Chapter 20 - Radiology and Nuclear Medicine

radiology

medical specialty concerned with study of x-rays and other technologies (U/S and MRI) to produce and interpret images of human body for diagnosis of disease

x-rays

invisible waves of energy

nuclear medicine

use of radioactive substances to diagnose disease - radioactive specific to location

radiologist

physician specialized in diagnosing and treating patients using imaging equipment

nuclear physician

physician who specializes in testing and treating patients with radioactive materials

radiologic technologists

radiographers, nuclear medicine technologists, sonographers

x-ray positioning

posteroanterior (PA): posterior source to anterior detector

anteroposterior (AP): anterior source to posterior detector

lateral view: left lateral = source at right and detector to left

oblique view: source slanting at angle from perpendicular

position of patient

abduction: away from midline

adduction: toward midline

eversion: turn outward

extension: lengthen/straighten limb

flexion: bend

decubitus: lying on side (lateral)

prone: lying face down, on belly

recumbent: lying down

supine: lying face up, on back

CT - computed technology

diagnostic x-ray procedure that produces a cross sectional image of body segmentco

contrast studies

radiopaque materials injected to obtain contrast with surrounding tissue when on x-ray film - barium enema

gamma camera

machine to detect gamma rays emitted from radiopharmaceuticals

gamma rays

high-energy rays emitted by radioactive substances in tracer studies

half-life

time for radioactive substance to lose half its radioactivity by disintegration

interventional radiology

therapeutic/diagnostic procedures by radiologist

in vitro

process, test, procedure performed, measured or observed outside living organism

in vivo

process, test, procedure is performed, measured or observed within living organism

ionization

transformation of electrically neutral substances into electrically charged particles

MRI - magnetic resonance imaging

use of magnetic field and radio waves to produce sagittal, coronal and axial images of body

nuclear medicine

medical specialty studies use radioactive substances in diagnosis of disease

PET - positron emission tomography

use of positron-emitting radioactive substances given intravenously to create a cross-sectional image of cellular metabolism - CT or MRI

radioimmunoassay

test combines radioactive chemicals and antibodies to detect minute quantities of substances in patient’s blood

radioisotope

radioactive form of an element; radionuclide

radiolabeled compound

radiopharmaceutical; used in nuclear medicine studies - radioactive given to patient

radiology

medical specialty concerned with study of x-rays and their use in diagnosis of disease

radiolucent

permitting the passage of x-rays

radionuclide

radioactive form of an element; radioisotope

radiopaque

obstructing the passage of x-rays, appear white

radiopharmaceutical

radioactive drug used for diagnostic and therapeutic purposes

scan

image area, organ or tissue of body obtained from ultrasound, radioactive tracer studies, CT or MRI

scintigraphy

diagnostic nuclear medicine test using radiopharmaceuticals and gamma cameras to create images - heart, thyroid, liver

SPECT - single photon emission computed tomography

radioactive tracer is injected intravenously and computer reconstructs 3D-image based on composite of many views

tagging

attaching a radionuclide to chemical and following its path in the body

tracer studies

use of radionuclide tags attached to chemicals and followed as they travel through the body

U/S

diagnostic technique that projects and retrieves high-frequency sound waves as they echo off body parts

ultrasound transducer

handheld device that sends and receives ultrasound signals

uptake

rate of absorption of radionuclide into an organ or tissue

ventilation-perfusion studies

ventilation and perfusion of pharmaceutical followed by imaging its passgae through respiratory tract - for PE

fluor/o

luminous

is/o

same

pharmaceut/o

drug

radi/o

xrays

roentgen/o

xrays

son/o

sound

therapeut/o

treatment

vitr/o

glass

viv/o

life

-gram

record

-graphy

process of recording

-lucent

to shine

-opaque

obscure

cine-

movement

echo-

a repeated sound

ultra-

beyond

characteristics of xrays

expose photographic plates, penetrate substances, invisible, travel in straight lines, scatter when hit solid, ionization

digital radiography

use digital xray detectors not photographic film, superior gray-scale, reduced xray exposure, faster, lower equipment and film cost, increased efficiency, enhanced diagnostic image, effective patient education tool

