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CHAPTER 23
Major Diagnostic Radiological Contributions to Breast Tissue Dose
Part 1. Sources of Information on Diagnostic Doses for 1920-1960
Gofman and O'Connor (p.11, 1985)
tabulated data (originally from Shleien and co-workers,
1977)
for medical radiographic examinations
(excluding examinations of the extremities). Note carefully that
these data are for a period at least a decade after the close of
the 1920 to 1960 period. The key point is that whatever doses such
examinations were giving in the 1977 period, we expect and shall
show that, for the same numbers of examinations, the doses must
have been considerably higher during the period of 1920 to 1960.
We shall examine the frequency of various examinations in the
post-1960 period and then examine the dose which must be considered
to have gone with such frequencies or other frequencies in the
earlier period.
All entries expressed as number of examinations per 100 persons (Annually)
Medical Radiographic Examinations Fluoroscopic Examinations
(excluding examinations of extremities) (including spot films and plates)
Age Group Number of exams Age Group Number of exams
(Years) per 100 persons (Years) per 100 persons
Under 15 16 Under 15 1
15-24 42 15-24 3
25-34 56 25-34 5
35-44 65 35-44 9
45-54 72 45-54 12
55-64 73 55-64 13
65-74 73 65-74 15
Since these frequencies are expressed per 100 persons, the size of
the total population is not at issue; at issue is the average dose
for the various examinations.
How Did Doses During the 1920-1960 Period Compare with Those Beyond 1960?
An absolutely essential introduction which is required to deal
realistically with the pre-1960 era consists of several facts and
several descriptions of reality concerning x-radiation practice
during the pre-1960 period. It will become abundantly clear why
this is so.
The Statements of C.B. Braestrup (1969)
C.B. Braestrup was intimately involved in engineering practice in
the radiation field in the early period. His report
(Braestrup 1969)
contains the following statement, according to
Shapiro 1990
at page 379:
"Within the first few years of Roentgen's discovery, the
application of x-rays in diagnosis required doses of the order of
1000 times that required today [meaning in 1969]. Radiographs of
heavy parts of the body took exposures 30-60 minutes long. Maximum
allowable exposures were set by the production of skin erythemas
(300-400 rad). Thus the skin served as a personal monitor. The
Wappler fluoroscope, manufactured around 1930-1935, produced
125-150 R/min at the panel. Skin reactions were produced and in
some cases, permanent injury. To minimize hazard, a 100 R per
examination limit was set in the New York City hospitals."
This is truly mind-boggling to hear of the earlier doses with x-ray
films and plates. Scientists and physicians in practice today have
trouble conceiving of a period where there was no agreed-upon
physical or chemical dosimeter to ascertain how much radiation was
being delivered. One monitor was, as Braestrup states
appropriately, the skin of humans. It was noted that with enough
radiation one finally achieves a reddening of the skin, known
medically as an erythema of the skin. The early roentgenologists
tended to make the assumption that if the skin had not reddened,
one could not be near any serious radiation source. And as a
number of these early radiologists died, their Journal showed
photos of "those who pioneered for their profession and gave their
lives in doing so." (See early years of American Journal of
Roentgenology and Radium Therapy.)
This dosimeter --- skin --- was crude. Response depended on how
big an area of skin had been irradiated. It depended on the voltage
across the x-ray tube (which determines kVp of the x-rays coming
out). It depended on window thickness of the x-ray tube and on the
amount and type of filtration between tube and patient.
It was the erythema dose-unit, which led authors to write about
delivering "one-tenth, one-fifth, or one-half an erythema." If one
studies those early issues of American Journal of Roentgenology,
he(she) will see the controversies about the appropriate use of the
erythema doses and the controversies about physical dosimeters that
would ultimately replace the living dosimeter.
