[ RadSafe ] Airport X-Ray scanners

Thu Dec 2 10:38:46 CST 2010

True. Current would be a direct indication of the number of photons
produced per second.

John

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Cary Renquist
Sent: Thursday, December 02, 2010 11:25 AM
To: The International Radiation Protection (Health Physics) MailingList
Subject: Re: [ RadSafe ] Airport X-Ray scanners

Hi John,

Wouldn't you need to know the current?  I don't think that the current
has been publicized.

The JH reports aren't really written well with regards to their
methodology... It is not clear that they took the walls of the chamber
into account.  They did perform HVL measurements, but they did not use
them for dose calculation.

---
Cary Renquist
cary.renquist at ezag.com

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Dixon, John E.
(CDC/ONDIEH/NCEH)
Sent: Thursday, 02 December 2010 08:12
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Airport X-Ray scanners

Am I correct in stating that X-ray measurements normally include the HVL
inherent in the machine's 'tube?'
If so, then one can manually calculate the deposition skin dose from 50
Kev Xrays corrected for the air distance and density to the passenger
(just like a patient). Keep in mind, a calculation should include the
mg/cm2 (range/thickness) of the window/wall thickness of the survey
instrument used. Some instruments compensate for these effects via
software applications. Were these things done?

Regards,
John 

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Cary Renquist
Sent: Thursday, December 02, 2010 10:02 AM
To: The International Radiation Protection (Health Physics) MailingList
Subject: Re: [ RadSafe ] Airport X-Ray scanners

I took a better look at the JH reports over the Thanksgiving Holiday:
No TLD or mammography film/chambers/etc in the Johns Hopkins study...
Only a large, 1800 cm^3, ion chamber and an Eberline (Bicron) micro-rem
meter were used in the study -- to me, these don't really seem
appropriate for properly characterizing 50 keVp x-rays (just gut feeling
-- I don't have much x-ray experience other some dosimetry labs years
ago).
It is not entirely clear whether they applied the appropriate correction
factor for the radiation being measured with respect to the 1800 cc ion
chamber -- they report the "exposure reading" for the device and have no
mention of the correction factor for 50 keV x-rays with 1.2 mm Al
filtration...  (this could result in an underestimation of ~25%)
I think that they just blindly took the readings from the HVL
measurements (where you really don't need the correction factor) and
used them for the effective dose.

Best regards,
Cary

---
Cary Renquist
cary.renquist at ezag.com

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of ReuvenGmail
Sent: Thursday, 02 December 2010 02:59
To: radsafe at health.phys.iit.edu
Subject: [ RadSafe ] Airport X-Ray scanners

Hi Mr. Perle:

I posed a simple and srteightforword question: were TLD and / or film
badge 
radiation measurements made on those machines?

Your did not answer in the same way.

I will be surprised if ANYBODY, be it the manufacturer or an FDA
operative 
bothered to take
an ACR mammography phantom and a mammography film / cassette, or a set
of 
TLDs to perform
initial, crude test for EVALUATIONS, are the scanners safe or do they
pose 
radiation risks to the public?

The RapiScan 1000 is manufactured in LA or San Diego. I presume that if
the 
manufacturer had indeed used TLDs etc. - you would have known about it.

I have studied the first published "Assessment of the Rapiscan Secure
1000" 
by Frank Cerra, July 21, 2006, and I can assure you that TLD / film were
NOT 
used.

Mr. Cerra utilized a Monte Carlo software (PCXMC) which needs to be fed 
several parameters before it can run. These parameters were ESTIMATED by
Mr. 
Cerra without proving the validity of his assumptions / estimations. I
have 
not checked the this software yet, but I suspect that like any other
Monte 
Carlo software I know, it deals with STATIC source of radiation.

In the next few days I'm going to study the more recent Assessment from
John 
Hopkins University, physics dept.  Knowing my physicists colleagues, I
will 
be deeply surprised if the John Hopkins guys used an ACR mammography
phantom 
with mammography cassette and / or TLD to
"Assess" the magnitude of radiation in these scanners!

Reading the RadSafe about these scanners conjures in my mind an Academic

Tea-Party version  chanting in a trans: "X-Ray Airport scanners are safe
and 
GOOD for ya!"

Respectfully,

Reuven Zach

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Date: Tue, 30 Nov 2010 18:02:41 -0600
From: "Perle, Sandy" <SPerle at mirion.com>
Subject: Re: [ RadSafe ] TSA Scanner is Health Risk
To: "The International Radiation Protection (Health Physics) Mailing
List" <radsafe at health.phys.iit.edu>
Message-ID: <A9138597-C0A9-4A2A-9DB4-BA44CB996F86 at mirion.com>
Content-Type: text/plain; charset="us-ascii"

Hello Reuven,

I am confident that there is a lot of data regarding these units. The 
primary issue for someone other than the government or the manufacturer
to 
monitor these units with TLD or other dosimeter is that the TSA must 
authorize the placing of these devices on a person entering the unit.
The 
pilot unions wanted to test but at that point in time, the TSA would not

allow dosimeters be in the unit. If you've ever been through one, they
make 
you take everything out of your pockets, including currency bills,
wallet, 
etc. A dosimeter is a no-no.

This list has provided links to studies and I have no quarrels with the
data 
presented that demonstrates that the dose received by an individual is 
small. I traveled all day today and the airports I went through did not
have 
these scanners. I would have gladly been scanned rather than the hand-on

body grope.

Regards,

Sandy
____________________
Sander C. Perle
President
Mirion Technologies
Dosimetry Services Division
2652 McGaw Avenue
Irvine, CA 92614

+1 (949) 296-2306 (Office)
+1 (949) 296-1144 (Fax)

Mirion Technologies: http://www.mirion.com/

On Nov 30, 2010, at 12:53 PM, ReuvenGmail wrote:

> Dear Mr. Perle,
>
> Do you happen to know if there are ANY measurements results
> using TLD monitors or film badge monitors to inform us with
scientifically
> derived results about the radiation exposure / absorption levels of 
> airport
> x-ray scanners to passengers?
>
> In the absence of such rudimentary measurements, nobody in this forum
has
> the grounds to "approve" or "disprove" these machines.
>
> With the obvious track record of the FDA, I would caution, though, any
> passenger, to avoid ANY x-ray exposure!
>
> The scanners operate at 50 KvP (!)
> Here is an example of reincarnation: Xeromammography, that has been
quite
> dead for the past 40 years, is gaining a tremendous and profitable 
> revival,
> in the transmogrifyed "X-Ray Back Scatter Scanner..."
>
> Regards,
>
> Reuven Zach
> Medical Radiation Physicist
>

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