University of South Carolina School of Medicine. RADIOLOGY. ICM. Introduction To Clinical Medicine. Francis Neuffer M.D. U.S.C. School of Medicine. Radiology Website : http://radiology.med.sc.edu. Overview . GOALS. Image creation Different modalities
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X-ray, CT, Nuclear Medicine
X-ray, visible light and radio waves are all electromagnetic radiation and only vary in frequency.
--Kilo Electron Volts
ORAL BARIUM CONTRAST
WITHOUT CONTRAST-plain or scout film
INTRAVASCULAR IODINE CONTRAST
-20 - -80
+20 - +80
CT WITH INTRAVENOUS IODINE CONTRAST
INTRA-ARTERIAL IODINE CONTRAST
IV IODINE CONTRAST
Metastatic bone disease
THAT’S MORE LIKE IT.
CT scans contribute approximately 45% of the U.S. population's collective radiation dose from all medical x-ray examinations.
CT is the LARGEST contributor to medical exposure to the U.S. population.
Estimated Number of CT Scans Performed
Annually in the United States
Emergency Radiology 2006 Oct: 13(1); 25-30
Ionizing radiation can cause free radicals which can break DNA.
Incomplete DNA repair can be lethal to cell or increase cancer risk or increase genetic defects in fetus.
Adapted from: Radiology 2009;253:293-296 Figure 2
CXR= 1/100 Background Radiation/Yr.
CT Scan= 1-4x Background Radiation/Yr.
Denver = 2x Background Radiation/Yr.
Deterministic effects—dose dependent.
Stochastic effects—probability of event
Cataracts, Skin Erythema & Burns,
(very rare -interventional procedures)
Acute Radiation Sickness-(Radiation accidents)
GI tract sloughing
probability increase - population effect
Hiroshima Nuclear Bomb survivors
50-100 mSv exposure
Nuclear Bomb Survivors
The estimated lifetime cancer mortality risks from a single full-body CT examination at age 45.
There is an excess cancer risk seen in
large groups of Hiroshima survivors.
Statistically CT scans WOULD increase
risk of cancer.
Children are considerably more sensitive to radiation than adults by about 3 times.
Children also have alonger life expectancy than adults, resulting in a larger opportunity for effect.
Radiation-induced cancers effects delayed1 to 2 decades or longer after exposure.
Children can receive a higher dose( ADULT SCAN) than
Thus risk for developing a radiation-related cancer can be several times higher for a pediatric patient.
SCANS ARE MADE TO SEPARATE TISSUE BASED ON THEIR T1 AND T2 TIMES.
X-ray, CT, Nuclear Medicine
IODINATED AGENTS are WATER SOLUABLE and can be given by oral or vascular routes.
With IODINE, there is a potential for RENAL TOXICITY in certain patients and ALLERGIC REACTIONS can occur.
BARIUM is a GI CONTRAST. It is a particulate inert material. Therefore it is not a vascular agent. It could be a problem if it perforated into the peritoneum.