Early fluoroscopy was in many ways even more mind-boggling, with
physician over-exposure, patient over-exposure, and numerous
technician and nurse over-exposures due to machines inadequately
shielded and beams inadequately collimated. We note the
introduction of the Wappler fluoroscope with a bountiful X-ray
output, 125-150 R/min at the panel. So the roentgenologists who
had become accustomed to a dearth of adequate exposure now found
themselves not realizing what could happen in two minutes.
Incidentally, the Wappler fluoroscope was a high-quality machine.
"Westinghouse liked the machine so well, it bought the company."
[Victor Kiam, please excuse borrowing your line.]
It is alarming to consider what these powerful machines meant in
terms of fluoroscopic dosage. The statement that skin reactions
were produced and in some cases, permanent injury was produced, is
chilling, but not unexpected. And to learn that New York City set
a 100 R examination limit on fluoroscopy in the New York hospitals
should not be assumed to mean that all was well elsewhere. No doubt
this is just a reflection of a little more concern there than
elsewhere.
It is very hard to doubt that average fluoroscopic doses for such
procedures as Upper G.I. Series, or Thorax Studies, or Gall-Bladder
Examinations (cholecystograms), were at least 2, 3, or 5 Roentgens
in the early period --- at a time when legislators tried to limit
such exposures per exam from exceeding 100 Roentgens. In
Part 3 of
this chapter, we surely underestimate exposure by using 3 Roentgens
as the entrance dose per average fluoroscopy in 1920-1960.
The Special Problems of Fluoroscopy in Pediatric Practice
Some special problems must be noted for newborns, infants, and
children in the pediatric years.
Dr. Hanson Blatz (Blatz 1970),
the director, Office of Radiation
Control, New York City Department of Health, is cited in Shapiro at
page 421 discussing the problem of the prescription of excess
numbers of x-rays.
What follows stretches the mind so much, we felt impelled to check.
We had known of Dr. Blatz, but had never met him. We telephoned
Dr. Karl Z. Morgan, widely recognized as the "father" of the health
physics profession. Yes, Karl knew his work well, and Karl gave
him an excellent recommendation in the health physics field.
These are Dr. Blatz's words from 1970 (as reported in
Shapiro 1990, p.421):
"The problem of excessive use of unnecessarily repeated
examinations is an abuse that could not be regulated under any
circumstances. Popular feeling and professional education have
been and will probably continue to be the only effective controls."
And:
"And I don't think we should overlook popular feeling. Those of
you who have been in the field a long time know that it was once
the practice of pediatricians to fluoroscope babies and young
children every month and when they had the annual checkup
[presumably in the 1940s and 1950s]. When we questioned this
practice, pediatricians would say, `Well, the parents expect it.
They think if I don't fluoroscope the patients, they are not
getting a complete examination'."
Non-Recorded Doses May Exceed Anything on Record
We now have confirmatory evidence from two sources that what
Dr. Blatz described for New York City was also happening in Rochester,
New York, and in Seattle, Washington. The observations of Franz
Buschke and Herbert Parker (1942)
and of James Pifer (1963) are
detailed in Chapter 31. Some
pediatricians (but not all) were
routinely fluoroscoping all their patients at the monthly
"well-baby" examination in the first and second years after birth.
Buschke and Parker ascertained that exposures from a skillful
examiner could add up --- by the second birthday --- to 200
Roentgens of entrance dose, and much more from a non-skilled
examiner.
Such information suggests that fluoroscopy in young children could
dominate the diagnostic radiation exposure in the 1920-1960
period. It would all depend on what fraction of pediatricians
engaged in this practice --- a practice which many of them may not
have recorded at all, and a practice for which they surely did not
record how long the x-ray beam was on, at each examination.
Do we know of anyone who had fluoroscopy during every pediatric
check-up? Yes, we do. While we were doing this study, we happened
to hear by letter from a woman in New York who remembers being
fluoroscoped at every pediatric exam from age 4 through age 12.
Before age 4, she has no recall one way or the other, and she can
not ask her mother who is no longer alive.
