Baby put through X-ray machine at LAX

MSNBC ^ | December 2006 | Associated Press

[UpAllNight]

Scanners for carry-on are limited to less than 1 mr.

[al baby]

im not sure

[GretchenM]

To the inexperienced traveler:

Terrorist weapon:

Baby:

[AFPhys]

I would be extremely surprised if that is the case for the luggage or other subject of the scanning. The 1mr level HAS to be the amount of external "leakage" allowable from the device, not the radiation it has on the inside doing its business.

[AFPhys]

According to this:
http://www.radiationcontrol.utah.gov/XRAY/Dental_e.htm
The Utah "Division of Radiation Control" claims that a "bite-wing" dental XRay requires 150-350mrem.

Don't want to get into a tif with you... I suspect that the "2mrem" you're recalling is "whole body exposure" that the subject gets in that procedure, not the amount of radiation that the Dental XRay uses to take a picture of that very localized area of the mouth.

[AFPhys]

Sorry, that sentence was long, and I didn't notice that my editing left a period in the middle of the sentence instead of a comma, or I could have left out all punctuation marks. Corrected, it should read:

"If you were to get dose of 30,000mrem, it is possible that a sophisticated blood test could detect that you were exposed to radiation, (Radiation workers in the US seldom get 100mrem/yr above background), but radiation sickness requires about double that dose to be in evidence.

That puts us in substantial agreement, leaving me to say that radiation sickness requires about 60,000mrem ... which is, as you say, about 500 times the annual dose allowed for radiation workers in the US.

Thank you for clarifying that such a dose has to be inflicted in a short time period to produce radiation sickness.

[UpAllNight]

--The Utah "Division of Radiation Control" claims that a "bite-wing" dental XRay requires 150-350mrem.
Don't want to get into a tif with you... I suspect that the "2mrem" you're recalling is "whole body exposure" that the subject gets in that procedure, not the amount of radiation that the Dental XRay uses to take a picture of that very localized area of the mouth. --

No. They say mR. There is a difference between mR and mrem. mrem is the effective dose.

[UpAllNight]

--I would be extremely surprised if that is the case for the luggage or other subject of the scanning. The 1mr level HAS to be the amount of external "leakage" allowable from the device, not the radiation it has on the inside doing its business. --

No. The limits have been verified for damage to photographic materials. In fact, actual tests show about 0.3 mR for the Rapidscan equipment used at airports and LESS THAN 10 mR for 100 passes using radiation badges.

[Patriotic1]

They don't examine what gets put in. In busy times, people are lined up with 5 people putting stuff in the bins.

[AFPhys]

You're right - there is a difference between a mRad and a mRem. However, in this case, they're equivalent:

There are several others places to cite, but for details see: http://www.radford.edu/~fac-man/Safety/Radiation/chp5.htm where they conclude:
"In summary, the roentgen is a unit of exposure, the rad is a unit of absorbed dose, and the rem is a unit of biological dose. The rem is the unit that is used to measure radiation doses to personnel. For practical purposes, however, the roentgen, rad, and rem are essentially equivalent for gamma and beta rays and can be used interchangeably. Commonly used subunits are milliroentgen, millirad, and millirem (mR), which are equal to 1/1000 of these units."

[AFPhys]

The airport scanner situation is somewhat unclear. It appears I was misled by the photographers fear-mongering... somewhat, at least. When I looked in detail at the GE linked website about the CTX scanners, I found it to be completely unhelpful. I found no solid support for that photography website that claimed up to 300mR could be inflicted by a CTX scanner. However, some articles and serious investigations have done written about this, and some manufacturers of small scanners are happy to give their low-ball figures. I'll try to distill what I found out here:

The total dose applied in a typical luggage scan is, as you say, definitely under 1mr, though that dose is applied at a high radiation rate. However, apparently if something suspicious is found inside checked luggage, some XRay machines such as the CTX models mentioned above, can switch to a "second scan" which is equivalent to tomography. That will raise the dose the luggage gets by large amounts, and THAT is probably what the photographer was warning people about, and indeed I found quite a few pictures on the web demonstrating the wide (about 10-15% of film width) "stripe" of damage that shows up VERY PROMINENTLY on fast film (ASA800) with this machine. Sorry, I didn't save a link to the any of the images, but they aren't difficult to find on the photography sites on the web that have studied this. Also, it is clear that not every "stripe" of the luggage gets the same dose - some parts really can get hammered, though.

From GE's site:"Like all GE CTX EDS machines, the CTX 5500 DS system uses technology derived from medical Computed Tomography (CT) to help locate and identify explosive devices concealed in checked baggage. As the conveyor moves each bag through the machine, the system produces a scan projection X-ray image. Using sophisticated computer algorithms, the CTX 5500 DS system analyzes these slice images and compares their properties with those of known threats."

Carry-on luggage is different: if something looks suspicious with the low-radiation scan, they'll simply have you pop it open, and there is never a high dose risk. Lesson: take film in carry-on, for sure. There are claims that the dose is safe for up to ASA1600 (very fast) film with some machines. However, if you have to go through many rounds of scans, it the effect is clearly cumulative, so I wouldn't depend on this too much if you're a professional film photographer - you could find yourself with foggy fast film for sure.

