Radiology Flashcards
What is an “X-ray ”?
Very short, penetrating electromagnetic waves (short, but varied wave lengths)
Used medically for image production & therapy
Type of radition in x rays
ioninzing radiation : that’s why they are dangerous.
faster moving - exposes you to more radiation
Photon
Mass less particles that travel at the speed of light and produce electromagnetic radiation. Their wavelength determines their energy.
Nonionizing radiation
def what can it cause?
has insufficient energy to break up atoms, however; sufficient energy in the form of heat may be produced to cause localized tissue damage.
Ionizing radiation
def what can it cause?
describes any radiation where the photon carries enough energy to ionize or break up an atom or molecule by removing an electron from its orbit.
Can cause biological changes.
E.g. DNA damage and mutations
Stochastic effects
Effects associated with exposures to low levels of radiation exposure over a long period of time
This concept stresses that no level of radiation exposure can be considered to be absolutely safe
T or false : radiation exposure that is not ultraviolet and is not ionizing does not cause significant damage as it is low frequency and is considered safe
False :
Stochastic (deterministic) effects
This concept stresses that no level of radiation exposure can be considered to be absolutely safe
Nonstochastic (Deterministic) Effects
Effects that are associated with much higher levels of radiation exposure, usually incurred over a much shorter period of time
Sterility changes, radiation burns, cataract formation and damage to; blood forming tissues, GI epithelium and CNS
radiation and pregancy (2)
Pregnant women should NOT undergo radiographic imaging unless suffering from serious illness or acute trauma
and cannot be determined by other means, especially sonography
ALARA Principle
As Low As Reasonably Achievable
How to minimize patient exposire to x rays (7)
Minimizing exposure time Maximizing distance from the tube Lead protection (thyroid, gonads) Using intensifying screens Modern equipment Collimate (restrict beam of X-rays to a smaller area) Avoid re-takes!!
How to minimize worker’s exposire to x rays (2)
Dosimeter Badges (measures exposure) Protective shielding
How are x rays created? (2)
Electrons are accelerated across a tube & impact a target
The x-ray beam is emitted from the target; it is shaped like a cone of diverging rays
what helps restrict the beams?
Collimators (shutters) on the tube housing help restrict the beam to the anatomical area of interest
what do speeds on xray cassettes do? 2
Effects radiation dose
Effects detail on films
What is a Radiograph
x ray
Created by variable amounts of beam attenuation
Attenuation is the process by which radiation loses its power as it travels through matter due to absorption or scattering of the beam
Structures of different densities become superimposed on one another on the image
How do dense materials look on a radiograph
DENSE materials attenuate the x-ray beam, resulting in less film exposure
METAL vs AIR
CROSS TRIANGULATE - what does it mean?
When ordering x-rays it is almost always necessary
to take 2 views at right angles to one another
Radiographer
X-ray Technician):
Takes radiographs & other imaging
Not a physician
Not trained to interpret radiographs
Radiologist
Interprets radiographs & other imaging
Physician with post-graduate education
what is KUB?
Kidney Urinary Bladder
Plain film radiographs examples
bone tumors ( always start plain) trauma and arthritis ( often the only imagine required)
What cannot be seen on plain films? 8
Details of Soft Tissue structures IVD herniations Specific muscles (usually) Ligaments and tendons (usually) Neuroanatomy details Vessels Many abdominal viscera
What are imaging guidleines for elderly ( over 65?)
CURRENT IMAGING GUIDELINES RECOMMEND MORE LIBERAL USE OF IMAGING AFTER AGE 65
Conditions that we use liberal imaging. Why? (5)
PRIMARY OSTEOPOROSIS DRUGS AFFECTING BONE DENSITY MALIGNANT BONE TUMOURS IMPORTANT ASYMPTOMATIC CONDITIONS: AAA (abdominal aortic aneurysm), PAGET’S, SOFT TISSUE ABNORMALITIES, ETC. DEGENERATIVE ARTHRITIDES
In older patients. risk less than reward
Low Back pain that cannot be seen on plain films of x-rays (3)
Muscle strains
Ligamentous sprains
Disc herniations
5 densities in order of density.
what colour are they?
Air, fat, water, bone, metal
least dense = air, more translucent (therfore more black)
most dense = metal, more white and opaque
Normal chest vs. normal rib technique. what do you see?
