Re: iodine treatment

["Sorensen, Scott" <ssorensen@saint-lukes.org>]

Using the NRC default "patient-specific" factors, I estimate that Thyroid
Cancer patients can be released immediately after administrations up to 221
mCi I-131.  Hospitals can also release Hyperthyroid patients immediately
after administrations up to 57 mCi I-131.  The default NRC values do appear
to be conservative (provided that patients follow their instructions), and
actual exposures should be less than 500 mrem.  Other factors can be used
when justified.

Regarding contamination concerns, the NRC states that these can be ignored
since the estimated ingestion dose is within the uncertainty of the external
dose.  The low ingestion dose estimate is based on the application of the
"Health Physics Magic Number" of 10-5 (basically you incorporate one hundred
thousandth of what you handle).

I too share Louie Tonry's nervousness about releasing patients receiving
therapeutic quantities of I-131.  The treatment rooms certainly do get
contaminated.  It's now been a couple of years since Reg Guide 8.39 was
issued (4/97).  Some questions for the list...

1)  Have the experiences been good or bad for those using "patient-specific"
factors?
2)  For those who have not adopted the new measures, why?
3)  How does ALARA fit into this?

Thanks for you thoughts,

-Scott Sorensen, RSO
 Saint Luke's Hospital of Kansas City
  ssorensen@saint-lukes.org

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