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Online
edition of India's National Newspaper
Revival
of risky medical X-ray practices
JACK SCHUBERT and Ralph
E Lapp in their eminently readable book entitled `Radiation — What It Is
and How It Affects You' wrote about a medical practice that had, in the
fifties, become almost a standard, among many firms like General Motors,
Ford and ChryslerThey used to send their executives off to a clinic for a
complete annual medical check up. The check up included X-ray screening of
the lungs, heart, stomach, upper and lower intestinal tracts, kidneys and
other organs. They received a whopping radiation dosage of about 50
roentgen in the bargain! (Roentgen is a unit of radiation exposure; a
chest X-ray may involve an exposure of about 0.1r). On April 26, 2002, the
U.S. Food and Drug Administration (USFDA) noted that some medical imaging
facilities are now promoting and marketing whole body CT scanning or
screening as a preventive or proactive health measure to healthy
individuals who have no symptoms or suspicions of disease. FDA asserted
that it knows of no scientific study demonstrating that whole body CT
screening is effective in detecting any particular disease early enough
for the disease to be treated or cured. According to FDA
"Any such presumed benefit of whole body CT screening is uncertain,
and such benefit may not be great enough to offset the potential harms
such screening could cause. Public health agencies and national medical
societies — the American College of Radiology, the American College of
Cardiology and the American Heart Association — do not recommend CT
screening". CT is a unique tool to
diagnose disease, trauma or abnormality and to plan, guide and monitor
treatment. It may help to determine the extent of the disease. But it is
not to be used indiscriminately. Screening of
symptom-less patients provides uncertain benefit with potential for some
risk. The dose received by a patient during a CT procedure is generally
much larger than that from most conventional X-ray procedures. The effective dose in CT
procedure is not much less than the lowest dose received by some of the
survivors of the atomic bombs. FDA noted that these survivors have
demonstrated a small but increased radiation related excess risk for
cancer. All radiation doses have
an associated risk; a small possibility of developing radiation-induced
cancer some time later in life. In a medically needed procedure, the
benefit to the patient far outweighs the risks. FDA warns that for a
person without symptoms, CT screening is unlikely to discover serious
disease and the potential harm to the individual may be greater than the
presumed benefit. The book by Schubert and
Lapp quotes a 1956 communication of the National Committee on Radiation
Protection, "one of the important sources of radiation exposure is
that applied by general practitioners. They have no techniques by which
you can really estimate the exposure given in a gastrointestinal tract
examination". The British Medical Journal (13th April 2002)
published a letter by a consultant radiologist K. Grower Thomas and his
colleagues from several other hospitals. They compiled a simple
questionnaire and interviewed 130 doctors of all grades including
consultant radiologists. They asked the physicians for an approximate dose
of radiation in a chest radiograph. This dose was to be taken as a unit of
one to calculate how many units a patient would receive for several types
of medical X-ray examinations carried out in a busy radiology department
(17 examinations in total). Believe it or not, only
3/130 scored a pass mark of 50 per cent in spite of a generous marking
scheme and no negative marking. "The degree of knowledge was
inversely proportional to seniority, with consultants scoring less than
junior colleagues. It was clear and worrying that doctors have no real
knowledge of radiation doses that their patients receive." I wrote about the Indian
experience in the same issue of BMJ. The Atomic Energy Regulatory Board
organised appreciation programmes on X-ray safety for the benefit of
radiologists, physicians, medical students and para-medical staff.
Invariably, everyone wanted to know the effect of irradiation on the
unborn child. We found that many specialists were not equipped to offer
advice on the magnitude of radiation doses in different medical X-ray
procedures. Responding to a Popular Science article on medical
X-ray protection, a few patients approached their radiologists to get some
idea about the radiation doses they receive in medical X-ray examinations.
Even senior specialists did not know. In reply to the letters
on the topic, Dr. Adrian K. Midgey, a general practitioner from the U.K.
reacted. "You cannot make it feasible for all of us to remember the
radiation dose in an examination since this is changeable and we have
other things to do than replace minimally useful numbers in our memory
with new improved and minimally useful numbers". He is correct up to a
point. But if the physician knew about the relative magnitude of the doses
in various procedures, it may help to reduce unwanted referrals of
symptom-free patients. Let us hope that our corporate hospitals will not
use CT indiscriminately for screening. K.S. Parthasarathy Atomic Energy
Regulatory Board Send this
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