A. Normal Chest Technique: allowing you to see heart, pulmonary vessels, and skeletal structures
B. Normal Rib Technique: pulmonary vessels become much harder to see, and the bones become easier to see
Peterson’s Rules (3)
Of the same patient?
Taken the same date?
Of the same anatomy?
what biological condition can hinder x ray imaging? why?
how to mitigate this?
obesity - causes poor penetration of underlying structures ie lung tissue
using a higher film speed
Search Pattern
ABC’S
Alignment: (dislocations, subluxations, curves) Bone: (Size, shape, density, correct number of bones, cortex intact) Cartilage (Joints) Soft Tissues
A in ABC’S
Alignment
- Normal curves
- Spine - Normal angles
- E.g. Genu varus and valgus in the knee - Normal joint alignment
- Subluxations (dysfunction of a joint), dislocations
Subluxations ?
Subluxations (dysfunction of a joint),
B in ABC’s
q’s to ask 6
Bone
Normal shape? Normal size? Normal density? Cortex intact? Medullary space? Correct number of bones?
C in ABC’s
3 q’s
Cartilage (joints)
Normal joint space width?
No loose bodies?
Articular cortex?
S in ABC’s
4 q’s
S = soft tissue
Normal density Normal size Normal contour Swelling? Mass? Calcifications?
CATBITES
What?
Categories of Bone Disease:
Congenital Arthritides Trauma Blood (Vascular) Infectious Tumour (Neoplastic) Endocrine/Metabolic Soft Tissue
When you see something that is not normal on a film, these categories give you a good checklist of things to consider in making the correct diagnosis
Tomography
what? advantages? 2 disadvantages? 3
Involves visualizing a selected anatomical layer
X-Ray tube moves in one direction while the cassette and film move in the opposite direction which produces a sharp in-focus image while structures above and below are blurred
Advantages: subtle fractures or early bone destruction identified before they appear on plain films
Disadvantages: Higher radiation dose, longer exposure times create motion artefacts and enough slices need to be obtained
CT: Computed Tomography
what?
Radiographic tube within a Gantry that emits a thin x-ray beam as it rotates 360° around the patient while information evaluated by computer formulates a transverse image of the slice
Should we do an abdominal CT?
Ultrasound is a more cost effective/non-invasive method for obtaining the same information
Contraindications and Disadvantages of CT (7)
Very few
Hypersensitivities to iodinated dyes
Higher radiation dose (3 – 5 rads compared to lumbar spine x-ray of 100 mrads)
Pregnancy
CT of children
Presence of metallic objects near area of interest may result in image artefact from beam scattering
Better detail may be obtained with MRI in some instances
Some patients may be claustrophobic
Bone Windows
how do they appear?
Window level and width that optimizes the attenuation values of bone. The attenuation coefficients of soft tissue have a dark grey appearance.
Soft Tissue Windows
what distinguishment can we not make?
Window level and width that optimizes the attenuation values of soft tissues. Differentiation of cortical or medullary bone is not possible with this setting.
MRI (Magnetic Resonance Imaging)
Image production is the result of a complex process involving the interaction of hydrogen protons with an external magnetic field
What is the correct order of this sequence for MRI?
- Normal random proton alignment that without the influence of an external magnetic field allow them to be in constant motion
- When the RF pulse is removed, a coil detects the energy transferred from the realignment of the protons to their equilibrium position which produces the image
- Radiofrequency pulse is applied, the H protons are excited to a higher energy state by altering their orientation
- Protons align due to strong magnetic field produced by an electromagnet housed in the MRI gantry
1, 4, 3, 2
MRI Generals
4
No Ionizing radiation
Images directly in any plane
Images larger sections of the body
No dangerous contrast agents required
What do we use in MRI instead of dangerous contrast agents?
Intravenous or intra-articular contrast sometimes used
Gadolinium & saline mixture
CNS? which modality do we want to use?
CT unless its acute
which modality do we want to use for boney detail?
