PAC555 Clinical Applications Quiz I

The major goals of clinical anatomy applications are to discuss the relationships between human anatomy and human __________ as well as to correlate anatomy with clinical __________

Disease; Diagnostic imaging

Diagnostic imaging can allow for evaluation of multiple __________ and can allow for simultaneous evaluation of neurological, vascular, and __________ etiologies of a complaint

Organ systems; Musculoskeletal

Preliminary abnormal findings on imaging at the point of care may help to __________ patients who need care most in communities with limited access to medical specialists

Triage

__________ accidentally discovered X-rays in his laboratory and was the first to use X-rays to visualize image of human __________. He was awarded a Novel prize in physics in 1901

Wilhem Roentgen (Germany, 1895); Bones

__________ developed prototype fluoroscope intended for use in the home. However, he abandoned his work with X-rays after his assistant, Clarence Dally, died of cancer related to radiation exposure in 1904

Thomas Edison (1896)

__________ discovered the radioactive compound radium chloride. She subsequently purified radium and discovered __________

Marie Curie (1989); Polonium

__________ is the only person to win a Nobel prize in two different scientific fields— Physics in 1903 and Chemistry in 1911

Marie Curie

Marie Curie died of __________ due to radiation exposure and is buried in a lead-lined grave due to radioactivity

Aplastic anemia

Radium was a prime form of medical misinformation in the mid 1900s and was used to promote male __________ health and was a __________ holder

Sexual; Cigarette

__________ was an Austrian psychiatrist and neurologist known for the first clinical use of ultrasound

Karl Dussik (1942)

Ultrasound does not pass through __________ and is therefore no longer used for brain imaging

Bone

__________ worked in EMI Laboratories in Britain and was noted to have developed the first CT scan. He was awarded a Nobel Prize in Medicine in 1979

Godfrey Hounsfield (1971)

What are the 3 fates of ionizing radiation in diagnostic imaging?

It can be transmitted, absorbed, or scattered

Transmitted Radiation…

Passes through the patient (creates image)

Absorbed Radiation…

Energy from x-rays is transferred to the patient’s tissues (exposes patient to radiation)

Scattered Radiation…

Changes its path away from the patient (exposes healthcare worker to radiation)

How do we measure radiation exposure?

Via absorbed doses, equivalent doses, and effect doses

An absorbed dose refers to energy deposited in __________ of tissue

1 kilogram

The SI unit of an absorbed dose is __________

The gray (Gy)

1 Gy = __________ rad

100 rad

Absorbed doses measure the __________ of energy, not the biological effect

Amount

Equivalent doses are an adjustment for biological effect caused by different types of __________

Radiation— not all forms of radiation do the same amount of damage even if the absorbed energy is the same

Alpha particles are approximately __________ times more damaging than X-rays, gamma rays, or electrons

20

Equivalent dose uses a __________ that corrects for the different biological effects of different types of radiation

Coefficient

The SI unit for equivalent dose is __________

Sievert (Sv)

1 Sv = __________ rem

100 rem

Effective doses are an adjustment for biological __________ caused by radiation in different tissues, depending upon the tissue exposed

Effects

Some tissues are more susceptible to the effects of __________ radiation than others

Ionizing

Radiation exposure to the bone marrow or endocrine tissue is much more biologically significant than radiation to the __________

Skin

Effective dose uses a __________ that corrects for the different biological effects of radiation on different tissues

Coefficient

The SI unit for effective dose is __________

Sievert (Sv)

Ionizing radiation can damage any cellular __________, either by directly disrupting bonds between atoms or by generating __________ which affect structure

Macromolecule; Free radicals

The most concerning biological effect of ionizing radiation is damage to __________, which may result in cancers or heritable mutations

DNA

What are the two groups of biological effects of ionizing radiation?

Deterministic effects + stochastic effects

Deterministic effects refers to direct __________ damage by radiation which exceeds physiological mechanisms for repair

Macromolecule

In deterministic effects, damage occurs when a threshold is met. __________ and __________ increase with increasing dose

Probability; Severity

Deterministic effects require a __________ dose (usually > .5 Gy). Most diagnostic procedures do not reach the threshold dose of these effects

High

Stochastic effects refer to probability increases with increasing __________ dose, but severity is independent of dose. These may occur at any level of exposure

Cumulative

Stochastic effects are usually due to DNA damage by __________

Free radicals

Many diagnostic procedures involving radiation exposure over the lifespan may result in adverse __________ effects of radiation

Stochastic

Doses as low as __________ mSv statistically increase risk of developing cancer

10 mSv

__________ refers to the principle of keeping radiation doses as low as reasonably achievable to avoid stochastic effects

ALARA

ALARA stands for…

As Low As Reasonably Achievable

What are the three ways to reduce external radiation exposure?

Keep distance, place something heavy in between (shielding), and shorten time while being close to radioactive materials

The simplest form of diagnostic imaging is __________

X-ray

X-ray requires two elements— what are they?

An x-Ray generator and a photosensitive surface that detects X-rays passing through the tissue

An X-ray generator emits radiation only when __________ and is not radioactive on its own

Energized

A photosensitive surface is either __________ or an electronic detector

Film

X-rays show 5 basic densities based upon the amount of radiation that is absorbed through the material- what are they?

