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ABCs of Radiation Therapy for Patients, Family and Friends

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A presentation on radiation therapy by David Kozono, MD, PhD.

Veröffentlicht in: Gesundheitswesen
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ABCs of Radiation Therapy for Patients, Family and Friends

  1. 1. ABCs of Radiation Therapy for Patients, Family and Friends David Kozono, MD, PhD
  2. 2. What is radiation therapy? • For lung cancer, radiation therapy is most often X-rays given externally using multiple beams that converge on the part of the body with tumor. • X-rays cannot be felt, seen, heard or otherwise perceived during treatment.
  3. 3. How is radiation given? • Using a linear accelerator (linac) source of radiation robotic table
  4. 4. • Patient positioning using tattoos How is radiation aimed? http://www.rtanswers.org
  5. 5. • Patient positioning using tattoos How is radiation aimed? http://xkcd.com/933/
  6. 6. How is radiation aimed? • Imaging to assure treatment accuracy and precision X-rays for daily verification of positioning CT for weekly confirmation of target localization
  7. 7. How is radiation aimed? Positioning X-rays CT: Plan CT: Week 5
  8. 8. Lung cancer infiltrates “normal” tissues Cancer Emphysematous Lung 3 cm Cancer GTV CTV PTV GTV = gross tumor volume; CTV = clinical target volume PTV = planning target volume
  9. 9. Treatment volumes GTV GTV CTV PTV
  10. 10. Organs at risk right lung left lung esophagus spinal cord
  11. 11. The challenge unavoidable overlap of target volume and esophagus
  12. 12. Radiation beams
  13. 13. Radiation dose
  14. 14. Expected side effects skin reddening very rare risk of spinal cord injury pain with swallowing lung inflammation
  15. 15. Why are there so many treatments? • A course is anywhere from a single treatment for symptom relief, up to seven weeks of daily treatment Monday–Friday for cure • Fractionation – Dividing radiation dose into multiple sessions – Spares healthy tissues more than tumors
  16. 16. Why are there so many treatments? Cancer cells Little sparing with fractionation Long-term side effects Significant sparing with fractionation 1 x 2 Gy 1 x 4 Gy 0 2 4 86 1210 Fractionated 1 x 2 Gy 1 x 4 Gy Fractionated 6 x 2 Gy 3 x 4 Gy 6 x 2 Gy 3 x 4 Gy Dose (Gy) Survivalfraction(log)
  17. 17. Common questions and answers • Am I radioactive after treatment (safe around young children)? – For about 0.000000000000000001 seconds – So, no…perfectly safe
  18. 18. Common questions and answers • Can you tell if the tumor is shrinking? – The daily X-rays ± weekly CT scans are mostly to verify positioning and tumor targeting. – Tumors continue to shrink for weeks after the final treatment. – We therefore typically perform scans about two months after completion of therapy.
  19. 19. Common questions and answers • Will you be repeating the treatment? – Unlike chemotherapy, we typically administer a single course of treatment. – If needed, additional treatment can be given on a case-by-case basis weighing the benefits and risks.
  20. 20. Common questions and answers • Is all this radiation, including X-rays and CT scans, safe? – Rate of second cancers due to radiation is less than 1 in 100 and likely closer to 1 in 1000. – Side effects depend on the area of the body that is treated; treatment will only be given if the benefits will likely outweigh the risks and the risks are acceptable.
  21. 21. Resources • Department website – http://www.dana-farber.org/Adult-Care/Treatment-and- Support/Treatment-Centers-and-Clinical- Services/Department-of-Radiation-Oncology.aspx • American Society for Radiation Oncology – http://www.rtanswers.org/ • LUNGevity – http://www.lungevity.org/about-lung-cancer/lung- cancer-101/treatment-options/radiation-therapy