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Re: Nuclear Medicine Dosages & Risks
Re: Nuclear Medicine Dosages & Risks
Is this information accurate?
Thank you.
DSH
--------------------------------------------------
"Stress tests using radiological agents confer low long-term risk of cancer,
but patients undergoing such examinations often receive little or inaccurate
information about these risks."
"A sestamibi scan is approximately 12 mSv. A thallium scan is approximately
25 mSv. (For comparison, the annual background radiation per annum a person
receives is approximately 3 mSv.)"
"A thallium scan corresponds the dose of 250 chest x rays, or an extra
cancer risk of about 1 in 16000 exposed patients (A. de González)."
"The lifetime risk of fatal cancer development is 4%/Sv or 0.004%/mSv or
about 0.1% for a thallium scan. Therefore, frequent usage of these tests
has to balance the benefits against the risks of radiation."
Is this information accurate?
Thank you.
DSH
--------------------------------------------------
"Stress tests using radiological agents confer low long-term risk of cancer,
but patients undergoing such examinations often receive little or inaccurate
information about these risks."
"A sestamibi scan is approximately 12 mSv. A thallium scan is approximately
25 mSv. (For comparison, the annual background radiation per annum a person
receives is approximately 3 mSv.)"
"A thallium scan corresponds the dose of 250 chest x rays, or an extra
cancer risk of about 1 in 16000 exposed patients (A. de González)."
"The lifetime risk of fatal cancer development is 4%/Sv or 0.004%/mSv or
about 0.1% for a thallium scan. Therefore, frequent usage of these tests
has to balance the benefits against the risks of radiation."
Re: Nuclear Medicine Dosages & Risks
D. Spencer Hines wrote:
> Is this information accurate?
>
> Thank you.
>
> DSH
> --------------------------------------------------
>
> "Stress tests using radiological agents confer low long-term risk of cancer,
> but patients undergoing such examinations often receive little or inaccurate
> information about these risks."
>
> "A sestamibi scan is approximately 12 mSv. A thallium scan is approximately
> 25 mSv. (For comparison, the annual background radiation per annum a person
> receives is approximately 3 mSv.)"
>
> "A thallium scan corresponds the dose of 250 chest x rays, or an extra
> cancer risk of about 1 in 16000 exposed patients (A. de González)."
>
> "The lifetime risk of fatal cancer development is 4%/Sv or 0.004%/mSv or
> about 0.1% for a thallium scan. Therefore, frequent usage of these tests
> has to balance the benefits against the risks of radiation."
>
>
That part of the Wikipedia is essentially based on an article in The
Lancet. The same issue also included the following comment from Peter
Herzog and Christina T Rieger:
"In today’s Lancet, Amy Berrington de González and Sarah Darby use
cancer-rate data from survivors of the Japanese atomic bombings as a
model to study the risk of cancer from diagnostic X-rays. These
researchers compiled their data on the incidence of cancers from tumour
registers in the UK and 14 other countries. They compared these cancer
rates with the numbers of X-ray procedures done in these countries and
statistically analysed the number of cancers induced by the radiation
exposure from these procedures. The lifetime risk of developing cancer
attributable to diagnostic X-rays was 0·6–1·8% in the countries
investigated, except in Japan, where the lifetime risk was 3·2%. In the
UK, for example, this exposure causes an annual excess risk of 700
cancer cases.
The Japanese survival data are the best available because there are no
other data showing the effect of ionising radiation on a large human
population; but the data have limitations. One limitation is that the
survivors were not only directly exposed with gamma rays from the bomb
detonations but also with beta radiation, and, most importantly, by
incorporation of radionuclides emitting beta and high-energy alpha
radiation from contaminated food, water, and dust in the air. This
additional exposure will not occur in patients undergoing radiological
examinations but contributes to the morbidity and mortality of the
atomic bomb survivors. Additionally the gamma rays to which the atomic
bomb survivors were exposed were of a different energy spectrum from
that used for diagnostic X-ray. Without better data, however, it is
probably adequate to use the Japanese data. But these additional
concerns should be taken seriously and the derived numbers for the
incidence of cancer caused by X-rays should be critically assessed in
future investigations, because the cancer risk is probably overestimated
with use of the Japanese data."
Adam White
D. Spencer Hines wrote:
> Is this information accurate?
>
> Thank you.
>
> DSH
> --------------------------------------------------
>
> "Stress tests using radiological agents confer low long-term risk of cancer,
> but patients undergoing such examinations often receive little or inaccurate
> information about these risks."
>
> "A sestamibi scan is approximately 12 mSv. A thallium scan is approximately
> 25 mSv. (For comparison, the annual background radiation per annum a person
> receives is approximately 3 mSv.)"
>
> "A thallium scan corresponds the dose of 250 chest x rays, or an extra
> cancer risk of about 1 in 16000 exposed patients (A. de González)."
>
> "The lifetime risk of fatal cancer development is 4%/Sv or 0.004%/mSv or
> about 0.1% for a thallium scan. Therefore, frequent usage of these tests
> has to balance the benefits against the risks of radiation."
>
>
That part of the Wikipedia is essentially based on an article in The
Lancet. The same issue also included the following comment from Peter
Herzog and Christina T Rieger:
"In today’s Lancet, Amy Berrington de González and Sarah Darby use
cancer-rate data from survivors of the Japanese atomic bombings as a
model to study the risk of cancer from diagnostic X-rays. These
researchers compiled their data on the incidence of cancers from tumour
registers in the UK and 14 other countries. They compared these cancer
rates with the numbers of X-ray procedures done in these countries and
statistically analysed the number of cancers induced by the radiation
exposure from these procedures. The lifetime risk of developing cancer
attributable to diagnostic X-rays was 0·6–1·8% in the countries
investigated, except in Japan, where the lifetime risk was 3·2%. In the
UK, for example, this exposure causes an annual excess risk of 700
cancer cases.
The Japanese survival data are the best available because there are no
other data showing the effect of ionising radiation on a large human
population; but the data have limitations. One limitation is that the
survivors were not only directly exposed with gamma rays from the bomb
detonations but also with beta radiation, and, most importantly, by
incorporation of radionuclides emitting beta and high-energy alpha
radiation from contaminated food, water, and dust in the air. This
additional exposure will not occur in patients undergoing radiological
examinations but contributes to the morbidity and mortality of the
atomic bomb survivors. Additionally the gamma rays to which the atomic
bomb survivors were exposed were of a different energy spectrum from
that used for diagnostic X-ray. Without better data, however, it is
probably adequate to use the Japanese data. But these additional
concerns should be taken seriously and the derived numbers for the
incidence of cancer caused by X-rays should be critically assessed in
future investigations, because the cancer risk is probably overestimated
with use of the Japanese data."
Adam White
Re: Nuclear Medicine Dosages & Risks
"Adam White" <adam.white@pbh-tr.nhs.uk> wrote in message
news:fu3522$88f$1@aioe.org...
> D. Spencer Hines wrote:
>> Is this information accurate?
>>
>> Thank you.
>>
>> DSH
>> --------------------------------------------------
>>
>> "Stress tests using radiological agents confer low long-term risk of
>> cancer, but patients undergoing such examinations often receive
>> little or inaccurate information about these risks."
>>
>> "A sestamibi scan is approximately 12 mSv. A thallium scan is
>> approximately 25 mSv. (For comparison, the annual background
>> radiation per annum a person receives is approximately 3 mSv.)"
>>
>> "A thallium scan corresponds the dose of 250 chest x rays, or an extra
>> cancer risk of about 1 in 16000 exposed patients (A. de González)."
