[Intl_DxMedPhys] [EXTERNAL] Radiotoxicity testing

Thu Jun 5 16:28:50 EDT 2025

And a funny story.  They moved some linear accelerators from Princess
Margaret Hospital on Sherbourne to the present site on University Ave.  The
CNSC required urine bioassay to determine if there was any DU contamination
of the movers.  When we did the testing we found activity in one of the
movers.  On further investigation, it was found that the mover lived on a
farm and drank well water.  The well water had high radon contamination.

Spencer M Fisher

On Thu, Jun 5, 2025 at 4:21 PM Spencer Fisher <sfisher373 at gmail.com> wrote:

> In Canada there are regulatory documents covering which isotopes require
> bioassay and the time frequency, and how they are to be performed.  Not
> only that, but the biosassay requirements are listed as conditions on the
> licence.  So all they have to do is read their licence.  For I-131, the
> bioassay is done via thyroid counting, not urine.  The required urine
> bioassays are for isotopes not usually used by NM techs.  For example
> Tritium, Uranium etc.  So for instance if there is DU shielding , then
> urine counting and wipe testing are licence conditions.
> On the other hand, there is nothing stopping you from doing urine
> bioassays to help allay staff fear.  When I was RSO of a major downtown
> hospital in Toronto, we did urine testing of the techs for Tc-99m when we
> started using aerosol for VQ scanning of the lungs.  Nothing was found.
> When I was the Corporate RSO at Ontario Ontario Power Generation, routine
> urine samples were collected from all employees for tritium as tritium is
> common in the CANDU reactors.
> So the best way to check is just to read the licence.  You can then call
> the CNSC licence compliance officer for the site if you have any questions.
>  Spencer M Fisher
>
> On Thu, Jun 5, 2025 at 3:45 PM Timmerman, Michael via
> Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu>
> wrote:
>
>> It looks like you are in Canada but I will share the regulatory
>> requirements here in the US, which may be helpful. The US NRC has a
>> regulatory guide that covers bioassay for radioiodine. In most cases, I
>> would only recommend bioassay if there
>>
>> It looks like you are in Canada but I will share the regulatory
>> requirements here in the US, which may be helpful.
>>
>>
>>
>> The US NRC has a regulatory guide that covers bioassay for radioiodine.
>> In most cases, I would only recommend bioassay if there is a suspected
>> exposure, such as an I-131 capsule breaking open. The NRC considers
>> capsules as sealed sources for the sake of bioassay requirements and the
>> risk to staff is minimal if the capsule is not broken. I did work with a
>> site in the past that administered liquid radioiodine to patients who could
>> not swallow a capsule; however, the activities used (imaging procedures
>> only) fell well below the NRC limits requiring bioassay. We are mainly
>> concerned with people handling unsealed airborne/volatile radioiodine,
>> which is not common in the medical setting nowadays; I-131 capsules, for
>> example, are formulated to be way less volatile than they used to be. This
>> is directly from the below regulatory guide: (3) Capsules (such as gelatin
>> capsules given to patients for diagnostic tests) may be considered to
>> contain the iodine in sealed form, and bioassay would not be necessary
>> unless a capsule were inadvertently opened (e.g., dropped and crushed).
>>
>>
>>
>> https://urldefense.com/v3/__https://www.nrc.gov/docs/ML1406/ML14064A060.pdf__;!!KGKeukY!0MCGUOB6vmfR_xf6Q06Ml8T5_PWRRuWLJYs5CO4EAWfcPrtN-N25mOiHt7PLhHXrRlr5GPY3gdUIH7EMhuD1GLz74nvtle6WYbQKOax3jg$ 
