Radiology Quiz 1

Wilhelm Conrad Roentgen

"Father of X-Ray"

Radiopaque

*Think OPAQUE* -blocks the passage of x-rays -Appear white

Radiolucent

*Think TRANSLUCENT* -allows for the passage of x-rays -appear dark, black, grey

Disadvantages of MRI

-$$$ initially and ongoing -tight tube = claustrophobia -safety issues with strong magnetic field -less available than CT -Have to stay still for long time -not as quick or easy

disadvantages of computed tomography

-$$$$$$ -radiation exposure -artifacts can degrade images -sophisticated computer processing -space for installation -adverse effects from contrast

Gas/air

-*Least resistance* = passes right through = black areas on film

What is computed tomography best for?

-*bone imaging* -Traumas (things that need to be done quickly) -helpful in chest and abdominal imaging

Advantages of ultrasound

-*no radiation* -real time images -portable -non invasive -relatively inexpensive and available

Factors that can affect test results

-Age (EX child won't stay still, elderly aren't as mobile) -mental status -physical limitations -ability to cooperate -tolerate contrast agents

Labels

-Always check id on film for your pt

Assessing radiographic quality

-Are you seeing what you need to see -Can you make an evaluation from films -enough contrast? over/under penetrated? -joints visible? -look at film as if pt is facing you

Special exams

-Avoid ordering special exams (CT, MRI, bone scans, etc) unless x-ray won't show it

Uses for fluoroscopy

-Barium studies -Genitourinary studies -Orthopedic surgery -Myelography

AP recumbent or supine AP

-Beam passes anterior to posterior

PA positioning

-Beam passes through pt from back to front aka *posterior to anterior* -heart minimally magnified, clear borders

Over penetration on x-ray

-Burnt appearance -too dark -hard to see lung markings

Silhouette sign

-Can't ID interfaces between densities -Can't see difference between structures (no interfaces)

Projection

-Direction of central beam EX where beam is coming from, horizontal, vertical

Types of densities seen on radiographs

-Gas/air -Fat -Fluid/soft tissue -Bone -Metal

Fat on x-ray

-Grey

Fluid/soft tissue/muscle/anything full of blood

-Grey -Darker

Rotation

-If not enough rotation = distortion of heart and vessels -look at heads of clavicles to see if properly rotated, should be equidistant from spinous process

Inspiration

-If you can see 10 posterior ribs= good (8 or 9 can be adequate) -If the inspiration isn't enough = crowds the ribs

Body further from film =

-Increased magnification -Larger more spread out imaging

What to know before you start radiology

-Labels -Previous exams -Quality of film -Special exams -radiation exposure -pregnancy -provide history -children -negative x rays -lag time -know what to order -ability to read radiographs -look at radiographs -if in doubt, ask -radiographs have limitations -anatomic variants -do radiographs in department

Spectrum of densities

-Lead/barrium -> white -Bone -> white -Air -> black

Benefits of digital imaging:

-No x-ray film costs -No lost film -No need for large film-storage spaces -No personnel needed to retrieve images -Can be easily manipulated to change brightness, contrast, mag.

What could cause silhouette sign?

-Pathologic -Error (under or over penetration)

Five technical factors for technical adequacy

-Penetration -Inspiration -Rotation -Magnification -Angulation

View

-Refers to an image as it is seen on radiograph EX PA, AP

Fluoroscopic imaging

-Used in surgeries -Ability to see a live image and the way that things move

Under penetration on x-ray

-Very white -too light -should be able to see thoracic spine

What does the radiologic technologist have control over that can affect the appearance of the image?

-X-ray tube -Voltage/current -exposure time -distance from patient

provide Hx

-always provide radiologist with good Hx so they know what they're looking at/for

What are ultrasounds helpful for?

-appendicitis -guiding catheter placement for thoracentesis/paracentesis -liver biopsies

What does the appearance of the x ray depend on?

-atomic number of body being x rayed

AP positioning

-beam passes through pt from front to back aka *anterior to posterior* -heart and mediastinum magnified and borders less clear

angulation

-beam should be angled properly -pt may not be able to stay/sit, need to work around it

Value of getting 2 radiographic views

-can see one view where everything looks fine, but look at another view at 90 degree angle = very different outcome EX elbow EX could see a lesion on lungs and looks like its in one area but second will show exactly where it is

radiographs have limitations

-cant and won't show you everything

What does nuclear medicine assist in diagnosing?

-cardiac -respiratory -Circulatory problems -malignancies -infections -thyroid function

Common uses for conventional radiography

-chest x-ray -plain film of abdomen -extremity x-ray

lag time

-clinical symptoms can show before radiograph EX pulmonary edema will show symptoms before x ray shows anything

myelography

-contrast studies of spinal sac and verve roots

Diagnostic radiology

-conventional radiology aka *plain films*

Body closer to film =

-decreased magnification -More true to actual size EX want the heart to be less magnified on film = move person closer to film

Divisions within radiology

-diagnostics plain films and fluoroscopy -mammography -ultrasound -computed tomography -magnetic resonance imaging -nuclear medicine -interventional radiology

radiation exposure

-don't expose pt to unnecessary radiation, but don't hesitate if it'll help

Principles of x-rays

-electrons drawn from cathode in electric field and x ray emitted

what is MR arthrography helpful for?

