WO1997013354A1

WO1997013354A1 - Medical image output device and method

Info

Publication number: WO1997013354A1
Application number: PCT/US1996/014226
Authority: WO
Inventors: Phillip A. Bolea
Original assignee: Imation Corp.
Priority date: 1995-10-05
Filing date: 1996-09-04
Publication date: 1997-04-10
Also published as: AU6914396A

Abstract

A medical image output device and method selectively drive an imaging module based on first input data corresponding to a diagnostic portion of the image or second input data corresponding to a non-diagnostic portion of the image. The imaging module thereby forms a visible representation of the image that combines both the diagnostic portion and the non-diagnostic portion of the image. The medical image output device and method are capable of providing reduced cost, reduced complexity, and enhanced flexibility. The medical image output device and method achieve such advantages by eliminating much of the custom hardware ordinarily required for integration of the diagnostic and non-diagnostic portions of the image, and by delegating processing of the diagnostic portion to an image input device.

Description

MEDICAL IMAGE OUTPUT DEVICE AND METHOD

Field of the Invention

The present invention relates to medical imaging technology and, more particularly, to techniques for processing medical image data generated by an image input device for presentation by an image output device.

Discussion of Related Art

A medical diagnostic imaging system typically includes an image input device and an image output device. The image input device may include an image acquisition device that generates digital input data representative of an original diagnostic image. The image acquisition device may include a diagnostic modality such as, for example, a magnetic resonance (MR) system, a computed tomography (CT) system, a conventional radiography (X-ray) system, a digital radiography system, or an ultrasound device. Alternatively, the image input device may include an image retrieval device that retrieves archived input data representative of the original diagnostic image. The image output device forms a visible representation of the original image on imaging media based on the input data provided by the image input device. The image output device may include, for example, a digital laser imager that forms a visible representation of the original image on radiation- sensitive media.

The input data generated by the image input device contains digital image values. Each of the digital image values corresponds to one of a plurality of pixels in the original image, and represents an optical density associated with the respective pixel. The image output device processes the digital image values to generate output data. The output data contains digital drive values that are used to drive an imaging module. Each of the drive values represents an exposure level necessary to accurately reproduce, on radiation-sensitive media, the optical density of a pixel in the original image. The drive values may be used, for example, to modulate the intensity of a scanned laser beam to expose the media at each pixel with an appropriate level of exposure. The media subsequently is developed, either by wet chemical processing or dry thermal processing, to form a visible representation of the original image.

The visible representation of the image formed by the image output device typically includes a diagnostic portion and a non-diagnostic portion. The diagnostic portion is represented by the input data generated by the image input device. Thus, the diagnostic portion is representative of a physiological object to be viewed by a physician for purposes of medical diagnosis. The non-diagnostic portion is represented by input data generated by the image output device. The non-diagnostic portion may include, for example, border regions of the image that frame the periphery of the diagnostic portion, text information in the border regions indicating the status of the image output device and/or the imaging media, and an optical density reference patch in the border regions used for closed loop control of the image output device. In existing medical imaging systems, the image output device includes custom image processing hardware that integrates the diagnostic portion and the non-diagnostic portion of the image into a single page of input data used to drive the imaging module. The image processing hardware also performs various image processing operations such as formatting, scaling, rotation, and contrast enhancement on the input data. Unfortunately, the custom image processing hardware significantly increases the cost and complexity of the image output device. For example, the image processing hardware requires a large amount of random access memory (RAM) storage to carry out integration of the diagnostic and non- diagnostic portions, perform necessary image processing operations, and store the resulting page of input data. In addition, the custom image processing hardware is difficult to modify, making the set of image processing operations provided by the image output device relatively inflexible.

In view of the cost, complexity, and inflexibility of medical image output devices incorporating existing image processing hardware, there is a need for an improved medical image output device. In particular, there is a need for a medical image output device for forming a visible representation of a medical diagnostic image on imaging media with reduced cost, reduced complexity, and enhanced flexibility.

