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Recent Advances in Radiation Therapies for Cancer

Explore the latest developments in radiation therapies for cancer treatment, including the differences between electron, photon, and proton/heavy ion radiations, as well as the use of the Bragg peak in cancer therapy. Learn about the goal of cancer therapies, the passage of radiation through matter, and the advantages of proton/heavy ion facilities.

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Recent Advances in Radiation Therapies for Cancer

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  1. Renfrew Colloquium Sept. 10, 2013 Nuclear Physics - a Blessing to Mankind:Recent Advances in Radiation Therapies for Cancer Ruprecht Machleidt Department of Physics, University of Idaho

  2. Outline • Cancer facts • How does radiation therapy work? • Passage of radiation through matter • Differences between electron, photon and proton/heavy ion radiations • The Bragg peak and its use in cancer therapy • Proton/heavy ion facilities • Conclusions Radiation Therapies Renfrew Colloquium 09/10/2013

  3. Cancer facts Cancer is the second largest killer. Radiation Therapies Renfrew Colloquium 09/10/2013

  4. Radiation Therapies Renfrew Colloquium 09/10/2013

  5. Radiation Therapies Renfrew Colloquium 09/10/2013

  6. Cancer facts • Cancer is the second largest killer. • How to fight cancer: detect it (early!) and erase it. • One way of detection: Imaging (CT, MRI, PET, …) • Erasing cancer: • Surgery, chemo (both are invasive), • Radiation (non-invasive, involved in 50% of cancer treatments) Radiation Therapies Renfrew Colloquium 09/10/2013

  7. How does radiation therapy work? • Radiation causes ionization. Radiation Therapies Renfrew Colloquium 09/10/2013

  8. How does radiation therapy work? • Radiation causes ionization. • Most ionization occurs on water (80% of our body) • Generates free radicals, e.g., OH*, chemically extremely reactive. • Radicals react with other molecules, disrupting and disabling them, e.g., DNA. • Cell with damaged DNA can continue to live, but dies at next cell division. Radiation Therapies Renfrew Colloquium 09/10/2013

  9. Healthy cells versus cancer cells Radiation Therapies Renfrew Colloquium 09/10/2013

  10. Healthy cells versus cancer cellsunder radiation • Healthy cells are able to repair themselves. • Cancer cells less able, and they divide more often (recall: cell-death occurs upon cell division). • Thus, more damage is done to cancer cells. Radiation Therapies Renfrew Colloquium 09/10/2013

  11. “Fractionation” Example: • Total dose: 80 Gray (Gy) • This is broken up into 40 portions: 2 Gy per portion • 5 portions per week (weekend free, healthy cells can recover) • Total radiation treatment: 8 weeks. • Fractionation enhances the survival of the healthy cells. Radiation Therapies Renfrew Colloquium 09/10/2013

  12. Goal of all cancer therapies Do lethal damage to the cancer (tumor). Do minimal damage to healthy tissue. Not so easy! What radiation is best suited to reach the above goal? Radiation Therapies Renfrew Colloquium 09/10/2013

  13. What radiations are there? And what are the differences? Radiation Therapies Renfrew Colloquium 09/10/2013

  14. Passage of radiation through matter:Energy deposition Bragg Peak Heavy Ions Photons Electrons Radiation Therapies Renfrew Colloquium 09/10/2013

  15. Differences in the energy depositions • Electrons: small depth, “superficial”. The light electrons bounce off heavy atoms: chaotic zigzag path. The electrons are not getting anywhere. • Photons: Exponential fall-off, like light passing through milky/foggy glass. • Protons and heavy ions: They have a mass; so they stop after losing their kinetic energy. Shortly before stopping, they do maximum ionization: Bragg peak. Radiation Therapies Renfrew Colloquium 09/10/2013

  16. Medical applications in cancer treatment • Electrons: Skin cancer (“superficial”) • Photons (X-ray): deeper lying tumors • Protons and heavy ions: deeper lying tumors What’s the difference between photons and protons? Radiation Therapies Renfrew Colloquium 09/10/2013

