Imaging Highlights

Imaging Techniques Used to visualize and examine internal body structures The three most common: 1.Radiography (x-ray) 2.Computed Tomography (CT) 3.Magnetic resonance imaging (MRI)

X-ray Many imaging techniques use x-ray which is invisible, odorless, and can’t be felt. Used to radiate cancer- yet overexposure can cause death. (See x-ray PP Google docs)

X-ray Image of hard-tissue. Internal structures created by the exposure of sensitized film to x-radiation. Resulting film known as an x-ray or radiograph Radiograph made up of shades of gray Radiopaque hard tissues, such as bone and tooth enamel, do not permit x-rays to pass through and appear white or light gray on radiograph Radiolucent air and soft tissues do permit x-rays to pass through, and appear as shades of gray to black on the radiograph

Positioning Describes the body placement and the part of the body closest to the film. Example: left lateral position, the left side of the body is placed nearest the film

positions.htmhttp:// positions.htm Hand out

PROJECTION Refers to the path the beam takes through part Anteroposterior projection (AP) Beam enters the front surface and exits the back surface of the part Posteroanterior projection (PA) Beam enters the back and exits the front of the part AP projection in supine position PA projection in prone position

Lateral Projections Normally the positioning terminology is used rather than projection –torso and head Right to left lateral projection Left to right lateral projection –extremities Mediolateral projection Lateromedial projection L lateral erect position R to L lateral projection

Oblique Projections Normally the positioning terminology is used –example RPO position = right anterior to right posterior projection (oblique AP)

Radiographpy vs Nuclear Medicine Radiography – source of radiation is external. Gamma rays pass through body and form radiograph Nuclear Medicine – source of radiation is radiopharmaceutical taken internally. X-rays pass out of body and form scan image.

Ionization Ability of x-rays to change substances thru which they pass Used to make radiographs and treat cancer May cause cell damage and even death

Nuclear Scan Radioactive isotope tagged to substance absorbed by specific tissue and injected into the blood Shows gross fx of organ Good for images of tumors or lesions

Common Scans Bone – fractures, tumors, inflammation, bone growth Brain – tumors, blood flow Liver – cirrhosis, hepatitis, tumors, cysts, abscesses Lung – blood clots, tumors Thyroid – function, tumors heart

Radioimmunoassay Mix blood with radioactive substance to determine specific blood protein concentrations Find antibodies and antigens (titers)

Radiation Therapy Treatment of CA with external radiation Stereotactic – focusing multiple beams at the same spot

Teletherapy vs Bradytherapy Bradytherapy – radiation source is internal Teletherapy – radiation source is external

Tomography Imaging method that produces tomes (cross sections) of body along any plane Shows structure Good for images of tumors- especially when contrast medium used

Mammography X-ray examination of the internal breast tissue Helps in diagnosing breast abnormalities

PET Scan Positron Emission Tomography Radioactive isotope is tagged to substance used by specific cells and injected into the blood Best way to show metabolism or specific functional areas, good for determining how well an organ is functioning, especially the brain and heart

CAT vs PET CAT – 2D tomes are reconstructed to show 3D images of structure PET – radiopharmecuticals are used to give 2D and 3D images of function

Magnetic Resonance Imaging Image produced when body is surrounded by powerful electromagnetic waves Best way to show structure in minute detail

Magnetic Resonance Imaging Gives good image of soft tissues Cannot use if metal is implanted in body Good for images of any type of structural damage

Sonogram sound waves bounced off organs produces image of deep structures Only imaging procedure safe for fetus Also used for thyroid, abdominal masses, inner heart structure, blood vessels

Contrast Medium Radio-opaque substance used to make hard-to-see structure show up on image Used in CAT scans and fluoroscopy

Radio-opaque vs Radiolucent Radio-opaque - Block x-rays Shows up as light color Radiolucent – Passes x-rays through Shows up as dark color

Fluoroscopy Visualization of moving structures as contrast medium moves through body Used with radio- opaque substances GI series, arteriograms

Cineradiography Filming images on fluroscope screen with a video camera

How to process an imaging request Check for allergies- if allergic to seafood the pt. might be allergic to iodine found in many radio- opaque dyes Age- below 12 may need extra help or sedation Weight- older MRI machines limited to max 300lb Pacemaker- may be damaged by exposure to MRI Metal items in body- artificial joints or internal fixation devices may contain metal that will heat up or be dislodged by the test

Image quality Target structures must be visualized Proper view must be shown Image must be clear ***The imager must make sure the image is of good quality before releasing the patient from the unit****

Unit Preparation Safety- equipment and safety monitors working properly Supplies- everything needed on hand

Commonly Visualized structures radiographic and fluoroscopic Chest x-ray (CXR)- heart lungs ribs Upper GI series- esophagus, stomach, small intestine Lower GI - colon

Patient Safety Check for previous imaging to prevent repeat exposure Give instructions and check for understanding Position correctly to prevent repeat Use gonadal shielding on children and patients of reproductive age Ask all women for LMP

Worker safety Reduce exposure time Stay as far from radiation source as possible and position body at right angle Use shielding appropriate for the test- lead apron, lead gloves Wear appropriate radiation detection device (dosimeter on front of body 1.Film badge- least accurate, good for 1 month 2.Thermoluminescent dosimeter- good for 3 months 3.Pocket ionizing chamber- most accurate

Workplace safety Geiger-Muller detector- detects quantity of radiation in the workplace Victoreen condenser R-meter- used to calibrate radiography equipment

Thermogram Media – infrared camera captures surface body heat Newer forms relate metabolic activity (function) to heat given off