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RE: Different colors of dose
Donna:
I think that perhaps the Nuclear Medicine tech needs a dose refresher in-service. If you check the Radar dosimetry site at
http://www.doseinfo-radar.com/RADARDoseRiskCalc.html
you will get the following statement to plug into a human research disclosure form for the 27 mCi bone scan:
"This research study involves exposure to radiation from a Tc-99m Medronate also known as Tc-99m Methyenediphosponate (MDP), . This radiation exposure is not necessary for your medical care and is for research purposes only. Using the standard way of describing radiation dose, from participating in this study, you will receive a total of 6293.7 mrad to your Bone Surfaces, 4795.2 mrad to your Urinary Bladder Wall and 919.079 mrad to your Red Marrow. Although each organ will receive a different dose, the amount of radiation exposure that you will receive from these procedures is equivalent to a whole body exposure of 693 days (1.898 years) of exposure to natural background radiation. This use involves minimal risk and is necessary to obtain the research information desired."
The calculated total effective dose was 569 mrem (5.69 mSv).
As was stated in a previous posting, the risks of radiation harm are far outweighed by the benefits but I do not think that it is proper to provide such a gross understatement of the dose to the patient. your posting is prompting me to check out what our techs are telling their patients.
I hope you have been following the postings concerning outpatient I-131 therapy treatments. With a 225 mCi load I am sure you are aware of how significant a source you will be. That dosage is just below our upper limit for outpatient treatment without specific patient uptake/excretion measurements and would only be given to patients that we are reasonable sure would abide with isolation restrictions for the first two days after administration (to give a 0.125 occupancy factor in the NRC NUREG-1556 App U equation).
Best of luck with your therapy.
Hobie Shackford, RSO
Roger Williams Hospital
Providence, RI
401-456-2471
hshackford@rwmc.org
-----Original Message-----
From: owner-radsafe@list.vanderbilt.edu
[mailto:owner-radsafe@list.vanderbilt.edu]On Behalf Of Donna O'Kelly
Sent: Thursday, April 01, 2004 11:26 PM
To: Radsafe@list.vanderbilt.edu
Subject: Different colors of dose
I have been a member of this list for almost two years now and never felt
the need to post until now. In the last six months, I have been diagnosed
with two primary cancers, kidney and thyroid. Luckily - both were caught
early, so I expect to be around for a long while.
My issue originates from my going to get a bone scan (27 mCi Tc-99m-MDP)
and the rad tech telling me I'm not getting any more dose than if I stayed
out in the sun for an hour. How do you even begin to counter that? (A
Landauer OSL on my hip over 3 days gave a dose of 67 mrem). Secondly, is
the fact that this 27 mCi is completely "safe" for me for medical purposes,
but if I wee to encounter this same isotope and activity at my facility, it
would be regulated and *I* would become a radiation area and visitors
wouldn't be allowed near it. But since I got it from a medical facility,
it was okay. I dunno is the 140 keV gamma from safer if it is given to me
in a medical facility??? I think not. There's so much hypocrisy to the
whole thing in my mind.
What about from CTs of the head, neck, abdomen and pelvis? Again, no harm
since it's a medical issue - but I encounter it at work...and it's just a
horrible thing.
I won't even go into the 225 mCi I-131 I'm getting ready to ingest..
I think this is a discrepancy that should be pointed out and addressed with
folks across the board. I've certainly incorporated this information into
the tours that I give at my facility.
Thoughts anyone?
Donna J. O'Kelly, Ph.D
Laboratory Manager
Reactor Health Physicist
Nuclear Engineering Teaching Laboratory
The University of Texas at Austin
J.J. Pickle Research Campus
10100 Burnet Road, Building 159
Austin, TX 78758
office: (512) 232-4174
fax: (512) 471-4589
http://www.me.utexas.edu/~netl
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