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Lesson 16

Lesson 16. Nuclear Medicine. What is Nuclear Medicine?. Diagnosis and Treatment of Disease using small amounts of radio-nuclides (radiopharmaceuticals)

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Lesson 16

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  1. Lesson 16 Nuclear Medicine

  2. What is Nuclear Medicine? • Diagnosis and Treatment of Disease using small amounts of radio-nuclides (radiopharmaceuticals) • In diagnosis (imaging) emitted radiation is detected by special detectors (cameras) from injected radio-nuclides to give real time 3 D images of the body. • In treatment, radio-nuclides are injected into the body, concentrated in the organ of choice and damage the tissue.

  3. Importance of Nuclear Medicine to students • Combines nuclear and radiochemistry, pharmacy, medicine, and radiation biology. • Nuclear medicine is a major employer of today’s nuclear and radiochemists, with an ever increasing demand for trained people. • Six figure starting salaries

  4. Special properties of 99Tcm • 142.7 keV gamma ray just perfect for imaging • 6 hour t1/2 minimizes radiation dose yet is tractable for hospital procedures • 10 million procedures per year in the US

  5. The 99Mo-> 99Tc decay is an example of transient equilibrium

  6. Milking

  7. Production of 99Mo

  8. Details and Problems • Currently AECL/MDS Nordion supply 40% of the world’s demand for 99Mo/99Tc. • Chemistry is performed on the irradiated targets by AECL resulting in a 99Mo soln. • The solnis shipped to MDS Nordion where it is loaded on the column and distributed. • The US demand requires about 34,000-46,000 Ci are produced per week.

  9. What is the Crisis? • These old reactors are nearing the end of their lifetime and their operation is not reliable. • Recently the Canadian and Dutch reactors underwent prolonged shutdowns • US use of 99Mo was curtailed and rationed. • President Obama gave orders to Steven Chu (Sec. of Energy) to “solve the problem.”

  10. Special Problems for the US • We have no domestic supply of 99Mo. US production was stopped in 1989. (It was claimed that non-US suppliers were subsidized and we could not compete.) • High cost production facilities, risk of reactor operations, low market price • The best techniques involve the use of HEU (19.7 % 235U) which poses a national security problem. • The waste from the production is significant.

  11. Positron Emission Tomography (PET) • PET imaging provides quantitative information about biochemical and physiological processes, in vivo • A tracer containing a positron emitter is injected, it decays emitting positrons and one detects the two 0.511 MeV photons resulting from the annihilation of the positron-electron interaction.

  12. Special things you can do with PET • Real time imaging of brain functions. Effect of drugs, Alzheimer’s disease, psychiatry. • 90% of use in oncology • Pharmacology

  13. Therapy • Oldest aspect of nuclear medicine • Idea is to use radiation to kill unhealthy cells • Problem is to do this without killing all the healthy cells. • A problem is that cancer cells are less oxygenated than normal cells and are more radiation resistant. • One trick is physical location, ie, fix the radionuclide in a cancer cell so that the decay will preferentially damage the cancer cell.

  14. Tricks • BNCT (Boron neutron cancer therapy) • Attach boron compounds to tumor locations. • Boron has a very high thermal neutron capture cross section • n+10B-> 11B->7Li + 4He • Re-oxygenation

  15. Bragg Curve Dosimetry

  16. Thanks to

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