Xray and CT

What type of resolution is improved with thicker slices and larger pixels?

contrast resolution

What type of resolution is improved with thinner slices and small pixels?

spatial resolution

What are the 4 anatomical structures and their associated shade of gray seen on an x-ray?

1. Air- Black 2. Fat- Gray-Black 3. Water- Gray (all soft tissues and fluids such as in nerves, blood, muscle, cartilage, tendons and ligaments) 4. Bone- White *contrast media (barium sulfate) can show up as a bright white outline *heavy metals can show up as solid white

What are the six basic categories of pathology in the classification of skeletal diseases?

1. Congenital 2. Inflammatory 3. Neoplastic 4. Metabolic 5. Traumatic 6. Vascular 7. Miscellaneous (osteoarthritis) *Ch 2 page 50

What are the radiographic characteristics of osteoporosis?

1. Cortical Thinning: ~ the periarticular regions where the cortex is will be thinner ~ cortical thickness is measured here 2. Low Bone Mass: ~ these increase bone radiolucency ~ rarefaction describes periarticular, localized areas of decreased density 3. Trabecular Changes: ~ trabeculae are thinned, sparsed out, and delicate, as there are little left (the remaining few may pop out on a radiograph) 4. Fractures: ~ most common sites are vertebral bodies, ribs, proximal humerus, distal radius, and proximal femur

What are the 3 major classifications of diagnostic radiographic imaging (which are based on the type of image receptor used to capture the x-ray image)?

1. Film/screen radiography 2. Fluoroscopic imaging 3. Digital imaging

What are the radiographic characteristics of osteoarthritis?

1. Joint Space Narrowing ~ loss of normal elastic resilience ~ loss of support for collagen fibrils, rendering them susceptible to friction ~ acceleration to shedding cartilaginous surface layers 2. Subchondral Sclerosis ~ Eburnation describes the polished ivory appearance of the exposed subchondral bone ~ areas of more stress, the subchondral bone hypertrophies and becomes more radiographically dense (sclerotic) ~ rarefaction can be present in areas of minimal stress 3. Osteophyte Formation: ~ may notice bone spurs, osteophyte formations, osteoarthritic lipping, or osteophytosis 4. Cysts or Pseudocysts ~ microfractures ~ synovial fluid into the altered spongy bone forms cyst-like lesions, evident as radiolucent areas 5. Soft tissue swelling ~ from fragments of dead cartilage can irritate the synovial membrane and cause inflammation and synovial effusion ~ joint deformities & misalignment can result from contractures or from altered joint surface congruity

What are the radiographic characteristics of the adult rheumatoid arthritis?

1. Soft Tissue changes: ~ early signs include fusiform periarticular swelling of small joints (can occur in larger joints too) 2. Articular Erosions: ~ subchondral one exhibits localized areas of resorption (shown thru radiolucent defects). Can develop into into synovial cysts or pseudocysts, formed by intrusion of synovial fluid into periarticular bone. 3. Osteoporosis: ~ local areas of decreased bone density (rarefaction) seen at periarticular regions due to increased blood flow to the synovium 4. Joint Space Narrowing 5. Joint Deformities: ~ joint subluxations, dislocations, maybe contractures 6. Potential Changes in the Cervical Spine

Radiographic diagnosis of skeletal pathology include three major factors, what are they?

1. category of the pathology 2. distribution of the lesion 3. predictor variables that characterize disease features *Ch 2 page 50

What are the four factors that determine the quality of a radiograph? provide a brief description of each

1. density = current that passes thru the structures' 2. contrast = regarding the different shades of gray 3. detail = accuracy of the structural lines recorded on the radiograph 4. distortion = related to the thickness of the structures *density & contrast are more photographic properties, while detail and distortion are more geometric properties

Describe the basics of an x-ray imaging system (also what do you need to produce an x-ray?)

1. generation of x-rays in a tube 2. beaming the x-rays to the patient 3. capturing the x-rays from the remnant beam exiting the patient 4. converting them into something measurable that yields a latent image at a receptor 5. converting the latent image into a visible image ~ source of electrons ~ a force to move these electrons rapidly in a desired direction ~ something to stop these electrons rapidly

Infections of the MSK system include three categories, name and describe?

1. osteomyelitis = Radiographic characteristics include soft tissue swelling, radiolucent lytic lesion, sequestra (isolated segments of dead bone usually surrounded by pus) & involucra (an envelope of immature periosteal bone that also becomes infected), and draining sinus tracts 2. Infectious or septic arthritis = Radiographic characteristics include soft tissue swelling, joint effusion, periarticular rarefaction, joint space narrowing, subchondral bone erosion 3. Cellulitis = Radiographic characteristics include soft tissue swelling, radiolucent streaks or bubbles representing gas gangrene.

radiologist vs radiographer

1. radiologist = physicians specializing in radiology 2. radiographer = Professional technicians who produce the images

radiology

A branch of medicine concerned with the use of radiant energy (as X-rays or ultrasound) in the diagnosis and treatment of disease.

What does "B" stand for in the radiographic search pattern? A. Bone density B. Bone thickness C. Bone alignment D. Bone volume

A. Bone density

What do the ABCs stand for?

Alignment Bone density Cartilage spaces soft tissues

Radiograph

An x-ray film containing an image of part of a patient's anatomy. Requires an x-ray beam source, a patient, and an x-ray film or image receptor

Who discoverd X-rays and was awarded the Nobel Prize in Physics in 1901? A. Marie Curie B. Ernest Lawrence C. Wilhelm Conrad Röntgen D. Alan Cormack

C. Wilhelm Conrad Röntgen

What is the imaging modality of choice in the acute setting with trauma?

CT scan

How is CT imaging different than X-ray?