The Immature Technology Available in the 1920 - 1960 Era
In the 1920-1960 period, film-speed was much slower than in the
post-1960 period. This had several repercussions. It took a longer
exposure to make a roentgenogram. And because it took a longer
exposure, the effect of motion was very serious for films, and
caused bad blurring of images. So there was a high tendency for the
roentgenologist to choose to do fluoroscopy. But more fluoroscopy
meant even higher doses. A massive improvement became available in
the later period, not available in most of the 1920-1960 era,
namely fast film-screens which could enhance images in
roentgenograms, and fast film screens which could enhance images in
fluoroscopic practice. So on both these counts, the doses in
1920-1960 were necessarily much higher than in the 1970's and
beyond, since lesser exposures became required with the faster film
screens.
Part 2. Radiological Doses in the Pre-1960 and the Post-1960 Eras
The Words of Dr. Francis Curry Concerning Practice as Late as in 1960
We have alluded to some of Dr. Curry's comments concerning x-ray
exposure from tuberculosis screening. But we must give some more
consideration of what some of his remarks must mean for dose
estimates for the 1920-1960 era.
Dr. Francis Curry, deputy director and later director of public
health and hospitals in San Francisco from 1960 to 1976, is quoted
by Caufield at page 144 as follows:
"What was so horrible about what was happening then is that so many
machines had no filters, no coning, no shielding. Many people were
getting total body exposures and were getting doses big enough to
show clinical symptoms."
If Dr. Curry had this to say about the 1950s, what are we to think
about doses in the far more immature era of 1920 to 1950?
We have now covered some of the crucial evidences that indicate we
must expect doses for any specific procedure in the 1920-1960 era
to be considerably higher than those in the mid-1970s, for which we
have some reasonably meaningful estimates of average doses for
major diagnostic radiological procedures.
How We Shall Handle the Diagnostic Doses in the 1920-1960 Period
1. We shall assume that the frequency of examinations (diagnostic
exams per 100 persons for any age bracket) is the same before 1960
as after 1960. There may be some difference, but we must carefully
differentiate between growth in total number of exams which is in
part related to population growth (which is large in that period)
and the frequency of examinations per 100 persons in each age
category after 1960.
2. The issue of "wasted radiation" is extremely important in our
handling of the dose estimates. For these considerations we turn to
an important publication of David Johnson and Walter Goetz
(1986).
Wasted Radiation in Diagnostic Medical Exposures in the Early
Period
It is a fundamental principle of diagnostic radiography today that
one never permits the beam of radiation to be of larger total area
than the area of the film exposed. All radiation in excess of that
needed for the film is "wasted radiation" --- exposing the patient
needlessly to radiation having nothing to do with diagnosis.
Johnson and Goetz
point out that enormous progress was made between
1964 and 1983 in reducing the amount of wasted radiation. For
1964, they found the total dose of radiation delivered in
diagnostic work was 3.2 times what was needed for the film. So
two-thirds of the exposure being experienced by the patient added
to injury but added nothing to diagnostic efficiency. By 1982, the
wasted radiation was almost all eliminated by proper collimation of
the beam.
What this tells us is that before 1960, the situation was even
worse --- with at least three times as much area of the body
exposed as was necessary. In effect, this means that a diagnostic
examination such as Upper G.I. Series undoubtedly exposed the
breasts unnecessarily. Examination of the chest exposed several
abdominal organs unnecessarily.
In Gofman and O'Connor (1985),
for each exam we provided the anatomic limits generally used for each
type of examination. Thus (at page 171) we find the following for
the Upper Gastro-Intestinal Exam:
"Length of Field: For adults, the field length is 43.2 cm, and
extends from 4 cm below the sternal notch to 6 cm below the iliac
crests. The field center is 6 cm below the xiphoid process ..."