CT
CI for MRI 3
Anything metallic
(Can draw them out of the body)
1st trimester – just because they don’t know
Welders ( shards in eye)
Fat image
T1
in MRI
Structures containing fat (bone, subcutaneous fat) appear bright. Structures containing water (CSF, edema, neoplasm, inflammation) appear dark
Water Image
T2
in MRI
Structures containing predominantly free water (neoplasms, edema, inflammation, nucleus pulposus, CSF) appear bright. Tightly bound water (ligaments, menisci, tendons) appear dark
Advantages of MRI 5
1. Excellent detail Superb soft tissue differentiation 2. Can image large sections 3. Multiplanar imaging capabilities 4. No ionizing radiation 5. Contrast (if used) is not dangerous – compared to ionidated
Limitations of MRI 3
- Stay very still for 45-50 minutes
- Inferior to CT in detecting an acute hemorrhage
- Inferior to CT for boney injury
Arthrography
what is it?
what is it used for? (4)
disadvantages? (5)
Dye injected into joint
Plain radiographs taken
Helps identify intra-articular derangements of menisci, cartilage, ligamentous and synovial abnormalities
disadvantages : invasive, interpreter dependency, and possible oversight of small lesions, risk of infection (MAIN), adverse reaction to dye
CT Arthrogram
when is it used?
Useful when there is metal in the region which limits effectiveness of MRI, or when the patient has a contraindication for MRI
MRI Arthrogram
useful in detecting precise images. cannot use if CI
Myelography
what is it? (2)
Advantages
Disadvantages
Complications
Iodinated, water- based contrast injected into the subarachnoid space at L2 or L3 level
Aids in disc, vertebral canal and nerve root disease
Advantages: useful in determining multi-level spinal stenosis and injury at the junction of the nerve root and cord
Disadvantages: invasive procedure that risks infection, nerve root damage or dural tears.
Complications include Headaches, Arachnoiditis (inflammation of arachnoid mater).
Postmyelogram headaches encountered 40% of cases
Sometimes used when patients too large for CT or MRI.
Arteriograms (Angiography)
what ?
how?
what purpose?
Iodine based dye injected
Often use femoral artery approach
Done with Fluoroscopy (motion images)
Cardiac catheterization is one of most common procedures
Cerebral angiograms also common
WP: Any vessel can be visualized
Coronary Angiography
what?
how?
why?
The “gold standard” for coronary artery disease
Catheter fed via Femoral artery
Contrast injected into coronary artery
For diagnosing the impact of heart attack and making heart activity visible
Angioplasty
While doing an Coronary Angiography
While they are in there” the decision to open a vessel and place a stent may be made
MR Coronary Angiography
what?
risks?
Where?
Useful in detection of stenosis in large coronary vessels, but not small branches
Risks: Same as any MRI procedure
Normal right coronary artery
Best way to See cardiac enlargement?
Can’t see on CXR (xray)
ECG/EKG better - not an imaging modality
Barium Studies: General
Performed & evaluated under fluoroscopy
study of the bowel
types of barium studies
types of barium studies (5)
Barium Swallow—evaluates esophagus
Barium Meal—evaluates stomach
Barium Meal/Follow-through—small intestine
Small bowel enema—barium injected into duodenum via a tube through nose
Barium Enema/Lower GI
Barium injected into rectum, sigmoid, large bowel up to ileocecal valve
Barium Swallow
—evaluates esophagus
Barium Meal
—evaluates stomach
Barium Meal
/Follow-through—small intestine
Barium Enema
Lower GI
Barium injected
into rectum, sigmoid, large bowel up to ileocecal valve
Patient Prep for Barium Study
Clear liquid diet before exam ( lower GI)
Upper GI - nothing to eat for 8 hours
Does Fluoroscopy use x rays?
yes
CI for barium studies
Barium by itself is an inert substance and completely harmless
However if it escapes into the abdominal or thoracic cavity through a perforation, it can cause severe inflammation
Thus barium studies should not be done in patients with suspected perforation
Water-soluble contrast material is used if perforation is suspected
Excretory Urography (IVP or IVU)
what?
The most basic radiographic study of the urinary tract (vascular delivery of contrast material)
Allows visualization of the renal collecting systems, ureters, and bladder for obstruction
How Is An IVP Performed (4)
- Radiopaque dye is injected (after a scout KUB) into a patient’s bloodstream
- Radiographs are taken
- as the dye is concentrated in the kidneys, and passed down the ureters to the bladder - A compression band
- may be applied to compress the ureters and keep dye in the area of the kidneys for longer, which improves image quality - Serial films are obtained over 15 to 30 min.
