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X-rays

MagazineOctober 1993 (Vol. 4 Issue 7)X-rays

Despite the known cumulative risks to you and your unborn children, this most routine medical test is still being overused on nearly every part of your body

Despite the known cumulative risks to you and your unborn children, this most routine medical test is still being overused on nearly every part of your body.

X-rays have become a routine procedure, and yet their long term effect on a person frequently exposed to them can be life threatening.

Dental x-rays may be particularly dangerous they are often taken by untrained staff. This means that necessary x-rays may be unreadable and have to be repeated, or that patients are subjected to far higher than necessary doses of radiation because staff don't know how to use the machine properly.

In the past dentists routinely engaged untrained staff to take x-rays. A short while ago two dentists, Paul Worskett and Nicola Salmon of Brierley Hill in the West Midlands, escaped suspension by their professional body for using untrained school leavers to take their x-rays when it became clear that dentists throughout Britain were doing exactly the same thing. The rationale of the Professional Conduct Committee of the General Dental Council was, presumably, that if these two were suspended, all the rest would have to be suspended, too.

A representative for one of them told the disciplinary hearing there is "a crisis in the profession" with dentists failing to train assistants to use x-ray machines.

Despite the cavalier attitude of these dentists and many in the medical profession, the links between radiation from x-rays and cancer are well known. According to the National Radiological Protection Board and the Royal College of Radiologists, unnecessary radiation from x-rays may be responsible for between 100 and 250 of the 160,000 cancer deaths in the UK every year and perhaps 1000 cancer deaths per year in the US. Indeed, in Malepractice: How Doctors Manipulate Women (Contemporary Books, 1982) the late Dr Robert Mendelsohn wrote that: "The genetic effects of one year of x-ray radiation may lead to as many as 30,000 deaths in future years". In the US, a study by the National Cancer Institute (JAMA, 13 March 1991) found a link between x-rays and multiple myeloma a form of bone cancer. They looked at more than 25,000 x-rays and concluded that with myeloma sufferers: "There was consistent evidence for a dose response trend regardless of the lagging interval. The most frequently exposed were at highest risk, reaching fourfold."

Yet in the US, seven out of 10 people are given x-rays every year (National Council on Radiation Protection and Measurements; 1989, Report 100). In the past, clinical radiation was thought to account for around 1 per cent of cases of leukemia and perhaps 1-2 per cent of all other cancers in the US. However, in 1991, the National Academy of Sciences' committee reported that estimates of lifetime cancer risk following relatively low doses of radiation may be as much as four times larger than previously thought (NAS, National Research Council. Health Effects of Exposure to Low Levels of Ionizing Radiation. Washington DC: National Academy Press).

Not surprisingly given the damage x-rays can do, doctors are supposed to use them only where they are "clinically justified". Yet, according to a 1992 study by the NRPB and the Royal College of Radiologists, up to one in five of them are given for no good reason. "At least 20 per cent of x-ray examinations currently carried out in the United Kingdom are clinically unhelpful in the sense that the probability of obtaining information useful for patient management is extremely low," they say.

In the US, according to Mendelsohn in Malepractice, 30 per cent of all x-rays taken every year (which amounts to nearly 300 million a year) are "ordered in cases where there is no valid medical need".

The likelihood of being subjected to an x-ray seems to depend less on your condition and more on the "personal preferences" of the doctor, the NRPB study concluded. Nearly 900,000 outpatient sessions and 160,000 in patients being treated by 722 consultants at five district hospitals were assessed by researchers at the department of epidemiology at the University of Wales. They found significant variations in the number of people referred for x-ray by individual consultants. For outpatients, there was a 13 fold variation, depending on which consultant headed the medical team; for in patients, the difference was eight fold. In the case of chest x-rays alone, it was a staggering 25 fold variation.

Unnecessarily repeated x-rays are another major cause of over use. According to the Consumers' Association (Which? January 1991), "before an x-ray is taken, hospital staff should check if the part of your body involved has been x-rayed before. If it has, you may not need another x-ray." Yet few hospitals or doctors bother to do this. Which? magazine interviewed a nationally representative sample of 2229 adults and found that 52 per cent of those who had had x-rays in the previous year were not asked whether they had already had that part of their body x-rayed before. Even of those who were asked, 70 per cent said this didn't happen until the day they had their x-ray, when it would probably have been too late to track down the earlier one anyway.

Far from making any effort to find existing x-ray films held by other institutions, a study in Glasgow suggests hospitals are incapable of keeping track of their own films (Independent, 14 May 1989). Marc Bransby-Zachary, an orthopaedic surgeon at Glasgow Royal Infirmary, analyzed 420 new patients referred by GPs to its outpatients department. About a third of them had already had an x-ray done but because of "administrative problems", the film was only available for nine patients and 125 had to be done again.

