Part 1. Identification of Current Radiation Sources of Especial Concern
Perhaps the most unintelligent response to this book, and what it teaches us about the most dreaded cancer feared by women, would be, "But many of the sources of breast irradiation no longer exist. So why should we concern ourselves about a problem of the past?"
A problem of the past? Hardly! It is the irradiation in the past and the present, but largely in the past, which is causing the largest share of the breast-cancers of today, of the recent past decades, and which will be causing large numbers of breast-cancers in decades to come.
If ever there were a memorable statement about forgetting the lessons of past follies in the exposure to radiation sources, it is that of George Santayana:
Those who cannot remember the past are condemned to repeat it."
Radiation Exposures Which Are No Longer Present
We no longer irradiate the thymus gland of newborn infants.
We no longer test for enlarged thymus gland before permitting pediatric surgery.
We do not treat infectious diseases, such as pneumonia, with x-rays.
We do not treat peptic ulcer with massive, ablation doses to the stomach.
We do not treat bronchial asthma with x-rays to the chest.
The dermatologists, who once claimed 80 separate benign diseases as best treated with roentgen rays or radium gamma rays, no longer treat any of those diseases with ionizing radiation.
The fluoroscopic "shoe-fitters" have left the shoe stores.
We are not aware of any pediatricians who still routinely fluoroscope babies and children at their monthly, semi-annual, and annual health checkups.
The beauty shops are not likely to be treating freckles or excess hair with x-rays.
Pertussis (whooping cough) is now quite well under control with immunization, but in any case we do not hear of x-ray treatment of this disease.
Hopefully the management of tuberculosis does not deteriorate to a point where collapse therapy, with extensive fluoroscopy, is again needed. Tuberculosis bears serious watching.
Acute and chronic mastitis are managed without x-ray therapy.
Most of the inflammatory disorders (bursitis, tendinitis, etc. as described by Dr. Dewing), are not likely to be treated with x-rays.
We have learned the lesson of cutting the dose to breasts to 1/20 of what they were in spine examinations by putting the x-rays into the back instead of into the front of the body.
Mammography doses have been reduced by a very large factor.
We no longer test nuclear weapons in the atmosphere.
Radiation Exposures Which May Be As Prevalent or More Prevalent Today
Radionuclides in Nuclear Medicine Diagnostic Procedures
The use of radionuclides in nuclear medical diagnostic procedures has increased appreciably. NCRP 100 (Table 4.1) gives data from Mettler (1985) showing the trend in diagnostic radionuclide examinations in the United States over a 10 year period, 1972 to 1982.
Year Exams 1972 1973 1975 1978 1980 1980 1981 1982 (in thousands) Source 1 Source 2 Total 3,300 3,500 4,800 6,400 5,800 6,400 7,000 7,400 Frequency of Exams Number per 1000 of Population 16 17 22 29 26 28 31 32
The actual absorbed population dose to organs such as the breast will still need evaluation.
General Diagnostic Radiology Examinations
We are particularly interested in what has been occurring in the post-1960 period, after our 1920-1960 period of data accumulation.
NCRP 100 Table 3.4 presents the "Hospital x-ray examinations in the United States"Year Examination 1964 1970 1980 Total (in thousands) 58,500 81,700 132,400 (Rate per 1000 population) 310 410 580
The increase in rate of exams, 1970 to 1980, using totals, is 132,400 / 81,700, or 1.62. This 62 % increment, NCRP 100 points out, occurred during a period of population increase of only 11 % (at p.15). The increment in rate per 1000 of population also confirms that the rise between 1970 and 1980 is a real increase since it is per 1000 of population.
It will require serious investigation to ascertain the extent to which this large increase in per capita "Hospital x-ray examinations" offsets x-ray exposures which are no longer used. It is not possible to state this quantitatively now, but it is an important agenda item for the near future, if we are to sustain or increase the annual incidence of breast-cancers or to see some decline in the future.
Fluoroscopic Examinations in General Diagnostic Radiology
and in Newer Sophisticated Invasive Procedures
It is a difficult problem to evaluate the radiation doses from all the fluoroscopies. Certainly (see Chapter 29) the high-dose fluoroscopic examinations which worry the FDA appear characterized as showing an astounding dose-increment per procedure in comparison with the fluoroscopies associated with past "usual" hospital diagnostic procedures. Also, much will depend upon the age-distribution of such high-dose fluoroscopic procedures.