- Serial films are obtained over 15 to 30 min.
Adverse Reactions To Contrast Material
Minor reactions are the most common
Seen in 5-10% with iodinated contrast
Urticaria, itching, nausea, vomiting = m/c
Non-iodinated agents can be used
RETROGRADE PYELOGRAM
what is it?
when can you use it?
Ureteral Catheter
Non-vascular delivery of contrast material
Normal renal function is not necessary for visualization
Diagnostic Ultrasound
aka?
what?
CI?
Uses Sound waves
AKA ‘sonogram’
no known CI or side effects
What is a diagnostic ultrasound good for? 6
Obstetrics (hip dysplasia) Abdominal and pelvic masses/cysts Heart (echocardiography) Breast imaging (cysts) Some musculoskeletal tendons, ligaments if peripheral in location (rotator cuff) Not good for bones and bowel
Advantages of ultrasound (3)
non-invasive, does not involve ionizing radiation, useful in visualizing soft tissue adjacent to joints
Disadvantages of ultrasound 2
Disadvantages: tissues too close to bone not visualized, metal implants inhibit detail of nearby soft tissues
How does ultrasound work?
what does it identify? 4
As a controlled sound bounces against objects, its echoing waves can be used to identify:
How far away the object is
How large the object is
The object’s shape
The object’s internal consistency (fluid, solid, mixed) and how uniform it is
Which imaging modality do you see in real time and can see movements of organs
Ultrasound
What is the doppler - how can you see it?
Evalute blood flow, clots etc.
Ultrasound
Proceedure of ultrasound (3)
Gel Applied Transducer Applied Creates and records sound waves Significant pressure may cause discomfort, especially if bladder full Produces live computer image
Which modalities are best for showing kidney stones but not gallstones
how do you see gallstones?
CT kidney stones
ultrasound - gallstones
Which modalities are best for showing kidney stones but not gallstones
how do you see gallstones?
CT kidney stones
ultrasound - gallstones
Echocardiogram
aka
what? (5)
AKA - ultrasounds
Evaluates pumping and valve function Motion image of the heart Detects flow and velocity of the blood Primarily used to evaluate murmurs Also used to evaluate location and extent of MI, valves dysfunction, clots, congenital heart defects and pericardium
Echocardiography
Benefits? 3
aka - heart ultrasound
No contrast agents used
Non toxic, non-invasive
No side effects
Doppler Ultrasound
what?
example conditions it can help diagnose (3)
Measures blood flow by measuring the rate of change in its pitch
May help diagnose many conditions, including:
blood clots, poorly functioning valves in veins, heart valve defects
How is colour produced on a Doppler ultrasound?
the amount of energy
What is Mitral regurgitation?
imposes a chronic overload on the left ventricle
What is nuclear medicine? short 2
examples 2
Relatively non-invasive
Uses radiopharmaceuticals to evaluate pathophysiologic abnormalities of various organ systems
aka tumors, fractures etc.
what vector do we use in nuclear medicine?
A radionuclide, given intravenously, can be chemically tagged to these substances from increased phsyological function
Radioactive pharmaceutical
aka a radionuclide - tagged to something we metabolize – localized in somewhere with high metabolic activity : fracture, tumours,
what does nuclear medicine not look at? or emphasize less
Doesn’t look at things anatomically but rather helps us understand the function – physiology
looks at both to diagnose and treat
How nuclear medicine works?
IV injection of radioactive material
need a detector - gamma camera
Scintigraphy
what does it do? (3)
what do we look for? (2)
what does it diagnose/not diagnose? (2)
aka - bone scan
IV injection of radioactive nuclide that emits gamma rays which Scintillate (sparkle)
very sensitive not specific
what do we look for?
- high osteoblastic activity
- uniform distribution of Radionuclide
what does it diagnose/not diagnose?
Not for osteoporosis
Measures increased physiology – fractures etc.
