Dose Rates from Patients -Reply

[Connie Ketarkus <KETARKUC@ohsu.edu>]

>>> "MIKE RUSSELL" <russelmj@songs.sce.com> 07/09/96 12:12pm >>>

     Here's a question for the medical HPs.

     A patient is given 175 mCi I-131 (thyroid cancer?), what is the
     occupational dose to the attending medical staff?

     What dose rate at 1 meter from the patient?

     Is occupational dose monitoring normally required for medical
     personnel?

     Thanks.

     Mike Russell
     russelmj@songs.sce.com

Mike,
I can only relate my experiences:
Dose of 131-I given:		Initial dose-rate: (one meter from anterior
chest/neck)
142mCi			76mRem/hour
145mCi			70mRem/hour
54mCi				25mR/hr
144mCi			75mR/hr
142mCi			70mR/hr
142mCi			80mR/hr
187mCi			80mR/hr
118mCi			60mR/hr
96mCi				50mR/hr
96mCi				60mR/hr
188mCi			135mR/hr
125mCi			65mR/hr
100mCi			70mR/hr


you get the idea . . . . . each patient is different.  their initial exposure
rate depends on their size (fat, skinny,
tall, short) and, most importantly, their neck and whole-body uptakes.

note, these are *initial* exposure rates, and these fall very rapidly, usually
to less than + in the first 
24 hours due to urinary excretion.

dose to the medical staff depends on how long (and how close) they spent with
the patient.  in my experiences, the nursing staff I provide with personal
instant-read dosimeters receive perhaps 1 to 5 mRem for the patient's *entire
stay*, most physicians receive no reportable exposure

occupational dose-monitoring is required for those workers who are "likely to
receive" 10% of the MPD
(maximum permissible dose).  Since the whole-body occupational MPD is
5000mRem/year,  the staff would have to argue that they are 'likely' to receive
500mRem from these patient(s) to insist upon dosimetry 

We provide personal dosimeters for anyone to use when entering the patients room
(family, clergy, staff) as a courtesy and as a way to ease the fears of those
who believe they are getting more exposure than they actually are  (me
included!!)


Hope this helps---Disclaimer:  I am not a Health Physicist

P.S.  yes, all the above patients were being treated to 'ablate' any remaining
thyroid tissue post-thyroidectomy for thyroid cancer (papillary or follicular)



Connie Ketarkus, BS, CNMT
Medical Physics Technologist
Oregon Health Sciences University Hospital