Yes Mammo does have a large dose to the breast but at least the dose to the rest of the body is minimised because of the decreased amount of scatter.
At 10:47 PM 7/11/2002 +1100, you wrote:
Hay, hay where did you get that info. on breast screening dose?
what are you quoting from? "(low kV -> less scatter because of compton effect as primary x-ray interaction)" It is the low kVp used in general radiography that is so easily absorbed by the body. It never gets to the film and is of no diagnostic value. That is why we use filters of 1-1.5mm Al to absorb this dangerous radiation.
But in mamography we remove this filtration to get soft tissue contrast/resolution.
Don't suggest that this is safe, it is very dangerous. High kVp's give better "penetration" (what-ever that is) and gives low contrast. Poor for human eye resolution. So we enhance it via CT video enhancement. You can't do that with a mammo.
A lot of discussion has emanated from the medical profession regarding the value of screening. Even mammography has come under scrutiny. Pap smears, bowel biopsy's and the whole range of diagnostic screening tests have been found wanting at times. Probably mammography is proven to be the best screen test - but is at a dangerous cost of radiation absorption.
How the hell radiologists can sit looking at 4-6 35 x 43cm films with 18 images each and not loose concentration I do not know. But I haven't seen any evidence at all to suggest that they have found unsuspected tumours on these "survey body CT's" It really is a money making exercise for the radiologist.(Or whoever is reporting them.)
Kevin
----- Original Message -----
From: Dieter
To: AIRNEWS
Sent: Wednesday, November 06, 2002 12:41 PM
Subject: RE: [AIR] Sydney Morning Herald 7/10/02 'Searching for trouble'
I think the point that we may be missing as radiation workers is the size of the dose involved with CT.
Yes there are valid points for screening, but if we go down that road I would rather pay an extra $400 an have a full body MRI. Screening tests is a great method for early detection of Ca but the criteria for screening is that the intervention (includes radiation) is of minimal impact of the subject and the final outcome is favourable. Screening mammography has the majority of its radiation confined to the breast (low kV -> less scatter because of compton effect as primary x-ray interaction). Whole body CT is a HUGE dose by comparison. It's like using a linear-accelerator to take a picture of a fractured wrist.
CT currently uses around 120kV and 400mAs per tube rotation. That's the equivalent of around 200 chest xrays. Granted MSCT now takes more slices per tube rotation and the dose should have decreased with the new 16 slice MSCT's but the dose given to a patient is still NOT inconsiderable.
If we are trying to say that whole body screening is a good thing then perhaps we should be looking at non-ionising radiation screening methods.
The stand point that we as radiation workers should be taking is not that whole body screening is a bad thing but that the amount of radiation that we use to screen for Ca may well be inducing Ca instead.
We often forget with CT just how much radiation is involved with a CT scan because we as operators sit back on our cosy chairs separated from the patient with automated voice recordings etc. The other trap we get sucked into is that unlike plain radiography, there is no penalty (operator wise) for over exposure, only under exposure. Thus patients tend to get 'just a little bit more' just to make sure'. If you did this with every plain ray you took you'd toast every thing.
Yes we have a duty to provide as safe as possible method for diagnosing disease but as radiation workers we also have a duty to limit the amount of radiation we give people to as little as possible.
I believe the 1985 NHMRC actually commented on not using x-rays for medico legal reasons to rule out the possibility of pathology but to supplement clinical indications. Do we ignore this altogether ?
We need to think hard about this one people.
Dieter
BAppSc(MIT)
At 10:18 PM 5/11/2002 +1100, you wrote:
It would be a pleasure Kevin! I see AIRNEWS as a forum to express ideas that may be used by the institute to understand how its members feel.
