Physics and Radiobiology of Nuclear Medicine

(Jeff_L) #1

gerous to health, alluding to the linear no-threshold (LNT) theory of the
dose–response relationship. Psychological warfare with anecdotal rhetoric
among the rival countries possessing nuclear weapons also creates fear of
radiation among the public. Dreading effects of radiation on children and
future offspring, and long-term damage to property are major concerns of
the public. Furthermore, the media often play a role in exacerbating the
problem of exposure from radiation accidents.
Is there a logical justification for this radiation phobia of the public? Def-
initely, nuclear detonation causes an instantaneous devastating effect on the
population and property, and so can be reason for fear and panic. But
the long-term effects of low doses of radiations, even from the fallout of the
atomic bombs in Japan and Chernobyl accident, have been shown to be rel-
atively small. The average individual lifetime dose from the Chernobyl
fallout is estimated to be 0.6 to 6 rem (6–60 mSv) (Jaworowski, 1999). By
comparison, the worldwide average annual dose rate of natural radiation
an individual receives on earth is 220 mrem (2.2 mSv) and the lifetime dose
of about 15 rem (150 mSv). In the United States, an individual receives an
annual dose of about 300 mrem (3 mSv) including radon and a lifetime dose
of 21 rem (210 mSv). These values are even ten times higher in some regions
in India and Brazil, and yet incidence of excess cancer is not shown to be
higher in these places.
People face risk of cancer, injuries, and even death from day-to-day living
activities, such as driving, smoking cigarettes, drinking alcohol, eating food,
and breathing air, in addition to hazardous job-related activities. Thirty-
three percent of the population will contract cancer just from these activi-
ties without any radiation exposure, and 22% will die from natural causes
(ACS, 2003). If the population is exposed to 1 rem (10 mSv) of radiation
exposure, the risk of cancer increases only by 0.1% and half of them
(0.05%) will die, which is quite negligible (BEIR VII, 2005). Based on these
arguments, it can be said that although nuclear explosions can be a cause
for grave concern, low-dose radiations from medical facilities, natural back-
ground, and the like, are fairly safe relative to the hazards of different living
activities, and the risk from such radiation exposure is small.
To allay the fears of radiation in the public’s mind is essential and criti-
cal. It can be achieved through education of the public. People knowledge-
able in radiation should talk to laymen explaining the relatively small risk
of low-level radiations compared to many other day-to-day living activities.
The media should play an important role in communicating this informa-
tion to the public. Radiation experts should hold regular public seminars to
explain the minimal risk of low-level radiation. Radiation-related profes-
sional organizations such as the Society of Nuclear Medicine, The Radio-
logical Society of North America, Health Physics Society, and American
Association of Physicists in Medicine should undertake appropriate
approaches of communication with the public to shed their concern and
fear of radiation.


264 15. Radiation Biology

Free download pdf