Introduction To Radiology Flashcards
What is the loss of energy of X-rays as it passes through the body called
Attenuation
Radiopaque/radiodense
Materials that absorb X-rays creating a white image
Radioluscent
Less dense tissues allowing the X-ray to pass through causing for a black image
Advantages to plain films
Fast
Inexpensive
Can be obtained almost anywhere
Widely used
Disadvantages of plain films
Utilizes ionizing radiation
Soft tissue is hard to visualize
Not recommended for pregnant women except in an emergency
Fluoroscopy definition
Low dose radiography to measure body in real time, typically used with contrast, and helpful with roceedures
CT Scan units of measurement
Hounsfield units is the scale to measure CT density
CTT characteristics
Uses ionizing radiation, and constructs 3d image from 2d slices in different planes. Saggiatal, coronal, and transverse
CT advantages
Excellent resolution, can see the brain, multiple planes, cheaper and faster than mri
CT disadvantages
High radiation dose, can require contrast, a little more expensive, cant visualize structures inside joints as well as MRI
Typical closed MRI scanner magnetic field strength
0.5-3.0
Open MRI field strength
0.1-1.0
T1 weighted image characteristics
Water is dark and better anatomical detail
T2 image characteristics
Water is bright and better for pathological lesions
MRI advantages
No ionizing radiation, multiple planes to scan, better detail, good for neuro imaging and soft tissue(muscle, tendon, ligament)
MRI disadvantages
Cant be manipulated like CT, confined, noisy, movement disrupts, expensive, very long, and very expensive and dangerous around anything metal
Ultrasound caracteristics
Uses sound waves
Echogenic
Tissue that reflects many echoes and is bright or white
Sonoluscent
Few or no echoes and is depicted as dark or black
Ultrasound advantages
No radiation, real time images, inexpensive, portable
Ultrasound disadvantages
Bone and air filled structures interfere with image, fat patients struggle
Background radiation
Radiation we are exposed to every day
Average background does
2.4mSv/yr
Most sensitive tissue to radiation is the
Thyroid
Why should femurs be internally rotated when obtaining an Ap pelvis film
So the necks can be assessed for fractures
Shentons line
Medial edge of the femoral neck and the inferior edge of the superior pubic ramus
4 radio graphic features of a posterior hip location
- Femoral head lateral and superior to the acetabulum***
- Fracture of the posterior rim of the acetabulum may occur
- Femur in internal rotation and adduction***
- Affected femoral head may appear smaller
What should you evaluate when looking at an X-ray of a knee
Signs of osteoarthritis (joint space narrowing, osteophyte formatoin, subchondral cysts) AP view
Lateral view is good for evaluation of the patella/if joint effusion i present
In all positions the patella is in contact with the femur and the femur in contact with the tibia
Sesamoid bone in the head of the gastrocnemius is called
Fabella
ABC’s to x-ray reading
A=adequqacy/alignment (minimum 2 views)
B=Bones (cortical outline of all bones)
C=cartilage (evaluate joint spaces for narrowing)
S=soft tissue