>>
>> "The lifetime risk of fatal cancer development is 4%/Sv or 0.004%/mSv or
>> about 0.1% for a thallium scan. Therefore, frequent usage of these tests
>> has to balance the benefits against the risks of radiation."
> That part of the Wikipedia is essentially based on an article in The
> Lancet. The same issue also included the following comment from Peter
> Herzog and Christina T Rieger:
Right.
> "In today’s Lancet, Amy Berrington de González and Sarah Darby use
> cancer-rate data from survivors of the Japanese atomic bombings as a model
> to study the risk of cancer from diagnostic X-rays. These researchers
> compiled their data on the incidence of cancers from tumour registers in
> the UK and 14 other countries. They compared these cancer rates with the
> numbers of X-ray procedures done in these countries and statistically
> analysed the number of cancers induced by the radiation exposure from
> these procedures. The lifetime risk of developing cancer attributable to
> diagnostic X-rays was 0·6–1·8% in the countries investigated, except in
> Japan, where the lifetime risk was 3·2%. In the UK, for example, this
> exposure causes an annual excess risk of 700 cancer cases.
>
> The Japanese survival data are the best available because there are no
> other data showing the effect of ionising radiation on a large human
> population; but the data have limitations. One limitation is that the
> survivors were not only directly exposed with gamma rays from the bomb
> detonations but also with beta radiation, and, most importantly, by
> incorporation of radionuclides emitting beta and high-energy alpha
> radiation from contaminated food, water, and dust in the air. This
> additional exposure will not occur in patients undergoing radiological
> examinations but contributes to the morbidity and mortality of the atomic
> bomb survivors. Additionally the gamma rays to which the atomic bomb
> survivors were exposed were of a different energy spectrum from that used
> for diagnostic X-ray. Without better data, however, it is probably
> adequate to use the Japanese data. But these additional concerns should be
> taken seriously and the derived numbers for the incidence of cancer caused
> by X-rays should be critically assessed in future investigations, because
> the cancer risk is probably overestimated with use of the Japanese data."
>
> Adam White
Good Points.
Thank you very much.
DSH
"Adam White" <adam.white@pbh-tr.nhs.uk> wrote in message
news:fu3522$88f$1@aioe.org...
> D. Spencer Hines wrote:
>> Is this information accurate?
>>
>> Thank you.
>>
>> DSH
>> --------------------------------------------------
>>
>> "Stress tests using radiological agents confer low long-term risk of
>> cancer, but patients undergoing such examinations often receive
>> little or inaccurate information about these risks."
>>
>> "A sestamibi scan is approximately 12 mSv. A thallium scan is
>> approximately 25 mSv. (For comparison, the annual background
>> radiation per annum a person receives is approximately 3 mSv.)"
>>
>> "A thallium scan corresponds the dose of 250 chest x rays, or an extra
>> cancer risk of about 1 in 16000 exposed patients (A. de González)."
>>
>> "The lifetime risk of fatal cancer development is 4%/Sv or 0.004%/mSv or
>> about 0.1% for a thallium scan. Therefore, frequent usage of these tests
>> has to balance the benefits against the risks of radiation."
> That part of the Wikipedia is essentially based on an article in The
> Lancet. The same issue also included the following comment from Peter
> Herzog and Christina T Rieger:
Right.
> "In today’s Lancet, Amy Berrington de González and Sarah Darby use
> cancer-rate data from survivors of the Japanese atomic bombings as a model
> to study the risk of cancer from diagnostic X-rays. These researchers
> compiled their data on the incidence of cancers from tumour registers in
> the UK and 14 other countries. They compared these cancer rates with the
> numbers of X-ray procedures done in these countries and statistically
> analysed the number of cancers induced by the radiation exposure from
> these procedures. The lifetime risk of developing cancer attributable to
> diagnostic X-rays was 0·6–1·8% in the countries investigated, except in
> Japan, where the lifetime risk was 3·2%. In the UK, for example, this
> exposure causes an annual excess risk of 700 cancer cases.
>
> The Japanese survival data are the best available because there are no
> other data showing the effect of ionising radiation on a large human
> population; but the data have limitations. One limitation is that the
> survivors were not only directly exposed with gamma rays from the bomb
> detonations but also with beta radiation, and, most importantly, by
> incorporation of radionuclides emitting beta and high-energy alpha
> radiation from contaminated food, water, and dust in the air. This
> additional exposure will not occur in patients undergoing radiological
> examinations but contributes to the morbidity and mortality of the atomic
> bomb survivors. Additionally the gamma rays to which the atomic bomb
> survivors were exposed were of a different energy spectrum from that used
> for diagnostic X-ray. Without better data, however, it is probably
> adequate to use the Japanese data. But these additional concerns should be
> taken seriously and the derived numbers for the incidence of cancer caused
> by X-rays should be critically assessed in future investigations, because
> the cancer risk is probably overestimated with use of the Japanese data."
>
> Adam White
Good Points.
Thank you very much.
DSH
Re: Nuclear Medicine Dosages & Risks
D. Spencer Hines wrote:
> Is this information accurate?
>
> Thank you.
>
> DSH
>
> "Stress tests using radiological agents confer low long-term risk of cancer,
> but patients undergoing such examinations often receive little or inaccurate
> information about these risks."
Yeah, that's probably accurate.
> "A sestamibi scan is approximately 12 mSv. A thallium scan is approximately
> 25 mSv. (For comparison, the annual background radiation per annum a person
> receives is approximately 3 mSv.)"
Well, it depends on what particular organ you are measuring. I'll assume
you mean whole-body effective dose equivalent.
According to the Cardiolite (sestamibi) package insert, the effective
dose equivalent is 13.3 mSv per 30 mCi dose.
According to the thallium package insert, the effective dose equivalent
is 0.22 mSv/MBq. An average dose is about 3.5 mCi which translates into
130 MBq. So the EDE for thallium-201 is 28.6 mSv.
> "A thallium scan corresponds the dose of 250 chest x rays, or an extra
> cancer risk of about 1 in 16000 exposed patients (A. de González)."
Sure.
> "The lifetime risk of fatal cancer development is 4%/Sv or 0.004%/mSv or
> about 0.1% for a thallium scan. Therefore, frequent usage of these tests
> has to balance the benefits against the risks of radiation."
Any test should be weighed between risks and benefits. These tests
(mibi, thallium) are not screening tools, or at least, they're not
supposed to be. They are to be used when there is a suspicion of
ischemic heart disease, or as follow-up to treatment.
Given that around 1 in 4 Canadians are going to die from cancer anyway
(according to the Canadian Cancer Society), the additional 0.1% risk is
practically negligible when weighed against the risks of undiagnosed
heart disease. In my opinion, anyway.
Andrew
D. Spencer Hines wrote:
> Is this information accurate?
>
> Thank you.
>
> DSH
>
> "Stress tests using radiological agents confer low long-term risk of cancer,
> but patients undergoing such examinations often receive little or inaccurate
> information about these risks."
Yeah, that's probably accurate.
> "A sestamibi scan is approximately 12 mSv. A thallium scan is approximately
> 25 mSv. (For comparison, the annual background radiation per annum a person
> receives is approximately 3 mSv.)"
Well, it depends on what particular organ you are measuring. I'll assume
you mean whole-body effective dose equivalent.
According to the Cardiolite (sestamibi) package insert, the effective
dose equivalent is 13.3 mSv per 30 mCi dose.
According to the thallium package insert, the effective dose equivalent
is 0.22 mSv/MBq. An average dose is about 3.5 mCi which translates into
130 MBq. So the EDE for thallium-201 is 28.6 mSv.
> "A thallium scan corresponds the dose of 250 chest x rays, or an extra
> cancer risk of about 1 in 16000 exposed patients (A. de González)."