These dimensions tell us, by reference to anatomical diagrams,
which organs are fully in the x-ray beam field, which organs are
far away even from the edge of the x-ray field, and which organs
are near the border of the x-ray field. When we are calculating
the dose in rads to an organ by using conversion factors from
entrance dose in Roentgens to absorbed organ dose in rads, we are
speaking of the organ dose for those organs fully in the x-ray
field. And we know about this from the position limits given above
under "Length of Field" and its position with reference to body
points.
The implication of the work of Johnson
and Goetz is that in the
earlier days (before 1964) the exposure field was much greater than
is the case for exams taken more recently. This means that organs
which would be partially in the field by methods used after 1983
could have been totally in the x-ray field before 1964. Organs
outside the field by 1984 standards might be partially or totally
within the field before 1964.
In Gofman/O'Connor 1985
at page 171, we listed six organs in
females which generate most of the cancer risk from an Upper G.I.
Exam: Large intestine, kidneys, pancreas, breasts, stomach, and
bronchi. But that is according to post-1980 standards of practice.
The reason why breast does not head the list of such organs is that
the breasts are not fully in the field. So, the estimated cancer
risk to breasts is less than it would be if the breasts were fully
in the x-ray field.
In the pre-1964 era (and our concern is for 1920-1960), the body
parts exposed represented 3 times or more than the area needed to
do the examination ---- and that wasted radiation brought the
breasts essentially fully in the x-ray field for some exams,
partially into the field for other common exams. And for some of
the common exams, the position of the beam is sufficiently far
enough away, that even with the wasted radiation, we consider that
there was essentially no exposure of the breasts in such exams, for
example, in the pelvic and hip exams. For such examinations, we
shall list the breast dose as zero. This will all come together as
we consider precisely how the estimates are actually made, in the
text which follows.
As we now prepare to estimate the diagnostic radiology doses for
1920-1960, we shall have to take into account for each of the
x-ray procedures just what fraction of the organ is in the x-ray
field before we can apply the conversion factor from Roentgens of
entrance exposure to rads absorbed by the organ --- in our case,
the breast-pair. And we necessarily must take wasted radiation
into account. We will let the reader know which organs are
regarded as fully in the field and which are only fractionally in
the field. Our analysis will give accounting for such differences
in developing our final estimates of breast-doses from diagnostic
radiology in the 1920-1960 period.
Part 3. Estimation of Diagnostic Radiology Doses for (1920-1960)
Step 1. What Were the Major Diagnostic X-Ray Procedures in Use?
NCRP 100 provides a
listing of the total number of such procedures
in the United States, for the 1964 - 1980 period in Table 3.7 at
page 15, based upon Mettler's work
(1987). Our interest is in the
tabulations for the 1964 period, since this is the closest to our
1920-1960 period. We shall need the frequencies listed here for
developing a final weighted average dose per diagnostic procedure.
Examination Number of Examinations (1964) Weighting
(thousands) Fraction
Skull 3,000 0.0442
Other Head and Neck 1,900 0.0280
Cervical Spine 2,900 0.0428
Chest Radiographic 32,400 0.4779
Abdomen (K-U-B) 2,800 0.0413
Cholecystogram 2,800 0.0413
Thoracic Spine 1,200 0.0177
Lumbar Spine 5,800 0.0855
Upper GI 5,500 0.0811
Barium Enema 3,000 0.0442
Pyelogram (Kidneys) 3,300 0.0487
Pelvis 2,100 0.0310
Hip 1,100 0.0162
------- -------
Total, all listed exams 67,800 1.0000
Excluded are extremities, since those are not tabulated in our frequency
per 100 diagnostic exams.
Excluded is Full-Spine, which is primarily a chiropractic exam, and has
been treated in the chiropractic chapter, 22.
Excluded are mammograms, which are treated in a
separate chapter.
Excluded are CT Scans, which were not available in the 1920-1960 period.
The weighting factors derived here will be appplied to the doses
per exam to reach our final conclusion of population average dose
for 1920-1960. It is not possible to be certain that the relative
distribution of exams was the same as in 1964, but any effects of
variation of the distribution will not be a major factor in our
dose estimation.
