Transcript JUSTIFICATION OF COMPUTERIZED TOMOGRAPHY EXAMINATIONS …

JUSTIFICATION OF COMPUTERIZED TOMOGRAPHY
EXAMINATIONS AND RADIATION RISKS IN EVERYDAY
RADIOLOGICAL PRACTICE
Darka R. Hadnađev, Olivera Nikolić, Sanja Stojanović
Center for radiology, Clinical Center of Vojvodina, Novi Sad, Serbia
Background:
 Rapid technical developments and an expanding list
of application have led to a dramatic increase in the
use of body CT in medical practice since its
introduction in 1975.
 A number of CT examinations has dramatically
increased, mainly for the new clinical applications
which technically improved CT scanners and made
it widely available.
Procedure analysis:
 A review of the most recent literature regarding uncritical CT
overuse and insufficient use of alternative non-ionizing diagnostic
modalities is presented.
 The popularity of CT imaging is high for many reasons:
- speed and ease of use
- new imaging techniques
- threat of a lawsuit
 Abdominal and pelvic CT examinations are two major contributors to this
increase in population radiation exposure because they are associated with
the greatest radiation burden among all types of CT procedures.
Table 1 Definition of 14 standard and four special examinations
frequently carried out on MSCT scanners along with the
corresponding average scan parameters and dose values, as
determined in a nationwide survey performed in Germany in 2002
 In Serbia, there are often uncritically
indicated control abdominal and pelvic CT
examinations.
 Numerous multiphase CT examinations
are performed often as unnecessary, as
well as the radiation dose the patient
receives on that occasion.
Table 2 Patient dose levels in Serbia
Courtesy of Professor Sanja Stojanovic (Personal Communications)
Table 3. Comparison of effective doses for standard CT exams
Literature
Our study
(eff. dose- mSv) (eff. dose- mSv)
CT head
2
2.4
CT thorax
8
6.1
CT abdomen
and pelvis
10
20
 The purpose of the study is to determine
the average effective dose per each CT
exam and to make the introduction of
patients radiation records in everyday
practice.
 There are three guiding principles to minimize
the radiation dose levels: justification,
optimization and limitation.
 The examination must be medically indicated
and it must use doses that are as low as
reasonably achievable (ALARA) without
compromising the diagnostic task.
 A consideration of evidence-based
recommendations for relevant clinical cases and
an understanding of the risk of disease for each
patient
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If patient doses are higher than the expected
level, but not high enough to produce
obvious signs of radiation injury, the problem
may go undetected and unreported, putting
patients at increased risk for long-term
radiation effects.
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Characteristics of deterministic effects:
Damage depends on absorbed dose
Threshold exists
Example: cataract, erythema, infertility etc.
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Characteristics of stochastic effects:
Severity is independent of absorbed dose
Threshold does not exist
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Probability of occurrence depends on absorbed
Example: radiation induced cancer, genetic effec
 Low-dose techniques are justified (e.g.,
CT colonography [CTC], repeat CT for
renal stone disease).
 Unjustified exams - for which CT is not
indicated or for which unnecessary series
are acquired.
 Once the determination is made that an
appropriate CT examination can benefit
the patient, CT parameters should be
optimized and dose reduction techniques
used to perform the diagnostic task at the
lowest appropriate level of radiation dose.
 CT scans are now used as a screening
procedure.
 CT lung screening-the only one accepted
so far
 CT colonography
 CT coronary angiography (Ca scoring)
 The shielding of superficial radiosensitive
tissues and the optimum selection of
settings are some of the technical
possibilities.
Conclusion:
 By informing and educating the clinicians
and radiologists primarily on the risk of
radiation and strategies to minimize it
during a CT exam, we can justify the
examination itself and the patient radiation
risk. Therefore, it is necessary to limit the
exam to the region of clinical interest by
which better quality would be achieved as
well as significantly reduced patient’s
dose.
Thank you for the attention!