Radiotherapy Physics - Flow Chart of Radiation Therapy

: 17 December 2018; Hits: 50569

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Flow Chart of Radiation Therapy

Consultation

When you some to the clinic, a radiation oncologist will review your current problem, past medical history, past surgical history, family history, medications, allergies, lifestyle and an organ system by organ system audit making use of any relevant x-rays and lab tests that you already have had. He/she will also perform a physical examination that will then to assess the extent of your problem and judge your general physical condition to estimate any influence it may have over your response to radiation therapy.

Simulation

The simulation process will help the radiation team plan a course of treatment designed especially for you. The radiation oncologist uses the x-rays images and the information gathered during the simulation to design and individualise your treatment plan.

Simulators are very precise machines that can duplicate the geometry of different types of treatment machines and by fluoroscopy and x-ray pictures allow us to visualise important structures inside patients. This information is translated into aiming points, distances and angles. With you lying on the simulator couch and with the use of light and laser projection systems we will place marks on your skin or on individually constructed immobilisation devices that will help level and position you in 3-dimensional space. Marking may be tattooed on the skin. Immobilisation devices will be constructed from one or more materials including thermally shaped plastics, vacuum forming beanbags, and plaster casts. You may need an appointment with the mould room for making of your immobilisation device.

Treatment Planning

The treatment planning team includes the radiation oncologist, radiographer and physicist. Using all available information, including that obtained from simulation, the final plan will determine the type of radiation, its size and shape and the number of radiation beams, and how much radiation is given through each beam. Radiation beams must be shaped to match their intended targets with the collimator jaws. Depending on the desired shape, additional blocking of the beam may be required. The treatment planning computer then calculates the desired dose distribution taking into account the sparing of normal healthy tissue and the tolerance of the patient as a whole. The radiation oncologist approved the final plan and the treatment parameters are printed in a hardcopy with the electronic version sent to the treatment machine treatment record system via the hospital network.

Machine Quality Assurance

The integrity and performance of most treatment machines were monitored and maintained by the physics workshop. The medical physicists performed the routine dose rate calibration of the linear accelerators and other treatment machines on a weekly basis. They also check on the machines’ performance parameters such as radiation field flatness, symmetry and beam energy on a regular basis. This is to make sure that the machines are in good order and the treatment plans are delivered as planed. The technicians and mechanics help on the repair and scheduled preventive maintenance of all variety of equipment encountered in a busy oncology department. They offer a fast-response service so that interruption to patient service is kept to a minimum.

Treatment Routine

The treatment room is deliberately kept cool to make sure that the equipment operates properly. You will be ask to lie on the treatment couch and the light will be dimmed so that the radiographers could align you with the machine using laser light mounted on the ceiling and walls. If you have been moulded a plastic cast, it will be used for fast and accurate alignment. During the radiation treatment you will not feel anything, but you may hear noises from the machines or notice blinking lights during therapy. You will be alone in the room during the actual treatment period (usually less than five minutes), but you can speak to the radiographers, who can see, hear and talk with you using a closed-circuit TV and microphone in the treatment room.

During each treatment session, the radiographers preset the linear accelerator and check that the correct amount of radiation is given. The machine will stop automatically after completion of treatment.

Port films are taken every few treatments to continue to verify your treatment.

Monitoring Your Progress

During the course of therapy, your radiation oncologist will see you regularly to follow your progress and to discuss your treatment. As treatment progresses, the doctor may make changes in the schedule depending on your response or reaction to the therapy.

Possible Side Effects

Over time, you may develop some side effects, which depend on the part of your body being treated. For example, you will not lose your hair unless you are undergoing radiation therapy to your head or you have undergone a combined treatment of chemotherapy. Some patients treated in the head and neck may

have dry throats and reddish skin reaction (avoid using soap and hot water). Patients receiving radiation in the abdomen or pelvic areas may have some nausea or diarrhea. These will go away in due course but if the condition is badly affecting you, seek the advice from your radiation oncologist.

You are not radioactive and it is not harmful to anyone around you unless you have an implant of radioactive seeds, wire or ingested/infused radiopharmaceuticals. It is not unusual to feel tired during the time you are receiving radiation therapy. Many patients find it helpful to take an afternoon nap or get more sleep each night. Usually, you can continue your normal lifestyle. Your body is your best guide.