Digital image self-
            adaptive acquisition in
            medical x-ray imaging
                       Bao Jie, ...
Content

                   What is X-ray fluoroscopy system and
                  digital acquisition system
            ...
1. What is X-ray fluoroscopy
              system and digital acquisition
                        system?



Aug.22,2000,W...
What’s X-ray fluoroscopy system?

          X-ray fluoroscopy system is a system for
         medical diagnosing that can ...
Construction of X-ray fluoroscopy system




Aug.22,2000,WCC2000   Jie BAO , ImageInfoLab , Hefei University of Technology...
Why study the digital acquisition of
         X-ray fluoroscopy system?(1)

          The digitalization of x-ray imaging ...
Why study the digital acquisition of
         X-ray fluoroscopy system?(2)

       There are three ways to digitalize x-ra...
The main difficulties in video
               digital acquisition
                   x-ray fluoroscopy image detection noi...
How to deal with them?
                  choose a appropriate working point automatically
                  and suppressed...
Digital video processing system(1)
                                                                                Enhance...
Digital video processing system(2)
       Host should analyze the input signal while sampling and
       quantization to a...
2. The principle and
        implementation of self-adaptive
              digital acquisition


Aug.22,2000,WCC2000   Jie...
Self-adaptive digital acquisition

          To resolve problems brought forward in
         section 1, we use digital sub...
Self-adaptive digital acquisition system




Aug.22,2000,WCC2000   Jie BAO , ImageInfoLab , Hefei University of Technology...
3.1Valid region recognition

          The acquired image is not entirely valid.
         Generally speaking, the valid re...
Valid observe region




             (a) Whole valid observe
             region. White line is                       (b)...
Valid region detection algorithm (1)

       1. Compute the histogram of left and right narrow
          edges of the imag...
Valid region detection algorithm (2)

        4. Generate initial mask(bilevel ) image of valid
            region. Perfor...
3.2 Background removing

        Nonuniform background will affect image quality
          and the computing of image char...
Background removing algorithm

        1.    Acquire and save device background signal (I1)
              when device is i...
3.3 Setting acquisition working point

        After above-mentioned pre-processing, we will
           adjust black level...
Meaning of offset, gain and reference




Aug.22,2000,WCC2000   Jie BAO , ImageInfoLab , Hefei University of Technology   ...
Meaning of black level and white level




Aug.22,2000,WCC2000   Jie BAO , ImageInfoLab , Hefei University of Technology  ...
Working point setting rule

        Decreasing offset will shift image to light zone,
           increasing offset will sh...
Dynamic range analysis of valid region

        Analyze the proportion of dark zone and light zone in the
           histo...
Self-adaptive
              acquisition parameters setting
                                                               ...
Universal acquisition parameters choosing

        It's very inefficient and unnecessary to setting best
            worki...
3. Experiment and Conclusions




Aug.22,2000,WCC2000   Jie BAO , ImageInfoLab , Hefei University of Technology   28
Run interface of self-adaptive
              acquisition module

                                                         ...
Valid region detection




                Original Image                          Valid region mask image             Sob...
Background removing




      device                       acquired                            image after
      backgroun...
self-adaptive adjusting(1):

                                                    Acquired image before
                   ...
self-adaptive adjusting(2):


                                                    Histogram of valid
                     ...
self-adaptive adjusting(3):

                                                    Acquired image after
                    ...
self-adaptive adjusting(4):

                                                    Histogram of valid
                      ...
Conclusions

       It's possible to implement self-adaptive acquisition of
      medical video image automatically by int...
Thank you!

