In New Zealand the typical rad exposure during a mammogram is considerably less than that surmised by Epstein, with a typical mammogram (2 shots per breast) exposing a woman to a cumulative total of just over 0.2 cGY.   Two yearly mammograms over a decade would give a cumulative exposure of 3.6cGy (rads) per decade.  New Zealand code of practice states that a dose of 0.15cGy per single view should not be exceeded in a mammogram.  The more your breasts are squashed between the X-ray plates, the lower will be the dose of radiation!

Taking all the factors into consideration, experts still conclude that the low risk of radiation exposure from mammograms is outweighed by increased likelihood of early cancer detection.  However, common sense suggests that this equation is altered by age, with premenopausal women being at greatest relative risk from radiation exposure, and also having lowest projected benefit from mammograms (due to their lower absolute risk of developing breast cancer, combined with the increased rate of false negative results due to denser breast tissue).  The combined effect of these two variables are a significant reason for women to seriously consider questioning the widespread recommendation of beginning mammograms at the age of 40.  (that’s a whole new blog in itself)

Reducing radiation exposure

• Question the necessity of X-rays and CT-scans on any given occasion.  Are they absolutely vital?
• Always request that your chest, breasts and abdomen be covered with a lead apron during X-rays – even dental X-rays.
• Resist the dentists suggestion of a dental X-ray at each visit, and save them for when they are absolutely necessary.
• Ask what dosage of radiation you will be exposed to.  Be very concerned by radiographers who either wont tell you or tell you they don’t know.  Cancel the procedure and go elsewhere!
• Go to specialist radiography centres for procedures involving radiation.  They are most likely to have regular and accurate calibration of radiation emitting equipment.

Measuring Radiation

1 Seivert = 100 rads

1 milliSeivert (mSv) = 0.1rad

1 Grey = 1 seivert

1 centriGrey (cGy) = 1 rad

Background radiation          0.5cGy/year (depending on location)

Chest X-ray (1 view)             0.025cGy

Mammogram (4 views)         0.5cGy

Fully body CT (breasts         6+ cGy

exposure)

In terms of breast tissue exposure from mammograms, 1 Grey equals 1 Seivert

To Your Wellbeing…

Lynda Wharton

lynda@lyndawharton.com
www.lyndawharton.com

In 1993 the Journal of the National Cancer Institute concluded that “total dose, age at first exposure, and time since first exposure are all determinants of the incidence rate ratio of breast cancer after exposure of the breast to ionizing radiation”. Time of exposure to radiation influences how great a negative impact there will be on breast tissue. Radiation exposure during childhood is thought to impart the greatest cancer risk, with exposure after the age of 40 having much less of an impact. Adolescent girls undergoing rapid breast tissue development are at the most risk of radiation damage to breast tissue

A fact sheet from Cornell University states “age at exposure is one of the most important determinants of future risk of developing breast cancer due to radiation later in life. Young girls are at highest risk and women irradiated around the menopausal ages are at low risk”. Before menopause, breast tissue has an increased sensitivity to radiation, possibly due to higher estrogen levels, so cumulative exposure to radiation prior to menopause poses a greater risk than the same cumulative exposure after the menopause.

While one exposure to radiation may not significantly increase our risk of breast cancer, cumulative exposures almost certainly do. Modern X-rays and mammograms deliver about ten times fewer rads than their earlier ancestors, but their cumulative impact is still of concern. When it comes to X-rays it is X-rays of the chest and coronary X-rays which pose the greatest risk to the breasts. However, radiation can scatter from X-rays anywhere in the body, including dental X-rays, to effect the breasts (Always request a lead apron be used for dental X-rays).

CT scans are now widely used in medical diagnosis, despite the fact that the radiation exposure from CT scans is many times greater than from an X-ray. The American National Cancer Institute says “CT scans comprise about 10% of diagnostic radiological procedures in US hospitals, but contribute an estimated 65% of effective radiation dose to the public from all medical X ray equipment”. Professor Eric Hall, from Columbia University, New York, says that a modern CT scan will expose a patient to the same amount of radiation as the inhabitants of Hiroshima and Nagasaki were exposed to!

(CONTINUED IN PART 2)

To Your Wellbeing…

Lynda Wharton

lynda@lyndawharton.com
www.lyndawharton.com