How is Nuclear Medicine Different from CT, US & MRI
exceptions (2)
In General:
CT, US, MRI provide anatomical or structural information
Nuclear imaging provides functional data
Some Exceptions: Colour Doppler (looks at blood flow) Functional MRI (detects neural function)
How is Nuclear Medicine Different from CT, US & MRI
exceptions (2)
In General:
CT, US, MRI provide anatomical or structural information
Nuclear imaging provides functional data
Some Exceptions: Colour Doppler (looks at blood flow) Functional MRI (detects neural function)
Hot spot in Scintigraphy
chief applications (3)
area of increased uptake - higher metabolism
Detection of metastasis
Detection of osteomyelitis (infection)
Can also detect fractures and inflammation
Cold spot in Scintigraphy
Area of decreased metabolism (less than normal)
“Cold Spot”
Types of Nuclear Medicine Scan (7)
Bone Scan PET SPECT Cardiovascular Imaging Lung Scan Ventilation and perfusion or V/Q scans Renal Scan Thyroid Scan
Bone scan generals
aka
sensivity? specificity?
what can it diagnose/not?
in nuclear medicine
SCINTIGRAPHY
VERY SENSITIVE to a wide variety of diseases
Can detect 3-5% bone loss
X-ray requires 30-50% bone loss before we detect it
VERY LIMITED SPECIFICITY
“Clinical correlation is required”
Bone scan – osteomyelitis ( serious pathological processes ) not osteopersosis
What does the patien need to do to prepr for a SCINTIGRAPHY?
void before and after image acquisition
Radionuclide is eliminated in urine and stool
Inject radionuclide
Risk of Nuclear MEdicine Scan (2)
Severe reactions to injections of radiopharmaceuticals are rare
Radiation dose is LOW compared to other studies that use ionizing radiation (xray)
Dose depends on the scan, and the quantity of radionuclide used
SPECT
what?
in contrast to?
advantages
application
in nuclear medicine
slices of physiological activity
in contrast to : CT
Compared to PET, SPECT is less expensive, and centres are more accessible but they produce images with less resolution
localized internal organ function by showing how blood flows to tissues and organs. class ex) dementia
Special notes about SPECT and MSK (3)
In the MSK system, SPECT is like bone scan and CT combined
Can produce a bone scan that looks at a specific plane in the body
Thus, can look at specific anatomical site
PET “ Position Emission Tomography”
what? (3)
How? 1
nuclear medicine image technique
3d images of the functional processes for the body
give anatomy and phys on the same image
inject radionuclide - produced in a cyclotron (special machine, very expensive, and limited availability)
we see hot spots where there are tumors etc.
Uses of PET (6)
” Position Emission Tomography”
clinical oncology detection of metastasis brain pathology planning evaluation of treatment
not a first line imagine proceedure
Limitations of PET
EXPENSIVE
“ Position Emission Tomography”
LIMITED Availability
Centres must have a cyclotron
Poor detail of anatomy, thus used IN COMBINATION with other imaging modalities (CT and MRI, most commonly)
Mammography (3)
what are the ulternatives?
X-ray examination of the breasts for detection of tumors
Takes approximately 30-45 minutes
Advise your patient: powder, lotion, perfume or deodorant can produce shadows on the mammogram
Alternatives:
US is typically used for further evaluation of masses found on mammography or palpable masses not seen on mammograms
MRI useful to evaluate questionable findings pre-surgical evaluation in patients with known breast cancer to detect
Bone Density Assessment (2)
DEXA scans (Dual Energy X-ray Absorptiometry)diagnostic measure of choice for osteoporosis
What is DEXA?
used in bone density assessment : fast, low radiation
measures Skeletal size, body composition and even software may distort result (over/underestimate density)
T score
Bone density assessment
The number of standard deviations away from the mean. The mean is derived from the age of peak bone mass (20 – 35 years).
-2.5 or worse constitute osteoperosis
each SD doubles risk of fracture and 10-15% loss of bone
less than -1 but greater than -2.5 = osteopenia (lower than normal)
Normal is -1
Z score
bone mineral density compared to the mean of an age matched population. Its usefulness has been questioned and is not recognized for quantifying osteoporosis
In bone density assessment , which body parts should be imaged? (3)
Hip and Lumbar Spine
Lots of trabecular bone
DEXA of femoral neck predicted hip fracture better than measurements at other sites
Calcaneus
Strong correlation with femoral neck density and future fracture risk
Radius
A Physician may not be able to assess whether a pt. with a low T-score at hand or forearm has substantial bone loss at other sites
what is a bone scan : layperson and what do we know?
Layperson : just a bone density test
we know that it is nuclear medicine
