[ RadSafe ] Re: CT radiation makes LESS cancer and deformity?

[howard long]

Reassure those fearing CT cancer or fetal deformities:
"Is Chronic Radiation an Effective Prophylaxis Against Cancer" 
(Chen, Luan et al, J Am Physicians and Surgeons 9:1:04)
"-cobalt-60 - formed into construction steel -10,000 persons 
occupied for 9-20 years received radiation doses that averaged 0.4Sv
cancer mortality 3.5/100,000 [vs 116 expected], 
 congenital heart malformations 1.5/100,000 [vs 23 expected]"

Also, from "Breast Cancer Incidence Among Atomic Bomb Survivors"
J Nat Cancer Inst 1979 Jan;62(1):17-21, Land, McGregor et al 
Table 2       0       1-9 rad  19-49 rad   50-99 rad  100-199 rad  >200 rad
Observed  109      34         37               11               16               18
Expected   127.8  42.3      33.0              9.4              6.5            6.0 

NOTE THAT WITH  1 TO 10 REM (rad) THERE IS LESS CANCER
even with the bomb (acute, like CT)

Howard Long MD MPH (epidemiology)



----- Original Message ----
From: "Brennan, Mike (DOH)" <Mike.Brennan at DOH.WA.GOV>
To: radsafe at radlab.nl
Sent: Thursday, November 29, 2007 9:45:31 AM
Subject: RE: [ RadSafe ] Radiation exposure of pregnant women more than doublesin 10 years

This article seems to ignore the question that I think should be at the
core of the decision to use ionizing radiation on pregnant women, or
indeed on any patient, or indeed any invasive medical procedure, whether
or not it involves radiation: Does this procedure increase or decrease
the patient's overall risk?  If the answer is "yes", then it should be
done, if there is no other procedure that will result in a greater net
risk reduction.  If the answer is "no", then the procedure shouldn't be
done.  There is, of course, a big gray zone where the relative risks and
advantages are not clear, and while it would be delightful to have every
patient informed enough to make an appropriate decision, I don't see
that happening any time soon.  Doctors will have to make those
decisions, and that's why they get paid the big bucks (or at least part
of the reason).

I do not claim that pregnant women are not being exposed unnecessarily;
I am saying that this article implies that without supporting the
position, and does it in a way I find suspicious.

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of ROY HERREN
Sent: Tuesday, November 27, 2007 9:49 PM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Radiation exposure of pregnant women more than
doublesin 10 years

Public release date: 27-Nov-2007


Contact: Linda Brooks
lbrooks at rsna.org
630-590-7762
Radiological Society of North America
  Radiation exposure of pregnant women more than doubles in 10 years
CHICAGO - The past decade has seen an unprecedented increase in the use
of radiologic exams on pregnant women, according to a study presented
today at the annual meeting of the Radiological Society of North America
(RSNA). 
  "Through medical imaging examinations, we are exposing pregnant women
to twice the amount of radiation as we did 10 years ago," said Elizabeth
Lazarus, M.D., assistant professor of diagnostic imaging at the Warren
Alpert School of Medicine at Brown University in Providence, R.I.
"Overall, the levels of radiation to which we are exposing pregnant
women are low, but they do carry a slight risk of harm to the developing
fetus."
  The researchers conducted a retrospective review of selected imaging
examinations - nuclear medicine, computed tomography (CT) and plain-film
x-rays - performed at Brown to determine how often these imaging exams
were utilized in pregnant women and the estimated resulting radiation
dose to the fetus. Data were compiled for the years 1997 through 2006
and compared to the number of infant deliveries per year.
  The investigators found that from 1997 to 2006, the number of imaging
studies performed on pregnant women increased by 121 percent. The
greatest increases were in the number of CT exams, which deliver more
radiation than many other radiologic procedures. An abdominal CT exposes
the patient to a radiation amount more than twice that of an x-ray of
the lower gastrointestinal tract. An abdominal ultrasound exposes the
patient to no ionizing radiation.
  CT is not routinely used in pregnancy, but pregnant women may undergo
CT to detect suspected life-threatening conditions such as bleeding in
the brain, blood clots in the lungs or appendicitis. Since CT exposes
the developing fetus to radiation, concerns are often raised regarding
overuse. The majority of CT examinations (approximately 75 percent)
analyzed in the study were performed in areas of the mother's body
separate from the uterus, so the fetus was not exposed to any direct
radiation. Even low levels of radiation have been shown to carry a small
risk of harm to a developing fetus.
  "While performing CT exams during pregnancy is still uncommon, we
found that pregnant women are being recommended for CT more often over
the last 10 years," Dr. Lazarus said.
  The researchers evaluated 5,235 examinations on 3,249 patients. During
the 10 years of the study, the number of patients imaged per year
increased from 231 to 447, and the number of exams per year increased
from 325 to 730. This represented an 89 percent increase in patients and
a 121 percent increase in examinations over the course of the study.
During the same 10 years, the number of deliveries only increased from
8,661 to 9,261, a rise of only 7 percent or less than 1 percent
annually. 
  Use of plain-film x-rays increased an average of 7 percent per year,
and the number of nuclear medicine examinations rose by approximately 12
percent annually. CT examinations increased by approximately 25 percent
per year. The average estimated fetal radiation exposure for CT was 0.69
rads, compared to 0.04 rads for nuclear medicine and 0.0015 rads for
plain-film x-rays. 
  Other studies have shown that use of high-tech modalities, such as CT
and magnetic resonance imaging (MRI), has increased in all patient
populations throughout the United States. According to Dr. Lazarus, some
of this increase is due to the development of new imaging techniques to
better diagnose abnormalities, and some is due to motivation by
hospitals and insurers to make fast diagnoses to shorten hospital stays
and improve patient care.
  Dr. Lazarus cautions healthcare consumers to be aware of this trend.
"I want to assure patients that CT can be a safe, effective test for
pregnant patients," she said. "However, there are alternatives that
should at least be explored. Pregnant patients should ask their doctors
about other imaging or diagnostic tests that may not expose the fetus to
radiation." 
  ###
  Co-authors are C. Debenedectis, M.D., W. Mayo-Smith, M.D., and
Patricia Spencer, M.D. 
  Note: Copies of RSNA 2007 news releases and electronic images will be
available online at RSNA.org/press07 beginning Monday, Nov. 26.
  RSNA is an association of more than 41,000 radiologists, radiation
oncologists, medical physicists and related scientists committed to
excellence in patient care through education and research. The Society
is based in Oak Brook, Ill. (RSNA.org)
  Editor's note: The data in these releases may differ from those in the
printed abstract and those actually presented at the meeting, as
researchers continue to update their data right up until the meeting. To
ensure you are using the most up-to-date information, please call the
RSNA Newsroom at 1-312-949-3233.