Sure.
> "The lifetime risk of fatal cancer development is 4%/Sv or 0.004%/mSv or
> about 0.1% for a thallium scan. Therefore, frequent usage of these tests
> has to balance the benefits against the risks of radiation."
Any test should be weighed between risks and benefits. These tests
(mibi, thallium) are not screening tools, or at least, they're not
supposed to be. They are to be used when there is a suspicion of
ischemic heart disease, or as follow-up to treatment.
Given that around 1 in 4 Canadians are going to die from cancer anyway
(according to the Canadian Cancer Society), the additional 0.1% risk is
practically negligible when weighed against the risks of undiagnosed
heart disease. In my opinion, anyway.
Andrew
Re: Nuclear Medicine Dosages & Risks
"Andrew Kerr" <apkerr@yahoo . com > wrote in message
news:bO9Nj.51724$612.19568@read1.cgocable . net ...
> D. Spencer Hines wrote:
>> Is this information accurate?
>>
>> Thank you.
>>
>> DSH
>
>> "Stress tests using radiological agents confer low long-term risk of
>> cancer, but patients undergoing such examinations often receive
>> little or inaccurate information about these risks."
>
> Yeah, that's probably accurate.
It can be annoying for a reasonably intelligent patient. The techs simply
don't have the time and are stressed by too many patients. The physicians
have often forgotten the details since their boards.
>> "A sestamibi scan is approximately 12 mSv. A thallium scan is
>> approximately 25 mSv. (For comparison, the annual background
>> radiation per annum a person receives is approximately 3 mSv.)"
>
> Well, it depends on what particular organ you are measuring. I'll assume
> you mean whole-body effective dose equivalent.
Yes. Precisely.
> According to the Cardiolite (sestamibi) package insert, the effective dose
> equivalent is 13.3 mSv per 30 mCi dose.
O.K. I like hard data like that. How many 30mCi doses does a 200 lb man
get and a 105 lb woman -- for a Cardiolite scan?
> According to the thallium package insert, the effective dose equivalent is
> 0.22 mSv/MBq. An average dose is about 3.5 mCi which translates into 130
> MBq. So the EDE for thallium-201 is 28.6 mSv.
Great! More hard data. EDE = Effective Dose Equivalent [Whole-Body]?
>> "A thallium scan corresponds the dose of 250 chest x rays, or an extra
>> cancer risk of about 1 in 16000 exposed patients (A. de González)."
>
> Sure.
O.K.
>> "The lifetime risk of fatal cancer development is 4%/Sv or 0.004%/mSv or
>> about 0.1% for a thallium scan. Therefore, frequent usage of these tests
>> has to balance the benefits against the risks of radiation."
>
> Any test should be weighed between risks and benefits. These tests (mibi,
> thallium) are not screening tools, or at least, they're not supposed to
> be. They are to be used when there is a suspicion of ischemic heart
> disease, or as follow-up to treatment.
Precisely. I'm certainly not suggesting they shouldn't be used.
> Given that around 1 in 4 Canadians are going to die from cancer anyway
> (according to the Canadian Cancer Society), the additional 0.1% risk is
> practically negligible when weighed against the risks of undiagnosed heart
> disease. In my opinion, anyway.
>
> Andrew
I concur.
1 in 4 Canadians will die from cancer?
Hmmmmm... I wonder what it is for Americans [folks in the United States].
Could you please point me to the source for the 1 in 4 Canadians?
Thanks very much. You are obviously a smart guy.
DSH
Lux et Veritas et Libertas
"Andrew Kerr" <apkerr@yahoo . com > wrote in message
news:bO9Nj.51724$612.19568@read1.cgocable . net ...
> D. Spencer Hines wrote:
>> Is this information accurate?
>>
>> Thank you.
>>
>> DSH
>
>> "Stress tests using radiological agents confer low long-term risk of
>> cancer, but patients undergoing such examinations often receive
>> little or inaccurate information about these risks."
>
> Yeah, that's probably accurate.
It can be annoying for a reasonably intelligent patient. The techs simply
don't have the time and are stressed by too many patients. The physicians
have often forgotten the details since their boards.
>> "A sestamibi scan is approximately 12 mSv. A thallium scan is
>> approximately 25 mSv. (For comparison, the annual background
>> radiation per annum a person receives is approximately 3 mSv.)"
>
> Well, it depends on what particular organ you are measuring. I'll assume
> you mean whole-body effective dose equivalent.
Yes. Precisely.
> According to the Cardiolite (sestamibi) package insert, the effective dose
> equivalent is 13.3 mSv per 30 mCi dose.
O.K. I like hard data like that. How many 30mCi doses does a 200 lb man
get and a 105 lb woman -- for a Cardiolite scan?
> According to the thallium package insert, the effective dose equivalent is
> 0.22 mSv/MBq. An average dose is about 3.5 mCi which translates into 130
> MBq. So the EDE for thallium-201 is 28.6 mSv.
Great! More hard data. EDE = Effective Dose Equivalent [Whole-Body]?
>> "A thallium scan corresponds the dose of 250 chest x rays, or an extra
>> cancer risk of about 1 in 16000 exposed patients (A. de González)."
>
> Sure.
O.K.
>> "The lifetime risk of fatal cancer development is 4%/Sv or 0.004%/mSv or
>> about 0.1% for a thallium scan. Therefore, frequent usage of these tests
>> has to balance the benefits against the risks of radiation."
>
> Any test should be weighed between risks and benefits. These tests (mibi,
> thallium) are not screening tools, or at least, they're not supposed to
> be. They are to be used when there is a suspicion of ischemic heart
> disease, or as follow-up to treatment.
Precisely. I'm certainly not suggesting they shouldn't be used.
> Given that around 1 in 4 Canadians are going to die from cancer anyway
> (according to the Canadian Cancer Society), the additional 0.1% risk is
> practically negligible when weighed against the risks of undiagnosed heart
> disease. In my opinion, anyway.
>
> Andrew
I concur.
1 in 4 Canadians will die from cancer?
Hmmmmm... I wonder what it is for Americans [folks in the United States].
Could you please point me to the source for the 1 in 4 Canadians?
Thanks very much. You are obviously a smart guy.
DSH
Lux et Veritas et Libertas
Re: Nuclear Medicine Dosages & Risks
D. Spencer Hines wrote:
> "Andrew Kerr" <apkerr@yahoo . com > wrote in message
> news:bO9Nj.51724$612.19568@read1.cgocable . net ...
>
>> D. Spencer Hines wrote:
>
>>> Is this information accurate?
>>>
>>> Thank you.
>>>
>>> DSH
>>> "Stress tests using radiological agents confer low long-term risk of
>>> cancer, but patients undergoing such examinations often receive
>>> little or inaccurate information about these risks."
>> Yeah, that's probably accurate.
>
> It can be annoying for a reasonably intelligent patient. The techs simply
> don't have the time and are stressed by too many patients. The physicians
> have often forgotten the details since their boards.
I met several medical students while I was studying to be a nuclear
medicine technologist. They had a grand total of one (1) lecture on
nuclear medicine throughout their schooling. Radiology residents would
get more, of course. But those who became family practitioners or
general internists usually don't have a clue what's involved in nuclear
medicine
>>> "A sestamibi scan is approximately 12 mSv. A thallium scan is
>>> approximately 25 mSv. (For comparison, the annual background
>>> radiation per annum a person receives is approximately 3 mSv.)"
>> Well, it depends on what particular organ you are measuring. I'll assume
>> you mean whole-body effective dose equivalent.
>
> Yes. Precisely.
>
>> According to the Cardiolite (sestamibi) package insert, the effective dose
>> equivalent is 13.3 mSv per 30 mCi dose.
