Re: CT scans & Heidi

[Guest guest]

One of the problems with being old is that you remember too much.

I can remember that radiation was " advertised " as being called " Sunshine

Units "

I can remember every store that sold shoes would have a machine to check the

wiggle of the toes and assure there was plenty of room. It was a self

processing fluoroscope machine. Kids spent a lot of time watching their toe

bones

wiggle in this device.

Use the sunscreen lotion folks, one of those life long lessons

Best Wishes, Poncho - GA

[Guest guest]

CINCINATTI, OH -- January 22, 2001 -- A new Children's Hospital Medical

Center of Cincinnati study shows that some children who get computed

tomography (CT) scans receive doses of radiation at strengths at least five

times greater than necessary. Radiologists can reduce doses of radiation

without compromising information in the images obtained, according to Lane

F. Donnelly, M.D., a staff radiologist at Cincinnati Children's and the

study's lead author.

CT is the primary imaging technique for children with abdominal pain,

suspected appendicitis, abdominal trauma, a suspected mass, or complicated

pneumonias. Like general radiography, CT uses ionizing radiation, or x-rays.

The radiation dose associated with CT, however, is much larger than the dose

associated with other imaging procedures. Radiation dose is particularly

important in children because of the relatively increased lifetime cancer

risk of children compared to adults.

" CT is often a necessary part of the evaluation of children with suspected

illness, " says Dr. Donnelly, whose study is published in the February

edition of the American Journal of Roentgenology. " The benefit from the

information obtained by the CT greatly outweighs the radiation risk.

However, although the risks of radiation associated with a CT examination

are extremely low, they are not zero. It's not only imperative to make an

accurate diagnosis, but also to strive to make the risks as minimal as

possible. "

CT accounts for about four percent of medical x-ray examinations. But it

contributes to an estimated 40 percent of the total radiation dose to the

population. Two technical factors -- tube current and pitch -- " can be

adjusted easily to reduce radiation exposure in the pediatric population and

have a profound affect, " says Dr. Donnelly. Tube current refers to the

amount of electrons used to generate the x-ray source. Pitch refers to the

ratio between the rate at which the table the patient lies on moves through

the scanner and the rate at which the scanner spins.

" The major disadvantage of decreasing the tube current is an increase in

noise, but this potential is counterbalanced in younger patients by their

smaller size, " says Dr. Donnelly. " In addition, pitch can be increased by

about half to reduce radiation dose by about a third, without any loss of

image quality. "

CT is able to depict anatomy at different levels within the body. This

ability, known as cross-sectional imaging, is possible because the x-ray

source rotates around the patient during a CT scan, encircling the patient

and capturing anatomical detail from many angles. Each rotation of the x-ray

beam produces a single cross-sectional " slice " of anatomy, like the slices

in a loaf of bread. A computer then creates an image by stacking the

individual image slices. Using this technology, physicians can view the

inside of anatomic structures, a feat not possible with general radiography.

Unfortunately, most studies of CT have been done on adults, and the same

dose of radiation typically has been used on children.

In addition, many CT units are equipped with software that automatically

chooses tube current based on optimal image quality calculated for adults.

" Efforts must be made to override these automatic parameters when imaging

children, " says Dr. Donnelly.

The radiologists in Cincinnati Children's section of body imaging, in the

department of Radiology, began examining lower doses of radiation about two

years ago, when Kathleen Emery, M.D., a staff radiologist, realized that

some other studies had begun to examine reduced dosages of radiation for CT

of the chest. " It began to bother us that we used parameters based on adults

studies, " she says. " Unlike general radiography, there is no penalty for

using a higher dose of radiation, whereas in regular x-rays, too high a dose

would result in a black picture. "

In the two years the radiologists have adjusted tube current and pitch, they

are unaware of any cases in which a diagnosis was undetected on a reduced

dose CT but became evident later. In addition, they have not had to repeat

studies at an increased tube current because of poor technical quality.

