Radiotherapy
What is Radiotherapy ?
Radiation therapy, or radiotherapy, is the use of various forms of radiation like X rays to safely and effectively treat cancer and other diseases. Radiation therapy works by damaging the genetic material within cancer cells. Once this happens, the cancer cells are not able to grow and spread. When these damaged cancer cells die, the body naturally removes them. Normal cells are also affected by radiation, but they are able to repair themselves in a way that cancer cells cannot. Radiation oncologists are doctors who develop a plan to deliver the radiation to the tumor area, shielding as much surrounding normal tissue as possible.
The goal of treatment with radiotherapy can be:
1. Cure the cancer: Treatment can be given with the intent of curing the cancer, for e.g Nasopharynx, Cervix, Many Head & neck cancers, Prostate,etc.
2. Adjuvant Treatment: After surgery based on high risk features the treatment with radiation is advised to reduce the risk of recurrence. For e.g, oral cavity, brain tumors, Breast ca, Ca endometrium, etc.
3. Neoadjuvant Treatment: The goal here is to shrink the tumor so that surgery can be carried out in a better fashion.For e.g, Ca Esophagus, Ca Rectum.
4. Palliative Intent: the goal is to reduce the symptoms caused by growing tumors, & to improve the quality of life.
Physicians have been treating patients with radiation therapy safely and effectively for more than 120 years. Nearly two-thirds of cancer patients are treated with radiation during their illness.
Types of Radiation Therapy
Radiation therapy can generally be delivered in three ways:
1. External beam radiation therapy: The treatment team uses a machine outside the body to direct radiation beams such as high energy X-rays, or particles, at the cancer. This category includes high-dose therapy called stereotactic radiation therapy. The radiation beam that is used for treatment is usually generated by a machine called a linear accelerator, or linac. The linear accelerator produces high-energy X-rays or electrons for the treatment of cancer.
2. Brachytherapy: This involves placing radioactive sources (such as radioactive seeds or a highly radioactive source) in or near the tumor.
3. Systemic radiation therapy: Radioactive drugs are given to the patient and travel through the bloodstream to treat cancer throughout the body.
External beam radiation therapy
It is also called radiotherapy involves a series of daily treatments to accurately deliver radiation to the tumor. Using treatment planning computers and software, your treatment team controls the size and shape of the beam, as well as how it is directed at your body, to effectively treat your tumor while sparing the surrounding normal tissue. There are many techniques in which radiotherapy beams can be delivered. Some of them are:
1. 3D CRT ( Conformal Radiotherapy)– Tumors are not all the same; they come in different shapes and sizes. Also, every patient’s body is unique. Three-dimensional conformal radiation therapy is a planning technique using computers and special imaging such as CT, MR or PET scans to show the size, shape and location of the tumor as well as surrounding organs. Your radiation oncologist can then precisely tailor the radiation beams to the size and shape of your tumor with special shielding. Because the radiation
beams are carefully targeted, nearby normal tissue receives less radiation and is then able to heal better.
2. Intensity Modulated Radiation Therapy (IMRT)– Intensity-modulated radiation therapy is a more complex treatment planning technique that allows radiation to be specifically shaped to cover the tumor and potentially spare more normal tissue than 3-D CRT.
3. Image Guided Radiotherapy (IGRT)– IGRT involves radiation treatment guided by imaging, such as CT, ultrasound, X-rays or MRI taken in the treatment room just before or during each radiation treatment. Because tumors can move between or during treatments, IGRT allows for better targeting of tumors.
4. Stereotactic radiotherapy– It is a specialized technique that allows treating radiation oncologists to use extremely focused beams of radiation to destroy certain types of tumors using higher doses than with daily lower-dose radiation treatments. Since the beam is so precise, we may be able to spare more healthy tissue. In selected cases, stereotactic treatments can be used to re-treat tumors that have received radiation before.
Stereotactic radiotherapy was first developed to treat brain tumors in a single dose, sometimes called stereotactic radiosurgery or SRS. In addition to treating cancers, radiosurgery can also be used to treat benign tumors and certain noncancerous neurologic conditions. High-dose treatment outside the brain is called stereotactic body radiation therapy (SBRT). It is typically given in a few treatments. Often used to treat tumors in the lungs, spine, prostate, pancreas, adrenal glands or liver, SBRT may allow radiation to be given in a way that is safer and more effective than other radiation techniques.
Many different types of beams are used for treatment in Radiation therapy. They are:
1. Gamma Rays: They were used when treated with Cobalt machines. Now treatment with these machines is less popular as they had more rates of side effects.
2. Photons/ High energy X rays: They are delivered by machines called as Linear Accelerators ( LInacs). Some of the popular ones are Trubeam STx, Versa HD, Halcyon, Tomotherapy, Cyberknife. They are the most common machines employed now to treat cancers.Many of them are equipped with all the advanced techniques mentioned above for treating cancers safely.
3. Electron Beams: They are also produced by Linacs but have limited application.
4. Proton & Carbon Ion: Here the use of protons & carbon ions to treat certain types of cancer and other diseases. The physical properties of these particles allow a more effective reduction of the radiation dose to nearby healthy tissue. As a result, proton beam therapy is often a favored type of therapy for treating pediatric cancers, tumors in the base of the skull, and reirradiation. However, the treatment costs are a prohibitive factor currently.
Side Effects:
Most of the side effects of radiation therapy are limited to the area being treated. They are usually temporary, mild and treatable. These symptoms typically begin in the second or third week of treatment. They may last for a few weeks after the final radiation treatment and typically go away by one to two months after completing radiation therapy.
Is Radiation Therapy Safe ?
Some patients worry about the safety of radiation therapy. Radiation has been used successfully to treat patients for more than 120 years. In that time, many advances have been made to ensure that radiation therapy is safe and effective. With each advance, new quality checks have been developed to ensure safe treatment.
If you undergo external beam radiation therapy, you will not be radioactive after treatment ends because the radiation does not stay in your body.