With a SPECT scan, a child is injected with a radioactive material directly into his bloodstream. Its radiation-emitting particles are carried to every nook and cranny of his body. How much does this raise the child's risk of getting cancer later in life?
SPECT scans are dangerous to children or adults, and can cause cancer 10 or 20 years down the road even when only used once to "diagnose" ADHD. Here's how it works.
Imagine you’re in one of those huge hotels with hundreds of windows facing out onto the parking lot. You walk to the window and look down and see a man with a rifle, waving it around as if he were thinking of spraying the entire building with bullets. And then you see the muzzle flash at the end of the rifle’s barrel, hear the crack sound of the shot, and, a half-second later, the shattering sound of glass somewhere off to your right on that huge wall of glass.
Given that situation, would you get away from the window? Would you feel “safe”?
What if the hotel had a thousand windows instead of a few hundred, and you knew the shooter could only fire a few bullets before he ran out of ammunition?
What if the shooter was actually doing something that the hotel had requested - say, shooting pigeons off the roof because they were pesky or carried disease - and every now and then he missed the pigeons and hit a window? Would you feel safer because there was a reason for his shooting? Would you continue to stand in the window, knowing the odds were low that you’d be hit and the shooting was useful for the hotel’s bird problem?
Better yet, would you put a child in the line of fire?
In order to make sense of this analogy, consider for a moment how radiation causes cancer.
The replication of cells is controlled by a small segment along a DNA double-helix. When something hits or damages the DNA in the cell, usually the cell simply dies. This is happening right now in millions of cells in your body as you read these words. The body is all set for it, with scavenger systems in place that recycle the cell’s nutrients.
Occasionally, however, instead of DNA being hit in ways that kill off the cell, that one little window on the DNA strand that controls its reproduction gets damaged. The cell loses its ability to know when to stop reproducing, and starts dividing as fast as it can. This is called cancer.
The four main things in our world that “hit” DNA in ways that cause it to become non-reproducible (and also leading to the cell’s demise) or super-reproducing (cancer) are oxygen-bearing chemicals (called “free radicals” or “oxidizers”), DNA-toxic chemicals (called “carcinogens,” with the chemicals in cigarette smoke being the most familiar to most people), DNA-reproduction-stimulating compounds (called “hormones” and the hormone-mimickers such as those found in certain plasticizers, pesticides, and sun-blocking chemicals) and ionizing radiation (the most well-known being UV radiation in sunlight, which causes skin cancer, and X-rays, which can cause cancer anywhere).
In part because our sunlight has become more lethal in the past 50 years and our environment and foods filled with industry-created carcinogens and hormones, one-in-two men and one-in-three women will get cancer in their lifetimes. We take anti-oxidant vitamins like C and E to reduce the damage, eat natural foods to avoid the chemicals, and wear sun-block, all in efforts to avoid damage to our DNA that might flip “on” the reproduction switch in a cell so it turns to cancer.
I remember when I was a child, walking home from school in the first grade in 1956. There was a shoe store on the way, and they had a really cool machine that I stuck my feet into dozens of times so I could see the bones in my toes and how the tissues of my foot fit my shoe. A friend of mine, now deceased from thyroid cancer, had radioactive radium pellets put into her sinus’ to stop recurrent sore throats and tonsillitis. My mother was encouraged to step out of the house and into a truck that traveled around giving women breast x-rays. And they were exploding bombs above the ground in Nevada so frequently that more radiation was released on America than we released on Hiroshima and Nagasaki combined.
We’ve learned a lot since 1956. The shoe-store fluoroscopes are banned, doctors don’t use radium anymore to treat sore throats, and almost all aboveground nuclear testing has been halted worldwide. We’re even recommending that women under 40 not get annual mammograms, in part because of concern that the radiation from the x-rays may cause more cancer than it would find. A study cited in Science News a decade or more ago reported a correlation between the number of dental x-rays a person had as a child and the development of cancers of the mouth and neck in adult years, leading dentists to begin wrapping people’s necks with lead aprons and to use tighter-beamed x-ray machines now in most dental practices (with a square, adjustable “gun” instead of a round scattershot beam).
Much of our current knowledge of the impact of radiation on humans comes from pioneering work done by Dr. John Gofman, Professor Emeritus of Medical Physics at the University of California at Berkeley, and Lecturer at the Department of Medicine, University of California School of Medicine at San Francisco. In the 1940s, while still a graduate student at Berkeley, Gofman made an international name for himself in the field of nuclear physics when he co-discovered protactinium-232 and uranium-232, protactinium-233 and uranium-233, and proved the slow and fast neutron fissionability of uranium-233, which made possible atomic bombs.