We regard an evaluation of the newer fluoroscopic procedures and the more "usual" ones for the post-1960 period, and especially for the recent period in the 1980s and 1990s, as another essential priority evaluation. Such evaluation is essential for making an assessment of future breast-cancer prospects --- in the decades to follow. We must remember that breast-exposures in the recent several decades will be the major determinants for breast cancer-incidence in the first quarter of the 21st century.
We note the American Cancer Society's advice in 1992:
"Fluoroscopy delivers larger doses of x-ray than that used in standard films. If there is an alternative means of making a diagnosis, fluoroscopy should be avoided."Part 2. Special Situations of Major Concern
The Intensive Care Units for Babies and Children
The remarkable accomplishments in the saving of the premature infant in the past several decades is well known. And the remarkable surgical accomplishments in the diagnosis and surgical therapy of congenital heart, vessel, and other abnormalities is equally well-known. We have encountered concern over the number of radiographic procedures which are utilized in the care of the premature neonates and other neonates requiring intensive care in the hospitals.
NCRP 100 (at pp.31-32) has stated the following: "The dose incurred in pediatric x-ray examinations is of interest since, in many circumstances, a large portion of the child's body is included in the primary beam ... Radiation doses to neonates requiring intensive care were examined in Great Britain by Robinson and Dellagrammaticas (1983). These babies are of particular concern since they may receive relatively large numbers of radiographs compared to adults, and such studies often include fluoroscopic examinations and CT scans. The mean active marrow dose from all examinations was found to vary inversely with the birth weight. Overall, children with lower birth weight received more examinations ... "
We are quite surprised at the paucity of sources of information concerning the very small neonates under intensive care, in the 1989 version of NCRP 100. It will be important to seek out more recent information on a much larger body of data in order to assess carefully the quantitative significance of extensive radiologic examinations in the neonatal intensive care unit.
Study of Doses in a Single Intensive Care Unit in a United Kingdom Hospital
The Robinson-Dellagrammaticas study (1983) consists of a series of 84 total subjects admitted to the Neonatal Intensive Care Unit at the Jessop Hospital for Women (Sheffield, U.K). These authors state:
"Radiological investigations remain one of the most important sources of information for the clinician in his evaluation of the severely ill newborn baby. Relatively large numbers of diagnostic X-ray examinations are given to some neonates requiring intensive care over the first few weeks of life. In some instances, we have noted up to 40 chest or abdominal films being taken, with, possibly, barium studies and CT scans also performed."
This series of cases includes 50 neonates with gestation periods up through 33 weeks. The data characterizing the findings are as follows:Gestation Number Survivors Mean Mean Mean of Birth No. of Number Babies Weight Films of CT Weeks Kg. Scans 26, 27 8 3 0.83 6.75 0.5 28, 29 15 11 1.15 10.5 0.33 30, 31 9 7 1.49 11.3 0.55 32, 33 18 16 1.80 3.67 0.28
The number of CT scans quoted is the average number of "cuts" (i.e., 2 slices)
The typical skin exposure in these neonatal X-ray examinations were:Exam Dose in milli-Roentgens Chest Films 5.8 Abdomen Films 6.2 CT scans 1550 Barium Enema 2310
The authors indicate that the Barium Enema estimate could be off a factor of two in either direction.
They also point out the enormous variation in exams per infant --- from those having a single chest radiograph to one having 43 films (15 chest radiographs, 24 abdominal films, a barium enema, and a CT scan).
Robinson and his colleague suggest that the cases requiring intensive care must be fewer than 3 % of the total number of births in the hospital during the period when these cases were collected. Since the hospital in question is a specialized maternity unit, it is expected to have a higher-than-average number of "high risk" cases. Therefore, overall, the radiation exposure in neonates requiring intensive care might not impose a large population dose for all births. Since this seems at variance with opinions we have heard, carefully-evaluated additional sources of information are definitely needed. One can wonder whether the financial arrangements for care of neonates can influence the results. Some United States experience will be sought out for recent decades.