I'm currently halfway through an oncology block and have learnt a lot about the ins and outs of the use of screening tests. Here is a list of criteria that has been created
1. Condition screened should be Important.
2. Acceptable treatment available.
3. Diagnostic and Treatment facilities available.
4. Early disease is Recognisable.
5. Treatment Options standardised.
6. Sensitive, specific, reproducible - Gaurantee.
7. Examination tolerated by pt.
8. Natural history of disease known.
9. Simple Inexpensive test.
10. Screening is Continuous.
1-10 spells iatrogenic to remind us that everything carries a risk. (I believe the original is from one of the Oxford med handbooks)
Mammograms, PAP smears and to a degree prenatal US detect abnormalities to which a successful intervention may be carried out. 5 year survival rates for breast Ca is up in the 90% range, advanced cervical cancer is a rarity in Australia (not so the 3rd world), whereas for some lung cancers 5 year survival is between 5-10%!
It is possible that full body scans may be the panacea of all screening tests however at this point in time there is no proof. It also just doesn't stack up as a cost-effective screening modality.
One thing that bugs me is that radiologists are quick to point out the necessity of good clinical history on a referral, in this situation it seems to me that it is a small needle hiding in a big haystack.
- -----Original Message-----
- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Kevin Power
- Sent: Sunday, 3 November 2002 9:41
- To: AIRNEWS
- Subject: Re: [AIRNEWS] Sydney Morning Herald 7/10/02 'Searching for trouble'
- You are right Peter, but we don't want members going out willy-nilly making statements on behalf of AIR, we need Institute guidance we need to act as a body. Then we could make Mike Sobotta our spokesman for the AIR policy on this matter.
- That is the democratic way.
- Kevin Power
- ----- Original Message -----
- From: Peter Rouse
- To: AIRNEWS
- Sent: Monday, October 07, 2002 9:33 PM
- Subject: RE: [AIRNEWS] Sydney Morning Herald 7/10/02 'Searching for trouble'
- No question the AIR needs a position. But "the AIR" position? Shouldn't that be "our" position? We should be careful not to abdicate responsibilities under the cloak of "them". At the end of the day, if the "them" are left with all the responsibility for action without your input, them you will wear the consequences (and the AIR is "us" not "them"). You are right! What a great PR position to present a responsible response to this. How do you think "we" should proceed?
- Peter
- -----Original Message-----
- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael Sobotta
- Sent: Monday, 7 October 2002 11:50 AM
- To: AIRNEWS
- Subject: [AIRNEWS] Sydney Morning Herald 7/10/02 'Searching for trouble'
- Does the AIR have a position on full body CT 'screening' examinations? What a nice article to get some publicity for radiographers standing up for the public in our position as 'defenders against aberrant radiation doses'!
- I for one would like to see at least a letter to the editor from the AIR stating their position. I would also be interested to see if there are any rads subscribing to AIRNEWS that perform these CTs. Is it under pressure from radiologist? Personal investment?
- mike sobotta
----- Original Message -----
From: Dieter
To: AIRNEWS
Sent: Wednesday, November 06, 2002 12:41 PM
Subject: RE: [AIRNEWS] Sydney Morning Herald 7/10/02 'Searching for trouble'
I think the point that we may be missing as radiation workers is the size of the dose involved with CT.
Yes there are valid points for screening, but if we go down that road I would rather pay an extra $400 an have a full body MRI. Screening tests is a great method for early detection of Ca but the criteria for screening is that the intervention (includes radiation) is of minimal impact of the subject and the final outcome is favourable. Screening mammography has the majority of its radiation confined to the breast (low kV -> less scatter because of compton effect as primary x-ray interaction). Whole body CT is a HUGE dose by comparison. It's like using a linear-accelerator to take a picture of a fractured wrist.
CT currently uses around 120kV and 400mAs per tube rotation. That's the equivalent of around 200 chest xrays. Granted MSCT now takes more slices per tube rotation and the dose should have decreased with the new 16 slice MSCT's but the dose given to a patient is still NOT inconsiderable.
If we are trying to say that whole body screening is a good thing then perhaps we should be looking at non-ionising radiation screening methods.
The stand point that we as radiation workers should be taking is not that whole body screening is a bad thing but that the amount of radiation that we use to screen for Ca may well be inducing Ca instead.