After receiving his PhD in nuclear physics, he went to work for the US Government to help develop the atomic bomb, and invented, along with Robert Oppenheimer and Robert Connick, the currently used process for extracting plutonium from irradiated uranyl nitrate. The bomb project finished, Gofman went back to college, this time to get his MD in 1946. In 1947, he transformed the world of heart disease prevention and treatment by developing a new flotation ultracentrifugal technique that discovered low-density lipoproteins (LDL) and high-density lipoproteins (HDL), and then he conducted the first prospective study demonstrating that high LDLs (also known as “bad cholesterol”) presented a risk for heart disease and high LDLs (also now known as “good cholesterol”) demonstrated a resilience against heart disease. He literally wrote the book on heart disease that’s still today used in medical schools, “Coronary Heart Disease,” published in first edition in 1959.
Recognizing that Gofman understood both nuclear physics and human medicine, in the early 1960s the Kennedy administration asked him if he’d start a Biomedical Research Division at the Lawrence Livermore National Laboratory, and supervise research into survivors of the Japanese atomic-bomb attack, Americans who’d been exposed to atomic and X-ray radiation, and look into the suspected relationship between radiation, DNA/chromosomes, and cancer. Dr. Gofman ran the research division at Lawrence Livermore from 1963 to 1965, and the things he learned in his research began to trouble him. Other researchers were pursuing similar paths, with the publication in 1965, by Dr. Ian MacKenzie, of a report entitled "Breast Cancer Following Multiple Fluoroscopies" (British J. Of Cancer 19:1-8), and in 1963, Wanebo and co-workers report "Breast Cancer after Exposure to the Atomic Bombings of Hiroshima and Nagasaki" (New England J. Of Med. 279: 667-671). In a groundbreaking analysis of the studies extant at the time, Gofman and his colleague Dr. Arthur Tamplin concluded that even very low levels of radiation could cause human cancers, and published their research in the highly respected medical journal Lancet (1970, Lancet 1:297). Gofman’s work led to a worldwide reevaluation of both medical radiation (and the elimination of those shoe-store machines) and of the way nuclear power plants were constructed and operated. Today he is still considered one of the leading experts on the effect of radiation on the human body.
Here’s what Dr. Gofman says to anybody who claims that nuclear medicine procedures (such as SPECT scans) are “safe”:
“In the mainstream medical literature are quite a number of epidemiological studies showing that even minimal doses of ionizing radiation induce extra cases of cancer” (emphasis added).
In a 1995 paper on low-dose radiation, Dr. Gofman pointed out that it only takes a single electron/photon-bullet (to use my analogy above), hitting the wrong part of a single cell, to cause cancer. Here’s how he summarized that paper on low-dose radiation, with five well-documented points that reflect the current state of knowledge:
“Point One: The radiation dose from x-rays, gamma rays, and beta particles is delivered by high-speed electrons, traveling through human cells and creating primary ionization tracks. Whenever there is any radiation dose, it means some cells and cell-nuclei are being traversed by electron-tracks. There are about 600 million typical cells in 1 cubic centimeter.
“Point Two: Every track --- without any help from another track --- has a chance of inflicting a genetic injury if the track traverses a cell-nucleus.
“Point Three: There are no fractional electrons. This means that the lowest ‘dose’ of radiation that a cell-nucleus can experience is one electron-track.
“Point Four: There is solid evidence that extra human cancer does occur from radiation doses which deliver just one or a few tracks per cell-nucleus, on the average.
“Point Five: Thus we know that there is no dose or dose-rate low enough to guarantee perfect repair of every carcinogenic injury induced by radiation. Some carcinogenic injuries are just unrepaired, or misrepaired…
“Conclusion: It is factually wrong to believe or to claim that no harm has ever been proven from very low-dose radiation. On the contrary. Existing human evidence shows cancer-induction by radiation at and near the lowest possible dose and dose-rate with respect to cell nuclei. By any reasonable standard of scientific proof, such evidence demonstrates that there is no safe dose or dose-rate below which dangers disappear. No threshold-dose. Serious, lethal effects from minimal radiation doses are not ‘hypothetical,’ ‘just theoretical,’ or ‘imaginary.’ They are real.”
