
- Death of bone (osteoradionecrosis)
- Vision loss
- Dry eyes
- Damage to the cranial nerve
- Swelling of the brain (increased intracranial pressure)
Preparing for Radiotherapy: Radiation Simulation
Before treatment, patients consult with their physician and radiology team to initiate the process of radiation simulation. As the term implies, radiation simulation allows patients to replicate their radiotherapy without actually getting radiation. The purpose of the simulation is to receive the full benefits of radiotherapy while reducing detrimental effects on other areas of the body. The simulation is conducted through a CT-scanner and it is a multi-step process.
To ensure radiation beams are directed at the correct location, the patient’s body is positioned in the spot necessary for each subsequent treatment. Immobilization devices are crucial to the patient remaining still on the treatment table. Examples of immobilization devices are breast boards, cradles, foam boxes, and custom molds fitted to the patient’s shape.
When the team is finally confident in the positioning for the radiotherapy, they take images of the area to be treated. Images are obtained by x-rays, PET scans (positron emission tomography), or CT scans (computed tomography) and are sent to a computer to set up the treatment field.
With a pen, an oncologist marks the patient’s skin according to the established treatment field. The markings are approximately the size of a freckle and serve as a guide to align the patient in the same position each treatment. Traditional pen markings are temporary and tend to wash off. Professionals now recommend radiotherapy markings be tattooed onto the patient’s skin to permanently mark the treatment field for future treatments.
The images taken earlier in the simulation process are used to generate a 3D model of the patient’s anatomy. The tumor and its location are the central focus. This step aids in dosimetry to calculate the dose of radiation administered during the radiotherapy session.
Radiotherapy Safety Precautions
Radiotherapy is a serious treatment that is not to be taken lightly. The medical team performs maintenance checks on radiotherapy equipment to guarantee the safety of patients. Top cancer centers recommend that patients and families abide by several safety measures to protect themselves from harm.
All radiotherapy treatments are given in a separate room to limit radiation exposure. With external beam radiotherapy, there are little precautions because the patient does not become radioactive other than when they are actively receiving radiation. However, internal beam radiation therapy causes patients to emit radiation. It is advised that visitors of patients receiving temporary internal beam radiation therapy limit their visits, keep a distance of at least 6 feet from the patient, and do not to visit if you are pregnant or younger than 18.
Exposure to permanent implants do not carry great risk for healthy individuals, but minors are at a greater risk because their bodies are developing. While the radioactivity of the permanent implant is at its highest, avoid close contact with children and pregnant women for 2 months.
Cheyanne is currently studying psychology at North Greenville University. As an avid patient advocate living with Ehlers Danlos Syndrome, she is interested in the biological processes that connect physical illness and mental health. In her spare time, she enjoys immersing herself in a good book, creating for her Etsy shop, or writing for her own blog.