Directed Reading—Evaluation Quiz

Journal of Medical Imaging and Radiation Sciences

Journal of Medical Imaging and Radiation Sciences 39 (2008) 42-44

Journal de l’imagerie médicale et des sciences de la radiation

www.elsevier.com/locate/jmir

Directed ReadingdEvaluation Quiz 1. A significant factor that limits the performance of filmscreen radiography and provides the motivation for developing digital imaging technologies is: (a) A film-screen detector exhibits poor contrast

resolution (b) A film-screen detector can show only a fixed optical

density for a single exposure (c) A film-screen detector can show artifacts that origi-

nate from the patient (d) A film-screen detector uses only kVp to control im-

5. The purpose of preprocessing operations in a digital imaging system is to: (a) Alter the contrast of the raw data acquired from the

patient (b) Make the image size smaller to reduce the image

transmission time to PACS (c) Apply corrections to the raw data acquired from the

patient (d) Make the image created from the raw data as sharp

as possible

age contrast 2. Image processing using a digital computer is referred to as: (a) Photoshop (b) Digital radiography (c) Digital photography (d) Digital image processing

6. The purpose of image postprocessing operations in a digital imaging system is to: (a) Enhance the contrast and sharpness of the image

created from the raw data (b) Correct the raw data and prepare it from histogram

analysis (c) Adjust the actual kVp used in the examination to

change the image contrast 3. In digital image processing, a digital image: 1. Is a numeric representation of an object

(d) Adjust the actual mAs used for the examination to

alter the density of the image

2. Is made up of a matrix of small, square regions called

pixels 3. Consists of a characteristic referred to as the bit depth 4. Comprises M columns, N rows, and k bits, which

7. To change an image from the spatial frequency domain into the spatial location domain is a function of: (a) The Fourier Transform

define its size

(b) The Inverse Fourier Transform

(a) 1 only

(c) A high-spatial frequency digital filter

(b) 1 and 2

(d) A low-spatial frequency digital filter

(c) 1, 2, and 3 (d) 1, 2, 3, and 4

4. In a digital image with a bit depth of 10, each pixel will have: (a) 10 shades of gray

8. For digital images, which of the following algebraic expressions can be used to calculate the size of the pixel? (a) Pixel size (P) ¼ Field-of-View (FOV) – Matrix size

(MS)

(b) 5 shades of gray

(b) P ¼ FOV  MS

(c) 256 shades of gray

(c) P ¼ MS/FOV

(d) 1024 shades of gray

(d) P ¼ FOV/MS

1939-8654/08/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi: 10.1016/j.jmir.2008.02.001

9. Baxes identifies 5 classes of image processing operations. In which class of operations does image segmentation and feature extraction belong?

15. In which of the following commercial photography software is the DICOM standard now included? (a) Photoshop

(a) Image compression operations

(b) Photoshop CS3 Extended

(b) Image enhancement operations

(c) Corel Draw

(c) Image analysis operations

(d) Microsoft Photo Imaging

(d) Image restoration techniques

16. In a spatial frequency filtering process, a high-pass filter: 10. Which of the following operations is used to change the gray scale (contrast) of a digital image? (a) Image synthesis

(a) Uses only high frequencies to sharpen images (b) Uses only low frequencies to sharpen images (c) Uses both low and high frequencies to sharpen images

(b) Image analysis

(d) Uses only low frequencies to smooth the image

(c) Image restoration (d) Image enhancement

11. Gray level mapping is an example of a: (a) Point operation (b) Local processing operation (c) Global processing operation (d) Geometric processing operation

12. Windowing, used to change the contrast and brightness of a digital image, belongs to the class of:

17. In digital image postprocessing, a low-pass digital filter is used to: (a) Sharpen the image (b) Blur the image to make it look smooth (c) Change the orientation of the image (d) Increase the noise present in the image

18. The position and orientation of an image can be changed by using a:

(a) Geometric processing operations

(a) Global processing operation

(b) Point processing operations

(b) Local processing operation

(c) Global processing operations

(c) Point processing operation

(d) Local processing operations

(d) Geometric processing operation

19. Image compression will:

13. A histogram is: (a) A graph of the matrix size versus the number of gray

levels in each column (b) A graph of the number of pixels plotted as a function

of the number of gray levels (c) An algorithm for sharpening images

(a) Increase transmission time and reduce storage space (b) Reduce transmission time only (c) Reduce transmission time and decrease image stor-

age space (d) Reduce image storage space only

(d) An algorithm for enhancing the contrast of digital

20. The term ‘‘compression ratio’’ refers to:

images 14. In digital image postprocessing, a look-up table (LUT) is used to: (a) Change the contrast of images

