Set Questions With Verified Answers
\.Window vs. Reconstruction on CT? - Answer- Reconstructions - processing of the raw CT
data allows for better resolution of the structures [higher resolution and higher contrast]
Reconstruction can be done in 3D (ortho) or in a linear way too (vascular)
\.What is the total range of hounsfield units availabe? - Answer- -1000 (air) to +1000 (metal)
[so range is 2000]
\.What does a typical computer display show for greyscale range? What can the human eye
actually distinguish? - Answer- 256shades (that means each shade of grey covers ~8HU)
The can only distinguish 17 shades of grey
\.What is a good way to check diaphragm flattening? - Answer- Look at the lateral film
Diaphragm will be flat like you can set a ruler down on the edge
\.What can a poor inspiration/hypoinflation appear like? - Answer- consolidation or PNA
\.How to look at the lung fields? - Answer- Sweep or a zig zag down the lung field (both in PA
and lateral views)
look for focal, diffuse, BL asymmetrical, interstital/vasc markings, lucencies (cavity/bullae/PTX),
,compare upper and lower and L/R zones
Middle
lower zones
\.Which hilum should always appear higher on the radiograph? - Answer- The LEFT sided
hilum should be higher - if its not its pathological
\.What to look for with the heart? - Answer- Size of the heart - the cadiac:thoracic cavity ratio
LA
LV
\.What mediastinal lines should be observed on PA film? - Answer- R paratracheal line
Azygous area
Azygoesophageal line
Paraaortic line (all the way down)
If you can see these you need to figure out the reason why
\.How to look at the bones on Xray? - Answer- Quadrant method [above and below the ribs]
(the middle lung section you just
also go down the spine looking for abnormalities, mets, or collapse
\.When should you START looking at OLD films? - Answer- AFTER you have COMPLETELY
evaluated the new scan
,\.What are the ACR appropriateness criteria? - Answer- The aim is to provide continuously
updated evidence-based algorithms that ensure the safest, most cost-effective, and most
efficient path to radiological diagnosis or intervention matched to specific variants of clinical
presentations.
Federal LAW requires referring physicians to consult Appropriate Use Criteria (AUC), such as ACR
Appropriateness Criteria, prior to ordering advanced imaging services (ADIS), including CT, MR,
nuclear medicine, and PET, for Medicare patients.
\.How are appropriateness criteria divided/staged? - Answer- Older appropriateness rating
tables used a numerical rating scale: • Usually Appropriate = 9, 8, or 7 • May be Appropriate = 6,
5, or 4 • Usually Not Appropriate = 3, 2, or 1
Newer appropriateness rating tables simply use the three categories: • Usually Appropriate
(Green cells in the table) • May be Appropriate (Yellow cells in the table) • Usually Not
Appropriate (Red cells in the table)
\.What lobe of lung is seen at the apicies? - Answer- The R and L upper lobes
\.What is the silhouette sign? - Answer- The visual interface between structures of different
density.
Its actually when a silhouette is LOST that we say its a "silhouette sign"
\.What is spine sign? - Answer- When the combined density of the vertebrae and some
source of fluid/consolidation make the vertebrae look MORE dense [just like ice over water
accentuates the ice appearing like they have increased density even though they still the same
ice]
, \.What are cases in which spine sign occur? - Answer- Spine sign - vertebral bodies should be
relative lucent (black) above the diaphragm on lateral projection.
-Lateral x-ray goes through spine + pneumonia and vertebra will appear whiter (fewer x-rays
reach detector since some are absorbed in the pneumonia)
- Helpful sign for detection of lower lobe pneumonia. - - Very useful for detecting LLL
pneumonia behind the heart.
- If vertebral bodies appear more dense (whiter) above the level of diaphragm, and part of one
of the diaphragms is obscured → spine sign → sign of lower lobe pneumonia
- There are other causes for the spine to appear whiter (such as a blastic bone metastasis).
\.What is the lingula aligned with? - Answer- The left heart border (this is more visible in the
lateral view xray)
\.What are air bronchograms? - Answer- Air-filled bronchi within an area of consolidation.
These are frequently seen in pneumonia, but can also be seen in some tumors and other lung
abnormalities
More common in alveolar disease
Air bronchogram ≠ pneumonia
Can be seen in lung cancer (adenocarcinoma with bronchioloalveolar pattern)
Can be seen in lymphoma of the lung
Seen in:
A. Pneumonia
C. Pulmonary edema
D. Pulmonary hemorrhage