Images produced through the use of ionizing
radiation are called conventional radiographs.
It is relatively inexpensive to produce, can be
obtained almost anywhere by using portable or
mobile machines, and are still the most widely
obtained imaging studies.
They require a source to produce the x-rays (the
“x-ray machine”), a method to record the image.
The major disadvantages of conventional
radiography are the limited range of densities it
can demonstrate and that it uses ionizing
BIOLOGICAL EFFECTS OF RADIATION
Radiation causes biological effects on a cellular
level either (1) by directly damaging molecules or
(2) by indirectly creating free radicals to disrupt
Deterministic effects (nonrandom): This is
damage that occurs when a threshold level is
met. Both the probability and the severity of the
effect are proportional to increasing dose, where
the dose is usually given in one exposure or several
exposures over a very short period of time.
BIOLOGICAL EFFECTS OF RADIATION
Stochastic effects (random): Damage that may
occur at any level of exposure, without a
These effects occur by chance, and while their
probability increases with an increasing dose,
their severity is independent of the dose.
These effects are due to damage of cellular
components, usually DNA, by free radicals, leading
to abnormal cell function if repair is incomplete or
Musculoskeletal: evaluate all bone elements.
Psoas muscle margin: straight, convex or absent.
Intestinal gas: overlap, displaced.
Calcifications: overlying the UT or outside.
Gas shadow: abnormal air at UT.
Medial deviation of the ureter should be considered
when the ureter overlies the ipsilateral lumbar
lateral deviation should be considered when the
ureter lies more than 1.5 cm beyond the tip of the
IODINATED CONTRAST MEDIA
Water soluble, they
and positive ions which
attract the negative and
positive poles of the
Do not dissociate and
are rendered water
soluble by their polar OH
Ionic contrast media Nonionic contrast media
TYPES AND FREQUENCY OF ACUTE
Acute idiosyncratic systemic reactions (also described as
allergy-like or anaphylactoid) are defined as
unpredictable reactions which occur within 1 h.
Chemotoxic reactions, are dose-related and dependent
on the physico-chemical properties of the contrast
ACUTE IDIOSYNCRATIC REACTIONS
Mild or minor reactions include nausea, mild vomiting,
urticaria and itching.
Moderate reactions include more severe vomiting,
marked urticaria, bronchospasm, facial or laryngeal
oedema, and vasovagal reactions.
Severe reactions include hypotensive shock, respiratory
arrest, cardiac arrest and convulsions.
RISK FACTORS FOR ACUTE IDIOSYNCRATIC
Type of Contrast Agent.
Previous Contrast Medium Reaction.
Drugs( B Blockers, Ca channel antagonist
and Inter leukin).
PREVENTION OF ACUTE IDIOSYNCRATIC
In any patient at increased risk of contrast medium
reaction, especially if there has been a previous reaction
to an iodinated contrast agent, use other modalities.
If iodinated contrast medium is still deemed essential the
risk of an acute reaction can be reduced by an
appropriate choice of contrast medium and
CHOICE OF CONTRAST MEDIUM
Nonionic low osmolality agents which are
associated with a four to five times lower risk
Nonionic CM is preferred specially if there is
history of previous reaction, allergy or
Previous history to nonionic CM?.
Most frequently steroids with or without additional H1
antihistamines have been recommended.
In severe reactors to ionic CM, steroids should be given
12&2 h before contrast medium.
The minimal effective time interval between steroids and
CM is considered unlikely to be less than 6 h.
Use nonionic contrast media.
Keep the patient in the Radiology Department for
30 min after contrast medium injection.
Have the drugs and equipment for resuscitation
MANAGEMENT OF ACUTE CM ADVERSE REACTIONS
The adverse event that occurs within 60 min of an
injection of contrast medium.
The mild reactions include flushing, nausea, arm
pain, pruritus, vomiting, headache, and mild urticaria.
They are usually of short duration, self-limiting and
generally require no specific treatment.
TREATMENT OF SPECIFIC REACTIONS
Nausea and Vomiting ( self limited, ? Anti-emetic).
Cutaneous Reactions ( treat if extensive).
Bronchospasm ( O2, bronchodil., ? Adrenaline).
Laryngeal Edema ( i.m adrenaline, O2).
Hypotension ( rise leg, rapid IV fluid).
Vagal Reaction ( as hypotension+ I.V atropine).
Generalized Anaphylactoid Reactions ( airway, O2,
rapid IV fluid, i.m adrenaline, ECG monitor).
LATE ADVERSE REACTIONS
Reactions occurring between 1 h
and 1 week after contrast medium
They are mainly mild or moderate
skin reactions and usually resolve
within 3–7 days.
Thee reduction in renal function induced by contrast
media which occurs within 3 days following
administration of contrast media in the absence of
an alternative etiology.
Most episodes of CIN are self-limited and resolve
within 1–2 weeks.
A persistent nephrogram on plain radiography or
CT of the abdomen at 24–48 h.
Pre-existing renal impairment [> 1.5 mg/dl], particularly when
secondary to diabetic nephropathy.
Large doses of contrast media and multiple injections within
The route of administration (IA > IV).
Dehydration and CHF. Hypertension, hyperuricemia and
prteinuria. Multiple Myeloma.
Type of CM.
PREVENTION OF CIN
Extracellular volume expansion, the choice of
normal (0.9%) saline when intravenous hydration is
The choice of low or iso-osmolar nonionic contrast
Lowest contrast medium dose consistent with a
diagnostic conclusion or a therapeutic goal.
EXTRAVASATION OF CM
Elevation of the Affected Limb.
Application of hot & cold fomentations.
Aspiration of subcutaneous fluid.
VCUG is commonly performed in children
with prenatally diagnosed hydronephrosis,
urinary tract infections, and voiding
The procedure should include assessment
of the spine and pelvis; masses or opaque
calculi; bladder capacity, contour, and
emptying capability; presence and grade of
reflux; and urethral appearance.
Clinical data and results of prior
imaging studies should be reviewed
before starting the examination.
Preliminary abdominal imaging usually
Several seconds after the contrast
material begins to flow, the minimally
filled bladder is imaged in the AP view.
A ureterocele or bladder tumor that is
well seen during early filling may
become obscured as more contrast
material enters the bladder
If reflux is observed during late bladder
filling, the ipsilateral renal fossa may be
imaged in the anteroposterior projection
prior to voiding.
IMAGING DURING VOIDING
A smaller than expected voiding volume
may also indicate a neurologic abnormality
(spastic bladder) or active bladder
At the conclusion of voiding, each
renal fossa should be imaged. Still
images may demonstrate reflux that is
not appreciated at fluoroscopy as well
as other anomalies or abnormalities.