Lecture 2: intro to radiology Flashcards
Interworking of X-Rays
XR tube, beam, and film used to create X-ray
Xray photons released from behind tube and strike film behind it
X rays may be absorbed or scattered
Radiopaque (xray image)
Dense metal or bone shows up more white on x ray
*atomic weight of target plays role in density
Radiolucent (xray image)
skin and fat appear more gray or black on x ray
Affect of distance on Xray
closer to film, better the picture.
Larger distance from film will warp imaging.
X ray view: AP
Anterior-Posterior (front to back)
X ray View: Lateral
side to side
X ray view: PA
Posterior to anterior (front to back)
Advantages of Xray (7)
Fast, inexpensive, readily available provides global view of area being examined low risk of adverse effects minimal pt prep no sedation required
Disadvantages of Xray (3)
insensitive and non-specific
image is affected by positioning
2D image
not all structures can be seen (gas and feces and affect image)
CT scan
*computed tonography
Uses several x-ray images and converts them into pictures
Used digital geometry processing to create 3D images
CT scanner emits series of narrow beams through the body, producing more detail than single beam from xray
Spiral CT
machine moves continuously around the body in a spiral, creating cross sectional images of body
able to detect small abdominal areas with precision
Helical CT
patient transported continuously through gantry while data are acquired during sevral 360 scans
Axial (CT view)
top to bottom
Coronal (CT view)
front to back
Sagital (CT view)
side to side
When to use CT… (5)
1) Rule out stroke (non contrast headCT)
2) detect internal injuries and bleeding
3) Diagnose bone disorders such as bone tumors and fractures
4) detect and monitor diseases and conditions such as cancer, heart disease, lung nodules, and lung masses
5) guide procedures such a sx, bx, and radiation therapy
Advantage of CT (5)
Readily available
Quick and painless
Shows bone changes better than any other method
only method to provide detailed images of bone, soft, tissue, and blood vessles
Can detect life threatening conditions
Disadvantage of CT (6)
exposure to radiation, allergies to contrast materials, more expensive than x ray, misinterpreted test results, limitations, unsuitable for pregnant women (unless dire situation)
***CT radiation exposure known to have enough radiation to increase cancer risks
MRI
Magnetic field used to align H protons in body
Radio frequency waves absorbed by protons and emitted as a signal
radio frequency currency coil picks up the signal and transmit it
computer processes data and an image is generated
MRI safety
MAGNET ALWAYS ON
- all implants must be checked before entering MRI
- patients with pacemakers and coclear implants must not have MRI or even enter room
- Medication pathced can cause burns
- ALL foreign objects must be checked by a tech
QUENCH
emergency shut down of MRI
When to use MRI (7)
abnormalities in brain and spinal cord
tumors, cysts, and other abnormalities in various parts of body
injuries or abnormalities in joints and soft tissues
some heart problems
Diseases of liver and abdominal organs
pelvic pain in women
breast cancer screenings
Coronal MRI views
front to back
Axial
top bottom
sagital
side to side
Advantages of MRI (4)
No radiation involved (more suitable for children and pregnant women)
painless
provides detailed pictures of most of the important organs and tissues in the body
non negatilve long term effects
Disadvantages of MRI (4)
powerful magnet attracts metal objects
expensive
loud-may cause hearing impairment
very lengthy- difficult to hold still
Ultrasound
involves exposing part of body to high frequency waves to produce pictures inside the body
Does not use ionizing radiation
Captured in real time- it can show the structure and movement of the body’s internal organs as well blood flowing throgh the vessels
When to use Ultrasound (5)
Can help diagnose a variety of conditions and assess organ damage following illness
Guise to procedures such as needle biopsies and joint injections
image the breasts and to guide bx of breast cancer
Diagnose a variety of heart conditions and assess damage after heart attack or diagnose vascular disease (echocardiogram)
OBGYN studies
Advantages of ulstrasound (6)
Most US scanning is non-invasive and usually painless
widely available, less expesnive than other testing and easy to use
Clear picture of soft tissue that does not show up on Xray
Pref. for imaging, dx, and monitoring pregnant women.