Step 2. Determination of the Dose for Each Complete Procedure
The basic data for each exam are provided both in
Gofman/O'Connor 1985 and in
Table 3.19 at pages 28-29 in NCRP
100. The entries are
essentially identical in both sources, except for a minor
difference in the estimated average number of films per procedure.
We warn the reader that Entrance Exposure in NCRP 100 is given in
coulombs per kilogram, whereas in Gofman/O'Connor, entrance
exposure is given in Roentgens. NCRP does provide the conversion
coefficient to Roentgens, the more familiar unit, by far.
We illustrate the procedure for determining breast-dose using the
Upper Gastro-Intestinal Series data. And we shall comment for this
and every other examination whether we regard the organ to be fully
in the x-ray field (in 1920-1960 practices) or not. If the organ
is fully in the field, the breast-dose will be as calculated. If
not fully in the field, we shall provide an estimate of the
fraction of the calculated dose to be used.
Upper Gastro-Intestinal Examination
Col.A Col.B Col.C Col. D Col.E Col.F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose Breasts Films HVL Adjust. per Breast-Pair
Roentgens Rads
AP 0.640 0.443 0.73 2.80 1.27 0.411
PA 0.547 0.020 1.15 2.86 1.55 0.036
LAT 1.147 0.210 0.05 3.01 1.61 0.017
OBL-PA 0.775 0.085 1.93 2.94 1.59 0.262
Total Average Dose ------> 0.726 rads
Explanations:
- Col. A provides the kinds of directions of the x-ray beam going
into the body.
AP (anterior-posterior) means the x-ray beam enters
the front of the body and exits through the back of the body.
PA (posterior-anterior) means the beam enters the back, and
exits through the front of the body.
LAT (lateral) means the beam enters one side of the body and
exits the other side.
Detailed specification gives the information as to whether the
beam enters the left side of the body or the right side. So
we have LAT-LR and LAT-RL.
OBL-PA (Oblique posterior-anterior) means the beam enters
half-way between the back and the side of the body. Had it
been OBL-AP, it would have meant a beam entering half-way
between the front and the side of the body.
- Col. B provides the entrance dose in
Roentgens. NCRP 100
gives this dose in coulombs per kilogram, which is convertible
to Roentgens. We have used the NCRP 100 values, after
conversion. They agree essentially perfectly with the
Roentgen values for the various exams in
Gofman/O'Connor 1985.
- Col. C provides the dose in rads received by a specific
organ for the entrance exposure and for the particular
direction, if the organ is fully in the field. The values for
dose per unit Entrance Exposure are in Table C, p. 404 of
Gofman/O'Connor 1985. The entries
for Female Breast are as follows (in rads per Entrance Roentgen):
Organ Beam Beam Beam Beam Beam
AP PA LAT-LR OBL-AP OBL-PA
Breast-Pair
Female 0.693 0.037 0.183 0.438 0.110
All of these values are for a beam quality ("hardness"),
expressed as a Half-Value Layer of 2.3 millimeters (mm) of
Aluminum (Al.). This corresponds to 30 keV x-rays.
Thus, for the first line (AP) direction of beam, Col. C is
obtained by multiplying 0.693 by Col.B entry in Roentgens.
(0.693 rads / Roentgen) x 0.640 Roentgens = 0.443 rads
But this is for one film and a beam quality of 2.3 mm Al. HVL.
- Col. D provides the average number of films per examination
(from NCRP
100). Of course, there are no fractional films. The
fractional values reflect the taking of 0 films in some
institutions, 1 film in others, 2 films in still others.
- Col. E provides the Half-Value Layer in mm Al.
- Col. F provides the adjustment factor for each HVL value.
Since these values are mostly not 2.3 mm Al., it is necessary to
use an adjustment factor for all values other than 2.3 mm Al. Such
adjustment factors are presented in Table D of
Gofman/O'Connor 1985. For the
AP direction and an HVL of 2.80 mm Al., the adjustment factor
is 1.27, which is the value entered in Col. F.