Agreeing with the dangers of radiation to radiosensitive children, the National Academy of Neuropsychology published an article in 1991 suggesting nuclear medicine should be limited exclusively to pure research (which is not done in a doctor's office), with appropriate informed consent about the dangers, safeguards and follow-up, no cost to the client, committee overview, etc. (Heaton,T.B. & Bigler, E.D. 1991. Neuroimaging techniques in neuropsychological research. Bulletin of the National Academy of Neuropsychology, 9, 14.)
When I broke my back skydiving in 1971, I had a series of x-rays. Each one was a very quick burst of radiation, and each one increased my lifetime risk of developing cancer. Those x-rays were considered “safe” from a medical point of view, even though every medical expert acknowledges they can cause cancer, but they were “safe enough” because the risk of not knowing how badly my spine was injured was outweighed by the small probability the x-rays would cause cancer. This is referred to as the “risk-benefit ratio” and is how the government determines what they will call a “safe” level of exposure to radiation or other toxins.
The shoe-store machine, however, because it delivered a more prolonged dose of radiation to me (instead of a “picture” that flashed me with X-rays for a thousandth of a second, it was a continuous “movie” flow of X-rays), was dramatically more destructive to my DNA, so much so that after Dr. Gofman’s research was published in the 1960s nobody could justify keeping the machines in the shoe stores any longer.
Neither of those radiation exposures, however, fired “bullets” of radiation at the most radiation-sensitive and cancer-reactive parts of my body - my brain, testicles, and much of my endocrine system (thyroid, etc.).
But with a SPECT scan, a child is injected with a radioactive material directly into his bloodstream. Its radiation-emitting particles are carried to every nook and cranny of his body. They flow into and irridadiate his developing testicles or her young ovaries and the eggs in them that will someday become children. The radiation flows with the blood into the thyroid, the uterus, pre-developing breast tissue, the adrenals, the pituitary, and even the bone marrow. Although most SPECT scannerss are only positioned to look for the “single photons” that are evoked by the detector when particles flash out of deep brain tissue, through the dura mater, through the bone of the skull, and the skin of the scalp to hit the SPECT detector, the entire body is filled with radiation.
If the SPECT scanner were put on the stomach, it would find radiation there; on the genitals, radiation there; on the feet, radiation there. “Bullets” are going off throughout the entire body - including in the child’s most radiosensitive organs such as developing breast, ovarian, testicular, uterine, and thyroid tissues. And the “hit” isn’t only for a fraction of a second, like it would be with an X-ray: the radioactive agent injected with a SPECT scan decays slowly, and is still detectible in the bloodstream for days after injection. (And each time one of the unstable radioactive atoms of the SPECT agent decays to something that’s no longer radioactive, it emits “bullet” particles in the process, those hitting and tracking through the nearby tissues of the body at the time of breakdown.)
Lately there has been a lot of talk about the use of SPECT scans to diagnose ADHD. Of particular concern is that some physicians are using this procedure, whose risk-benefit ratio is considered acceptable for things like brain injury after a car accident or stroke (the main use for SPECT scans), on children. Children are far more susceptible to radiation-induced cancer than are adults, in part because radiation damage accumulates over time and cancers from radiation usually pop up decades after the initial exposure, and in part because their tissues are still developing and growing.
In 1997, at an ADHD conference in Israel, I had coffee with the National Institute of Health’s Dr. Alan Zametkin, who had done PET scan studies (which use lower-doses of radiation) on the brains of adults with ADHD to look for differences, and whose work had recently appeared on the cover of the Journal of the American Medical Association’s magazine. I asked Dr. Zametkin about the use of SPECT scans on children, and he told me flatly that he considered it both wrong and dangerous for the children.
While his PET scan studies had injected radioactive isotopes into the veins of their research subjects, they’d used a multi-million-dollar ultra-sensitive PET scanner to look for the action of the isotopes, meaning less radiation was needed to be injected than with the SPECT scan machines, which are affordable for an emergency room or doctor’s office but less sensitive. (A PET scanner fills a room and is normally only found in a hospital or research facility: portable SPECT scan machines are available for emergency clinic and field use at much lower prices.) And Zametkin’s studies had been done on consenting adults (not children) who were fully informed of the risks they were taking in receiving a full-body dose of decaying radiation, and who had not paid Dr. Zametkin to be in the study but were instead monitored for ill-effects from the radiation and offered other compensations.