We often forget with CT just how much radiation is involved with a CT scan because we as operators sit back on our cosy chairs separated from the patient with automated voice recordings etc. The other trap we get sucked into is that unlike plain radiography, there is no penalty (operator wise) for over exposure, only under exposure. Thus patients tend to get 'just a little bit more' just to make sure'. If you did this with every plain ray you took you'd toast every thing.
Yes we have a duty to provide as safe as possible method for diagnosing disease but as radiation workers we also have a duty to limit the amount of radiation we give people to as little as possible.
I believe the 1985 NHMRC actually commented on not using x-rays for medico legal reasons to rule out the possibility of pathology but to supplement clinical indications. Do we ignore this altogether ?
We need to think hard about this one people.
Dieter
BAppSc(MIT)
At 10:18 PM 5/11/2002 +1100, you wrote:
It would be a pleasure Kevin! I see AIRNEWS as a forum to express ideas that may be used by the institute to understand how its members feel.
I'm currently halfway through an oncology block and have learnt a lot about the ins and outs of the use of screening tests. Here is a list of criteria that has been created
1. Condition screened should be Important.
2. Acceptable treatment available.
3. Diagnostic and Treatment facilities available.
4. Early disease is Recognisable.
5. Treatment Options standardised.
6. Sensitive, specific, reproducible - Gaurantee.
7. Examination tolerated by pt.
8. Natural history of disease known.
9. Simple Inexpensive test.
10. Screening is Continuous.
1-10 spells iatrogenic to remind us that everything carries a risk. (I believe the original is from one of the Oxford med handbooks)
Mammograms, PAP smears and to a degree prenatal US detect abnormalities to which a successful intervention may be carried out. 5 year survival rates for breast Ca is up in the 90% range, advanced cervical cancer is a rarity in Australia (not so the 3rd world), whereas for some lung cancers 5 year survival is between 5-10%!
It is possible that full body scans may be the panacea of all screening tests however at this point in time there is no proof. It also just doesn't stack up as a cost-effective screening modality.
One thing that bugs me is that radiologists are quick to point out the necessity of good clinical history on a referral, in this situation it seems to me that it is a small needle hiding in a big haystack.
- -----Original Message-----
- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Kevin Power
- Sent: Sunday, 3 November 2002 9:41
- To: AIRNEWS
- Subject: Re: [AIRNEWS] Sydney Morning Herald 7/10/02 'Searching for trouble'
- You are right Peter, but we don't want members going out willy-nilly making statements on behalf of AIR, we need Institute guidance we need to act as a body. Then we could make Mike Sobotta our spokesman for the AIR policy on this matter.
- That is the democratic way.
- Kevin Power
- ----- Original Message -----
- From: Peter Rouse
- To: AIRNEWS
- Sent: Monday, October 07, 2002 9:33 PM
- Subject: RE: [AIRNEWS] Sydney Morning Herald 7/10/02 'Searching for trouble'
- No question the AIR needs a position. But "the AIR" position? Shouldn't that be "our" position? We should be careful not to abdicate responsibilities under the cloak of "them". At the end of the day, if the "them" are left with all the responsibility for action without your input, them you will wear the consequences (and the AIR is "us" not "them"). You are right! What a great PR position to present a responsible response to this. How do you think "we" should proceed?
- Peter
- -----Original Message-----
- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael Sobotta
- Sent: Monday, 7 October 2002 11:50 AM
- To: AIRNEWS
- Subject: [AIRNEWS] Sydney Morning Herald 7/10/02 'Searching for trouble'
- Does the AIR have a position on full body CT 'screening' examinations? What a nice article to get some publicity for radiographers standing up for the public in our position as 'defenders against aberrant radiation doses'!
- I for one would like to see at least a letter to the editor from the AIR stating their position. I would also be interested to see if there are any rads subscribing to AIRNEWS that perform these CTs. Is it under pressure from radiologist? Personal investment?
- mike sobotta