- Col.G. This is the final value in rads for organs fully in
the x-ray field.
Col. G entry = (Col. C entry) x (Column D entry) x (Col. F entry)
= 0.443 rads/film x 0.73 films
x 1.27
= 0.411 rads.
Since we consider that the breasts are essentially fully in the
field with the wasted- radiation factor of the period 1920-1960,
there will be no adjustment for this value of 0.411 rads for the AP
view of Upper Gastro-Intestinal Exam.
This general procedure is followed for all other projections, PA,
LAT, OBL-PA. The sum of all the rad doses in Col. G represents the
total dose to breasts for this particular roentgen examination, for
organs fully in the x-ray field.
All other examinations are handled similarly.
We can now calculate what the dose is for all the major diagnostic
radiological exams to use for 1920-1960 estimates of combined
dose.
- Note: The unseen "trailing digits" in the calculations
sometimes cause results to look "off" in very small ways.
CERVICAL SPINE
Col.A Col.B Col.C Col.D Col.E Col. F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose,R Breasts Films HVL Adjust. per Breast-Pair
AP 0.26 0.180 1.45 2.23 0.96 0.251
PA 0.15 0.006 0.04 2.43 1.07 0.000
LAT 0.17 0.031 1.27 2.35 1.02 0.040
OBL-PA 0.20 0.022 0.89 2.35 1.05 0.020
Total Average Dose 0.311 rads
Adjustment for breasts not fully in field = 0.5.
Final Average Dose 0.156 rads
RIBS
Col.A Col.B Col.C Col.D Col.E Col. F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose,R Breasts Films HVL Adjust. per Breast-Pair
AP 0.357 0.247 0.87 2.24 0.97 0.209
PA 0.289 0.011 0.80 2.44 1.07 0.009
LAT 0.186 0.034 0.08 2.98 1.34 0.004
OBL-PA 0.627 0.069 1.20 2.38 1.05 0.087
Total Average Dose 0.308 rads
No adjustments for organ not fully in field.
Final Average Dose 0.308 rads
SHOULDER (We cut Column C in half, since exam is of one shoulder.)
Col.A Col.B Col.C Col.D Col.E Col. F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose,R Breasts Films HVL Adjust. per Breast-Pair
AP 0.194 0.067 1.45 2.15 0.92 0.089
PA 0.147 0.003 0.04 2.10 0.83 0.000
LAT 0.973 0.089 0.15 2.53 1.22 0.016
OBL-PA 0.306 0.017 0.13 2.30 1.00 0.002
Total Average Dose 0.108 rads
No adjustments at all for breasts not fully in x-ray field.
Final Average Dose 0.108 rads
THORACIC SPINE (WIDE)
Col.A Col.B Col.C Col.D Col.E Col. F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose,R Breasts Films HVL Adjust. per Breast-Pair
AP 0.663 0.459 1.07 2.37 1.04 0.511
PA 0.516 0.019 0.00 2.50 1.19 0.000
LAT 1.457 0.267 0.93 2.42 1.12 0.278
OBL-PA 0.756 0.083 0.12 2.42 1.12 0.011
Total Average Dose 0.800 rads
No adjustments at all for breasts not fully in x-ray field.
Final Average Dose 0.800 rads
CHOLECYSTOGRAM (Gall-Bladder)
Col.A Col.B Col.C Col.D Col.E Col. F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose,R Breasts Films HVL Adjust. per Breast-Pair
AP 0.543 0.376 0.48 2.46 1.08 0.195
PA 0.547 0.020 1.41 2.41 1.11 0.032
LAT 0.752 0.138 0.13 2.51 1.20 0.021
OBL-PA 0.744 0.082 1.21 2.52 1.21 0.120
Total Average Dose 0.368 rads
No adjustments at all for breasts not fully in x-ray field.
