The Atomic Ocean Liner

[Default] Thus spake Tom K :

On 3/28/10 11:41 AM, AZ Nomad wrote:
On Sun, 28 Mar 2010 18:15:38 +1100, Gettamulla wrote:
On Sat, 27 Mar 2010 19:29:25 -0400, wrote:

I certainly would not cruise on a nuclear powered cruise ship. Not only
because of the possibility of a major catastrophe, but because even a
small leakage could cause cancers.

Let's see, the US Navy has had how many "major catastrophe's" due to
its nuclear reactors? I can't count them on both hands. Unless I cut
off all of my fingers. 0. zero. nada. zilch. none.


I did 3 tours on the Nimitz and now I don't need the lights on to read in bed at night...

It's no worse than having a chest x-ray.

Chest X-rays are also dangerous.

So is undiagnosed lung cancer.


X-rays have the "short wavelength/high frequency" energy potential to
disrupt particles at the sub atomic level. If that happens to an atom
in the DNA of one of your cells... and you get a bad mutation... and
that DNA replicates... BOOM: CANCER.

Um, alpha particles are much more dangerous. They are more likely to
interact with you than an x-ray. Higher frequency is less dangerous
than lower frequency. Of course, I only spent two years learning that
sort of thing.

Are you aware that the exposure to a chest x-ray is approximately the
same as an 8 hour commercial airline flight?


Did you notice that even with dental X-rays, they put that lead vest
thingee on you...

It's called ALARA, As Low As Reasonably Attainable. An ethical
obligation we have to protect the patient. (I am not a dental
hygenist, I'm an x-ray technologist).


X-rays are next to Gamma rays on the electromagnetic spectrum. That's
the high energy, deadly end of the spectrum.

Um, a 120 kVp x-ray is much safer than an 80 kVp exposure. And
mamograms, at about 45-50 kVp are even more "dangerous". But the
danger there is much less than the danger of breast cancer.

Higher voltage = higher frequency.

You know, even when I was working in "specials" (now referred to as
vascular intervention) and would sometimes rack up as much as three
hours of exposure in a day, my TLD showed almost negligible exposure,
even though it has to be worn outside of the lead.


http://www.worsleyschool.net/science...c/spectrum.gif

You're reading it wrong, backwards. Actually, higher energy = more
penetration. More penetration means that more of the x-ray wave gets
through and there is less scatter, which is where the danger is to the
human body.



--Tom

Next time you have an x-ray, ask the technologist what technique
he/she used. Ask for kV and mAs (pronounced mass). High kV/low mAs
is the safest, but you have to balance them for the best image. With
digital we can fiddle around with the image quite a bit, but you still
need something reasonably diagnostic to begin with.

My technique chart says a PA chest is 120 kVp @ 20 mAs and a lateral
is 130 @ 30 for an average sized person. PA is standing facing the
image receptor (that board) and lateral is with your left side against
it. Hand is 60 @ 2.4 for a PA and oblique and 60 @ 3.2 for a lateral.
And so it goes.

Please don't spread misinformation like this. It's almost as bad as
saying that the Alaska cruise passenger tax is driving away pax. And
almost as dangerous.
--

- dillon I am not invalid

The more I drink, the less I think. The less I think,
the better I feel. The better I feel, the more I drink.
And so goes the circle of life.

On 4/2/10 10:34 PM, Dillon Pyron wrote:


Um, alpha particles are much more dangerous. They are more likely to
interact with you than an x-ray. Higher frequency is less dangerous
than lower frequency. Of course, I only spent two years learning that
sort of thing.


Wanna explain how you think that high energy is less dangerous than
lower energy on the electromagnetic spectrum?

Last time I looked at an electromagnetic spectrum chapter, the high
frequency / short wavelength gamma rays were the most high energy and
dangerous, and next to gamma rays on the spectrum were X-rays.