Criteria for the Care of the Neonates
Some of the neonates requiring the most radiation exposure will carry an appreciable excess rate of development of breast-cancer beyond the age of 30 years. That is no reason for withholding necessary radiation exposures in the intensive care unit. Thirty, forty, fifty, or sixty years of good life surely are worthwhile, even if a later cancer is a result in some cases. Robinson and Dellagrammaticas indicate their concern that some of the radiation exposure may be unnecessary, as they state (p.397):
"The highest doses are received in CT scans and barium examinations and it is recommended that the need for these should be carefully considered and requests for such examinations only made by experienced staff." We would agree.
Persons Involved in Accidents, Occupational and Other
It has come to our attention that there is what has been described as "massive" use of x-ray films in the resolution of compensation claims for industrial and non-industrial injury in accidents. It has been pointed out that the various groups and individuals involved in litigation have quite differing opinions concerning the number and type of x-ray films needed. The result in some cases is that a stack of films "inches thick" results before a settlement is reached. Some of those films are the result of follow-up examinations in the therapy of accidental injuries.
A large number of these accidental injuries involve the back and the neck. Cervical, dorsal, and lumbar spine films can all be sources of radiation to the breasts. We know that orthopedic and chiropractic examinations (and repeat examinations) are involved in many such cases, so the increment in breast-doses from these sources may not be negligible. Some of the individuals involved in such cases have suggested that the unnecessary radiation in such cases is far from negligible. Our only comment is that radiation received in settlement of such compensation claims can be enough to have a major effect on radiation-dose to the breast, with ensuing breast-cancers several decades later. Some serious study of this issue would be worthwhile.
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o - The Difference between X-Rays and Diagnostic "Nuclear Medicine"
Diagnostic nuclear medicine usually involves putting radioactive substances into a patient's body, and then interpreting the radiation which reaches the outside of the patient from those sources inside. The patient "remains radioactive" until the radio-nuclide either decays or is excreted from the body.
By contrast, x-rays do not make a patient radioactive at all. The radiation exposure from x-rays (including x-rays from a fluoroscopy machine) lasts only as long as the x-ray beam is "on." X-rays (like gamma rays) are a type of light --- some of which passes right through the body and is then recorded by a film or other image-receiver on the opposite side. The dose to internal organs comes from the x-rays which do not pass all the way through the patient.
An essay by Dr. George E. Pfahler at his 80th birthday
More Good Than Evil
A half century ago Pierre Curie said, that "in criminal hands, radium might become dangerous .... is humanity ripe enough to profit by learning the secrets of nature, or might not that knowledge prove harmful? I believe that humanity will obtain More Good Than Evil from future discoveries."
The discovery of radioactivity by Becquerel and the Curies has been an incalculable blessing, and radium has eased pain, parried death, and given life to numberless cancer sufferers. And yet Pierre Curie was a greater prophet than he knew, for this same discovery was the seed from which was developed the most potent agent for suffering, death and mass destruction the world has ever known. Radioactivity, the bane and blessing of modern man, is an example of the utter impartiality of science in ministering to the best and the worst that is in us. Science is not to blame, for it is the servant of man. The fault lies in man himself, who wills to put science to such paradoxical uses.
On the credit side of the ledger of man's stewardship of radioactivity is the application of the many forms of radiation to the treatment of cancer --- first Roentgen's "new kind of rays," then radium and radon with the numerous refinements and techniques, followed by the radioactive isotopes resulting from nuclear fission. Advances in supervoltage therapy, particle-accelerating beams, precision targeting, rotation therapy, and induction of greater tumor susceptibility to radiation have made radiotherapy a worthy partner to surgery --- previously the sole cure for cancer.
Of greatest importance in the long-term control of cancer are the rapidly accumulating data concerning the effects of ionizing radiations on normal and cancer cells, particularly the effects on genes and chromosome and the effects in nucleic acid synthesis.
Thus radiant energy from the many sources now available has become a valuable factor not only in the immediate therapy of cancer but also in research by revealing more and more of the intaimate physiology of the cell in which the cause of cancer still lies hidden.
Surely, from the discoveries of Roentgen, of the Curies, and of those following them has come More Good Than Evil.
From CA: A Bulletin Of Cancer Progress
Vol.5, No.1: 2. January 1955.