| chgoeditor |
Jul 1, 2013 4:04 pm |
Warning pop-up when you attempt to view the report on the Association of Physicists in Medicine's website.
And a second time in a colored box on the front page of the report.
And a third time on the second page of the report.
Quote:
DISCLAIMER: This publication is based on sources and information believed to be reliable, but the AAPM, the authors, and the editors disclaim any warranty or liability based on or relating to the contents of this publication.
The AAPM does not endorse any products, manufacturers, or suppliers. Nothing in this publication should be interpreted as implying such endorsement.
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From the summary:
Quote:
For a standard man of 178.6 cm (510) tall and 73.2 kg (161.4 pounds), the
effective dose from a single-pose, two-sided scan was determined to be 11.1 nSv (nSv = 10–9Sv) and the skin dose to be 40.4 nGy (nGy = 10–9 Gy). This effective dose is equivalent to 1.8 minutes of background dose received by the average individual in the U.S. in 2006 and is approximately equivalent to 12 seconds of naturally occurring dose during an average flight.
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So I'm standing in the scanner for, what?, 15 seconds and I receive a dose that's 11.1 nSv. It would take me seven times as long (1.8 minutes) to get the equivalent dose if I were not in the scanner.
Another quote, from page 3:
Quote:
1.1 What This Report Does and Does Not Address
It is not the goal of this report to either advocate or discourage use of these systems.
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From page 9:
Quote:
The energy-corrected air kerma measurements at reference point averaged for all tested units was 0.046 µGy with a standard deviation of 0.003 µGy and a range of 0.04 µGy to 0.052 µGy. This average exposure value, corrected for distance to the phantom entrance plane, was used for
all PCXMC calculations. The default adult Cristy phantom representing a “standard man” has a height of 178.6 cm (5 feet, 10 inches) and a weight of 73.2 kg (161.4 pounds). As this underestimates the average size of the adult population in the United States, the average heights and weights for an adult U.S. man and woman over age 20 were obtained from the 2003–2006 National Health Statistics Report produced by the Centers for Disease Control and Prevention (CDC) and also used as input data for dose estimation.
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Personally I'm smaller in both weight and stature.
From page 10:
Quote:
Note also that larger-size subjects receive somewhat smaller doses, and smaller subjects receive larger doses, even when accounting for their respectively smaller and greater distances from the scanner face due to their different thicknesses. This is not due to variation in machine exposure, but is a result of the different absorption patterns due to differences in tissue mass of the scanned subjects (absorbed dose is energy absorbed per unit mass). A similar phenomenon is experienced in medical x-ray procedures where smaller patients receive more dose for a given machine output as a result of their smaller size/mass.
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Oh, joy. So I'm smaller than the average American, so I'm actually receiving a larger dose? |
