Radiology Dr. Chung 9/23

Question 1

Xrays

Answer 1

• ionizing radiation: Electromagnetic radiation (gamma rays or X rays) or particulate radiation (a- and b-particles, neutrons, etc.) which has sufficient energy to remove electrons from the atoms of material with which it interacts
• contrast radiography, fluoroscopy, CT/CAT

Question 2

Xrays

Answer 2

• ionizing radiation: Electromagnetic radiation (gamma rays or X rays) or particulate radiation (a- and b-particles, neutrons, etc.) which has sufficient energy to remove electrons from the atoms of material with which it interacts
• contrast radiography, fluoroscopy, CT/CAT

Question 3

Mammography

Answer 3

• low energy x-ray beam to maximize contrast

Question 4

CT scanner

Answer 4

• Enormous increase in density discrimination
• Cross-sectional anatomy: 3D image
• Functional information, e.g., infarcts
• Less invasive, e.g. CT for PE instead of angiography
• Very fine detail possible depending on slice thickness
• Rapid evaluation of critical patient

Question 5

CT scanner

Answer 5

• Enormous increase in density discrimination
• Cross-sectional anatomy: 3D image
• Functional information, e.g., infarcts
• Less invasive, e.g. CT for PE instead of angiography
• Very fine detail possible depending on slice thickness
• Rapid evaluation of critical patient

Question 6

Mammography

Answer 6

• low energy x-ray beam to maximize contrast

Question 7

sound waves

Answer 7

• Ultrasound uses sound for imaging
• Advantages - Safe, Noninvasive, Inexpensive (relatively), Visualizes motion
• Disadvantages: Highly dependent on skilled technologist, Will not penetrate bone or air, Many artifacts
• Air does not transmit sound well. Soft tissue and fluid are good at transmitting sound well. Bone does not transmit sound well
• Sound can’t penetrate dense things: bone, calcium, hair
• Can determine the velocity of blood flow with ultrasound – can see the narrowing of vessels based on the flow velocity
• Ultrasound Evaluation of Breast Mass

Question 8

CT scanner

Answer 8

• Enormous increase in density discrimination
• Cross-sectional anatomy: 3D image
• Functional information, e.g., infarcts
• Less invasive, e.g. CT for PE instead of angiography
• Very fine detail possible depending on slice thickness
• Rapid evaluation of critical patient

Question 9

Nuclear Medicine/gamma rays

Answer 9

• Evaluates function rather than structure
• Uses trace amounts of radioactive atoms attached to other molecules to form radiopharmaceuticals
• IMPORTANT FOR ONCOLOGY: tumor localizatoin, staging, evaluation for metastasis
• also for cardiac, GI, infectious dissease and brain trauma imaging

Question 10

PET scan

Answer 10

• Positron (antimatter!) Emission Tomography
• 18F-fluorodeoxyglucose (FDG) most common
• Primarily used for diagnosis, staging & monitoring of cancers: breast, cervical, colorectal, esophagus, head & neck, lung, lymphoma, melanoma
• FDG is a glucose analog that is uptaken by cancer and shows up on imaging

Question 11

sound waves

Answer 11

• Ultrasound uses sound for imaging
• Advantages - Safe, Noninvasive, Inexpensive (relatively), Visualizes motion
• Disadvantages: Highly dependent on skilled technologist, Will not penetrate bone or air, Many artifacts
• Air does not transmit sound well. Soft tissue and fluid are good at transmitting sound well. Bone does not transmit sound well
• Sound can’t penetrate dense things: bone, calcium, hair

Question 12

Magnetic fields / radio frequency waves

Answer 12

• Production of images using signal information from protons No ionizing radiation
• Uses strong magnetic field
• MRI scanner:
  Can be done in any sort of plane that we want
  Ultrasound not good for imaging through bone – Cat scans and radiographs cannot pass through electron dense materials – MRI can image areas right next to bones, because don’t have the electron density problem.
• unparalleled for neuro, brain and spine
• Advantages over CT and plain films
  Multi-planar ability compared to radiography
  Insensitive to obscuration by bone
  Better soft tissue contrast
• Disadvantages
  Low signal areas (relatively few spinning protons) difficult to distinguish from each other – lungs don’t have high number of spinning protons, hard to get signal from lungs
  Claustrophobia- sticking patients in a coffin like thing
  Some medical devices contraindications to scan
  Artifact prone
  Patient monitoring difficult

Question 13

contraindications to MRI

Answer 13

Pacemakers whether active or not
Epidural pacers
Cochlear implants
Orbital metallic fragments (skull films)
Ferromagnetic cerebral aneurysm clips

Question 14

Dobhoff Tube

Answer 14

feeding tube

- preferentially want it in the small valve in duodenum, don’t want it in stomach because can lead to esophageal reflux

Question 15

NG (Nasal Gastral Tube)

Answer 15

want both ports in stomach]- this is not for feeding, it is for decompressing people, goes into stomach to get rid of gas

Question 16

ETT

Answer 16

Endo-trachial tube

• 5-7 cm above carina in adult
• long plastic tube placed in someones trachea to help them breathef

Question 17

PIC/IJ/SCV

Answer 17

central venous line

- want tip to be in Superior Vena Cava

Question 18

Particularly bad places to put lines

Answer 18

• venous catheters in arteries (clue: red pulsating blood)
• chest drains in liver, spleen or mediastinum - could lacerate the organ
• Dobhoff (feeding tube) in trachea/bronchi, pull it out then take an xray to make sure you haven’t damaged the area
• feeding tube in brain
• SCL in jugular bulb/brain
• ETT in esophagus rather than trachea

Question 19

Subdural hematoma

Answer 19

Subdural (venous)
Crescent shaped
Crosses sutures- longer
Acute, subacute, or chronic
Subdural (venous)
Crescent shaped
Crosses sutures- longer
Hyperdense-isodense-hypodense
Acute, subacute, or chronic
Can be subtle alongside skull-blood windows
Look for mass effect and ‘thick cortex’

Question 20

Epidural hematoma

Answer 20

Epidural (arterial)
Lens/football shaped
Limited by sutures, may be associated fracture
Medical emergency

Question 21

Tension Pneumothorax

Answer 21

• presents in Xrays as base of diaphragm being uneven
• A pneumothorax (pl. pneumothoraces) is an abnormal collection of air or gas in the pleural space that separates the lung from the chest wall and which may interfere with normal breathing.
• the amount of air in the chest increases markedly when a one-way valve is formed by an area of damaged tissue, leading to a tension pneumothorax. This condition is a medical emergency that can cause steadily worsening oxygen shortage and low blood pressure.
• Medical emergency
• Often but not necessarily total lung collapse
• Mediastinal shift
• Diaphragmatic depression
• Hypotension, pulsus paradoxus, hypoxia