  17. PHOTONS Tumor Radiation Therapies Renfrew Colloquium 09/10/2013

  18. PHOTONS Radiation Therapies Renfrew Colloquium 09/10/2013

  19. PROTONS Radiation Therapies Renfrew Colloquium 09/10/2013

  20. PROTONS more energy Deeper lying Tumor Radiation Therapies Renfrew Colloquium 09/10/2013

  21. “Bragg Peak” PRO-TONS PHOTONS Radiation Therapies Renfrew Colloquium 09/10/2013

  22. “Bragg Peak” PROTONS more energy PHOTONS Radiation Therapies Renfrew Colloquium 09/10/2013

  23. Reducing the disadvantage of photons: “Multi-field” • Further refinements: Intensity Modulated Radiation Therapy (IMRT): Five or more fields with different intensities. • But the same is done with protons and then multi-field is even more effective, because you start from a better beam: Intensity Modulated Proton Therapy (IMPT). Radiation Therapies Renfrew Colloquium 09/10/2013

  24. Shaping the proton beam for 3D conformal irradiation of the tumor Radiation Therapies Renfrew Colloquium 09/10/2013

  25. Comparison Protons - Photons for a brain tumor Radiation Therapies Renfrew Colloquium 09/10/2013

  26. Comparing different treatment protocols for prostate cancer Radiation Therapies Renfrew Colloquium 09/10/2013

  27. Some History 1905 W. H. Bragg and R. Kleeman, University of Adelaide, discover the “Bragg Peak” using alpha particles from radium; Phil. Mag. 10, 318 (1905). 1946 R. R. Wilson proposes medical use of protons; Radiology 47, 487 (1946). 1954 First human treatedat Berkeley. 1961 Harvard starts proton therapy (9000 patients treated by 2003). 1988-90 First hospital-based proton accelerator (synchrotron) built at Loma Linda University Medical Center, S. California. 2012 16,000-th proton patient treated at Loma Linda; 39 proton centers world-wide; more than 96,000 patients treated world-wide.

  28. Radiation Therapies Renfrew Colloquium 09/10/2013

  29. Loma Linda Radiation Therapies Renfrew Colloquium 09/10/2013

  30. The Proton Center at Loma Linda Radiation Therapies Renfrew Colloquium 09/10/2013

  31. The proton beam treatment room (gantry) from the patients view Radiation Therapies Renfrew Colloquium 09/10/2013

  32. In contrast: a photon treatment “center” Radiation Therapies Renfrew Colloquium 09/10/2013

  33. The cost Proton facilities are expensive, but when run efficiently [16 hours per day (two shifts), 64 patients per treatment room per day, 3 rooms: 192 patients per day], the cost per patients gets within a factor of two to photon (X-ray, “conventional”) radiation therapy. Radiation Therapies Renfrew Colloquium 09/10/2013

  34. The cost: example Proton therapy: ≈$60,000 Photon (X-ray, “conventional”): ≈$30,000 BUT: you have to add the follow-up cost. With large side effects, there are large follow-up costs. $5,000 follow-up costs per year (for a photon case with severe side effects) generates costs of $50,000 in 10 years, $100,000 in 20 years, … Radiation Therapies Renfrew Colloquium 09/10/2013

  35. Radiation Therapies Renfrew Colloquium 09/10/2013

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  38. Some useful links • www.protons.com • www.proton-therapy.org • www.protonbob.com Radiation Therapies Renfrew Colloquium 09/10/2013

  39. Conclusions • Nuclear physics saves lives every day. • Radiation treatment using beams of heavy charged particles (protons, ions) allows to focus on localized tumors due to the Bragg peak, thus, dramatically reducing negative side effects. • It is the preferred method for the removal of tumors that are difficult to reach by surgery (scull base, back of the eye) or where surgery has typically large side effects (prostate cancer). • Proton therapy has been used for 50 years and is well tested with long-term (10y) follow-up studies. It is not experimental. • Medicare and most (but not all!) health insurances pay nowadays for proton therapy. • However your doctor may have never heard about proton therapy or thinks that it is something very weird and untested. Radiation Therapies Renfrew Colloquium 09/10/2013

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