Aug.22,2000,WCC2000   Jie BAO , ImageInfoLab , Hefei University of Technology   37
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Digital image self-adaptive acquisition in medical x-ray imaging

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  • Jie Bao, Jun Gao & Xudong Zhang (2000). Digital Image Self-Adaptive Acquisition in Medical X-Ray Imaging. In Proceedings of International Conference on Intelligent Information Processing (IIP 2000), IFIP World Computer Congress (WCC).
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Digital image self-adaptive acquisition in medical x-ray imaging

  1. 1. Digital image self- adaptive acquisition in medical x-ray imaging Bao Jie, Gao Jun et.al. Lab on Image Information Processing Hefei University of Technology , China Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 1
  2. 2. Content What is X-ray fluoroscopy system and digital acquisition system The principle and implementation of self- adaptive digital acquisition Experiment and Conclusions Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 2
  3. 3. 1. What is X-ray fluoroscopy system and digital acquisition system? Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 3
  4. 4. What’s X-ray fluoroscopy system? X-ray fluoroscopy system is a system for medical diagnosing that can render image of the body of patient by convert X-ray which pass through and attenuated by the body into visible light and record it on film or other media. It’s a very common method for examination in hospitals. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 4
  5. 5. Construction of X-ray fluoroscopy system Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 5
  6. 6. Why study the digital acquisition of X-ray fluoroscopy system?(1) The digitalization of x-ray imaging is very important for PACS (Picture Archiving and Communication system); high-quality digital X-ray medical images are indispensable for PACS data source. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 6
  7. 7. Why study the digital acquisition of X-ray fluoroscopy system?(2) There are three ways to digitalize x-ray imaging  Computed Radiography (CR)  Digital Radiography (DR)  Video digital acquisition. Advantages of video digital acquisition : ability to see dynamic change of organs, device simplicity, operating convenience, and low-cost Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 7
  8. 8. The main difficulties in video digital acquisition x-ray fluoroscopy image detection noise and digital quantum noise Adjusting imaging contrast and resolution Device background signal Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 8
  9. 9. How to deal with them? choose a appropriate working point automatically and suppressed background signal by software Improve hardware quality of x-ray imaging system Choose grabber board with high quantization precision Voltage stabilization and electromagnetic shielding Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 9
  10. 10. Digital video processing system(1) Enhancement Annotation Display Diagnose manual Information navigation x-ray video NSPgrabber board Host Report Aided diagnose Aided ment treat Control Archiving and backup Query and management PACS Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 10
  11. 11. Digital video processing system(2) Host should analyze the input signal while sampling and quantization to adjust grabber board setting for valid signal to utilize the dynamic range sufficiently, and to make device working in linear range. The grabber board we used is NSP (Native Signal Process) frame-grabber board DT3153-LS, it can adjust reference, offset, gain, black level and white level by software, which make it possible for self-adaptive acquisition by software. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 11
  12. 12. 2. The principle and implementation of self-adaptive digital acquisition Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 12
  13. 13. Self-adaptive digital acquisition To resolve problems brought forward in section 1, we use digital subtraction technique to realize background removing for self- adaptive acquisition, and monitor the dynamic range of image valid region to search for the best acquisition working point automatically. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 13
  14. 14. Self-adaptive digital acquisition system Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 14
  15. 15. 3.1Valid region recognition The acquired image is not entirely valid. Generally speaking, the valid region is a circle. We should only count on valid region while removing background and analyzing the image feature to adjust acquisition parameters, so we must recognize the valid region at first. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 15
  16. 16. Valid observe region (a) Whole valid observe region. White line is (b) Valid observe region detected region edge by with occlusion improved seed algorithm. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 16
  17. 17. Valid region detection algorithm (1) 1. Compute the histogram of left and right narrow edges of the image, the gray-level corresponding to histogram peak value is the gray-level of invalid region. 2. Perform median filtering to remove noise. 3. Grow region using classical seed growing algorithm starting from any invalid point. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 17
  18. 18. Valid region detection algorithm (2) 4. Generate initial mask(bilevel ) image of valid region. Perform Sobel operator to this image to extract its edge. 5. Detect circle by general Hough transform; get the radius and the center of the circle. 6. Generate valid region mask using result of step 5. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 18