The low frequency / long wavelength (opposite) end of the spectrum is
radio waves which aren't dangerous (unless you're listening to Rush)...

At least that's what my college chemistry textbooks say... (except for
the Rush part, that is...)

--Tom

[Default] Thus spake Tom K :

On 4/2/10 10:34 PM, Dillon Pyron wrote:


Um, alpha particles are much more dangerous. They are more likely to
interact with you than an x-ray. Higher frequency is less dangerous
than lower frequency. Of course, I only spent two years learning that
sort of thing.


Wanna explain how you think that high energy is less dangerous than
lower energy on the electromagnetic spectrum?

I'm not thinking, I'm reading what experts say.


Last time I looked at an electromagnetic spectrum chapter, the high
frequency / short wavelength gamma rays were the most high energy and
dangerous, and next to gamma rays on the spectrum were X-rays.

High energy passes through the body with little interaction with the
cells. Low energy likes to be stopped.


The low frequency / long wavelength (opposite) end of the spectrum is
radio waves which aren't dangerous (unless you're listening to Rush)...

At least that's what my college chemistry textbooks say... (except for
the Rush part, that is...)

Aw, chemistry? Or physics? (I'll grant you that one, assuming we are
about the same age)

"Principles of Radiographic Imagin; An Art and Science" Carlton &
Adler, ISBN 1-4018-7194-1, Chapter 13 (This is the least
helpful)

"Radiologic Science for Technologists; Physics, Biology and
Protection" Bushong ISBN 0-323-02555-3, Chapters 33 through 40

"Radiation Protection; in Medical Radiograpy" Sherer, Visconti and
Ritenour ISBN 0-323-03600-9

Those are my sources, cite your's.


Oh yeah, Dillon Pyron, RT(R) ARRT

Shall we debate fields of expertise?


--Tom
--

- dillon I am not invalid

The more I drink, the less I think. The less I think,
the better I feel. The better I feel, the more I drink.
And so goes the circle of life.

On Fri, 02 Apr 2010 21:34:58 -0500, Dillon Pyron
wrote:

Higher voltage = higher frequency.

Perhaps in X-Rays, but in general voltage and frequency are not related.
You can have high voltage DC, and high voltage AC currents.

You know, even when I was working in "specials" (now referred to as
vascular intervention) and would sometimes rack up as much as three
hours of exposure in a day, my TLD showed almost negligible exposure,
even though it has to be worn outside of the lead.


http://www.worsleyschool.net/science...c/spectrum.gif

You're reading it wrong, backwards. Actually, higher energy = more
penetration. More penetration means that more of the x-ray wave gets
through and there is less scatter, which is where the danger is to the
human body.

That's not entirely correct. The absorption in human bodies goes up and
down according to the frequency of the radiation - it's not linear. The
FCC says:

"In the case of exposure of the whole body, a standing ungrounded human
adult absorbs RF energy at a maximum rate when the frequency of the RF
radiation is in the range of about 70 MHz. This means that the
"whole-body" SAR is at a maximum under these conditions. Because of
this "resonance" phenomenon and consideration of children and grounded
adults, RF safety standards are generally most restrictive in the
frequency range of about 30 to 300 MHz."
http://www.fcc.gov/oet/rfsafety/rf-faqs.html

On 4/7/10 10:25 AM, Dillon Pyron wrote:

High energy passes through the body with little interaction with the
cells.


Gamma Rays (highest energy, highest frequency/shortest wavelength) DO
have interaction with cells. That's why it's used for medical device
sterilization. It kills bacteria cells. Killing qualifies for
"interaction" to me.

One webpage of a company that performs gamma sterilization:

http://www.isomedix.com/Gamma/

"How does gamma irradiation work?
High-energy photons are emitted from an isotope source (Cobalt 60)
producing ionization (electron disruptions) throughout a product. In
living cells, these disruptions result in damage to the DNA and other
cellular structures. "

--Tom