CT scans & Heidi

> Heidi,

>

> Another good reason to not have any unnecessary ct scans is that

> each one gives off over 100 times more radiation than a single chest

> xray..and this can't be good for a person. Hope I'm not repeating

> myself in case you already know this as it has been a major

> discussion on all of the support groups I'm a member of.

>

> The doctors who did this study did say that if one has frequent CT

> scans, to request an apron the radiologists wear and place it over

> the reproductive organ area or other area you want to protect, so

> they won't get damaged in any way...and if it is a child having a CT

> scan, to make sure the dose of radiation is turned down to the

> lowest possible on the Scanner.

>

>

>

>

>

>

>

>

[Guest guest]

Radiation risks

Treatment > Radiotherapy > Radiation Risks

Last Updated: 02/20/2003

The risks and benefits of radiation treatment are poorly

understood by most cancer patients. Our goal for this section of

Lymphomation.org is to post useful information associated with the side

effects and risks of radiotherapy treatments. It's important to note that

almost all treatments have risks and that many factors must be considered

when you and your doctor select a treatment including: your diagnosis, the

risks of not treating, the potential risks and benefits of other treatments,

your age, and many other factors.

Questions needing answers:

What are the risks of secondary cancers when receiving

localized radiation treatment?

What herbs, vitamins, or drugs (if any) can be taken to

reduce the risks associated with radiotherapy treatment and tests? (See

Radioprotective Strategies)

How much radiation is received in a CT scan, and how many

scans can be safely taken? (See CT Imaging)

The following was composed by Suzanne Perth on the NHL-follic

e-mail support list. Thank you, Suzanne, for your work.

Radiation Risks - by Suzanne Perth, Western Australia.

I don't know about the Medical curriculum in US medical schools,

but here is an extract directly from my lecture notes on the effects of

ionizing radiation on human bodies.

" The potential for medical diagnoses was rapidly put to use and

by the turn of the century x-rays were being used routinely to diagnose a

range of medical conditions. However the rapid application of x-rays led to

the rapid realization of the hazard associated with its use. It was found

that excessive radiation led to serious tissue damage and death.

The effects of radiation are out of all proportion to the amount

of energy deposited, for example, a single dose of 10gray given to the whole

body will kill almost anyone who receives it, unless they are given a bone

marrow transplant. However, 10gray deposits only 10 Joule per kg of tissue

(1 gray = 1 Joule/kg). You should easily be able to calculate that 10 J/kg

represents a temperature rise of only 0.003 deg C, (remember that the bodies

specific heat is 3500J/kg/K). Why is radiation so damaging? The main reason

is that it produces ionization of the material that it passes through. Thus,

chemical changes may occur which are extremely harmful to the body. For

example, ionization can convert safe ions to extremely toxic and dangerous

materials. "

My own example: Sodium is present in all our tissues as the ion

Na+ and is necessary for the transmission of nerve impulses. However, Na

metal is toxic to the body in even tiny doses. Na and Cl are both toxic, but

if you take one electron from Na and add it to Cl, you get common salt.

" A dose of 2 Gry will cause sickness in a substantial portion of

the population (25%) while 10 Gry will cause eventual death for most.

Exposure over a long time to relatively low doses may result in

the induction of cancer. In fact, this and genetic damage are the only known

effects of very low doses of radiation.

Cancer is the most likely consequence of radiation and it is

believed that any dose of radiation no matter how small will have a

probability of inducing cancer. There is usually a delay of 5 to 10 years

between the exposure and the induction of cancer. One Gry of radiation to

the whole body will give a probability of cancer of about 4% for adults and

rather more for children. This risk is additive so that multiple small doses

over a number of years will give the same risk as from the total dose given

on a single occasion. (Provided that the total dose is not too high).

Random genetic risk is approximately 1% for each Gry of

irradiation. etc., .......

Radiation is commonly used in medicine, in fact medical exposure

is by far the largest man made source of radiation. It far exceeds all other

sources of exposure such as nuclear reactors, nuclear explosions or the

industrial use of radiation.

