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Re: Tl-201

We have a policy requiring individuals to notify Radiation Protection of all

nuclear medicine treatments.  The individual's TLD is collected, and he is

prohibited from entering a radiologically restricted area (RRA) until he can

clear our contamination monitors.  He also receives a "get out of jail free

card" to allow him to bypass our final portal monitors at the protected area

boundary.



If there is some overriding reason that such a person must enter a RRA (This

hasn't happened, yet.), he would receive entrance and exit whole body counts

to identify any internal occupational dose.



The opinions expressed are strictly mine.

It's not about dose, it's about trust.

Curies forever.



Bill Lipton

liptonw@dteenergy.com





Marty.Bourquin@GRACE.COM wrote:



> Since the individual is alarming portal monitors how do you handle

> access of the individual to potentially contaminated areas?

> And secondly how do you handle the fact they are "still irradiate their

> TLDs from the inside out"?  Do you keep them out of work for 4-5 weeks?

>

> We typically dont find out a person has had TI administered until

> they're on their way out and set off the portals and friskers. (they

> conviently forget to mention it until then).

>

> Marty Bourquin

> W.R.Grace

> Manager EHS, RSO

>

> -----Original Message-----

> From: mlantz33@CYBERTRAILS.COM [mailto:mlantz33@CYBERTRAILS.COM]

> Sent: Monday, August 05, 2002 1:39 PM

> To: willim01@mskcc.org

> Cc: radsafe@list.vanderbilt.edu

> Subject: Re: Tl-201

>

> Matt is absolutely correct.  I just saw two messages that implied that

> we were wrong in telling Kurt Geber that Tl-202 is the cause of the

> portal monitor alarms.  They reasoned that Tl-202 was less than 5% of

> the original activity.  In fact, it is usually less than 2% in the MANY

> cases I have seen  -- ON DAY 1.

>

> However, at day 60, it is 99% of what the individual has in them.  This

> is simple decay of two radionuclides, one with a short half-life and

> one with a slightly longer half-life.

>

> We happen to have portal monitors AND whole body counters at our site.

> So, it is very simple to evaluate a portal monitor alarm and show the

> Tl-202 begin to dominate over time.  Therefore, when workers still

> irradiate their TLDs from the inside out, alarm portal monitors, and

> make the assessment of other internal radionuclides difficult to

> separate (past 30 days, as was the original question), it isn't because

> of the Tl-201 that, yes, was 95% of the mix on day 1, it is because of

> the Tl-202.

>

> Mike Lantz, CHP

>

> willim01@mskcc.org wrote:

>

>      Kurt,

>

>      It is not excessive and someone hit it right on.  It is the

> impurity

>      (Tl202, T1/2 12.2 d) that's hanging around still alarming the

> portals;

>      4 to 5 weeks sounds about right.

>

>      Obtain a copy of HPS Vol. 61. No.3 pp. 427-430, 1991, Michael

> Stabin

>      and Audrey Schlafke-Stelson for other nuclides and contaminants of

>      interest.

>

>

>      Matt Williamson

>      Memorial Sloan-Kettering Cancer Center

>      New York, NY  10021

>

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