>
> O.K. I like hard data like that. How many 30mCi doses does a 200 lb man
> get and a 105 lb woman -- for a Cardiolite scan?
That depends on the institution and how they perform the test. We mostly
use a 2-day protocol which would involve 25 mCi one day and 30 mCi the
other. A lot of places use a 1-day protocol because they can do more
patients per week (ie: more revenue). That usually involves 10 mCi for
the first part and 30 mCi for the second.
We choose our protocol based on patient's weight. In our hospital, a
200lb man or woman would get a 2-day protocol. A 100lb man or woman
would get thallium. There are technical reasons why we do this.
There is a new high-speed camera coming out with dramatically reduced
doses needed (2-10 mCi). I'm not sure if it's commercially available
yet, or if it has been validated against the traditional style camera
(it's different technology). I think Cedars-Sinai is working on it.
>> According to the thallium package insert, the effective dose equivalent is
>> 0.22 mSv/MBq. An average dose is about 3.5 mCi which translates into 130
>> MBq. So the EDE for thallium-201 is 28.6 mSv.
>
> Great! More hard data. EDE = Effective Dose Equivalent [Whole-Body]?
Yes, EDE is a whole-body equivalent dose. Nuclear medicine tracers
deliver different exposures to different organs, depending on the method
that the tracer is cleared from the body and the physical
characteristics of the tracer itself. The EDE is calculated from those
other exposures. The EDE assumes a "normal" 70kg patient with good
kidney and liver function, who voids their bladder appropriately (not
dehydrated), etc.
>
>> Given that around 1 in 4 Canadians are going to die from cancer anyway
>> (according to the Canadian Cancer Society), the additional 0.1% risk is
>> practically negligible when weighed against the risks of undiagnosed heart
>> disease. In my opinion, anyway.
>>
>> Andrew
>
> I concur.
>
> 1 in 4 Canadians will die from cancer?
>
> Hmmmmm... I wonder what it is for Americans [folks in the United States].
> Could you please point me to the source for the 1 in 4 Canadians?
I suspect it's pretty much the same for Americans. Cancer incidence
depends on a lot of factors of course. I got that statistic from the
Canadian Cancer Society's 2008 Cancer Statistics report.
* w w w .cancer.ca/ccs/internet/mediareleaselist/0,,3543 434465 435804 langId-en.html
> Thanks very much. You are obviously a smart guy.
>
> DSH
>
> Lux et Veritas et Libertas
Andrew
D. Spencer Hines wrote:
> "Andrew Kerr" <apkerr@yahoo . com > wrote in message
> news:bO9Nj.51724$612.19568@read1.cgocable . net ...
>
>> D. Spencer Hines wrote:
>
>>> Is this information accurate?
>>>
>>> Thank you.
>>>
>>> DSH
>>> "Stress tests using radiological agents confer low long-term risk of
>>> cancer, but patients undergoing such examinations often receive
>>> little or inaccurate information about these risks."
>> Yeah, that's probably accurate.
>
> It can be annoying for a reasonably intelligent patient. The techs simply
> don't have the time and are stressed by too many patients. The physicians
> have often forgotten the details since their boards.
I met several medical students while I was studying to be a nuclear
medicine technologist. They had a grand total of one (1) lecture on
nuclear medicine throughout their schooling. Radiology residents would
get more, of course. But those who became family practitioners or
general internists usually don't have a clue what's involved in nuclear
medicine
>>> "A sestamibi scan is approximately 12 mSv. A thallium scan is
>>> approximately 25 mSv. (For comparison, the annual background
>>> radiation per annum a person receives is approximately 3 mSv.)"
>> Well, it depends on what particular organ you are measuring. I'll assume
>> you mean whole-body effective dose equivalent.
>
> Yes. Precisely.
>
>> According to the Cardiolite (sestamibi) package insert, the effective dose
>> equivalent is 13.3 mSv per 30 mCi dose.
>
> O.K. I like hard data like that. How many 30mCi doses does a 200 lb man
> get and a 105 lb woman -- for a Cardiolite scan?
That depends on the institution and how they perform the test. We mostly
use a 2-day protocol which would involve 25 mCi one day and 30 mCi the
other. A lot of places use a 1-day protocol because they can do more
patients per week (ie: more revenue). That usually involves 10 mCi for
the first part and 30 mCi for the second.
We choose our protocol based on patient's weight. In our hospital, a
200lb man or woman would get a 2-day protocol. A 100lb man or woman
would get thallium. There are technical reasons why we do this.
There is a new high-speed camera coming out with dramatically reduced
doses needed (2-10 mCi). I'm not sure if it's commercially available
yet, or if it has been validated against the traditional style camera
(it's different technology). I think Cedars-Sinai is working on it.
>> According to the thallium package insert, the effective dose equivalent is
>> 0.22 mSv/MBq. An average dose is about 3.5 mCi which translates into 130
>> MBq. So the EDE for thallium-201 is 28.6 mSv.
>
> Great! More hard data. EDE = Effective Dose Equivalent [Whole-Body]?
Yes, EDE is a whole-body equivalent dose. Nuclear medicine tracers
deliver different exposures to different organs, depending on the method
that the tracer is cleared from the body and the physical
characteristics of the tracer itself. The EDE is calculated from those
other exposures. The EDE assumes a "normal" 70kg patient with good
kidney and liver function, who voids their bladder appropriately (not
dehydrated), etc.
>
>> Given that around 1 in 4 Canadians are going to die from cancer anyway
>> (according to the Canadian Cancer Society), the additional 0.1% risk is
>> practically negligible when weighed against the risks of undiagnosed heart
>> disease. In my opinion, anyway.
>>
>> Andrew
>
> I concur.
>
> 1 in 4 Canadians will die from cancer?
>
> Hmmmmm... I wonder what it is for Americans [folks in the United States].
> Could you please point me to the source for the 1 in 4 Canadians?
I suspect it's pretty much the same for Americans. Cancer incidence
depends on a lot of factors of course. I got that statistic from the
Canadian Cancer Society's 2008 Cancer Statistics report.
* w w w .cancer.ca/ccs/internet/mediareleaselist/0,,3543 434465 435804 langId-en.html
> Thanks very much. You are obviously a smart guy.
>
> DSH
>
> Lux et Veritas et Libertas
Andrew
Re: Nuclear Medicine Dosages & Risks
"Andrew Kerr" <apkerr@yahoo . com > wrote in message
news:zKtNj.52330$dA2.21463@read2.cgocable . net ...
> D. Spencer Hines wrote:
>> "Andrew Kerr" <apkerr@yahoo . com > wrote in message
>> news:bO9Nj.51724$612.19568@read1.cgocable . net ...
>>
>>> D. Spencer Hines wrote:
>>
>>>> Is this information accurate?
>>>>
>>>> Thank you.
>>>>
>>>> DSH
>>>> "Stress tests using radiological agents confer low long-term risk of
>>>> cancer, but patients undergoing such examinations often receive
>>>> little or inaccurate information about these risks."
>>> Yeah, that's probably accurate.
>>
>> It can be annoying for a reasonably intelligent patient. The techs
>> simply don't have the time and are stressed by too many patients.
>> The physicians have often forgotten the details since their boards.
>
> I met several medical students while I was studying to be a nuclear
> medicine technologist. They had a grand total of one (1) lecture on
> nuclear medicine throughout their schooling. Radiology residents would get
> more, of course. But those who became family practitioners or general
> internists usually don't have a clue what's involved in nuclear medicine
That's Appalling! But I'm sure it's on the mark and correlates with what
I've seen. Even cardioloists are weak on the technical details.