Examples of the use of radiation in medicine are: simple chest

x-ray 1mGy (skin) abdominal x-ray 5mGy (skin) pelvis x-ray 5-10mG (skin) CT

scan 10-20 mGy (per slice) angiography 10-100mGy (skin) nuclear medicine

10-20 mGy (specific organs)

Therapy 20-50 Gy (treated volume)

Thus it should be evident that radiation is dangerous and that

no dose of radiation is totally safe, yet its benefits cause it to be used

routinely in medicine.

The first point to note however is that mankind has been subject

to natural radiation throughout the whole of history. The earth is

radioactive and so is each and every person on it. There are parts of the

earth where the radiation level is quite high either due to the

radioactivity of the earth in that area, or due to the increased cosmic

radiation which occurs at altitude. On the Darling Scarp (just outside

Perth) there are areas where the natural radiation level is about 5mGy per

annum. If you fly in a jet the radiation level rises to about 5UGy per hour.

Thus a round trip to Europe represents an additional radiation dose of about

0.2mGy. " (Of course this if from Perth in Western Australia.)

HALF HOUR BREAK HERE AS I HAD TO GO OUTSIDE AND HELP MY HUSBAND

DELIVER A CALF. . . .

Now back to the mini-lecture!!

" Important rules to keep in mind are:

1. Radiation should only be used where the the benefits exceeds

the risk to the patient. For most uses of radiation, safety limits are

applied to protect workers or the general public. With the medical use of

radiation no such safety levels are prescribed. The matter is entirely in

the hands of the medical profession so it is important that they are

knowledgeable concerning the hazards of radiation.

2. The dose of radiation should be minimized by using it in an

optimal manner. This is of course only relevant to those practitioners who

actually make direct use of radiation.

3. If in doubt, consult an expert. For example,. a radiologist,

to advise on the efficacy of a particular investigation or a radiation

physicist, for foetal dose calculations and risk estimates. There have been

two recent examples where GPs have advised patients to have an abortion

following a minimal exposure to radiation. This represents an extraordinary

level of ignorance both as to the risks involved and to the availability of

expert advice. "

Another thing is that Radiation risks are tallied and calculated

over a population. What this means is that if 1 million people have a chest

x-ray (5mGray each), the total dose of radiation administered to these

people is about 10Gray, and one of these people will die as a result of

radiation induced sickness. What this means is that in a population the size

of Australia (20 million), 2-3 people die each year of radiation induced

cancers and genetic damage. A population the size of the US would give even

worse figures. The advent of ct scans has made it even worse. 2-3 people per

year in Australia will die as a result of them.

I'm not sure if this is enough information to give GPs who can

send people for all sorts of radiation based tests, but I know that those

who actually practice in the field do a lot more study as to the effects and

dangers of radiation. I believe that doctors are well aware of the dangers

of radiation, whether they choose to admit that they may be partly

responsible for causing a disease in their patients is, I suppose, a matter

of choice for the individual doctor.

There is a category of morbidity and mortality that is

attributed to " Iatrogenic " causes in statistics. This is just a nice way of

saying that the person died of complications associated with treatment given

by the medical profession. A high percentage of deaths in hospitals are

attributed to " Iatrogenic causes " . Of course, the general public reading

these figures will have no idea that the number of deaths directly caused by

" treatment " is so high. I think it is a terrible way of presenting

statistics to people, and interferes with their right to give " informed

consent " . I don't suppose that many of my colleagues feel the same way.

Regards

Suzanne Perth, Western Australia.

CT scans & Heidi

> Heidi,

>

> Another good reason to not have any unnecessary ct scans is that

> each one gives off over 100 times more radiation than a single chest

> xray..and this can't be good for a person. Hope I'm not repeating

> myself in case you already know this as it has been a major

> discussion on all of the support groups I'm a member of.

>

> The doctors who did this study did say that if one has frequent CT

> scans, to request an apron the radiologists wear and place it over

> the reproductive organ area or other area you want to protect, so

> they won't get damaged in any way...and if it is a child having a CT

> scan, to make sure the dose of radiation is turned down to the

> lowest possible on the Scanner.

>

>

>

>

>

>

>

>