Rapid Responses to:
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Rapid Responses: Rapid Responses published:
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Too much CT
- John P Coffey (12 May 2007)
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Reply to Dr. Coffey
- Steven Birnbaum (17 May 2007)
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Re. CT scanning: too much of a good thing
- Masoom Muttalib (21 May 2007)
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John P Coffey, Consultant Radiologist Royal Preston Hospital PR2 9HT
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Despite the enormous and burgeoning radiation safety and exposure- regulation industry, no cancer has ever been attributed to medical radiation except on the most dubious stochastic extrapolations. Indeed there is evidence that no significant radiation induced physiological damage occurs in mammalian tissue below a threshold of 400 to 800 mSv, illustrating the so-called "dog-leg" effect as opposed to a ppresumed linear effect of radiation damage. The "take home" message is that medical diagnostic radiation is entirely safe at all dosages used and hysterical efforts to persuade the public otherwise should be resisted. Yours sincerely, Dr. J. P. Coffey Competing interests: None |
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Steven Birnbaum, Radiologist Nashua, New Hampshire, USA 03060
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I beg to differ with Dr. Coffey's response to my recent piece in the BMJ. There are indeed many episodes of diagnostic radiologic induced carcinogenesis that have documented carefully in the medical literature. Two of these involve two cohorts of female tuberculosis patients managed with therapeutic pneumothorax monitored with fluoroscopy who have clear cut dose related increases in breast and thyroid cancers. Similary children therapeutically irradiated at low doses for tinea capitis and an enlarged thymus have similar increased rates of thyroid cancers. Female patients who had many films for monitoring of scoliosis have been carefully noted to have an increased incidence of thyroid and breast cancer. The principles of radiation protection involve ALARA (As Low As Reasonably Achievable). This is clearly not happening when young patients have received as many as 33 helical CT scans for renal stone disease. Rather than decry the "hysteria" of the radiation safety industry as Dr. Coffey does, I would think he as a consulting radiologist would be much more inclined to the ALARA principle rather than his own opinions which are misinformed and clearly opposed to patient safety. Competing interests: None declared |
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Masoom Muttalib, Specialist Registrar in Surgery Birmingham UK
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Editor: Dr. Birnbaum has raised important points in the case described. Changes in packed cell volume should be correlated clinically. In addition to considering whether the blood sample was taken from the arm with a drip, clinical features of increasing abdominal pain / tenderness or haemodynamic instability are poignant. A haemoglobin check using a venous sample for blood gas analysis would show any precipitous fall, within minutes of taking the sample, thereby refuting spurious results. With respect to radiation dose awareness from medical imaging, in the UK since 1988 it has been a requirement for doctors directing radiation exposures to be certified in POPUMET (Protection of Persons Undergoing Medical Examinations or Treatment). This has been offered to all UK doctors, including medical students in their final year of training. Ionising Radiation (Medical Exposures) Regulations 1999 (in compliance with the EC Euratom Directive) have superseded this. CT scanning undoubtedly has its advantages, but its use should not be divorced from the clinical features of the patient. With improving spiral CT multi-array detector technology and the increasing use of MRI, the radiation exposure attributable to CT scanning may indeed reduce. The principle of radiation protection remains in keeping with the adage: primum non nocere – first do no harm. Competing interests: None declared |
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