Dr. Zametkin’s perspective represents the mainstream scientific view of using nuclear medicine, particularly with children, for anything other than pure research or life-threatening illness or injury. This is probably why when Daniel Amen told Dr. Zametkin that he intended to use SPECT scans on children, Dr. Zametkin reacted negatively. To quote Dr. Amen, “He gave me an angry look and said that the imaging work was just for research: It wasn’t ready for clinical use, and we shouldn’t use it until much more was known about it.” (Healing ADD, Amen, 2001)
Of course, much is known about the effects of SPECT and PET scans. They require injecting the entire body with a continual “spray of bullets” that decay over time. Their radiation exposure doesn’t last a thousandth of a second, like an x-ray, or even a few seconds like a fluoroscope: it lasts for hours, days, and traces remain for weeks. Everywhere in the body. With every single particle emitting radiation as it decays, and that radiation penetrating millions of cells on its way out of the body. While it is possible to say that “no studies have shown that SPECT scans or the radiation levels used in them cause cancer,” it is a bit disingenuous: the only reason one could say that is that no such studies have ever been done. Actually, they’re not necessary: there is no such thing as “purely safe” radiation, just “risk-acceptable safe” radiation in the context of the need for the procedure.
There are techniques for imaging the brain that do not require injecting people with radioactive isotopes. The best-known and most widely used is the QEEG, which measures electrical activity at over a hundred different points on the scalp and then uses a computer to create a mapped image of brain activity. These have become quite sophisticated, and involve no danger whatsoever because they’re totally passive, “reading” the brain’s own electrical activity instead of injecting something into the body which is then measured as it shoots back out of the body.
So the next time somebody suggests a SPECT scan for you or your child, imagine yourself standing in that hotel window, looking down at shooter on the lawn. You’re a cell in your body, and the shooter is just one of the millions of particles of radioactive substance about to be injected into your or your child’s vein prior to the SPECT scan.
And don’t forget to duck.
AEC 1970. Atomic Energy Commission. Reports dated March 27 and May 4, 1970, from John R. Totter, Director of AEC's Biology and Medicine Division, to U.S. Senator Mike Gravel of Alaska. Totter was reporting on a pilot study of Alaskan natives by J.G. Brewen.
Barcinski 1975. M.A. Barcinski et al, "Cytogenetic Investigation in a Brazilian Population Living in an Area of High Natural Radioactivity," Amer. J. of Human Genetics 27: 802-806. 1975.
Baverstock 1981. Keith F. Baverstock et al, "Risk of Radiation at Low Dose Rates," Lancet 1: 430-433. Feb. 21, 1981.
Baverstock 1983. Keith F. Baverstock + J. Vennart, "A Note on Radium Body Content and Breast Cancers in U.K. Radium Luminisers," Health Physics 44, Suppl.No.1: 575-577. 1983.
Baverstock 1987. Keith F. Baverstock + D.G. Papworth, "The U.K. Radium Luminizer Survey," British J. of Radiology, Supplemental BIR Report 21: 71-76. (BIR = Brit. Inst. of Radiology.) 1987.
Boice 1977. John D. Boice, Jr. + R.R. Monson, "Breast Cancer in Women after Repeated Fluoroscopic Examinations of the Chest," J. of the Natl. Cancer Inst. 59: 823-832. 1977.
Boice 1978. John D. Boice, Jr. et al, "Estimation of Breast Doses and Breast Cancer Risk Associated with Repeated Fluoroscopic Chest Examinations..." Radiation Research 73: 373-390. 1978.
Chase 1995. Marilyn Chase, quoting radiologist Stephen Feig, in "Health Journal," Wall Street Journal, p.B-1, July 17, 1995.
Evans 1979. H.J. Evans et al, "Radiation-Induced Chromosome Aberrations in Nuclear Dockyard Workers," Nature 277: 531-534. Feb. 15, 1979.
Gofman 1971. John W. Gofman + Arthur R. Tamplin, "Epidemiologic Studies of Carcinogenesis by Ionizing Radiation," pp.235-277 in Proceedings of the Sixth Berkeley Symposium on Mathematical Statistics and Probability, July 20, 1971. University of California Press, Berkeley.
Gofman 1981. John W. Gofman. Radiation and Human Health. 908 pages. ISBN 0-87156-275-8. LCCN 80-26484. Sierra Club Books, San Francisco. 1981.