-evaluate unstable or post operative joints

What does radiographic do for healthcare providers?

-gives detailed info about medical conditions -minimally invasive

Lateral decubitus positioning

-good to see *fluid levels* -pt lies on side, PA position on side -named by side thats face down -beam is *horizontal*

Disadvantages of fluoroscopy

-higher x ray doses than plain -potential contrast allergy -decreased resolution -no cross sectional imaging

Advantages of MRI

-images without radiation -great for soft tissues (muscles, tendons, etc) -images in all planes -no iodinated contrast

Previous exams

-important from comparison -can see if what you're seeing now was visible at last exam

advantages of conventional radiology

-inexpensive -easily obtainable -good for chest and bones -low radiation -non invasive

disadvantages of nuclear medicine

-intermediate to high dose radiation -$$$$ -poor anatomical detail

genitourinary studies

-intravenous pyelogram -cystogram -urethrogram -voiding cystouretherogram

Fluoroscopy

-ionizing radiation, real time images -allows for evaluation of motion of body parts -images on video screen and captured as static or videos

disadvantages of conventional radiology

-limited range of densities -uses ionizing radiation -2D only

interventional radiology

-minimally invasive = field is always growing -usually, contrast dye = visualize vascular anatomy

Barium studies

-modified barium swallow -barium swallow -upper GI -small bowel follow through -enterolysis -defogram -barium enema

Oblique x-ray position

-named by relationship of pt to film EX left anterior oblique or right anterior oblique

Ultrasound

-narrow beam of high-energy sound waves = image/outline of structures

MR arthrography

-newer application of MRI -direct injection of gadolinium before MRI

What are ultrasounds useful for?

-obstetrics -evaluation of renal function -spleen -liver -aorta -gallbladder

Disadvantages of ultrasound?

-operator dependent -limited field of view -patient prep -body habitus -blind spots

Lateral x-ray position

-passing beam through side -Named by *side closest to film*

Position

-posture of pt at exam EX prone, supine, erect, etc

mammography

-radiographs of breast tissue to check for breast masses or other lesions -can also use ultrasound for abnormal physical exams

advantages of nuclear medicine

-readily available -minimally invasive -functional/molecular imaging (looks at the physiology) -good for looking at cancer -> cancer shows lots of metabolic activity which is what nuclear medicine looks for

advantages of computed tomography

-readily available -quick, painless -only portion of body surrounded -images not degraded by bowel gas or obesity -multiple planes -more info/better resolution

Advantages of fluoroscopy

-relatively inexpensive -readily available -real time images -table and X-ray tube moveable -good for operations -good for interventions

Magnetic resonance imaging (MRI)

-scanner with large magnet -radio wave antenna sendings signals to body -> receives signals back -returning signals converted -> pictures but computer = 2D and 3D images that show tissue and vascular anatomy

Radiation

-some risk for cumulative exposure, but benefit is greater than the risk (*pregnancy is the exception*) -doses from x-ray is less than we get from environment

Lordotic position

-standing AP where pt arches back to elevate clavicles -good to get clavicles out of view, see lung apices EX Tb

Uses for interventional radiology

-therapeutic procedures to treat stenosed vessels under fluoroscopic, ultrasonic, MRI or CT guidance -ultrasound for placement of peripheral catheters -inferior vena cava filter -ultrasound guidance to drain fluid in pleural space and abdomen -ultrasound or CT guidance for biopsies

What besides diagnostic radiography, is radiation used for?

-therapeutic purposes for cancer treatments

Nuclear medicine

-use radioisotope =emission of gamma rays and recorded by camera

Computed tomography (CT)

-utilizes x-rays & *cross sectional images = detail 2D pictures that can be made into 3D pictures* -beam passed around body at different angles = cross section using filtered back projection algorithm

Interface

-where two densities meet EX Arm >fat and muscle appear different from bone

Bone X-ray

-white

When is it appropriate to order an x-ray?

1. You know what it will show you before ordering 2. Dx can't be made solely from hx and physical 3. medico-legal reasons (25-35% of reasons) 4. If you suspect abuse in children 5. Longer you practice = increased experience = increased knowledge

When did Wilhelm Roentgen discover x-rays?

1895

Difference in absorption of electromagnetic waves...

= variation in exposure of x ray film = allows detail of image to be formed where densities meet

What can x rays NOT penetrate?

Heavy metals

What is the standard position for a chest x-ray?

PA

Lead

Used for protection during x-ray since can't pass through

thoracentestis

drain fluid from pleural space

What is the most accurate way to evaluate breasts abnormalities?

mammography

paracentesis

surgical puncture to remove fluid from the abdomen

Magnification

the ratio of an object's image size to its real size

X-rays

waves of electromagnetic radiation that penetrate structures within the body = images of structures on photographic film