Lect 01 Teletherapy machines 1.pdf

4, · photon Introduction ❑ Radiotherapy plays a crucial part in treating lots of different canc...

4, · photon Introduction ❑ Radiotherapy plays a crucial part in treating lots of different cancers. ❑ New technology is making it more precise and reducing side effects. ❑ It works by firing x-rays or other intense bundles of energy at cancer cells, damaging their DNA. If a cancer cell can't repair its damaged DNA, it dies. Patient being treated with modern radiation therapy equipment. M.SC. MEDICAL PHYSICS DR. KHALID I HUSSEIN  Introduction Role of Medical Physicists 942 82 % - ·S- Any time radiation used in medicine, the MP Optimization of machine setting to improve is in the background to sure that every thing - image quality, making an accurate diagnosis safe and no more than the necessary - radiation is used. M.SC. MEDICAL PHYSICS DR. KHALID I HUSSEIN  Introduction Role of Medical Physicists Design and testing of radiation shielding to In radiotherapy the role physicists is to help keeping staff and patients safe. make sure the patient is getting the right amount radiation in a right place and minimize the dose to the OAR. ->did risk * M.SC. MEDICAL PHYSICS DR. KHALID I HUSSEIN  - Introduction. F manale ❑ During the first 50 years of radiation medicine the technological progress - was aimed mainly towards: _ e ◦ Development of analog imaging techniques. ◦ Optimization of image quality with concurrent minimization of dose. ◦ Ever increasing energies and beam intensities. &is ❑ During the past two decades most developments in radiation medicine - were related to: ◦ Integration of computers in imaging 2 ◦ Development of digital imaging techniques W ◦ Incorporation of computers into therapeutic dose delivery with high energy linear accelerators (linacs). -45. # linac &? M.SC. MEDICAL PHYSICS DR. KHALID I HUSSEIN  Introduction · Ex Standard machines used for modern radiotherapy: ve a 50 -80 ❑ X-ray machine: ↳ Kilo Peach surface voltage ◦ Superficial x-ray machine: 50 - 80 kVp ◦ Orthovoltage x-ray machine: 80 - 350 kVp => ❑ Cobalt-60 teletherapy machine ray gamma ❑ Linear accelerator (linac): modern. , ◦ Megavoltage x rays: 6 - 25 MV - and electron - ◦ Electrons: 6 - 30 MeV Photon M.SC. MEDICAL PHYSICS DR. KHALID I HUSSEIN  Introduction Specialized machines used for modern radiotherapy: ❑ Microtron: megavoltage x rays and electrons - > ❑ Betatron: megavoltage x rays and electrons - - ❑ Neutron machines ❑ Proton machines M.SC. MEDICAL PHYSICS DR. KHALID I HUSSEIN  Aim of Radiotherapy The aim of radiotherapy is to deliver maximum dose and uniform dose to the tumor volume and minimal dose to the normal tissue or organ at risk. 9 61? , 595 The main requirements of Radiation used in radiotherapy: ❑High particle energy for penetration and skin sparing. ❑High particle flux for sufficient dose rate. ❑Not too expensive. ❑Reliable ❑Simple to operate ❑Safe. M.SC. MEDICAL PHYSICS DR. KHALID I HUSSEIN  Type of treatment Radical intent: aiming for a cure without producing undesirable long-term consequences for patient. for most common cancers- requires high doses. Adjunct therapy: add-on therapy, and adjuvant care, is therapy that is given in addition to the primary or initial therapy to maximize its effectiveness. Palliative intent: disease cannot be cured - aiming to “control” the disease, reduce unpleasant symptoms, improve the quality of life for patient but not “cure” the cancer - lower doses usually given. M.SC. MEDICAL PHYSICS DR. KHALID I HUSSEIN  Fractionation: A Basic Radiobiologic Principle ❑Fractionation, or dividing the total dose into small daily fractions over several weeks, takes advantage of differential repair abilities of normal and malignant tissues. ❑Prescription of radiotherapy treatment is the responsibility of the radiation oncologist and usually follows agreed guidelines, taking into consideration individual patient factors, such as the expected risk–benefit ratio of treatment, comorbidities and consideration of scheduling of other treatment modalities. ❑Alternative fractionation schedules using fewer larger fractions in a shorter overall time (hypofractionation) have been developed, especially in the UK and Canada, driven initially by resource constraints, but now supported by extensive published clinical data, e.g. for breast and prostate cancer as well as for palliative treatments.  Class activity (Group 1 presentation) ❑ What is the purpose of fractionation in radiation treatment for cancer patients? ❑ The Five R’s of Radiobiology. ❑ Survival curve and linear quadratic model. ❑ Biological Effective Dose (BED).