Gofman 1986. John W. Gofman, "Assessing Chernobyl's Cancer Consequences: Application of Four `Laws' of Radiation Carcinogenesis." Paper presented at the 192nd national meeting of the American Chemical Society, symposium on Low-Level Radiation. Sept. 9, 1986.
Gofman 1990. John W. Gofman. Radiation-Induced Cancer from Low-Dose Exposure: An Independent Analysis. 480 pages. ISBN 0-932682-89-8. LCCN 89-62431. Committee for Nuclear Responsibility, San Francisco. 1990.
Goldberg 1995. Henry Goldberg. Introduction to Clinical Imaging: A Syllabus. From the Steven E. Ross Learning Center, Department of Radiology, Univ. of California S.F. Medical School. 1995.
Harvey 1985. Elizabeth B. Harvey et al, "Prenatal X-Ray Exposure and Childhood Cancer in Twins," New England J. of Medicine 312, No.9: 541-545. Feb. 28, 1985.
Hoffman 1989. Daniel A. Hoffman et al, "Breast Cancer in Women with Scoliosis Exposed to Multiple Diagnostic X-Rays," J. of the Natl. Cancer Inst. 81, No.17: 1307-1312. Sept. 6, 1989.
Howe 1984. Geoffrey R. Howe, "Epidemiology of Radiogenic Breast Cancer," pp.119-129 in (book) Radiation Carcinogenesis: Epidemiology and Biological Significance, edited by John D. Boice, Jr., and Joseph F. Fraumeni. Raven Press, New York City. 1984.
Hulka 1995. Barbara S. Hulka + Azadeh T. Stark, "Breast Cancer: Cause and Prevention," Lancet 346: 883-887. Sept. 30, 1995.
Kodama 1993. Yoshiaki Kodama et al, "Biotechnology Contributes to Biological Dosimetry...Decades after Exposure," in Radiation Effects Research Foundation's RERF Update 4, No.4: 6-7. Winter 1992-1993.
Lloyd 1988. D.C. Lloyd et al, "Frequencies of Chromosomal Aberrations Induced in Human Blood Lymphocytes by Low Doses of X-Rays," Internatl. J. of Radiation Biology 53, No.1: 49-55. 1988.
MacMahon 1962. Brian MacMahon, "Prenatal X-Ray Exposure and Childhood Cancer," J. of the Natl. Cancer Inst. 28: 1173-1191. 1962.
Maruyama 1976. K. Maruyama et al, "Down's Syndrome and Related Abnormalities in an Area of High Background Radiation in Coastal Kerala [India]," Nature 262: 60-61. 1976.
Miller 1989. Anthony B. Miller et al, "Mortality from Breast Cancer after Irradiation during Fluoroscopic Examinations..." New England J. of Medicine 321, No.19: 1285-1289. 1989.
Modan 1977. Baruch Modan et al, "Thyroid Cancer Following Scalp Irradiation," Radiology 123: 741-744. 1977.
Modan 1989. Baruch Modan et al, "Increased Risk of Breast Cancer after Low-Dose Irradiation," Lancet 1: 629-631. March 25, 1989.
Myrden 1969. J.A Myrden + J.E. Hiltz, "Breast Cancer Following Multiple Fluoroscopies during Artificial Pneumothorax Treatment of Pulmonary Tuberculosis," Canadian Medical Assn. Journal 100: 1032-1034. 1969.
Skolnick 1995. Andrew A. Skolnick, quoting radiologist Stephen Feig and citing “many radiation physicists,” in "Medical News and Perspectives," J. Amer. Medical Assn. 274, No.5: 367-368. Aug. 2, 1995.
Stewart 1956. Alice M. Stewart et al, "Preliminary Communication: Malignant Disease in Childhood and Diagnostic Irradiation In-Utero," Lancet 2: 447. 1956.
Stewart 1958. Alice M. Stewart et al, "A Survey of Childhood Malignancies," British Medical Journal 2: 1495-1508. 1958.
Stewart 1970. Alice M. Stewart + George W. Kneale, "Radiation Dose Effects in Relation to Obstetric X-Rays and Childhood Cancers," Lancet 1: 1185-1188. 1970.
UNSCEAR 1993. United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and Effects of Ionizing Radiation: UNSCEAR 1993 Report to the General Assembly, with Scientific Annexes. 922 pages. No index. ISBN 92-1-142200-0. 1993. Committee for Nuclear Responsibility, Inc. Post Office Box 421993, San Francisco, CA 94142, USA.
The paper by Dr. Gofman cited above can be found on the web.