By law, the radiation dose must be "as low as reasonably practical" but, again, many hospitals are routinely flouting this requirement and many patients are getting far higher doses than necessary. In 1983, a survey of 20 hospitals found that the average dose of radiation given to patients for the same type of x-ray could vary by as much as 20 times (Which? January 1991). And in 1990, the NRPB reported that patients in some hospitals are receiving doses 20-30 times higher than necessary for obtaining diagnosis. The Royal College believes that the population dose from diagnostic radiation in the UK could be halved without reducing diagnostic effectiveness.

Poorly maintained and antiquated machines are the worst culprits for dishing out too high doses. As a spokesperson for the Royal College was quoted as saying in the BMJ (14 December 1991): "Two years ago, physicists were saying that old x-ray equipment was giving out bigger doses than Chernobyl." Even at the proper dose, the amount of radiation involved in an x-ray can be formidable. In the few minutes it takes to have a simple dental x-ray, your body absorbs a dose equivalent to three days' worth of background radiation. A barium enema used to check for abnormalities of the stomach and digestive tract is the equivalent to 3.5 years' worth of background radiation (see table, p 2).

All radiation is harmful (and your body never "forgets" the radiation it has received), but some groups are particularly vulnerable to its damaging effects. Unborn children are especially susceptible and pregnant women should, therefore, avoid all x-rays except in extreme, life threatening situations.

The link between exposure of fetuses to radiation and childhood cancer is well documented (Int J Cancer; 46, 362-365, 1990. British J of Cancer; 62 (1): 152-68, July 1990). In Health Shock (Englewood Cliffs, NJ: Prentice-Hall 1982), M Weitz claims that the x-rays given to about a quarter of all pregnant women during the 1950s and 1960s "caused between 5 and 10 per cent of all childhood cancers in America and Western Europe".

In Medicine on Trial (Pantheon), Charles Inlander et al add that x-rays can also cause "major birth defects, including small head size, mental retardation, skeletal deformities, and eye and heart defects". They also cite a claim by John Goffman and Egan O'Connor (X-Rays: Health Effects of Common Exams, San Francisco: Sierra Club Books, 1985) that radiation can cause "non specific infant mortality during the first year of life, and often the first week".

Despite all the evidence, hospitals often don't bother to check whether a woman may be pregnant. The Which? survey found that three out of 10 women being x-rayed between their ribs and their knees said no attempt was made to find out if they were pregnant; and another two out of 10 said there was only a notice in the x-ray room asking them to tell staff if they could be pregnant.

Once they are born, children remain at increased risk. Again as cited in Medicine on Trial, Goffman and O'Connor claim that "a newly born child is about 300 times more sensitive than a 55 year old to induction of cancer by radiation." Five year old children are "about five times more likely to get later radiation induced cancer than an adult given the same radiation dose at age 35," they add.

Men and women at or below reproductive age are also at increased risk of harm. The reproductive organs are susceptible to radiation damage and should always be protected from exposure during x-ray by a lead shield. Yet, very often this doesn't happen. In the Which? survey, 42 per cent of men and 66 per cent of women had no such protection. And a study of three teaching hospitals (BMJ, 30 May 1992) found that just 29 per cent of children undergoing pelvic x-rays had adequate protection. Some 40 per cent were given no shielding at all; and in 31 per cent of cases, the lead shield was wrongly positioned. "This avoidable excess radiation exposure to the gonads. . may increase the potential for disease in the future offspring of these patients," the study concludes.

In Malepractice, Dr Mendelsohn wrote that the evidence was "overwhelming" that women who had accumulated much radiation during their lives had an increased risk of delivering a baby with Down's Syndrome and that this, rather than age alone, was responsible for an older woman's increased risk.

Even if your x-ray really is necessary, and is done by a skilled operator, using modern, low dosage equipment, with your sexual organs fully protected, there is still the very strong risk of the result being misinterpreted. In Medicine on Trial, the authors claim that: "Nearly every published study puts the mistake rate of x-ray readers at 20 to 40 per cent." They cite a study by Dr Leonard Berlin (Radiology, May 1977; 123, 523) which found that radiologists working at Harvard University "disagreed on the interpretation of chest radiographs as much as 56 per cent of the time. Moreover, there were potentially significant errors in 41 per cent of their reports."

Dr Berlin adds that "studies have shown that up to 20 per cent of colon tumours are missed in the lower gastrointestinal series.

In a recent study at the University of Missouri, an error rate of 30 per cent was reported among staff radiologists for chest radiographs, bone studies, gastrointestinal series, and special procedures."


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