CT- computed tomography

computer controls motion of xray source and detectors, process data and produce image

contrast studies

barium sulfate: upper and lower GI

iodine compoundsL angiography, arthrography, cholangiography, digital subtraction, angiography (DSA), hysterosalpingography, meylography, pyelography

fluoroscopy

imaging technique that gathers real-time moving images using a fluoroscopy of internal structures or patients

• multiple shots/pictures per second to show moving picture - like U/S

• has radiation

interventional radiology

minimally invasive procedure using medical imaging guidance - through a vessel

• stent, angioplasty, embolization, ablation, biopsy, drainage procedure, tumor treatments

  • pinhole surgery

ultrasound

sound waves, frequency greater than 20 kilohertz

• used to detect objects and measure distances

• used throughout body

• no ionizing radiation

  • pregnancy (radiation, increases leukemia risk in fetus)

MRI - magnetic imaging

strong magnetic fields, magnetic field gradients, radio waves to form images

• better for soft tissue structures like brain and abdomen

nuclear medicine

radionuclides/radioisotopes: alpha particles, beta particles, gamma rays

• nuclear medicine tests: in vitro - test tube, in vivo - in body

  • half-life: time required to lose half its radioactivity (disintegration) - length of time stay in body

in vitro procedures

analysis of blood and urine

• radioimmunoassay (RIA)- radioactive chemicals and Ab to detect hormones and drugs in patients blood (digitalis detection, hypothyroidism in newborn)

in test tube

in vivo procedures

radioactive substance given to patient to evaluate organ function/image

• radiopharmaceutical (labeled compound) concentrates in organ

• scintiscanner (gamma camera) detection instrument produces picture (scintiscan)

in body

procedure using radionuclides

bone scan (malignancies/stress fractures)

lymphoscintigraphy

PET scan

PET/CT scan

SPECT

cardiolite scan

TI scan

thyroid scan

radioactivity

nucleus unstable and will decay to more stable - radioactive decay (spontaneous)

• unstable nucleus decays gives out":

  • alpha particle (a)

  • beta particle (b)

    • gamma ray (g)

radionuclide (radioisotope)

substance gives off high-energy particles/rays as it disintegrates

half-life

time in which one half of atoms of radioactive isotope disintegrates into another nuclear form

• half-life varies billionths of a billionth of a second to billions of years

  • physical or radiological half-life

in vitro

in test tube

in vivo

in body

bone scan

nuclear scanning test identifies new areas of bone growth/breakdown

• evaluate bon damage, detect cancer that has metastasized to bones, monitor conditions that can affect (infection/trauma)

  • detect problem earlier than x-ray

PTBLK metastsasizes to bone

lymphoscintigraphy

nuclear medicine test, locate LN and identify spread of cancer, locate sentinel nodes for surgical removal

• diagnose lymph system diseases

PET scan

combined use of positron-emitting radionuclides and emission CT

• PET technology generates high-resolution images of body function and metabolism

  • PET scanning is useful diagnostic tool aiding diagnosis of many disease states - oncology, neurology, cardiology

PET-CT scan

combines PET and CT techniques to have more accurate image

• for surgical planning, radiation therapy and cancer staging

PET-MRI scan

MRI combines with PET scan

• MRI for soft tissue anatomy

• PET scan evaluates function imaging

  • oncology, cardiology, neurology

SPECT

single-photon emission tomography - IV injection of radioactive tracer

• computer reconstruction of 3D images with many views

  • liver tumors, cardiac ischemia, diseases of bone/spine

99M technetium sestamibi (cardiolite) scan

uses radioactive substance (tracer) produces images of heart muscle - with exercise test = determines areas with not enough blood

• diagnose coronary heart disease, with blockages of coronary arteries

sestamibi scan, myocardial perfusion scan, cardiac nuclear imaging

thallium scan

thallium 201 injected IV to evaluate heart perfusion (myocardial)

• high concentration in well-perfused heart muscle

  • infarcted or scarred myocardium = lack of thallium 201 uptake

thyroid scan

radioactive iodine (iodine-123) given oral

• thyroid scanned to determine size and shape of glands

• mass/nodule see if malignancy

radioactive technetium IV: hyper functioning thyroid nodules accumulate more radioactivity - hotspot

thyroid cancer doesn’t concentrate radioactivity and is cold spot

obstructing passage of x-rays

radiopaque

handheld device that sends and receives U/S signals

transducer

movement away from midline

abduction

patient lying on back

supine