4 Image Quality

Question 1

level of detail that can be seen on an image

Answer 1

Spatial Resolution

Question 2

How small an object can e seen on a PARTICULAR IMAGING SYSTEM

Answer 2

Limiting Spatial Ressolution

Question 3

two (in xray) and three (in ct and mri) dimaenions of a single image

Answer 3

spatial dimesion

Question 4

Most asic measure of he esolution properties of an imaging system. Response of the imageing ssystem to the input to theimaging system (point source).

Answer 4

Point Spread function or Impule Response Function

Question 5

imaging system with the same PSF (Point Spread Function) at all locations in the field of view

Answer 5

Stationary or Shift Invariant Imaging System

versus PSF that vary depending on the position
Nonstationary

Question 6

FN = 1/2 triangle
Sets the upep bound on the spatial frequecyy that can be detected for a digital detector system with detector pitch (triangle).

Answer 6

Nyquist Frequency

Question 7

occurs when frequencies higher than the Nyquist frequency are imaged p 73

Answer 7

Aliasing

Question 8

Ability to detect very subtle changes in gray scale and distinguih them from the noise in the image.
Characterized by the measuements that pertain to the signal-to-noise ratio in in image

Answer 8

Contras Resolution

Question 9

source of image noise
silver grains
77

Answer 9

Grain noise

Question 10

source of image noise
happens when electrons associated with noise are added into the signal prior to amplification circuits, thn their noise contibuion will be amplified as well p 78

Answer 10

Electrical noise

Question 11

Source of image noise

whn gopus of dtector elements that are read out may have different offset noise and gain characteristics

Answer 11

Structure noise

Question 12

——- image is mesures with no radiation incident on the detector.
These two calibration images then can be used to correct for structured noise using the so called ——–

Answer 12

offset image

field correction algorithm

Question 13

source of image noise

generated by patent anatomy

Answer 13

Anatomical noise

Question 14

solution to anatomical noise

1. acquires before and afer the injection of fascular contrast agents
2. subtracting ribs in the xray

Answer 14

1. digital subtraction angiography

2. dual-energy subtraction techniques

Question 15

conceptual visual method for combining the concepts of spatial resolution and contrast resolution

Answer 15

CD diagram

Question 16

—– of an imaging system is a characterization of an xray imaging system used by imaging scientists, which describes overall frequency-dependent SNR performance of the system.
It is the ratio of SNR squared output from the systems to the SNR squared of the signal input into the system

Answer 16

Detective Quantum Efficiency

Question 17

fundamental contrast that arises from the signal AFTER it has interacted with the patient but before it has been detected.

Answer 17

Subject contrast

Question 18

actual anatomical or funtional changes in patient’s tissues

Answer 18

intrinsic component

Question 19

relates to how the image-acquisition protocol can be optimized to enhance subject contrast.
example, gadolinium in MR and iodine in CT

Answer 19

Extrinsic factors of

Question 20

detector system can have profound impat o nhow the subject contrasst incident

Answer 20

detector contrast

Question 21

converiton of analog sinal to digital and its two steps

Answer 21

digitization
sampling
quantization

Question 22

The _____ is an object size-independent measure of the signal
level in the presence of noise. Tm

Answer 22

The contrast-to-noise ratio (CNR)

Question 23

____ of an imaging system is a characterization of an x-ray imaging system, used by imaging scientists, which describes the overall frequency-dependent SNR performance of the system. In conceptual terms, the _______ can be defined as the ratio of the
SNR2 output from the system to the SNR2 of the signal input into the system

Answer 23

Detective Quantum Efficiency