>>>> "A sestamibi scan is approximately 12 mSv. A thallium scan is
>>>> approximately 25 mSv. (For comparison, the annual background
>>>> radiation per annum a person receives is approximately 3 mSv.)"
>>> Well, it depends on what particular organ you are measuring. I'll assume
>>> you mean whole-body effective dose equivalent.
>>
>> Yes. Precisely.
>>
>>> According to the Cardiolite (sestamibi) package insert, the effective
>>> dose equivalent is 13.3 mSv per 30 mCi dose.
>>
>> O.K. I like hard data like that. How many 30mCi doses does a 200 lb man
>> get and a 105 lb woman -- for a Cardiolite scan?
>
> That depends on the institution and how they perform the test. We mostly
> use a 2-day protocol which would involve 25 mCi one day and 30 mCi the
> other. A lot of places use a 1-day protocol because they can do more
> patients per week (ie: more revenue). That usually involves 10 mCi for the
> first part and 30 mCi for the second.
O.K. So that would seem to be 55 mCi for the 2-day protocol and 40mCi for
the 1-day protocol.
> We choose our protocol based on patient's weight. In our hospital, a 200lb
> man or woman would get a 2-day protocol. A 100lb man or woman would get
> thallium. There are technical reasons why we do this.
The 100 lb man or woman would get only Thallous Chloride [Myoview], 25 mSv
of Thallium-201 and no Tc-99m Sestamibi [Cardiolite] at all? Why is that?
> There is a new high-speed camera coming out with dramatically reduced
> doses needed (2-10 mCi). I'm not sure if it's commercially available yet,
> or if it has been validated against the traditional style camera (it's
> different technology). I think Cedars-Sinai is working on it.
Great!
>>> According to the thallium package insert, the effective dose equivalent
>>> is 0.22 mSv/MBq. An average dose is about 3.5 mCi which translates
>>> into 130 MBq. So the EDE for thallium-201 is 28.6 mSv.
O.K. We have 25 mSv above and 28.6 mSv here. That's a pretty close
correlation.
>> Great! More hard data. EDE = Effective Dose Equivalent [Whole-Body]?
>
> Yes, EDE is a whole-body equivalent dose. Nuclear medicine tracers deliver
> different exposures to different organs, depending on the method that the
> tracer is cleared from the body and the physical characteristics of the
> tracer itself. The EDE is calculated from those other exposures. The EDE
> assumes a "normal" 70kg patient with good kidney and liver function, who
> voids their bladder appropriately (not dehydrated), etc.
Roger.
>>> Given that around 1 in 4 Canadians are going to die from cancer anyway
>>> (according to the Canadian Cancer Society), the additional 0.1% risk is
>>> practically negligible when weighed against the risks of undiagnosed
>>> heart
>>> disease. In my opinion, anyway.
>>>
>>> Andrew
>>
>> I concur.
>>
>> 1 in 4 Canadians will die from cancer?
>>
>> Hmmmmm... I wonder what it is for Americans [folks in the United
>> States].
>> Could you please point me to the source for the 1 in 4 Canadians?
>
> I suspect it's pretty much the same for Americans. Cancer incidence
> depends on a lot of factors of course. I got that statistic from the
> Canadian Cancer Society's 2008 Cancer Statistics report.
>
> * w w w .cancer.ca/ccs/internet/mediareleaselist/0,,3543_434465_435804_langId-en.html
>
>> Thanks very much. You are obviously a smart guy.
>>
>> DSH
>>
>> Lux et Veritas et Libertas
>
> Andrew
"Andrew Kerr" <apkerr@yahoo . com > wrote in message
news:zKtNj.52330$dA2.21463@read2.cgocable . net ...
> D. Spencer Hines wrote:
>> "Andrew Kerr" <apkerr@yahoo . com > wrote in message
>> news:bO9Nj.51724$612.19568@read1.cgocable . net ...
>>
>>> D. Spencer Hines wrote:
>>
>>>> Is this information accurate?
>>>>
>>>> Thank you.
>>>>
>>>> DSH
>>>> "Stress tests using radiological agents confer low long-term risk of
>>>> cancer, but patients undergoing such examinations often receive
>>>> little or inaccurate information about these risks."
>>> Yeah, that's probably accurate.
>>
>> It can be annoying for a reasonably intelligent patient. The techs
>> simply don't have the time and are stressed by too many patients.
>> The physicians have often forgotten the details since their boards.
>
> I met several medical students while I was studying to be a nuclear
> medicine technologist. They had a grand total of one (1) lecture on
> nuclear medicine throughout their schooling. Radiology residents would get
> more, of course. But those who became family practitioners or general
> internists usually don't have a clue what's involved in nuclear medicine
That's Appalling! But I'm sure it's on the mark and correlates with what
I've seen. Even cardioloists are weak on the technical details.
>>>> "A sestamibi scan is approximately 12 mSv. A thallium scan is
>>>> approximately 25 mSv. (For comparison, the annual background
>>>> radiation per annum a person receives is approximately 3 mSv.)"
>>> Well, it depends on what particular organ you are measuring. I'll assume
>>> you mean whole-body effective dose equivalent.
>>
>> Yes. Precisely.
>>
>>> According to the Cardiolite (sestamibi) package insert, the effective
>>> dose equivalent is 13.3 mSv per 30 mCi dose.
>>
>> O.K. I like hard data like that. How many 30mCi doses does a 200 lb man
>> get and a 105 lb woman -- for a Cardiolite scan?
>
> That depends on the institution and how they perform the test. We mostly
> use a 2-day protocol which would involve 25 mCi one day and 30 mCi the
> other. A lot of places use a 1-day protocol because they can do more
> patients per week (ie: more revenue). That usually involves 10 mCi for the
> first part and 30 mCi for the second.
O.K. So that would seem to be 55 mCi for the 2-day protocol and 40mCi for
the 1-day protocol.
> We choose our protocol based on patient's weight. In our hospital, a 200lb
> man or woman would get a 2-day protocol. A 100lb man or woman would get
> thallium. There are technical reasons why we do this.
The 100 lb man or woman would get only Thallous Chloride [Myoview], 25 mSv
of Thallium-201 and no Tc-99m Sestamibi [Cardiolite] at all? Why is that?
> There is a new high-speed camera coming out with dramatically reduced
> doses needed (2-10 mCi). I'm not sure if it's commercially available yet,
> or if it has been validated against the traditional style camera (it's
> different technology). I think Cedars-Sinai is working on it.
Great!
>>> According to the thallium package insert, the effective dose equivalent
>>> is 0.22 mSv/MBq. An average dose is about 3.5 mCi which translates
>>> into 130 MBq. So the EDE for thallium-201 is 28.6 mSv.
O.K. We have 25 mSv above and 28.6 mSv here. That's a pretty close
correlation.
>> Great! More hard data. EDE = Effective Dose Equivalent [Whole-Body]?
>
> Yes, EDE is a whole-body equivalent dose. Nuclear medicine tracers deliver
> different exposures to different organs, depending on the method that the
> tracer is cleared from the body and the physical characteristics of the
> tracer itself. The EDE is calculated from those other exposures. The EDE
> assumes a "normal" 70kg patient with good kidney and liver function, who
> voids their bladder appropriately (not dehydrated), etc.
Roger.
>>> Given that around 1 in 4 Canadians are going to die from cancer anyway
>>> (according to the Canadian Cancer Society), the additional 0.1% risk is
>>> practically negligible when weighed against the risks of undiagnosed
>>> heart
>>> disease. In my opinion, anyway.
>>>
>>> Andrew
>>
>> I concur.
>>
>> 1 in 4 Canadians will die from cancer?
>>
>> Hmmmmm... I wonder what it is for Americans [folks in the United
>> States].
