Ultrasound

Question 1

Curvilinear

Answer 1

OB patients, Deep, Low Frequency

Ultrasound is curved at top

Question 2

Phase Array

Answer 2

Vascular/IV entry/Thyroid, Shallow, High Frequency

Ultrasound is pointed at top

Question 3

Linear

Answer 3

Heart, Deep, Low Frequency
Anechoic regions have high resolution
(ultrasound is flat at top)

Question 4

Definition of Medical Imaging and Radiology

Answer 4

Medical Imaging - technique and process of creating visual representations of the interior of a body for clinical analysis + medical interpretation
Radiology - science that uses Medical Imaging to diagnose and treat diseases within the body

Question 5

Radiography (how it works, pros/cons)

Answer 5

1. ionizing radiation - particle/electromagnetic wave has Energy necessary to remove electron from atom
2. electron emitted from cathode, interacts with metal, X-rays generated and sent to object being imaged
3. Pros: Widely available, good screening tool, low cost, fast
4. Cons: Ionizing Radiation (still low dose), 2-D - overlapping structures, limited level of tissue detail

Question 6

Computed Tomography (how it works, pros/cons)

Answer 6

TECHNICALLY STILL A TYPE OF RADIOGRAPH

1. 3-D radiograph, rotate source and detector around patient
2. 3 imaging planes (coronal, sagittal, axial)
3. allows for adjustments of gray level/contrast in same data set - windows allow you to investigate different structures
4. Pros: high tissue resolution, very fast, available, can reconstruct infinite planes
5. Cons: ionizing radiation, uses iodinated contrast - may cause renal failure

Question 7

Ultrasound (how it works, pros/cons)

Answer 7

1. transducer transmits high freq sound waves to body and echoing waves generate image
2. Measure echo waves for distance, size, shape and consistency
3. Pros: noninvasive, no ionizing radiation (good for Ob/kids), evaluate blood flow real time, portable
4. Cons: too dependent on skills of sonographer, can not penetrate air/bone (sound waves reflected)
   Heart Ultrasound = Echocardiogram

Question 8

Anechoic v. Hypoechoic v. Hyperechoic

Answer 8

Anechoic - No reflected sound waves, looks black (air and fluid)
Hypoechoic - Less reflected sound waves, looks darker gray (soft tissue)
Hyperechoic - More reflected sound waves, looks whiter (bone/fat)
FAT is WHITEST (All reflected)

Question 9

Magnetic Resonance Imaging (how it works, pros/cons)

Answer 9

1. Magnetic fields and radiofrequency pulses used to change rotation of H-atoms in body’s water: pulse of energy disturbs spin angle - measure how they realign (Hyperintense v. Hypointense)
2. Pros: No ionizing radiation, exquisite detail
3. Cons: Expensive, need to sedate claustrophobics, can’t work for pacemakers, longer scan time - more sensitive to patient motion
   MRA: Magnetic Resonance Angiogram

Question 10

Nuclear Medicine (how it works, types)

Answer 10

1. Physiologic imaging - many radioactive tracers and tests
2. Positive Emission Tomography (PET): fluorescently labelled glucose taken up by metabolically active cells - help detect tumors
3. Interventional Radiology - minimally invasive procedures - open blood vessels, stopping internal bleeding, restoring blood flow, biopsy

Question 11

List 5 X-ray Densities from Blackest to Whitest

Answer 11

1. Air
2. Fat
3. Soft-Tissue/Fluid
4. Mineral (Bone)
5. Metal

Question 12

What is ALARA, Radiation Dose, and Radiation Exposure vs. Background

Answer 12

1. ALARA: as low as reasonably achievable - weighing the risk of imaging with the potential diagnostic/therapeutic benefit
2. Radiation dose: energy of ionized radiation absorbed (Chest X-ray: low. Abdomen CT - 50-100x higher)
3. Chest X-ray: 2-3 days of cosmic background radiation
   Chest CT: 1 year of cosmic background radiation
   Reduce exposure by decreasing individual dose for CT exams