Summary of the Invention

The present invention is directed to a medical image output device and method for forming a visible representation of a medical diagnostic image on imaging media, and to a medical imaging system incorporating such a medical image output device and method. The medical image output device and method are capable of providing reduced cost, reduced complexity, and enhanced flexibility. The medical image output device and method achieve such advantages by eliminating much of the custom hardware ordinarily required for integration of the diagnostic and non- diagnostic portions of the image, and by delegating processing of the diagnostic portion to an image input device.

Brief Description of the Drawings Fig. 1 is a diagram of an article of imaging media on which a visible representation of a medical diagnostic image is formed; and

Fig. 2 is a functional block diagram of an exemplary embodiment of a medical imaging system incorporating a medical image output device, in accordance with the present invention.

Detailed Description

Fig. 1 is a diagram of an article 10 of imaging media on which a visible representation of a medical diagnostic image is formed by a medical image output device. The article of imaging media 10 may comprise, for example, a sheet of radiation-sensitive film or paper appropriate for viewing with a light box. As shown in Fig. 1, the visible representation of the image formed on article 10 includes a diagnostic portion 12 and a non-diagnostic portion. The diagnostic portion 12 is representative of a physiological object to be viewed by. a physician for purposes of medical diagnosis. The non-diagnostic portion includes border regions 14, 16, 18, 20 that frame the periphery of diagnostic portion 12. Each of border regions 14, 16, 18, 20 may contain a region of continuous optical density, a region of continuous optical density and text information, or a region of continuous optical density and an optical density reference patch 22. The reference patch 22 can be sensed with a densitometer and used to control the medical image output device.

Fig. 2 is a functional block diagram of an exemplary embodiment of a medical imaging system 24, in accordance with the present invention. As shown in Fig. 2, the medical imaging system 24 comprises a medical image input device 26 and a medical image output device 28. The structure of image output device 28 may be used to implement a medical image output method, in accordance with the present invention. The medical image output device 28 and method are capable of forming a visible representation of both the diagnostic and non-diagnostic portions of an original image while achieving reduced cost, reduced complexity, and enhanced flexibility. As will be described, the medical image output device 28 and method achieve such advantages by eliminating much of the hardware ordinarily required for integration of the diagnostic and non-diagnostic portions of the image, and by delegating processing of the diagnostic portion to image input device 26.

The image input device 26 shown in Fig. 2 may include an image acquisition device that generates input data representative of the diagnostic portion of an original image. The input data generated by image input device 26 will be referred to herein as first input data. The image acquisition device may include a diagnostic input modality such as, for example, a magnetic resonance (MR) system, a computed tomography (CT) system, a conventional radiography (X-ray) system, a digital radiography system, or an ultrasound device. Alternatively, image input device 26 may include an image retrieval device that retrieves the first input data from archived records in a data storage device. The first input data generated by image input device 26 contains digital image values. Each of the digital image values corresponds to one of a plurality of pixels in the original diagnostic portion of the image, and represents .an optical density associated with the respective pixel.

The image input device 26 sends the first input data to image output device 28 for formation of a visible representation of the image on imaging media. In the exemplary embodiment of Fig. 2, image output device 28 includes an image data multiplexer 30, an image data memory device 32, an imaging module 34, and an image data controller 36. The image data memory device 32 may comprise a random access memory (RAM) device. The imaging module 34 may comprise a scanning laser module for exposing pixels on a sheet of radiation-sensitive film or paper with a laser beam. The scanning laser module scans the imaging media with the laser beam to form scan lines of pixels. The scan lines extend in a relatively low frequency y-axis, whereas the pixels in each scan line extend in a high frequency x-axis. The image data controller 36 may comprise a field programmable gate array 38 and an embedded programmable controller 40. The field programmable gate array 38 can be used to control the high frequency x-axis scanning, whereas embedded controller 40 can be used to control the relatively low frequency y-axis scanning. An example of a suitable field programmable gate array is the A1240A, commercially available from Actel of Sunnyvale, California. An example of a suitable embedded controller is the MC68332, commercially available from Motorola of Phoenix, Arizona. The image data multiplexer 30, image data memory device 32, and image data controller 36 can be mounted together on an interface board within image output device 28.