>> Could you please point me to the source for the 1 in 4 Canadians?
>
> I suspect it's pretty much the same for Americans. Cancer incidence
> depends on a lot of factors of course. I got that statistic from the
> Canadian Cancer Society's 2008 Cancer Statistics report.
>
> * w w w .cancer.ca/ccs/internet/mediareleaselist/0,,3543_434465_435804_langId-en.html
>
>> Thanks very much. You are obviously a smart guy.
>>
>> DSH
>>
>> Lux et Veritas et Libertas
>
> Andrew
Re: Nuclear Medicine Dosages & Risks
On Apr 16, 5:59 pm, "D. Spencer Hines" <pant...@excelsior . com > wrote:
> The 100 lb man or woman would get only Thallous Chloride [Myoview], 25 mSv
> of Thallium-201 and no Tc-99m Sestamibi [Cardiolite] at all? Why is that?
>
Forgive my nit-pickyness, but Th-201 != Myoview.
Myoview is tetrofosmin, another perfusion agent similar to Cardiolite
On Apr 16, 5:59 pm, "D. Spencer Hines" <pant...@excelsior . com > wrote:
> The 100 lb man or woman would get only Thallous Chloride [Myoview], 25 mSv
> of Thallium-201 and no Tc-99m Sestamibi [Cardiolite] at all? Why is that?
>
Forgive my nit-pickyness, but Th-201 != Myoview.
Myoview is tetrofosmin, another perfusion agent similar to Cardiolite
Re: Nuclear Medicine Dosages & Risks
O.K. What's the brand name for the Thallous Chloride, Th=201?
DSH
"Imabug" <eugenemah@gmail . com > wrote in message
news:180e8cc2-5c70-4cea-a5a7-83bab17e2a39@59g2000hsb.googlegroups . com ...
> On Apr 16, 5:59 pm, "D. Spencer Hines" <pant...@excelsior . com > wrote:
>> The 100 lb man or woman would get only Thallous Chloride [Myoview], 25
>> mSv of Thallium-201 and no Tc-99m Sestamibi [Cardiolite] at all? Why is
>> that?
>>
> Forgive my nit-pickyness, but Th-201 != Myoview.
>
> Myoview is tetrofosmin, another perfusion agent similar to Cardiolite
O.K. What's the brand name for the Thallous Chloride, Th=201?
DSH
"Imabug" <eugenemah@gmail . com > wrote in message
news:180e8cc2-5c70-4cea-a5a7-83bab17e2a39@59g2000hsb.googlegroups . com ...
> On Apr 16, 5:59 pm, "D. Spencer Hines" <pant...@excelsior . com > wrote:
>> The 100 lb man or woman would get only Thallous Chloride [Myoview], 25
>> mSv of Thallium-201 and no Tc-99m Sestamibi [Cardiolite] at all? Why is
>> that?
>>
> Forgive my nit-pickyness, but Th-201 != Myoview.
>
> Myoview is tetrofosmin, another perfusion agent similar to Cardiolite
Re: Nuclear Medicine Dosages & Risks
D. Spencer Hines wrote:
>
> That's Appalling! But I'm sure it's on the mark and correlates with what
> I've seen. Even cardioloists are weak on the technical details.
Their job isn't to know how the test is performed, but to know what to
do with the results.
> O.K. So that would seem to be 55 mCi for the 2-day protocol and 40mCi for
> the 1-day protocol.
Roughly, yes. That is how we do our tests.
>> We choose our protocol based on patient's weight. In our hospital, a 200lb
>> man or woman would get a 2-day protocol. A 100lb man or woman would get
>> thallium. There are technical reasons why we do this.
>
> The 100 lb man or woman would get only Thallous Chloride [Myoview], 25 mSv
> of Thallium-201 and no Tc-99m Sestamibi [Cardiolite] at all? Why is that?
Thallous chloride is the pharmaceutical, Thallium-201 is the isotope.
Technically it would be Thallium-201 chloride. It is not related at all
to Myoview or Cardiolite.
Myoview is also known as tetrofosmin. Cardiolite is also known as
sestamibi. Both of those are pharmaceuticals that are labeled with a
radioactive isotope called Technetium-99m. That's the Tc-99m part.
Technetium-99m is a gamma ray emitter with a single photopeak with an
energy of 140 kiloelectron volts (keV) and a physical half-life of 6 hours.
Thallium-201 has three peaks at around 80, 120 and 200 keV. Most of the
photons coming from thallium-201 are from the 80 keV peak (which is
actually an x-ray, not a gamma ray). Tl-201 has a half-life of 73 hours.
Most gamma rays (or x-rays) just pass right through the tissue
surrounding the heart. Some are absorbed by the tissue, and some are
"scattered," meaning they change directions and lose energy. Scattered
photons degrade the image quality and lower the resolution because they
appear to the camera as if they're coming from somewhere they're not.
Higher energy photons (rays) have a better chance of making it all the
way through the tissue without being absorbed or scattered.
Larger doses of a radiopharmaceutical provide more information
(radioactive counts) in the image, which gives better resolution.
The longer half-life of thallium-201 prevents us from using larger doses
as the exposure would be unacceptable. If we use thallium on a large
patient, we lose a large amount of information due to scattered photons
and "attenuation" (absorbed photons) reducing the resolution of the
image, which reduces the sensitivity of the test.
So, we use Tc-99m agents on our larger patients to improve image
quality. The 6 hour half-life of Tc-99m allows us to give a larger dose
without substantially increasing the radiation exposure.
The Tc-99m agents have a drawback though, in that they are cleared from
the body through the liver and gastrointestinal tract. In many patients,
the liver or a loop of bowel can come close enough to the heart to
actually interfere with the image of the heart. This is what we call
"gut activity" and it's a problem with technetium agents. There are ways
to reduce this activity. Thallium does not tend to have this problem, or
at least not as much.
We can use thallium on the smaller patients because we don't have to
worry as much about scatter.
In our institution, we do everyone over 180lbs as a 2-day protocol,
everyone under 150lbs as a thallium, and those in-between using the
1-day sestamibi protocol. When doing a 1-day protocol, the rest dose is
small (10 mCi) so we don't want to do a large person with that small of
a dose. The physicians that run my department are very particular about
the quality of the work we do, so getting the best images possible is
important.
Andrew
D. Spencer Hines wrote:
>
> That's Appalling! But I'm sure it's on the mark and correlates with what
> I've seen. Even cardioloists are weak on the technical details.
Their job isn't to know how the test is performed, but to know what to
do with the results.
> O.K. So that would seem to be 55 mCi for the 2-day protocol and 40mCi for
> the 1-day protocol.
Roughly, yes. That is how we do our tests.
>> We choose our protocol based on patient's weight. In our hospital, a 200lb
>> man or woman would get a 2-day protocol. A 100lb man or woman would get
>> thallium. There are technical reasons why we do this.
>
> The 100 lb man or woman would get only Thallous Chloride [Myoview], 25 mSv
> of Thallium-201 and no Tc-99m Sestamibi [Cardiolite] at all? Why is that?
Thallous chloride is the pharmaceutical, Thallium-201 is the isotope.
Technically it would be Thallium-201 chloride. It is not related at all
to Myoview or Cardiolite.
Myoview is also known as tetrofosmin. Cardiolite is also known as
sestamibi. Both of those are pharmaceuticals that are labeled with a
radioactive isotope called Technetium-99m. That's the Tc-99m part.
Technetium-99m is a gamma ray emitter with a single photopeak with an
energy of 140 kiloelectron volts (keV) and a physical half-life of 6 hours.