can evaluate blood flow
Real time imaging
Disadvantage of US (6)
quality depends on expertise of operator
anotomical detail is poor bc of low resolution
cannot evaluate bones, lung, or bowel
images poor in obese patients
images are poor when air or gas is present
small field of view
Urography
imagining and contrast material to evaluate or detect blood in urine, kidney, or bladder stones and cancer in urinary tract
Angiography
Detects aneurysm or blockage of vessel
angiogram uses radiopaque substance to make blood vessels visible under x-ray
MRA, MRV, areMR studies of arterial and venous flow
Helps guide interventional radiotlogiss and surgeons in repair of diseased blood vessles
Types angiography
x-ray-fluoroscopic, 3D CT-COW, MRA-COW, MRV-Sinus Flow
Myelography
special spinal cord x-ray examination used to help determine cause of pain, numbness, and/or weakness in back, arms, or legs.
contrast medium is injected into the spinal canal under x ray guidance to provide the spinal cord and nerve roots. series of x ray then taken.
My be perfomred along with other tests like MRI, CT, and regular spinal xray films
Can help find cause of pain that cannot be ofund by other tests
When to order myelogram (6)
previous spine surgery
narrowing of spinal canal
tumor of infection causing problems with spinal cord or nerve roots
spinal disc that ruptured
inflammation of membrane that covers the brain and spinal cord
problems with blood vessels to the spine
Arthrogram
MRI w/ contrast injected into joint prior to imagine
order when suspect labral tears and when patients have ad previous surgery on joint
Sialography
Glands?
Contrast Media (6)
Barium, Air, Gastrografin, CO2, iodine, gadolinium
Barium
*contrast Media used in fluorscopic procedures (upper and lower GI)
Air
*contrast media used in barium lower GI studies
“Double contrast” study comes from intriducing barium unto the colon and then puffs of air to show the different contrast of the bowel
Gastrografin
*contrast media used in fluoroscopic and CT procedures (Upper and lower GI) used over barium if a suspected bowl perforation. iodine base.
CO2 (3)
1) negative contrast agent in that is displaces blood when injected intravenously.
2) has a role in angiography, low risk as it is natural product (no risk of allergic rxn).
3) **can only be used below diaphragm as there is a risk of embolism in neruvascular structures. also must be used carefully to avoid contamination with room air when injected.
Iodinated contrast
- contrast media used in x-ray and CT procedures. can be oil based or water souble.
- oil based is slowly absorbed by body and only used in sliographis and hysterosalpingographic exams.
- ionic- most commonly used. can cause severe allergies.
- non-ionic organic compound, not used often due to cost. not as many rxns.
Gadolinium
*contrast media used in MRI. iron base contrast.
Barium Rxns (5)
stomach cramps, diarrhea, nausea, vomiting, and constipation
*usually avoided if patients increase fluid intake after procedure
Iodinated contrast adverse Rxns
IV reaction is most comon
-mild: nausea, vomiting, headache, itching, flushing, rash, hives
- Medium: severe skin rash or hives, wheezing, abnormal heart rhythms, increased/decreased BP, difficulty breathing
- Severe: difficulty breathing, cardiac arrest, swelling of throat or other parts of body, convulsions, extremely low BP
Gadolinium rxns
1-5% patientes experience brief headache, naseua, or dizzyness. Symptoms pass 5-10 minutes of administrations
-period of developing nephrogenic systemic fibrosis can occur for some patients if proper protocol is not followed
**imperative that patients with a hx of kidney or liver disease, diabetes, HBP or over age of 60 obtain recent creatinine level so that the tech and caclulate GFR (glomerular filtration rate) for patient.
Contrast Rxn treatment
- ABCs: assess airways, breathing, and circulation
- ACLS: ?
- stop infusion immediatley
- anaphylactoid rxns= SQ epi, O2, IV fluids, antihistamines
- mild: benedryl 150mg and observation
interventional Radiology
specialized field where doctors interpret medical images and also perform minimally invasive surgical procedures
transcatheter embolization, trans jugular intrahepatic portosystemic shunt, percutaneous aspiration needle bx of thorax/abdomen, percutaneous abcesses drainage, CT guided/ ultrasound guided LP (lumbar puncture) and others!
