Re: " Nuclear reactor not necessary for medicine: doctors "

[daleboyce@charter.net]

" Nuclear reactor not necessary for medicine: doctors "Hi all,



For those of you not close to the nuclear medicine industry, reactors are necessary for nuclear medicine isotopes. Cyclotrons have a limit to the amount of activity they can make due to the energy lost by ionization.  Very high heat loads are generated in small amounts of material, so it takes many machines just to meet the needs for one diagnostic isotope.  Moreover, the target materials often must be separated isotopes, and are expensive.



On top of that, cyclotrons tend to produce neutron deficient isotopes. In the case of F18 this is useful for PET scans especially due to the short half-life off-setting the very high dose rate due to the positron, and the annihilation gammas.  However, for positron emitters the 511 gammas from positrons are a detriment in therapeutics as they tend to cause non-localized exposure. Electron capture isotopes are great for diagnostics due to the low dose rate, are for the same reason relatively poor candidates for therapeutics.



In reactors the high flux and high cooling capacity combined with the thermal energies of the neutron allow large amounts of activity to be made with small amounts of target material.  Reactor production is really the only way to produce therapeutic quantities of isotopes such as I131 and Ho166.



Yttrium 90 is a common candidate for development of therapeutics since it can be milked from existing supplies of Sr90.  However, its chemical, and decay properties are not universally adaptable to new therapeutics being developed. 



Dale

daleboyce@charter.net

  ----- Original Message ----- 

  From: Franta, Jaroslav 

  To: Radsafe (E-mail) 

  Sent: Monday, August 30, 2004 9:49 AM

  Subject: " Nuclear reactor not necessary for medicine: doctors "





  Hmmm -- makes one wonder how it would be if everyone thought the same way, and nobody built reactors.... 



  Jaro 

  ^^^^^^^^^^^^^^^^^^^^ 



  Fed: Nuclear reactor not necessary for medicine: doctors 

  Australian Associated Press General News 

  30 August 2004  



  N SYDNEY, Aug 30 AAP - There was no medical justification for a new nuclear reactor in Sydney, doctors said today. 



  Emerging technology would soon replace the need for radioactive isotopes, currently used in the diagnosis and treatment of illnesses including cancer, Associate Professor Lou Irving said today.



  "It's likely that in the long-term - 10 years plus - isotopes generated by nuclear reactors will be redundant for medical purposes and it will be taken up by isotopes generated by cyclotrons (magnetic particle accelerators), or by other technology," he said.



  Prof Irving, the director of respiratory medicine at Royal Melbourne Hospital, joined other doctors in Sydney today to call for the government to abandon plans to build a new nuclear reactor in Sydney's suburban Lucas Heights.



  Even if medicine continued to need radioactive isotopes, Prof Irving said they could be sourced from other countries. 



  "There are alternative sources of isotopes that are currently being used and, in fact, most countries throughout the world import their isotopes," he said.



  Former diplomat, Adjunct Professor Richard Broinowski said it would be a furphy to say Australia would lose its place on the board of the International Atomic Energy Agency (IAEA) if the reactor wasn't built.



  "In my view, as a former diplomat, it's absolutely irrelevant to Australia's credentials as a nuclear player," said Prof Broinowski, of the University of Sydney.



  Conservationists backed the doctors' calls to abandon plans for a new reactor. 



  "Since 1997, the Howard government's sole justification for the construction of this new $350 million nuclear reactor has been that it is essential for the production of life-saving medicines," said Australian Conservation Foundation director Don Henry.



  "We don't need a nuclear reactor to create nuclear medicines. 



  "We can have access to state-of-the-art nuclear medicine by importing some reactor-produced isotopes and producing the remainder here in cyclotrons."