Thallium-201 has three peaks at around 80, 120 and 200 keV. Most of the
photons coming from thallium-201 are from the 80 keV peak (which is
actually an x-ray, not a gamma ray). Tl-201 has a half-life of 73 hours.
Most gamma rays (or x-rays) just pass right through the tissue
surrounding the heart. Some are absorbed by the tissue, and some are
"scattered," meaning they change directions and lose energy. Scattered
photons degrade the image quality and lower the resolution because they
appear to the camera as if they're coming from somewhere they're not.
Higher energy photons (rays) have a better chance of making it all the
way through the tissue without being absorbed or scattered.
Larger doses of a radiopharmaceutical provide more information
(radioactive counts) in the image, which gives better resolution.
The longer half-life of thallium-201 prevents us from using larger doses
as the exposure would be unacceptable. If we use thallium on a large
patient, we lose a large amount of information due to scattered photons
and "attenuation" (absorbed photons) reducing the resolution of the
image, which reduces the sensitivity of the test.
So, we use Tc-99m agents on our larger patients to improve image
quality. The 6 hour half-life of Tc-99m allows us to give a larger dose
without substantially increasing the radiation exposure.
The Tc-99m agents have a drawback though, in that they are cleared from
the body through the liver and gastrointestinal tract. In many patients,
the liver or a loop of bowel can come close enough to the heart to
actually interfere with the image of the heart. This is what we call
"gut activity" and it's a problem with technetium agents. There are ways
to reduce this activity. Thallium does not tend to have this problem, or
at least not as much.
We can use thallium on the smaller patients because we don't have to
worry as much about scatter.
In our institution, we do everyone over 180lbs as a 2-day protocol,
everyone under 150lbs as a thallium, and those in-between using the
1-day sestamibi protocol. When doing a 1-day protocol, the rest dose is
small (10 mCi) so we don't want to do a large person with that small of
a dose. The physicians that run my department are very particular about
the quality of the work we do, so getting the best images possible is
important.
Andrew
Re: Nuclear Medicine Dosages & Risks
"Andrew Kerr" <apkerr@yahoo . com > wrote in message
news:vdzNj.51849$612.15710@read1.cgocable . net ...
> D. Spencer Hines wrote:
>>
>> That's Appalling! But I'm sure it's on the mark and correlates with what
>> I've seen. Even cardiologists are weak on the technical details.
>
> Their job isn't to know how the test is performed, but to know what to do
> with the results.
>
>> O.K. So that would seem to be 55 mCi for the 2-day protocol and 40mCi
>> for the 1-day protocol.
>
> Roughly, yes. That is how we do our tests.
Thanks.
>>> We choose our protocol based on patient's weight. In our hospital, a
>>> 200lb
>>> man or woman would get a 2-day protocol. A 100lb man or woman would get
>>> thallium. There are technical reasons why we do this.
>>
>> The 100 lb man or woman would get only Thallous Chloride [Myoview], 25
>> mSv of Thallium-201 and no Tc-99m Sestamibi [Cardiolite] at all? Why is
>> that?
>
> Thallous chloride is the pharmaceutical, Thallium-201 is the isotope.
> Technically it would be Thallium-201 chloride. It is not related at all to
> Myoview or Cardiolite.
Yes, I understand that. How did I write it incorrectly? Thallous Chloride
is not used in Nuclear Medicine?
> Myoview is also known as tetrofosmin. Cardiolite is also known as
> sestamibi. Both of those are pharmaceuticals that are labeled with a
> radioactive isotope called Technetium-99m. That's the Tc-99m part.
>
> Technetium-99m is a gamma ray emitter with a single photopeak with an
> energy of 140 kiloelectron volts (keV) and a physical half-life of 6
> hours.
Yes, I've seen 6.02 hours.
> Thallium-201 has three peaks at around 80, 120 and 200 keV. Most of the
> photons coming from thallium-201 are from the 80 keV peak (which is
> actually an x-ray, not a gamma ray). Tl-201 has a half-life of 73 hours.
Yep. 73.5 hours, I believe.
> Most gamma rays (or x-rays) just pass right through the tissue surrounding
> the heart. Some are absorbed by the tissue, and some are "scattered,"
> meaning they change directions and lose energy. Scattered photons degrade
> the image quality and lower the resolution because they appear to the
> camera as if they're coming from somewhere they're not. Higher energy
> photons (rays) have a better chance of making it all the way through the
> tissue without being absorbed or scattered.
>
> Larger doses of a radiopharmaceutical provide more information
> (radioactive counts) in the image, which gives better resolution.
So, the Tc-99m gives better resolution because the higher energy photons
from the 140 kEv peak pass through the tissue without being absorbed or
scattered?
> The longer half-life of thallium-201 prevents us from using larger doses
> as the exposure would be unacceptable. If we use thallium on a large
> patient, we lose a large amount of information due to scattered photons
> and "attenuation" (absorbed photons) reducing the resolution of the image,
> which reduces the sensitivity of the test.
Understood. Nicely explained.
> So, we use Tc-99m agents on our larger patients to improve image quality.
> The 6 hour half-life of Tc-99m allows us to give a larger dose without
> substantially increasing the radiation exposure.
Roger.
> The Tc-99m agents have a drawback though, in that they are cleared from
> the body through the liver and gastrointestinal tract. In many patients,
> the liver or a loop of bowel can come close enough to the heart to
> actually interfere with the image of the heart. This is what we call "gut
> activity" and it's a problem with technetium agents. There are ways to
> reduce this activity. Thallium does not tend to have this problem, or at
> least not as much.
Understood.
> We can use thallium on the smaller patients because we don't have to worry
> as much about scatter.
Simply because there is less flesh to do the scattering?
> In our institution, we do everyone over 180lbs as a 2-day protocol,
> everyone under 150lbs as a thallium, and those in-between using the 1-day
> sestamibi protocol. When doing a 1-day protocol, the rest dose is small
> (10 mCi) so we don't want to do a large person with that small of a dose.
> The physicians that run my department are very particular about the
> quality of the work we do, so getting the best images possible is
> important.
Good for them and you guys too. This is in Canada?
DSH
"Andrew Kerr" <apkerr@yahoo . com > wrote in message
news:vdzNj.51849$612.15710@read1.cgocable . net ...
> D. Spencer Hines wrote:
>>
>> That's Appalling! But I'm sure it's on the mark and correlates with what
>> I've seen. Even cardiologists are weak on the technical details.
>
> Their job isn't to know how the test is performed, but to know what to do
> with the results.
>
>> O.K. So that would seem to be 55 mCi for the 2-day protocol and 40mCi
>> for the 1-day protocol.
>
> Roughly, yes. That is how we do our tests.
Thanks.
>>> We choose our protocol based on patient's weight. In our hospital, a
>>> 200lb
>>> man or woman would get a 2-day protocol. A 100lb man or woman would get
>>> thallium. There are technical reasons why we do this.
>>
>> The 100 lb man or woman would get only Thallous Chloride [Myoview], 25
>> mSv of Thallium-201 and no Tc-99m Sestamibi [Cardiolite] at all? Why is
>> that?
>
> Thallous chloride is the pharmaceutical, Thallium-201 is the isotope.
> Technically it would be Thallium-201 chloride. It is not related at all to
> Myoview or Cardiolite.
Yes, I understand that. How did I write it incorrectly? Thallous Chloride
is not used in Nuclear Medicine?
> Myoview is also known as tetrofosmin. Cardiolite is also known as
> sestamibi. Both of those are pharmaceuticals that are labeled with a
> radioactive isotope called Technetium-99m. That's the Tc-99m part.
>
> Technetium-99m is a gamma ray emitter with a single photopeak with an
> energy of 140 kiloelectron volts (keV) and a physical half-life of 6
> hours.