CT scan: ~ more advanced technology ~ more expensive ~ next step if suspected injuries are not seen on an x-ray, uses multiple x-ray images ~ takes axial images of the body, created by up to x1000 projections from different angles ~ provides a 3D ~ gives a detailed view (shows different layers of the bone - also to check for tumors) ~ more exposure to radiation

Which of the following is NOT a factor in radiographic image interpretation? A. Foundations in imaging technology B. Dimensional perception and knowledge of anatomy C. Characteristic patterns of pathology D. Non-organized search pattern

D. Non-organized search pattern

density (radiograph)

Density is defined as the amount of blackening on the radiograph and does this by varying the current (milliamperage & exposure time).

detail (radiograph)

Detail is the geometric sharpness or accuracy of the structural lines recorded on the radiograph. Usually because of motion artifact.

distortion (radiograph)

Difference between actual object and the recorded object. Usually either size or shape distortion. The closer to the image receptor (& closest to the central ray) the less distortion.

radiation

Energy that is radiated or transmitted in the form of rays or waves or particles.

Radiopaque contrast is called negative contrast (T/F)?

False

The thicker and object is the less radiodensity it possess relative to thinner objects of the same substance (T/F)?

False

Xrays are electromagnetic radiation on a wavelength greater than visible light (T/F)?

False

Bone density

General Bone Density: ~ soft tissue vs. bone (cortical vs. cancellous), Textural Abnormalities: ~ normal trabecular architecture Long Bone Density Changes: ~ Sclerosis at areas of increased stress such as weight-bearing surfaces or site of ligamentous, muscular, or tendon attachment

Alignment

General Skeletal Architecture: ~ size, appearance, number of bones (even absence thereof), & developmental/congenital deformities General Contour of Bone: ~ normal/abnormal cortical outline, irregularity, bony outgrowth, past surgical sites Alignment of Bones to adjacent Bones: ~ normal joint articulation & spatial relationship, factures, dislocations, subluxations

Who invented the CT (computer tomography) scan?

Godfrey Hounsfield in 1972

Cartilage spaces

Joint Space Width: ~ well preserved joint spaces imply normal cartilage or disk thickness? Subchondral Bone: ~ smooth surface? Epiphyseal plates ~ normal size relative to epiphysis and skeletal age?

soft tissues

Muscle: ~ Look for wasting, swelling, edema, hemorrhage, or tumor Fat Pads & Fat Lines: ~ displacement is usually due to swelling Joint Capsule: ~ distended due to swelling or effusion Periosteum: ~ normally rather indistinct, can have periosteal reaction Miscellaneous: ~ gas ~ calcification ~ foreign bodies

contrast (radiograph)

Radiographic contrast is the difference among various adjacent radiographic densities. Greater variation = high contrast, and Less variation = low contrast.

Radiolucent

Substances that are easily penetrated by x-rays, therefore have less radiodensity. Appear black on a radiograph. Examples include air and fat.

Radiopaque

Substances that are not easily penetrated by x-rays, therefore has a greater radiodensity. Appear white/light on a radiograph. Examples include bone-borders, spine processes, bone tubercles & tuberosities

ALARA stands for as low as reasonably achievable (T/F)?

True

High radiation exposure is the major disadvantage of CT scans (T/F)?

True

One of the major advantages of radiography is the excellent definition of Bone (T/F)?

True

Radiolucent means easily penetrated by x-ray and therefore is less radiodense (T/F)?

True

The image quality factors of radiographs of density and contrast are photographic properties (T/F)?

True

Thicker slices in CT improves the contrast resolution of the image (T/F)?

True

Describe Wolf's Law and how it applies to bone remodeling?

Wolf's law states that bone in a healthy person or animal will adapt to the loads under which it is placed. This is directly related to function. Bone is also deposited in sites subjected to stress and reabsorbed in sites deprived of stress.

What is meant by "one view is NO view"?

at least 2 images, as close to 90 degrees of each other as possible, are required to view all 3 dimensions of a structure. Hence, there are multiple ways to view a structure to gain useful info about said structure

What tissue is best represented in a CT scan?

osseous and soft tissues

The thicker an object is, the more __________________ it possesses relative to a thinner object made of the same substance.

radiodensity

radiodensity

the combination of physical qualities of an object that determine how much radiation it absorbs from the x-ray beam

How does the shade of gray in an x-ray, looking at anatomical structures, come about?

thru the molecular interactions of x-rays with body tissues, the radiodensity of said tissue, and NOT by the image receptor used (the equipment that converts the x-ray into a visible image)

What are the three characteristics the CT scans high-lite in the human body?

~ bony alignment ~ fractures ~ loose bodies in a joint *I dont know wh

How is CT imaging the same as X-ray?

~ both are a type of imaging scan. ~ you can have both x-rays and CT scans completed within minutes. ~ can be used to help with the diagnosis of one or more medical conditions. ~ you need to remain still for all three tests according to the instructions given by the technologist.

Radiodensity depends on the _______________ and ______________ of the tissue/structure.

~ composition (atomic number & vol. density) ~ thickness

The ______________ ______________ is generally the first diagnostic study to be done following the clinical examination. ________________ ________________ are the most efficient means to demonstrate bone and joint abnormalities.

~ conventional radiograph ~ conventional radiographs

What are the advantages of CT?

~ detailed depiction of normal anatomy & pathological process in cross-section ~ less time consuming than an MRI or US ~ allows accurate measurements of osseous alignment in any plane ~ less expensive than an MRI ~ less problematic & claustrophobia compared to an MRI

What are the disadvantages of CT?

~ high radiation exposure relative to most conventional radiographs ~ less soft tissue contrast compared to an MRI ~ diagnostic US can have static vs dynamic exams, CT scans don't have this

What are the two categories of bone tumors?

~ nonaggressive ~ aggressive