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A presentation that briefly explains the physics behind radiotherapy as a medical technology.


  1. 1. Ashley Raiteri
  2. 2. What energy does radiotherapy use? Radiation therapy (US and Canada) is also known as radiation oncology, irradiation or radiotherapy (UK and Australia). Radiation therapy uses electromagnetic radiation, such as x- rays, gamma rays, electron beams or protons to kill or damage cancer cells to stop/slow them from growing or multiplying. • Radiotherapy can take place before, during or after treatment and in conjunction with other treatments such as chemotherapy or surgery. • About 50% of all cancer patients receive some form of radiation therapy during the course of their treatment. PET-CT scan used to pinpoint area of cancerous tissue in the brain
  3. 3. How is the radiation generated? • Radiotherapy is completed internally (brachytherapy) or externally Brachytherapy • Brachytherapy can be employed alone or with external radiotherapy as well • The radiation is received through a source placed next to/in the treatment area or a small radioactive rod, a “seed”, is inserted into the treatment area NOTE: As much as a complex geometric localisation program is used to only target cancerous tissue, healthy tissue is still often damaged as well: however, due to the cancer cells being weaker to radiation, healthy tissue can usually recover from the prescribed dose. External Radiotherapy • External radiotherapy is the most common form of radiotherapy • The beam (either photons or charged particles) that generates ionization (and through that irradiation) is generated by a linear particle accelerator(LINAC for short) • The LINAC both generate electrons and accelerate them to generate a high-energy beam • The high-energy beam penetrates the tissue of the patient to ionize the cancer cells and damage them “Seeds”
  4. 4. How does the energy interact with the tissue? • When the energy reaches the tissue, the interaction that occurs is ionization (acquirement of positive or negative charge) • This ionization happens either directly to the cancer DNA or indirectly by the ionization of water (the ionized water produces free radicals, which then damage the DNA)
  5. 5. How does the tissue receive the energy? • The cancerous tissue receives the energy in the form of radiation, where it damages the DNA of the cancer cells. • The radiation is able to primarily destroy the cancerous tissue over healthy tissue because the single- stranded DNA of cancer is vulnerable to radiation, whereas the double-stranded DNA of healthy tissue is usually able to recover from irradiation.
  6. 6. Advantages of radiotherapy 1. The localisation of radiation allows for the significant lessening of damage to healthy tissue 2. Radiotherapy is useful during before and after as well as during treatment because it can effectively stop cancer and tumours 3. Patients claim that the daily treatment does not impede significantly on their daily schedule 4. Radiotherapy can still be given when surgery is considered unsuitable or unfit 5. The radiotherapy itself is relatively painless
  7. 7. Possible side affects of radiotherapy • Side effects of radiotherapy can be acute or chronic, which means that they will occur during the treatment or some time (as long as years) after the treatment, respectively • Side effects depend on the specific area that is being treated, dosage, general medical condition and other treatments that are being received at the time Acute Side Effects • Skin irritation • Damage at regions exposed to radiation (eg. Hair loss) • Fatigue • Nausea Chronic Side Effects • Fibrosis (restricted movement at affected area) • Bowel damage -> diarrhoea and bleeding • Memory loss • Infertility • Rarely, a second cancer caused by the radiation exposure Other disadvantages: • Radiotherapy machines take up large amounts of space and are not mobile – large distances may have to be travelled to receive treatment • Radiotherapy machines must be set up in rooms that contain radiation • When used alone, radiotherapy cannot do much to help cancer that has already metastasized (spread throughout the body)
  8. 8. Hair loss is common when radiotherapy treatment is made on the head or neck Vein irritation 3 years after radiotherapy
  9. 9. LINAC demonstration
  10. 10. 1/5 2/5 Radiotherapy Interview