The image output device 28 uses a first portion of image data memory device 32 as a first memory for handling the diagnostic portion of the image. Prior to an imaging operation, embedded controller 40 loads the first memory in image data memory device 32, as indicated by line 42, with a lookup table. The lookup table can occupy a first page of RAM in image data memory device 32. The lookup table in the first memory contains first output data addressable by the first input data generated by image input device 26. The first output data contains digital drive values that are used to drive imaging module 34. Each of the drive values in the first output data represents an exposure level necessary to accurately reproduce, on radiation-sensitive media, the optical density of a pixel in the diagnostic portion of the original image. The drive values may be used, for example, to modulate the intensity of the scanned laser beam in imaging module 34 to expose the media at each pixel with an appropriate level of exposure. The first output data in the lookup table is a composite characterization of imaging module 34 and the imaging media. The output data is recalculated by embedded controller 40 based on changes in the exposure characteristics of imaging module 34 and/or changes in the sensitometric response of the imaging media used. Changes in the exposure characteristics of imaging module 34 can be monitored by sensing an optical density reference patch 22 formed on the imaging media, as described with reference to Fig. 1. Changes in the sensitometric response will occur between different types of imaging media and between different lots of the same imaging media. Thus, changes in sensitometric response can be monitored by sensing the optical density reference patch and by reference to the particular type of imaging media used. If desired, embedded controller 40 may load the first memory in image data memory device 32 with multiple lookup tables providing output data for different types of imaging media. The multiple lookup table can be loaded into separate pages of RAM in image data memory device 32.

The first output data in the lookup table is addressable by the first input data to drive the formation of the diagnostic portion of the image by imaging module 34. The image output device 28 preferably performs no significant image processing operations on the first input data prior to application to the lookup table. Rather, in accordance with the present invention, image processing operations such as formatting, scaling, rotation, and contrast enhancement are delegated to a computer workstation associated with image input device 26. Thus, the first input data preferably is pre-processed by image input device 26. Because the workstation already provides sufficient computing power, delegation of the image processing operations ordinarily will not add significant cost to the image input device 26. The first input data can be used by image output device 28, without further processing, to simply address the first output data in the lookup table in image data memory device 32. In this manner, custom hardware dedicated to complex image processing operations can be eliminated from image output device 28, resulting in reduced cost and complexity. In addition, delegation of the image processing operations to image input device 26 allows the user to more freely manipulate the first input data at the workstation, providing enhanced flexibility.

The image output device 28 uses a second portion of image data memory device 32 as a second memory for handling the non-diagnostic portion of the image. Prior to an imaging operation, embedded controller 40 loads the second memory in image data memory device 32, as indicated by line 42, with second output data addressable by second input data generated by image data controller 36. Like the first output data, the second output data contains digital drive values that are used to drive imaging module 34. Also like the first output data, the second output data is recalculated by embedded controller 40 based on changes in imaging module 34 and/or the imaging media. Unlike the first output data, however, each of the drive values in the second output data represents an exposure level necessary to reproduce the optical density of a pixel in the non-diagnostic portion of the original image.

During an imaging operation, image data controller 36 selectively drives imaging module 34 with either the first output data or the second output data to form visible representations of the diagnostic and non-diagnostic portions of the image. The image data controller 36 selectively drives imaging module 34 by addressing either the first output data or the second output data in image data memory device 32. Specifically, for diagnostic portions of the image, image data controller 36 applies the first input data generated by image input device 26 to address the first output data in the lookup table contained in the first memory of image data memory device 32. For non- diagnostic portions of the image, image data controller generates second input data to address selected portions of the second output data in the second memory of image data memory device 32. In each case, the respective first or second output data is used to drive imaging module 34.