Yes, I've seen 6.02 hours.
> Thallium-201 has three peaks at around 80, 120 and 200 keV. Most of the
> photons coming from thallium-201 are from the 80 keV peak (which is
> actually an x-ray, not a gamma ray). Tl-201 has a half-life of 73 hours.
Yep. 73.5 hours, I believe.
> Most gamma rays (or x-rays) just pass right through the tissue surrounding
> the heart. Some are absorbed by the tissue, and some are "scattered,"
> meaning they change directions and lose energy. Scattered photons degrade
> the image quality and lower the resolution because they appear to the
> camera as if they're coming from somewhere they're not. Higher energy
> photons (rays) have a better chance of making it all the way through the
> tissue without being absorbed or scattered.
>
> Larger doses of a radiopharmaceutical provide more information
> (radioactive counts) in the image, which gives better resolution.
So, the Tc-99m gives better resolution because the higher energy photons
from the 140 kEv peak pass through the tissue without being absorbed or
scattered?
> The longer half-life of thallium-201 prevents us from using larger doses
> as the exposure would be unacceptable. If we use thallium on a large
> patient, we lose a large amount of information due to scattered photons
> and "attenuation" (absorbed photons) reducing the resolution of the image,
> which reduces the sensitivity of the test.
Understood. Nicely explained.
> So, we use Tc-99m agents on our larger patients to improve image quality.
> The 6 hour half-life of Tc-99m allows us to give a larger dose without
> substantially increasing the radiation exposure.
Roger.
> The Tc-99m agents have a drawback though, in that they are cleared from
> the body through the liver and gastrointestinal tract. In many patients,
> the liver or a loop of bowel can come close enough to the heart to
> actually interfere with the image of the heart. This is what we call "gut
> activity" and it's a problem with technetium agents. There are ways to
> reduce this activity. Thallium does not tend to have this problem, or at
> least not as much.
Understood.
> We can use thallium on the smaller patients because we don't have to worry
> as much about scatter.
Simply because there is less flesh to do the scattering?
> In our institution, we do everyone over 180lbs as a 2-day protocol,
> everyone under 150lbs as a thallium, and those in-between using the 1-day
> sestamibi protocol. When doing a 1-day protocol, the rest dose is small
> (10 mCi) so we don't want to do a large person with that small of a dose.
> The physicians that run my department are very particular about the
> quality of the work we do, so getting the best images possible is
> important.
Good for them and you guys too. This is in Canada?
DSH
Re: Nuclear Medicine Dosages & Risks
D. Spencer Hines wrote:
>
> Yes, I understand that. How did I write it incorrectly? Thallous Chloride
> is not used in Nuclear Medicine?
There was a time that thallium-201 was the only tracer used for cardiac
studies. Now most institutions use one of the Tc-99m agents, either
Cardiolite or Myoview.
> So, the Tc-99m gives better resolution because the higher energy photons
> from the 140 kEv peak pass through the tissue without being absorbed or
> scattered?
Yes. However, it's not really an issue with a small patient.
>> In our institution, we do everyone over 180lbs as a 2-day protocol,
>> everyone under 150lbs as a thallium, and those in-between using the 1-day
>> sestamibi protocol. When doing a 1-day protocol, the rest dose is small
>> (10 mCi) so we don't want to do a large person with that small of a dose.
>> The physicians that run my department are very particular about the
>> quality of the work we do, so getting the best images possible is
>> important.
>
> Good for them and you guys too. This is in Canada?
I am in Canada, yes. My department is fairly unique I think, in that we
actually choose a different protocol depending on patient size. Many
places don't use thallium at all any more. Thallium studies generally
take longer (we image for a longer time due to the reduced dose) and are
less flexible schedule-wise, meaning that we can't do as many people as
we can with Tc-99m.
Andrew
D. Spencer Hines wrote:
>
> Yes, I understand that. How did I write it incorrectly? Thallous Chloride
> is not used in Nuclear Medicine?
There was a time that thallium-201 was the only tracer used for cardiac
studies. Now most institutions use one of the Tc-99m agents, either
Cardiolite or Myoview.
> So, the Tc-99m gives better resolution because the higher energy photons
> from the 140 kEv peak pass through the tissue without being absorbed or
> scattered?
Yes. However, it's not really an issue with a small patient.
>> In our institution, we do everyone over 180lbs as a 2-day protocol,
>> everyone under 150lbs as a thallium, and those in-between using the 1-day
>> sestamibi protocol. When doing a 1-day protocol, the rest dose is small
>> (10 mCi) so we don't want to do a large person with that small of a dose.
>> The physicians that run my department are very particular about the
>> quality of the work we do, so getting the best images possible is
>> important.
>
> Good for them and you guys too. This is in Canada?
I am in Canada, yes. My department is fairly unique I think, in that we
actually choose a different protocol depending on patient size. Many
places don't use thallium at all any more. Thallium studies generally
take longer (we image for a longer time due to the reduced dose) and are
less flexible schedule-wise, meaning that we can't do as many people as
we can with Tc-99m.
Andrew
Re: Nuclear Medicine Dosages & Risks
Does the package for the Th-201 agent have a brand name, like Cardiolite or
Myoview for the Tc-99m sestamibi agent?
DSH
Lux et Veritas et Libertas
Does the package for the Th-201 agent have a brand name, like Cardiolite or
Myoview for the Tc-99m sestamibi agent?
DSH
Lux et Veritas et Libertas
Re: Nuclear Medicine Dosages & Risks
D. Spencer Hines wrote:
> Does the package for the Th-201 agent have a brand name, like Cardiolite or
> Myoview for the Tc-99m sestamibi agent?
Try the following links:
* w w w .anazaohealth . com /content.cfm?page id)
* w w w .mdsnordion . com /documents/elibrary/molecular-isotopes/Thallium-201/Tl-201 Can.pdf
You will see that there is no brand name.
If doubt if they will sell it to you :-)
Adam White
D. Spencer Hines wrote:
> Does the package for the Th-201 agent have a brand name, like Cardiolite or
> Myoview for the Tc-99m sestamibi agent?
Try the following links:
* w w w .anazaohealth . com /content.cfm?page id)
* w w w .mdsnordion . com /documents/elibrary/molecular-isotopes/Thallium-201/Tl-201 Can.pdf
You will see that there is no brand name.
If doubt if they will sell it to you :-)
Adam White
Re: Nuclear Medicine Dosages & Risks
D. Spencer Hines wrote:
> Does the package for the Th-201 agent have a brand name, like Cardiolite or
> Myoview for the Tc-99m sestamibi agent?
>
> DSH
>
> Lux et Veritas et Libertas
>
>
There's no brand name for thallium-201 as far as I know. Thallous-201
chloride IS the radiopharmaceutical. Thallium doesn't have to be
attached to anything to go to your heart.
With the Tc-99m agents, Tc-99m is the radioactive part, and it is
attached to another chemical depending on what we want to to image. For
the heart, we use tetrofosmin or sestamibi, for bones we use a phosphate
compound, etc.
Andrew
D. Spencer Hines wrote:
> Does the package for the Th-201 agent have a brand name, like Cardiolite or
> Myoview for the Tc-99m sestamibi agent?
>
> DSH
>
> Lux et Veritas et Libertas
>
>
There's no brand name for thallium-201 as far as I know. Thallous-201
chloride IS the radiopharmaceutical. Thallium doesn't have to be
attached to anything to go to your heart.
With the Tc-99m agents, Tc-99m is the radioactive part, and it is
attached to another chemical depending on what we want to to image. For
the heart, we use tetrofosmin or sestamibi, for bones we use a phosphate
compound, etc.
Andrew