>> <https://urldefense.com/v3/__https://www.nrc.gov/docs/ML1406/ML14064A060.pdf__;!!KGKeukY!1ESpz4uV1rSR-_UfmqcnZfq1ctWqRFluRtV2TYECbRPCzUbRVfWU0PKPV0a7wLnBRJHJwHVVuZ29WXVAVeF88buDF2Q2_9_cWuYSqsejQlLU0GFUMmslZb3S$>
>>
>>
>>
>> The US NRC also has regulations covering when internal monitoring is
>> required and this is based on the annual limit on intake (ALI) for the
>> radioisotope in question. Anyone likely to exceed 10% of the ALI must be
>> monitored for internal occupational dose. It is extremely unlikely for a
>> nuclear medicine technologist to exceed these levels unless something goes
>> horribly awry during an administration (or several). For example, the ALI
>> for Tc-99m is 80 mCi by oral ingestion or 200 mCi by inhalation. For
>> Lu-177, we are looking at 2 mCi by oral ingestion or inhalation.
>> Radioiodine limits are a lot lower (in the uCi range for I-125 and I-131)
>> but again, the likelihood is very low when using capsules. We see “likely
>> to exceed” a lot in NRC regulations, which requires us to make an educated
>> decision on what “likely” means.
>>
>>
>>
>>
>> https://urldefense.com/v3/__https://www.nrc.gov/reading-rm/doc-collections/cfr/part020/part020-1502.html__;!!KGKeukY!0MCGUOB6vmfR_xf6Q06Ml8T5_PWRRuWLJYs5CO4EAWfcPrtN-N25mOiHt7PLhHXrRlr5GPY3gdUIH7EMhuD1GLz74nvtle6WYbS_Lq0FdA$ 
>> <https://urldefense.com/v3/__https://www.nrc.gov/reading-rm/doc-collections/cfr/part020/part020-1502.html__;!!KGKeukY!1ESpz4uV1rSR-_UfmqcnZfq1ctWqRFluRtV2TYECbRPCzUbRVfWU0PKPV0a7wLnBRJHJwHVVuZ29WXVAVeF88buDF2Q2_9_cWuYSqsejQlLU0GFUMokebqvS$>
>>
>>
>>
>> I’ve never needed to perform bioassays in my previous roles as RSO. It’s
>> not impossible but I would guess it is rather unlikely nowadays. Interested
>> if others have any thoughts on this topic as well.
>>
>>
>>
>> Best,
>>
>>
>>
>> Mike
>> ________________________________________
>>
>> *Mike Timmerman, MS, DABR*
>>
>>
>> *Diagnostic Medical Physicist Sanford Health – Sioux Falls Region *Mobile:
>> (541) 213-1075
>>
>> [image: Icon Description automatically generated with medium confidence]
>>
>>
>>
>> *From:* Intl_dxmedphys_wd_osu_list
>> <intl_dxmedphys_wd_osu_list-bounces+michael.timmerman=
>> sanfordhealth.org at lists.osu.edu> *On Behalf Of *Idris Elbakri via
>> Intl_dxmedphys_wd_osu_list
>> *Sent:* Thursday, June 5, 2025 5:36 AM
>> *To:* intl_dxmedphys_wd_osu_list at lists.osu.edu
>> *Subject:* [EXTERNAL] [Intl_DxMedPhys] Radiotoxicity testing
>>
>>
>>
>> Dear colleagues, I received an inquiry about radiotoxicity urine testing
>> for nuc. medicine technologists. The question is if/when should those be
>> required, if at all. As I am not a NM expert, I am reaching out to see if
>> someone on this list
>>
>>
>>
>> Dear colleagues,
>>
>>
>>
>> I received an inquiry about radiotoxicity urine testing for nuc. medicine
>> technologists. The question is if/when should those be required, if at all.
>>
>>
>>
>> As I am not a NM expert, I am reaching out to see if someone on this list
>> can provide some insights. Thanks in advance for your responses.
>>
>>
>>
>> Idris
>>
>>
>>
>> Dr. Idris Elbakri
>>
>> CANQAP LTD
>>
>> https://urldefense.com/v3/__http://www.canqap.com__;!!KGKeukY!0MCGUOB6vmfR_xf6Q06Ml8T5_PWRRuWLJYs5CO4EAWfcPrtN-N25mOiHt7PLhHXrRlr5GPY3gdUIH7EMhuD1GLz74nvtle6WYbRaIW892Q$ 
>> <https://urldefense.com/v3/__http:/www.canqap.com__;!!KGKeukY!yTQkSO5dfACjQkULfShIlpIeyU23-Zc7UdMAflCNrEt8CTkIo-5R8uPFKXyYnDNyEtM5HyuzVH7vLXWOroD172Aa0Fx4ZyeZXjy0BQ$>
>>
>>
>>
>>
>>
>>
>>
>>
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