Final Average Dose 0.368 rads
LUMBAR SPINE
Col.A Col.B Col.C Col.D Col.E Col. F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose,R Breasts Films HVL Adjust. per Breast-Pair
AP 0.884 0.612 1.03 2.37 1.03 0.650
PA 0.543 0.020 0.03 2.48 1.09 0.001
LAT 3.198 0.585 1.33 2.58 1.26 0.981
OBL-PA 1.109 0.122 0.46 2.51 1.20 0.067
Total Average Dose 1.698 rads
No adjustments at all for breasts not fully in x-ray field.
Final Average Dose 1.698 rads
ABDOMEN (KIDNEY-URETER-BLADDER)
Col.A Col.B Col.C Col.D Col.E Col. F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose,R Breasts Films HVL Adjust. per Breast-Pair
AP 0.663 0.459 1.28 2.54 1.12 0.658
PA 0.419 0.015 0.23 2.45 1.15 0.004
LAT 2.097 0.384 0.07 2.51 1.20 0.032
OBL-PA 1.221 0.134 0.11 2.44 1.14 0.017
Total Average Dose 0.712 rads
No adjustments at all for breasts not fully in x-ray field.
Final Average Dose 0.712 rads
BARIUM ENEMA
Col.A Col.B Col.C Col.D Col.E Col. F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose,R Breasts Films HVL Adjust. per Breast-Pair
Barium Enema
AP 0.760 0.526 1.52 2.95 1.33 1.064
PA 0.771 0.029 0.93 2.92 1.58 0.042
LAT 4.012 0.734 0.49 3.12 1.67 0.601
OBL-PA 1.349 0.148 1.02 3.05 1.66 0.251
Total Average Dose 1.958 rads
Adjustment for breasts not being fully in field = 0.33
Final Average Dose 0.646 rads
INTRAVENOUS PYELOGRAM (Kidney Exam)
Col.A Col.B Col.C Col.D Col.E Col. F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose,R Breasts Films HVL Adjust. per Breast-Pair
AP 0.597 0.414 4.51 2.47 1.08 2.015
PA 0.442 0.016 0.20 2.53 1.22 0.004
LAT 0.527 0.096 0.04 2.59 1.27 0.005
OBL-PA 0.915 0.101 0.70 2.59 1.26 0.089
Total Average Dose 2.112 rads
Adjustment for breasts not being fully in field = 0.33
Final Average Dose 0.697 rads
CHEST
Col.A Col.B Col.C Col.D Col.E Col. F Col. G
Beam Entrance Rads to No. of Beam Beam HVL Final Rads
Direction Dose,R Breasts Films HVL Adjust. per Breast-Pair
AP 0.050 0.035 0.10 2.44 1.07 0.004
PA 0.027 0.001 0.92 2.51 1.20 0.001
LAT 0.081 0.015 0.50 2.80 1.47 0.011
OBL-PA 0.120 0.013 0.02 2.49 1.19 0.000
Total Average Dose 0.016 rads
No adjustments at all for breasts not fully in x-ray field.
Final Average Dose 0.016 rads
PELVIS exam gives just about 0 rads to breast --- too low in position
Final Average Dose 0.00 rads
HIP exam gives just about 0 rads to breast---- too low in position.
Final Average Dose 0.00 rads
SKULL seems too high to affect the breasts
Final Average Dose 0.00 rads
OTHER HEAD AND NECK
It is reasonable to take the average of skull and cervical spine doses.
(0.156+0.00)/2 = 0.078 rads
Final Average Dose 0.078 rads
Now we list the estimated total number of diagnostic x-ray
procedures and their dose in order to obtain an overall average
dose.