  19. 19. 3.2 Background removing Nonuniform background will affect image quality and the computing of image characteristic to adjust acquisition parameters. So a digital subtraction will remove background signal while keep the validity of information. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 19
  20. 20. Background removing algorithm 1. Acquire and save device background signal (I1) when device is idle. 2. Acquire images to be observed (I2). 3. Perform image operation in valid region : I3=I1-I2 ; I4=NOT I3; 4. I4 is the image signal removed of background. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 20
  21. 21. 3.3 Setting acquisition working point After above-mentioned pre-processing, we will adjust black level, white level, gain, reference and offset automatically based on histogram analysis of image valid region to obtain best acquisition quality.  Black level = - offset  White level = reference / gain -offset Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 21
  22. 22. Meaning of offset, gain and reference Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 22
  23. 23. Meaning of black level and white level Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 23
  24. 24. Working point setting rule Decreasing offset will shift image to light zone, increasing offset will shift image to dark zone, namely offset behaves as brightness adjusting; decreasing reference will compress image to light zone, increasing reference will compress image to dark zone, namely reference behaves as contrast adjusting. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 24
  25. 25. Dynamic range analysis of valid region Analyze the proportion of dark zone and light zone in the histogram of image valid region, the aim of adjusting is to keep proper proportion of dark zone and light zone for best image acquisition performance. Setting brightness at first to ensure dark zone isn't too much then setting contrast( that is, properly setting white level by adjusting reference). Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 25
  26. 26. Self-adaptive acquisition parameters setting B e g in R e a d in e s s ju d g m e n t I m a g e a c q u is itio n V a lid re g io n re c o g n itio n , b a c k g ro u n d re m o v in g V a lid re g io n a n a ly s is D y n a m ic ra n g e T o o d a rk T o o b rig h t W h ile ( d a r k z o n e is to o m u c h & & o ff s e t W h ile ( d a r k z o n e is to o f e w & & o ff s e t is is n o t o u t o f lo w e r b o u n d ) not out of upper bound) D e c r e a s e o ff s e t I n c r e a s e o ff s e t I m a g e a c q u is itio n , b a c k g ro u n d I m a g e a c q u is itio n , b a c k g ro u n d re m o v in g re m o v in g V a lid re g io n a n a ly s is V a lid re g io n a n a ly s is L ig h t z o n e a n a ly s is L ess M o re W h ile ( lig h t z o n e is to o m u c h & & W h ile ( lig h t z o n e is to o fe w & & re fe re n c e is n o t o u t o f u p p e r b o u n d ) re fe re n c e is n o t o u t o f lo w e r b o u n d ) D e c re a se re fe re n c e In c re a se re fe re n c e I m a g e a c q u is itio n , b a c k g ro u n d I m a g e a c q u is itio n , b a c k g ro u n d re m o v in g re m o v in g V a lid re g io n a n a ly s is V a lid re g io n a n a ly s is End Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 26
  27. 27. Universal acquisition parameters choosing It's very inefficient and unnecessary to setting best working point every time we take fluoroscopy. In practice, expert judgment and adjusting is used to choose universal acquisition parameters. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 27
  28. 28. 3. Experiment and Conclusions Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 28
  29. 29. Run interface of self-adaptive acquisition module Run interface of self-adaptive acquisition module in ImagePro™ implemented by Visual C++6.0 Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 29
  30. 30. Valid region detection Original Image Valid region mask image Sobel edge-detect image integrated valid region Rim of Valid Region by improved algorithm Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 30
  31. 31. Background removing device acquired image after background image with removing signal nonuniform device background background Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 31
  32. 32. self-adaptive adjusting(1): Acquired image before self-adaptive adjusting. Black level=0V, white level =0.7V, offset=0V, gain=1, reference =0.7V Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 32
  33. 33. self-adaptive adjusting(2): Histogram of valid region in (1). mean = 70.48, median value=54. Image is too dark. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 33
  34. 34. self-adaptive adjusting(3): Acquired image after self-adaptive adjusting. Black level =-0.042V, white level =0.258V, offset=0.042V, gain=2, reference= 0.6V scapula Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 34
  35. 35. self-adaptive adjusting(4): Histogram of valid region in (3). mean = 121.19. median value = 113. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 35
  36. 36. Conclusions It's possible to implement self-adaptive acquisition of medical video image automatically by integrating various images processing method. The proposed method has recognized the valid region of image and removed the background, then adjusted acquisition parameters by analyzing image dynamic range to obtain best acquisition quality. But there still some problem remained to be resolved. Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 36
  37. 37. Thank you! Aug.22,2000,WCC2000 Jie BAO , ImageInfoLab , Hefei University of Technology 37
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