Air, Fat, Fluid or soft tissue, Calcium, and Metal

On an x-ray, __________ appears black and absorbs the least x-rays on conventional radiographs

Air

On an x-ray, __________ is gray, somewhat darker than soft tissue

Fat

On an x-ray, __________ appears medium-gray

Fluid or soft tissue

__________ and __________ have the same density on conventional radiographs

Fluid (e.g. blood); Soft tissue (e.g. muscle)

On an x-ray, __________ is the most dense, naturally occurring material and absorbs the most x-rays. It appears light gray

Calcium

On an x-ray, __________ usually absorbs all x-rays and appears the whitest

Metal

What are the advantages of x-ray? (3)

-Relatively quick

-Inexpensive

-Semi-portable (can be done at bedside in hospital or with mobile imaging unit)

What are the disadvantages of x-ray? (5)

-Requires ionizing radiation

-Limited range of density (only 5)

-Reduces 3D structure to 2D image (usually need to obtain at least two images)

-Acquiring images usually requires a licensed X-ray tech or special license for the provider

-Is a snapshot in time— does not show change

__________ is essentially a “x-ray video”

Fluoroscopy

Fluoroscopy uses ionizing radiation to visualize events in the body in __________

Real-time

Fluoroscopy can be used to guide invasive procedures as the camera and table __________ freely to obtain the best projection

Move

Computed Tomography (CT) uses __________ to obtain serial images through various regions of the body

X-rays

In a CT, the x-ray source and detectors are mounted on a __________ that rotates around the patient

Gantry

What are the advantages of CT over conventional x-ray? (3)

-Can quickly obtain images through large volumes of body

-Processed via computer algorithms that allow for better differentiation between tissue densities

-Can be post-processed into 3D reconstructions to allow for better visualization

CTs can be considered as a __________— a 2D image depicted by the computer as a single pixel in an image matrix

Slice

CT “slices” have a discrete __________, so each pixel corresponds to a volume of space in the body, This volume of space is called a __________

Thickness; Voxel

In CT, each voxel is assigned a specific numerical value based on its density. This value is called the __________ unit

Hounsfield unit

Structures that are more dense have a higher __________ and will have more positive Hounsfield units

Attenuation

Structures which are less dense have a lower __________ and will have more negative Hounsfield units

Attenuation

Like conventional X-ray, __________ structures appear white and __________ structures appear black

More dense; Less dense

What are the 6 densities measured in CT and what are their Hounsfield numbers?

What is Window Level (WL)?

Hounsfield unit value in the center of the window width

What is Window Width (WW)?

Range of Hounsfield units displayed

CT images are obtained in one or more of 3 imaging planes. What are they and what do they divide?

Axial: Divides the body into upper and lower sections

Sagittal: Divides the body into right and left sections

Coronal: Divide the body into anterior and posterior sections

What are the advantages of CT? (4)

-Expanded gray scale allows for greater ability to differentiate between various tissue densities

-Widely available

-Rapid

-Ability to created 3D image reconstruction

What are the disadvantages of CT? (3)

-Utilizes ionizing radiation at a higher dose than conventional x-ray

-Equipment and staffing is expensive

-More complex to interpret

Ultrasound probes (or transducers) contain a __________ that converts electrical signals into sound waves, and vise-versa

Piezoelectric crystal

__________ allows a single transducer to both transmit sound waves into a tissue and receive the sound waves that reflected back

Piezoelectric crystal

True or False: The ultrasound transducer can transmit and listen at the same time

False- it cannot

Ultrasound waves are sent in __________, followed by a pause to “listen” to returning sound waves as they are reflected off tissue surfaces

Pulses

The sound waves transmitted into tissue are described by their…

Wavelength, frequency, and amplitude

In ultrasound, c = __________

c= speed of sound (a constant for a specific tissue)

In ultrasound, λ = __________

wavelength of the transmitted wave

In ultrasound, f = __________

Frequency of the transmitted wave

High frequencies (low wavelengths) provide __________ resolution, but at the expense of being able to see deeper structures

High

Low frequencies allow imaging of __________ structures and obese patients, but at the expense of resolution

Deep

__________ is a property of the ultrasound transducer that cannot be easily adjusted with ultrasound machine controls

Frequency

The appearances of an ultrasound image depends on the type of __________ used

Transducer

__________ transducers are used for vascular and musculoskeletal applications and produce a rectangular image

Linear

__________ transducers (used for abdominal imaging) and __________ transducers (used for cardiac imaging) produce a cone-shaped image known as sector format

Curvilinear; Phased array

In a sector format image, the narrow part of the cone-shaped image is __________ to the ultrasound probe

Closest

The portion of the image nearest the ultrasound probe is called the __________

Near field

The portion of the image furthest from the ultrasound probe is called the __________

Far field

Areas between the near field and far field are called the __________

Mid field

Anechoic:

Completely black, often a fluid-filled structure (vessel or cyst). Occurs due to no echo

Hypoechoic:

Darker than surrounding tissues

Isoechoic:

Same color/appearance as surrounding tissues

Hyperechoic:

Brighter than surrounding tissues

What are the advantages of ultrasound? (5)

-Portable

-Allows visualization of physiology in real time

-Extremely safe (no ionizing radiation)

-Safe for children + pregnant patients

-Can be used for procedure guidance

What are the disadvantages of ultrasound? (3)

-Cannot penetrate bones or air

-Image quality is suboptimal in obese patients

-Image acquisition requires training and practice

__________ makes use of the magnetic properties of hydrogen atoms to generate images

Magnetic Resonance Imaging (MRI)