Breast Rads Times
Exam Rads Access Frequency Frequency
Skull 0.000 3,000 0.0
Other Head and Neck 0.078 1,900 148.2
Cervical Spine 0.156 (0.5) 2,900 451.0
Chest Radiographic 0.016 32,400 518.4
Ribs 0.308 NA Not calculated
Shoulder (One) 0.108 NA Not calculated
Abdomen (KUB) 0.712 2,800 1993.6
Biliary 0.368 2,800 1030.4
Thoracic Spine 0.800 1,200 960.0
Lumbar Spine 1.698 5,800 9848.4
Upper GI 0.726 5,500 3993.0
Barium Enema 0.646 (0.33) 3,000 1938.4
Pyelogram 0.697 (0.33) 3,300 2300.0
Pelvis 0.000 2,100 0.0
Hip 0.000 1,100 0.0
Sum 67,800 23181.34
Dose for Average Exam ----> 0.342 rads
Dose to breasts per person = (0.342 rads per exam) x (exams per person).
This follows since we have calculated the mean dose from
all exams, excluding exams of extremities.
Medical Radiographic Examinations 1920-1960: Each yielding 0.342
rads to breast.
Age Group Number of Exams Breast Dose (Rads)
per Person per Person
Under 15 years 0.16 0.055
15-24 years 0.42 0.144
25-34 years 0.56 0.192
35-44 years 0.65 0.222
45-54 years 0.72 0.246
55-64 years 0.73 0.250
65-74 years 0.73 0.250
Now we shall consider the additional dose from fluoroscopic exams.
We shall very conservatively estimate the fluoroscopic exposure at
3 Roentgens per exposure, at a beam half-value layer of 2.3 mm Al.
In view of the discussions above concerning limiting fluoroscopic
exams to 100 Roentgens per exam in New York, it would be hard to
consider 3 Roentgens of entrance dose per average fluoroscopy in
1920-1960 as any sort of overestimate. By contrast, the entrance
dose from each pediatric fluoroscopy was estimated by Buschke and
Parker (1942, p.527)
to be 8 Roentgens if the examiner was skilled,
or considerably higher if the examiner was inexperienced. Below,
however, readers will see that we use zero as the annual average
breast-dose from fluoroscopy for children below age 15.
For all the other ages, we will pretend that the fluoroscopic beam
was never used from front to back (the AP view) --- an unrealistic
approximation which clearly results in an underestimate of
breast-dose for all the age-groups below. Additionally, we will
assume that only one-third of the fluoroscopies exposed breast
tissue. So we calculate as follows:
- For breast in PA view, 0.037 rads per Roentgen for 2.3 mm Al as half-value layer.
- For 3 Roentgens exposure, total dose = 3 x 0.037 = 0.111 rads.
- And assume only 1/3 of the fluoroscopies affected the breast tissue.
- Breast Dose from fluoroscopic examinations, = (1 /3) x 0.111 = 0.037 rads.
- No adjustment for beam hardness is needed at 2.3 mm Al half-value layer.
Fluoroscopic Examinations (including spot films and plates)
Average
Age Group Number of Exams Breast-Dose in Rads
per Person per Person, per Year
Under 15 years 0.01 0.000
15-24 years 0.03 0.001
25-34 years 0.05 0.002
35-44 years 0.09 0.003
45-54 years 0.12 0.004
55-64 years 0.13 0.005
65-74 years 0.15 0.006
Final Total Doses to Breasts at Various Ages,
Roentgenograms + Fluoroscopic Exams
Average Rads, Total
Age Group Breast Dose per Breast-Dose per Breast-Dose
Person (films) Person (fluoroscopic) per Person
Under 15 years 0.055 + 0.000 0.055
15-24 years 0.144 + 0.001 0.145
25-34 years 0.192 + 0.002 0.194
35-44 years 0.222 + 0.003 0.225
45-54 years 0.246 + 0.004 0.250
55-64 years 0.250 + 0.005 0.255
65-74 years 0.250 + 0.006 0.256
Transfer of Source Data to the Master Table
(Col.P)
This final tabulation, taking into account roentgenographic and
fluoroscopic exams, exceedingly conservatively stated, will provide
entries for every single age-year in the Master Table,
Column P.
# # # # #
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