Radiation therapy or radiotherapy is the use of ionizing radiation to destroy cancer cells.
There are two types of radiation therapy. One is External Beam Radiation and the other is Internal Radiation also called Brachytherapy.
In external beam radiation therapy, treatment is delivered using high energy x-rays that are emitted from a machine and penetrate through the skin to the area where the cancer is located. There is also superficial x-ray treatment for skin related conditions.
Internal radiation also called brachytherapy, involves implanting radioactive sources inside the patient’s body tissue (interstitial radiation) or the radiation sources are placed in an applicator, which is inserted into a cavity (intracavitary radiation).
External Beam Radiation is the most common type of radiotherapy. It is used for the treatment of all types of cancer. Some of the common ones treated include cancers of the breast, prostate, head and neck, brain, lung, cervix and rectum.
The machine used to deliver External Beam Radiation Therapy, is a Varian Linear Accelerator. It has inbuilt advanced technology that delivers radiation treatment to very high accuracy and precision. It produces higher energy radiation that is more penetrating than Cobalt technology that is offered elsewhere on the island. This results in much higher radiation dose delivered to the cancer cells or tumour and with less skin damage than Cobalt.
At ROCJ, Brachytherapy or internal radiation is offered for the treatment of prostate cancer. In prostate brachytherapy, tiny radioactive iodine seeds (I-125) are inserted into the prostate using a needle, while the patient is under general anaesthesia. Ultrasound and x-ray equipment are used to guide the physicians to precisely place 60 - 110 seeds into the prostate gland. The seeds emit low doses of radiation, which are absorbed by the cells in the prostate and destroy the cancer. Surrounding organs such as the bladder and rectum receive minimal radiation exposure from this procedure.
Superficial Radiation Treatment is offered for the treatment of keloids, skin cancer and surgical scars.
Planning for cancer treatment is a necessary and vital step before treatment takes place. Several procedures are undertaken to ensure accuracy, safety and reproducibility. These include simulation, medical physics, dosimetry and treatment plan verification.
Simulation The first procedure is Simulation, which involves the use of a Conventional Simulator for 2-Dimensional Planning or CT Simulation for 3-Dimentional Planning. Simulation allows for the visualisation of the internal organs from any angle and to locate and determine the exact size of the cancer to be treated.
During simulation the area to be treated is marked on the patient’s skin with a special ink to ensure that the set up is the same every time and that treatment will be administered to the same place throughout the course of treatment.
Persons needing treatment for head and neck cancer will have a mask made for them. The mask is made from a mesh-like hard plastic, which is molded over the patients face, head and neck. It is specially fitted and painless to use. The mask must be worn during treatment to ensure that the head does not move so that the radiation beams are delivered to the same spot every time.
Medical Physics & Dosimetry
The Medical Physics Unit uses the information from simulation to plan the technical aspects of the treatment using a 3-Dimensional computerized treatment planning system: Here calculations are done to determine the exact dose of radiation necessary for treatment, the size, shape and angles of the radiation beams to be used. Special shielding blocks are designed to shape the radiation beams in order to minimize the dose received by surrounding normal tissues while optimizing the radiation dose to the cancer site.
Fabrication Of Treatment Devices
Also done in the planning phase is the fabrication of treatment devices to be used in External Beam Radiation - such as blocks to shield areas close to the treatment site in order to minimize radiation effects to surrounding tissue. Immobilization devices such as facial masks for persons with head and neck cancers are also fabricated in the planning phase.
Treatment Planning Verification
Before the execution of the treatment plan the patient revisits the Simulator Room where the plan designed for treatment is verified.
The radiation therapist will take time to correctly position the patient on the treatment table guided by the treatment plan provided by Medical Physics and the marks on the patient’s skin or mask from Simulation. The gantry of the treatment machine is rotated to the predetermined angle required for the delivery of radiation treatment. Once the set up has been completed customized shielding blocks are inserted in the beam pathway, as required.
During the treatment session the gantry may be moved to deliver radiation at multiple angles. The Actual treatment time for each position (angle) is generally very short -less than or slightly greater than one minute. The time spent for the entire treatment process that is from the patient’s entry into treatment room until end of treatment usually takes between 15 and 20 minutes.
Portal or verification films are regularly done over the course of treatment to ensure that the set-up is the same throughout the treatment.
The patient is monitored regularly by the staff nurse and is reviewed weekly by the radiation oncologist. The patient also has an important role to play by ensuring that the instructions given regarding the “Dos and Don’ts” while undergoing radiation therapy are followed.
Consultations with our nutritionist are also an integral part of the treatment process and recommendations are made regarding diet. This ensures that the patient maintains a good nutritional status during treatment.
The patient’s blood count will also be checked because radiation treatment may significantly reduce the number of white blood cells that fight infection.
In order to benefit fully from radiation treatment, it is important that patients do not miss any of the daily treatment session.
Side effects will depend on the treatment dose, the length of treatment and the area being treated (Check the related pamphlet included for details). Some common side effects are- tiredness and fatigue, diarrhea and hair loss in the area being treated, loss of appetite, anxiety and depression. Skin irritation is also likely in the area being treated. The area may become dry, itchy and dark. However the symptoms will decrease after treatment.
It is important that the patient discusses any side effects that may be experiencing with a member of the ROCJ treatment team, who will provide advice and take appropriate measures to relieve symptoms.
For External Beam Radiation the treatment requires just short daily visits from Monday to Friday for 2 to 8 weeks, depending on the location and stage of the cancer. How long it lasts depends on the type of cancer, the stage of the cancer and how well the patient responds to the radiation treatment.
Myth:Radiation will cause me to miss my daily routine
Fact: While fatigue is often common during radiation treatment, many patients can still maintain their normal daily schedule including work and school. As treatment nears the end, the fatigue may increase. That does not mean you have to give up your routine; just be sure to get the rest you need.
Myth:Radiation therapy will make me radioactive
Fact: If your treatment involves external radiation, you are not radioactive. The radiation is delivered in doses to treat the abnormal tissue and once the machine is turned off, the radiation does not linger within you. You can maintain a normal routine and go near or around anyone, including pregnant women and babies.