Lecture 3: Imaging Modalities: decisions Flashcards
What are radiographs good at looking at
Bones
Radiographs have limited ___detail but contrast can help with that
Soft tissue
What is the biggest con of radiographs
Superimposed structures
What are some disadvantages for plain film radiographs
Requires processor, money for chemicals, and can have artifacts from processing
How does computed radiography work
Have screen film place into reader and creates digital image
What are the advantages for digital radiology
Fast process, no film required, few artifacts
Identify which X-ray modalities were used and how do you know
Left: plain
Right: CR
Middle: DR- more crisp
Identify which X-ray modalities were used and how do you know
Left: plain
Middle: CR
Left: DR- better at seeing soft tissue
Which X-ray modality is best at seeing soft tissue: plain, CR or DR
DR
Ultrasound is great for looking at ___
Soft tissue
Ultrasound of eye- what wrong
Cataracts- front of eye appears thicker/ whiter on ultrasound
What is the difference between x-rays and gamma rays
- X-rays produced from electron shell- knock out other electrons to make energy
- Gamma rays from nucleus- decays and release energy
What is the most common gamma ray
99mTcO4
How does technetium metastable work in nuclear medicine
Decays to 99Tc which is then taken up by stomach, thyroid glands, salivary glands
Identify 1-4 and what does it tell you
- Salivary glands
- Thyroid glands
- Heart
- Stomach
1 thyroid gland is very bright because hyper functioning whereas other thyroid gland is suppressed
How can you use technetium/ nuclear medicine to evaluate portosystemic shunt
- Give technetium rectally
- Enters blood—> liver—> heart
- Normal should have bright spots in liver, if shunt will bypass over liver
How does a bone scan work
- Bind 99mTc with methylene diphosphate (MDP)
- MDP binds hydroxyapetite which is present during osteoblastic activity
What modality is this and what is wrong
Bone scintigraphy
Tumor on ribs- black spots indicate increased osteoblast activity
What type of imaging is CT
Cross-sectional imaging
How does a CT work
Uses x-ray tube with adjacent detectors that measure amount of attenuation of beam by patient and create 1 image
What is the hounsfield/ CT unit measurement of bone
300-3000
What is the hounsfield/ CT measurement for mineralized disc
100-300
What is the hounsfield/ CT measurement for acute hemorrhage
42-58
What is the hounsfield/ CT unit for gray matter in brain
35
