quiz 1 review session - university of...

University of Washington Medical Center, Department of RadiologyDiagnostic Imaging Section

A copy of this lecture is available at: http://courses.washington.edu/radxphys/

Quiz 1Review Session

http://courses.washington.edu/radxphys/

2©UW and DPS

Question Intro to Rad I

3©UW and DPS

Question Intro to Rad I

If the mAs selected for a radiograph is doubled, what is the effect?

A. The noise is increased by a factor of 2B. The speed of the photons produced in the anode is doubledC. The dose to the patient is increased by a factor of 4D. The number of photons produced in the anode is doubledE. The chance that an individual photon makes it through the

patient is increased by a factor of 50%

4©UW and DPS

Question Intro to Rad II

5©UW and DPS


6©UW and DPS


7©UW and DPS

Question Intro to Rad III

8©UW and DPS

Question Intro to Rad III

Decreasing the OID will have what affect on the magnification factor?

A. Mag IncreaseB. Mag DecreaseC. No Change

B. Decreasing OID, increases SOD. Mag = SID/SOD, therefore Mag decreases

9©UW and DPS

This diagram exhibits the readout process used in what radiographic image receptor?

A. Film-screenB. Direct DigitalC. Computed RadiographyD. In-Direct Digital

Question Radiographic Detectors

C. Computed Radiography relies upon a CR cassette inserted into a plate reader. A laser is raster scanned, and resultant emitted light intensity is digitized

10©UW and DPS

GE Precision 500D GE PACS

St Dev = 0

Question Radiographic Detectors

What is a likely cause of the poor image quality on the right image?A. Insufficient Image Matrix SizeB. Quantum MottleC. Insufficient Image Bit DepthD. Incorrect Image Receptor

C. Best answer is bit depth, not enough unique numbers available to offer image contrast, too flat

11©UW and DPS

Question Radiation Protection

According to NCRP Report 160 (2009), what is the annual Effective Dose to the average American?

A. 0.07 mSvB. 0.5 mSvC. 3.1 mSvD. 6.2 mSvE. 50 mSv

D. Memorization. What is E?

12©UW and DPS

Question Radiation Protection

According to NCRP Report 160 (2009), what is the annual Effective Dose to the average American from background radiation?

A. 0.07 mSvB. 0.5 mSvC. 3.1 mSvD. 6.2 mSvE. 50 mSv

C. Memorization.

13©UW and DPS

Question Intro to Mammo

14©UW and DPS


15©UW and DPS


16©UW and DPS

Question Intro to Ultrasound

Sound travels fastest in which of the following?

A. LungB. BoneC. BloodD. FatE. Air

The speed of sound in a medium is dependent on two properties—density and a property known as the bulk modulus. The bulk modulus is a measure of compressibility. The less compressible a given medium is, the faster sound will travel through it given its mechanical wave properties. Sound travels significantly slower through air than bone for this reason.

17©UW and DPS

Question Intro to Ultrasound

As an ultrasound beam passes through the gallbladder below, which wave property remains constant?

A. Amplitude B. Frequency C. Wavelength D. Angle

As sound travels from one medium to another, frequency remains constant. Because frequency remains constant, amplitude and wavelength must change.

18©UW and DPS

Question Intro to Fluoroscopy

Compared to Continuous fluoroscopy, Pulsed Fluoroscopy

A. Delivers a higher total radiation dose to the patient

B. Has poorer image qualityC. Has better temporal resolutionD. Is more susceptible to lag artifactsE. None of the above

19©UW and DPS


For best image quality, the patient should be positioned:

A. As close to the tube as possibleB. As far from the tube as possibleC. As close to the Image Receptor as possibleD. As far from the Image Receptor as possible

20©UW and DPS


For minimization of radiation dose, the patient should be positioned:

A. As close to the tube as possibleB. As far from the tube as possibleC. As close to the Image Receptor as possibleD. As far from the Image Receptor as possible

©UW and David Zamora 21

What is the reason for the difference between the 2 CT images below?

A. kVB. mAsC. Slice widthD. Rotation timeE. Reconstruction

kernel

Question Intro to CT


Question Intro to CT

Which of the following will least likely have an effect on the quantum mottle in CT?

A. Patient sizeB. Iterative reconstructionC. kVD. mAsE. Window level


Question Radiation Biology

Which of the following cells are considered the most radiosensitive?

A. NeuronsB. Crypt cellsC. Bone MarrowD. Spermatogonia


Question Radiation Biology

Which of the following is classified as a deterministic or non-stochastic effect?

A. CancerB. CataractC. MutationD. All of the above


Question Radiation Effects

What is the dose limit to the embryo of a pregnant radiologist for the entire pregnancy?

A. 50 mSvB. 10 mSvC. 5 mSvD. 1 mSv


Question Radiation Effects

What is the threshold for causing transient erythema due to radiation exposure during an interventional procedure?

A. 0. 5 GyB. 1 GyC. 2 GyD. 5 Gy


Question Radiation Risks and Estimating Cancer Risk

The average excess relative risk of cancer for the general population based on the ICRP is approximately between_________.

• A) 1-2% per Sv• B) 2-4% per Sv• C) 5-6% per Sv• D) 5-10% per Sv• E) 10-15% per Sv


Question Image Processing and Reconstruction

In 5-dimensional medical imaging, where the first three dimensions refer to the 3D spatial representation of the volume (x,y,z), the 4th and 5th dimensions refer to:

• a) Information provided by blood sampling and organ motion, respectively

• b) Information provided by dual-tracer SPECT or PET imaging

• c) Respiratory gated and cardiac gated signals• d) Temporal and sensor (metabolic, functional or

physiological) dimensions, respectively


Question Image Perception, Display and PACS

The 20-20-20 rule:

• a) Is the time from acquisition to completion to finalization of an examination.

• b) Limits noise amplification in image processing.• c) Refers to an easy way to reduce eye fatigue.• d) Shorthand for the ACR control limits for white-

level, black-level and ambient lighting.

quiz 1 review session - university of...

Documents