(a) The ratio of computer storage required to save the

original image to that of the compressed image data (b) The ratio of storage space needed to save the com-

pressed image to that of the original image

(b) Display the image in a different orientation

(c) The ratio of the matrix size to the field-of-view

(c) Blur anatomical structures in digital images

(d) The ratio of lossy compression to that of lossless

(d) Decrease image noise

compression

E. Seeram and D. Seeram/Journal of Medical Imaging and Radiation Sciences 39 (2008) 42-44

43

21. If the original size of a digital image file is 20MB, a 4:1 compression ratio will result in a compressed file size of:

24. Which of the following will produce a better image quality at high compression ratios?

(a) 5 kB

(a) JPEG

(b) 5 MB

(b) Run length encoding

(c) 20 MB – 4.1 MB

(c) Huffman encoding

(d) 500 bits

(d) JPEG 2000

22. A lossless or reversible compression framework does not include: (a) Image transformation

25. The Canadian Association of Radiologists (CAR) has accepted the use of irreversible compression in primary diagnosis for several modalities except for:

(b) Encoding

(a) Computed tomography

(c) Quantization

(b) Magnetic resonance imaging

(d) Original image

(c) Mammography (d) Flat-panel digital radiography of the chest

23. In which component of a lossy or irreversible compression framework does compression take place? (a) Image transformation component (b) Encoding (c) Quantization (d) Between transformation and quantization

*Answers to these questions can be found on page 48

44

E. Seeram and D. Seeram/Journal of Medical Imaging and Radiation Sciences 39 (2008) 42-44

 A talk on the use of personal digital assistants (PDAs) in the clinical site was very informative. Students still need to keep manual lists of examinations they have done or participated in, and, with stricter privacy policies, a password protected way to gather the data seems like a reasonable measure to investigate.  The technology that many of the other educators were using with online testing was intriguing. I could see a future in this because of our geographically large distances in Eastern Ontario, from Pembroke to Cornwall through Ottawa and back to Kingston. The hard part with any workshop is to return to work and implement everything you have learned. The UK’s entire diagnostic radiography program of PBL was daunting. So I chose to watch my students and found a very interesting trend. I thought that PBL would fit wonderfully into communication and patient care topics; but I can see now that, with the group of students I have this year, it is actually going to flourish in the more technical and theory-based subjects. A couple of weeks ago I delivered a series of lectures building on the theories of electromagnetism, generators, and motors that led up to explaining the induction motor of the x-ray tube. At one point during the lecture I stood back a bit and, before I knew it, a couple of students were up at the white board drawing diagrams; one was Googling on his cell phone. We had a group of students at the back of the

class who were hashing out the basics of the theories, and a group at the front who were beyond that and going into more advanced thinking. It was dynamic and amazing to watch. One of my goals for the conference was to discover new and exciting ways to teach curriculum that is based on theory as opposed to my real-life experiences as a technologist. The impromptu PBL session that happened before my eyes was very exciting and seemed satisfying to the students involved. I now have a direction that seems clear and can proceed with converting some curriculum modules to PBL. The opportunity to attend the Leadership Academy for Educators was wonderful. I am very grateful to the CAMRT for choosing me to attend as well, as well as to the ASRT for including and hosting Canadian educators. I encourage others to apply to the Academy and to research some of the theories and software programs that I mentioned in this column. I sent in a form to the ASRT before starting the Academy that asked for my motivation for applying for the opportunity. Rereading it, I see that I was hoping to ‘‘get through the learning curve portion of a new career quickly’’ so that I could regain balance in my life. What I discovered was that the role of an educator has a learning curve that doesn’t seem to end, and that I can look forward to the enjoyment of learning and trying new theories and skills for many years to come.

DIRECTED READING d ANSWERS

48

1. a

8. d

15. b

22. c

2. d 3. d 4. d

9. c 10. d 11. a

16. a 17. b 18. d

23. c 24. d 25. c

5. c 6. a 7. b

12. b 13. b 14. a

19. c 20. a 21. b

K. Hubbard/Journal of Medical Imaging and Radiation Sciences 39 (2008) 47-48