The "leakage rates" for all the scanners are all sub-mrem/hr, despite the high radiation dose rate used for the scans within the scanners (which I was not able to determine at all). Again, no surprise.

And for anecdotal amusement, a blog had this from a photographer who did his own experiment, and this agrees nicely with the more professional studies:

Jonathan Kroner , apr 05, 2002; 10:33 a.m.
On a recent trip from Miami to Bangkok (approx. 26 hours in the air) I had 9 rolls of 800 speed fuji hand inspected and one roll (which was already in the camera) was subjected to one "film safe" machine. All the film was developed and printed before returning. The "film safe" role was visibly duller than the rest. Standing alone, I might not have noticed the quality degradation of the "film safe" roll. However, in contrast to the others, it was obvious that "film safe" machines can degrade film quality. Also, that long flights do not visibly degrade the film. Prospectively, when it matters, I will purchase and develop film at my destination.

Robert Segal , apr 05, 2002; 10:45 a.m.
For "film safe" read "film not-so-destructive-as-a-CTX"

Bottom line, as I said in my concluding remarks in my Post#48, the baby is quite safe from any "radiation exposure" damage from this incident, though I might worry about damage from his exposure to his caretakers. That was the entire point of my post.

Thanks for the reasoned discussion. I have to go now. I wish you a Merry Christmas.

[CougarGA7]

If you put the baby throught the x-ray do you still have to take its shoes off?

[UpAllNight]

--You're right - there is a difference between a mRad and a mRem. However, in this case, they're equivalent:--

Correct. However, the ESE units do not take into account the "effective" dose to the skin. The skin has a multiplier of about 0.01 thus making 200 mR ESE equivalent to about 2 mRem effective skin dose.

[AFPhys]

The multiplier is apparently taken into account in the Utah graph above. Easiest thing here now is to look for another place to settle this.

Another source has everything in the same units- mrem:
http://www.uvm.edu/~radsafe/?Page=xray.analytical.html

Background and other dose levels;

* 295 mrem (millirem) - average background dose in U.S.
* 300 mrem - average dose from 1 abdomen radiograph
* 200 mrem - average dose from 1 dental radiograph
* 20 mrem - average dose from 1 chest radiograph
* 3 mrem - average dose to UVM personnel in 1 year

[UpAllNight]

--The multiplier is apparently taken into account in the Utah graph above.--

No. The Utah data is ESE in mR. No biological damage multipliers are used. It is strictly used to compare machine output.

[UpAllNight]

NRC:

Effective dose equivalent (HE) is the sum of the products of the dose equivalent to the organ or tissue (HT) and the weighting factors (WT) applicable to each of the body organs or tissues that are irradiated (HE = ÓWTHT).

[AFPhys]

Sorry. You're information on this seems to be in error. The following (where measurements are in Sv - which is strictly DOSE measurement) is from Adani's website, a maker of medical XRay devices, and again we don't have to worry about mixed units:

"Dose equivalent is a quantity that takes into account "radiation quality" which relates to the degree in which a type of ionizing radiation will produce biological damage. Not all radiation has the same biological effect, even for the same amount of absorbed dose. The Dose equivalent is obtained by multiplying the Absorbed dose by a Quality Factor. The resulting quantity can then be expressed numerically in Sieverts (Sv, 1 Sv = 1 J/kg)..."
http://www.adani.by/prod_securpersonal_xray.php

Radiation source........ Effective dose
X-ray tomography of head 50,000 µSv (max.)*, 10,000(typical)
Dental X-ray radiography: 5,000 µSv (max.)*,. 1,000(typical)
Chest X-ray radiography:... 400 µSv (max.)*,... 100(typical)

Since 1mSv=100mrem, dental XRay = 100-500mrem biological dose to the tissue.

I'm going on to my Christmas weekend, and have really lost interest in this, since the baby will be just fine getting zapped by the screening machine. Please feel free to take this up with Adani and UVM if you like, and if you dispute their dosage figures for dental XRays.

[UpAllNight]

You should have posted the next paragraph:

Effective dose

Different tissues (or body parts) are not equally sensitive to a kind of radiation. That is, if the entire body were irradiated with uniform beam of a single type of radiation, some parts of the body would react more dramatically than others. The effective dose to an individual is calculated as a weighted average of the dose equivalent to different body tissues by using Tissue Weighting Factors designed to take into account different tissue contributions to overall effective biological damage to the body. Effective dose is used as a measure of the likelihood of stochastic effects of radiation exposure: carcinogenesis and hereditary effects. The SI unit of Effective dose is Sievert.

The effective dose is important to estimate the biological effect of irradiation but it cannot be measured directly with any instrument. A sophisticated thorough study using an anthropomorphic human body phantom was performed to estimate the typical effective doses received by the individuals from DRS SecureScan. The results of this study were described in the report (Department of Radiology of Long Island Jewish Medical Center (New York), report "Radiation Evaluation for the CONPASS Body Scanner", 06/21/2002). All data related to the DRS SecureScan effective doses are based on the above mentioned report.

[UpAllNight]

--Please feel free to take this up with Adani --

I prefer not to take it up with some Russian company that cannot meet US standards for their machine.