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Radiation Protection in Radiotherapy

Radiation Protection in Radiotherapy

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Radiation Protection in Radiotherapy

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  1. Radiation Protection inRadiotherapy IAEA Training Material on Radiation Protection in Radiotherapy Part 1 Aim and Role of Radiotherapy Introductory Lecture

  2. Radiotherapy • One of the main treatment modalities for cancer (often in combination with chemotherapy and surgery) • It is generally assumed that 50 to 60% of cancer patients will benefit from radiotherapy • Minor role in other diseases Siemens Oncology Part 1: Introductory lecture

  3. Objectives of the Module • To become familiar with • the principles of radiotherapy • the role of radiotherapy in cancer management • the cost effectiveness of radiotherapy • To appreciate the importance of radiation dose in radiotherapy Part 1: Introductory lecture

  4. Contents of the Lecture 1. Cancer management and radiotherapy 2.Approaches for dose delivery External beam radiotherapy Brachytherapy 3. Features of a radiotherapy department 4.Self test at the end of the lecture ”Quick test” Part 1: Introductory lecture

  5. Cancer incidence (WHO) Part 1: Introductory lecture

  6. Major indications for radiotherapy • Head and neck cancers • Gynaecological cancers (e.g. Cervix) • Prostate cancer • Other pelvic malignancies (rectum, bladder) • Adjuvant breast treatment • Brain cancers • Palliation Part 1: Introductory lecture

  7. Approaches • Palliative radiotherapy to reduce pain and address acute symptoms – e.g. bone metastasis, spinal cord compression, ... • Radical radiotherapy as primary modality for cure – e.g. head and neck • Adjuvant treatment in conjunction with surgery – e.g. breast cancer Part 1: Introductory lecture

  8. Aim Patient Critical organs • To kill ALL viable cancer cells • To deliver as much dose as possible to the target while minimising the dose to surrounding healthy tissues target Beam directions Part 1: Introductory lecture

  9. Prognostic Factors • Cancer type and stage • Patient performance • Radiation dose • ... Good prognosis survival Bad prognosis time Part 1: Introductory lecture

  10. Prognostic Factors • Cancer type and stage • Patient performance • Radiation dose • ... Accurate dose delivery matters! Part 1: Introductory lecture

  11. Dose response 100% response means the tumour is cured with certainty (TCP) or unacceptable normal tissue damage (e.g. paralysis) is inevitable Part 1: Introductory lecture

  12. Dose response Therapeutic window: Maximum probability of Complication Free Tumour Control Part 1: Introductory lecture

  13. Dose should be accurate • To target: • 5% too low - may result in clinically detectable reduction in tumour control (e.g. Head and neck cancer: 15%) • To normal tissues: • 5% too high - may lead to significant increase in normal tissue complication probability = morbidity = unacceptable side effects Part 1: Introductory lecture

  14. “Deviations from Prescribed Dose” • May involve severe or even fatal consequences. • IAEA Basic Safety Standards (SS 115): ”…require prompt investigation by licensees in the event of an accidental medical exposure…” Part 1: Introductory lecture

  15. Options for dose delivery • External beam radiotherapy = dose is delivered from outside the patient using X Rays or gamma rays or high energy electrons (refer to part 5 of the course) • Brachytherapy = dose delivered from radioactive sources implanted in the patient close to the target (brachys = Greek for short distance; refer to part 6 of the course) Part 1: Introductory lecture

  16. External beam radiotherapy Part 1: Introductory lecture

  17. External Beam Radiotherapy • Typically fractionated - e.g. 30 daily fractions of 2Gy up to a total dose of 60Gy • Superficial/orthovoltage photons (50 to 400kVp) for skin or superficial lesions • Megavoltage photons (60-Co or linear accelerators = linacs) for deeper lying tumours. • Megavoltage electrons from linacs for more superficial lesions Part 1: Introductory lecture

  18. Superficial/orthovoltage unit Part 1: Introductory lecture

  19. Modern Cobalt 60 unit Part 1: Introductory lecture

  20. Linear accelerator with electron cone Electron applicator Part 1: Introductory lecture

  21. Brachytherapy Interstitial implant for breast radiotherapy Intracavitary gynecological implant Part 1: Introductory lecture

  22. Brachytherapy • Implant of radioactive materials (e.g. 137-Cs, 192-Ir) close to the target area • Intracavitary, interstitial and mould surface applications • Low dose rate, LDR, (60Gy in about 5 days) and high dose rate, HDR, (several fractions of several Gy in few minutes each) applications Part 1: Introductory lecture

  23. Example for HDR Brachytherapy Part 1: Introductory lecture

  24. A radiotherapy department is part of a health system Radiotherapy Department National Cancer System Oncology Host hospital Part 1: Introductory lecture

  25. Patient Flow in Radio-therapy …not necessarily a straightforward process Part 1: Introductory lecture

  26. Patient flow in radiotherapy • Depends on: • disease site and stage • departmental protocols • treating clinician • resources available Part 1: Introductory lecture

  27. Components of a Radiotherapy Department • Diagnostic facilities (CT, MRI, …) • Simulator (refer to part 5 of the course) • Mouldroom • Treatment planning • External beam treatment units (parts 5 and 10) • Brachytherapy equipment (part 6) • Clinic rooms, beds, ... Part 1: Introductory lecture

  28. Layout of a Department Part 1: Introductory lecture

  29. Layout of a Department Physics & workshops Simulator Planning Clinics Two linac bunkers Offices Patient waiting Part 1: Introductory lecture

  30. Professionals in radiotherapy • Radiation oncologists • Other clinicians • Medical radiation physicists • Radiation therapists • Nursing staff • Radiation safety officer • Information technology officer • Administrative staff Part 1: Introductory lecture

  31. Features of Radiotherapy • High and potentially lethal absorbed dose is required to cure cancer • High technology environment • Individualized treatment approach • Complex treatment set-up Part 1: Introductory lecture

  32. Features of Radiotherapy • High and potentially lethal absorbed dose is required to cure cancer • High technology environment • Individualized treatment approach • Complex treatment set-up • Quality assurance, treatment verification and radiation protection essential Part 1: Introductory lecture

  33. Summary • Radiotherapy is an important cancer treatment modality • Accuracy of dose delivery is essential for good outcomes • The complex and high tech environment requires attention to quality assurance and radiation protection Part 1: Introductory lecture

  34. Where to Learn More • Other parts of the course, handouts • References: • Radiotherapy physics textbooks (as per reference list) • IUCC Cancer Statistics • Radiotherapy textbooks (e.g. Perez and Brady 1998) • Site visit of a radiotherapy department (day xxx of the course) Part 1: Introductory lecture

  35. Any questions? Part 1: Introductory lecture

  36. Question: What is the main cancer treated with radiotherapy in your country and what would be a typical treatment approach? (Number of fractions? Total dose?) Part 1: Introductory lecture