Lesson 16
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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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Lesson 16

Lesson 16

Nuclear Medicine


What is nuclear medicine

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.


Importance of nuclear medicine to students

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


Special properties of 99 tc m

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


Lesson 16

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


Lesson 16

Milking


Production of 99 mo

Production of 99Mo


Details and problems

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.


What is the crisis

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.”


Special problems for the us

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.


Positron emission tomography pet

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.


Special things you can do with pet

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


Therapy

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.


Tricks

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


Bragg curve dosimetry

Bragg Curve Dosimetry


Lesson 16

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