Principles for Interpretation, Roentgen Signs, and Perception

Question 1

describe roentgen signs (6)

Answer 1

1. size
2. shape
3. number
4. opacity:
5. location
6. margin

SSNOLM

need all to describe a lesion!!

Question 2

describe image perception

Answer 2

based on 3 aspects

1. general: basic component in the formation of a concept
2. depth: visual ability to perceive the world in 3 dimensions
3. visual: ability to interpret information from visible light reaching the eyes

perception and interpretation is the ability to deduce an abnormality/disease from normal radiographic anatomy (or alterations of normal) and apply these pieces of information to context of a clinical patient

Question 3

describe principles of radiographic interpretation

Answer 3

just be consistent!!

can use a systematic approach, go inside out, or go outside in

identify any abnormalities, describe them using roentgen signs, then create a problem list!

use the cone of certainty to try to tie findings together; if can tie together, differential list will be smaller

Question 4

what are 5 pitfalls of interpretation?

Answer 4

1. obvious lesion giving satisfaction of search and stops the systematic approach: find a broken bone and miss a lung mass
2. decision making error: lack of knowledge about pathophysiology causes abnormalities to be inappropriately given equal weight
3. no lesion seen: may indicate lack of systemic approach
4. tunnel vision: searching only for what you are expecting, can cause you to read a lesion into a radiograph that is not present or failure to look beyond your pre-radiograph bias
5. recognition error: see a lesion but not recognize it as abnormal, or a lack of anatomical knowledge leads you to think a normal variant is actually abnormal

Question 5

how do you name a radiographic projection?

Answer 5

1. direction of x-ray: where it is entering and where it is exiting
2. area imaged

examples: mediolateral projection of the left antebrachium

plus! in axial skeleton we add the side of the recumbency to the name of lateral projections: left lateral projection of the thorax

remember! must have at least 2 projections at 90 degree angle to each other to form a 3D projection from the 2D images of a structure!

Question 6

describe the structure of a radiographic report (4)

Answer 6

1. description of lesion using roentgen signs
2. conclusion: based on your description of abnormal anatomy, what pathophysiology is present? use DAMNIT scheme
3. differential diagnoses: what diseases need to consider? prioritize! radiographs really help to narrow down differential list bc are often one of the first diagnostics run
4. next steps: make a plan based on what you now know

Question 7

give 4 strengths and 2 weaknesses of radiography

Answer 7

strengths:
1. rapid diagnostic
2. widely used
3. relatively inexpensive
4. screening test

weaknesses:
1. ionizing radiation
2. superimposition of structures