To commence an imaging operation, image input device 26 transmits an image request signal to embedded controller 40, as indicated by line 44. The embedded controller 40 responds by sending a wait signal to image input device 26, as also indicated by line 44, and loads the contents of image data memory device 32, as indicated by line 42. The embedded controller 40 then activates field programmable gate array 38, as indicated by line 46, to start driving imaging module 34 to form a first scan line. The embedded controller 40 includes a line counter for counting the number of lines scanned by imaging module 34. The field programmable gate array 38 includes a pixel counter for counting the number of pixels scanned by imaging module 34 within each scan line. The line counter and pixel counter are used to determine the scan position within the image, and whether the scan position corresponds to the diagnostic or non-diagnostic portion of the image. With reference to Fig. 1, it is necessary to first drive imaging module 34 to form scan lines in an upper border region 14. The line count maintained by embedded controller 40 indicates that the scan position is in upper border region 14. To form the first scan line in upper border region 14, field programmable gate array 38 generates second input data in the form of an address and sends the address to image data multiplexer 30, as indicated by line 48. Thus, the second input data is not really representative of an optical density of a pixel, but rather corresponds to an address in memory containing a drive value for the pixel. The multiplexer 30 sends the address represented by the second input data to image data memory device 32, as indicated by line 50. The address generated by field programmable gate array 38 corresponds to a first pixel within a first scan line of upper border region 14 in the image. In response to the address, image data memory device 32 outputs a digital drive value from the second output data contained in the second memory, and sends the drive value to imaging module 34, as indicated by line 52, to form the first pixel on the imaging media. The field programmable gate array 38 sends a pixel strobe signal to imaging module 34, as indicated by line 54, prior to enabling the output of image data memory device 32 with a control signal, as indicated by line 56.

The second output data in the second memory of image data memory device 32 need not contain data for each scan line in the non-diagnostic portion. Because much of the non-diagnostic portion contains continuous optical density regions, such data would be duplicative. Thus, field programmable gate array 38 can be made to generate second input data that addresses the same second output data for different scan lines that are duplicative of one another. The field programmable gate array 38 can be configured to address the same second output data for duplicative scan lines based on the line count maintained by embedded controller 40. Repetitive addressing of the same second output data greatly reduces the amount of RAM required by image output device 28, resulting in accompanying reductions in the cost of the image output device. The field programmable gate array 38 continues to address drive values in the second output data by, for example, using the pixel counter to increment the address sent to image data memory device 32 via multiplexer 30. The field programmable gate array 38 addresses the second output data in rapid succession. The imaging module 34 sends a line synchronization signal to field programmable gate array 38, as indicated by line 58, indicating that the imaging module is ready to receive the drive values for an entire scan line. The imaging module 34 may include a buffer sufficient to store at least one scan line of drive values. The field programmable gate array 38 returns control to embedded controller 40 when the pixel count has reached a value indicating the end of the scan line, as indicated by line 46. In response, embedded controller 40 increments the line count, and determines whether the next scan line corresponds to a diagnostic or non-diagnostic portion of the image.

The diagnostic and non-diagnostic portions of the image can be fixed in size, and thereby begin and end at fixed scan line numbers. As an alternative, image input device 26 can be configured to send to embedded controller 40 data indicating a varying size of the diagnostic portion of the image. The embedded controller 40 can use the size data to calculate beginning and ending scan line numbers for comparison to the line count when determining diagnostic and non- diagnostic portions of the image. In either case, if the next scan line corresponds only to a non- diagnostic portion of the image, embedded controller 40 activates field programmable gate array 38 to generate second input data for addressing the next line of drive values contained in the second output data of image data memory device 32. If the next scan line contains a diagnostic portion of the image, however, embedded controller activates field programmable gate array 38 to queue first input data from image input device 26.

With reference to Fig. 1, scan lines containing a diagnostic portion of the image will also contain a non-diagnostic portion in the form of side border regions 16, 20. The handling of scan lines containing a diagnostic portion of the image can be handled by one of two approaches. According to a first approach, image input device 26 can be configured to provide first input data representative of the entire scan line including both diagnostic portion 12 and non- diagnostic side border regions 16, 20. To carry out a scan according to this approach, field programmable gate array 38 sends a start-of-line signal to image input device 26, as indicated by line 60. In response, image input device 26 sends first input data representative of the entire scan line to multiplexer 30, as indicated by line 62. The multiplexer 30 sends the first input data to image data memory device 32. The image data memory device 32 references the first input data to the first output data in the lookup table contained in the first memory. The image input device 26 sends a pixel strobe signal to field programmable gate array 38 for each digital value in the first input data, as indicated by line 64. The pixel strobe signal enables field programmable gate array 38 to increment the pixel count and to control the output of image data memory device 32 to drive imaging module 34. When the pixel count indicates the end of the scan line, field programmable gate array 38 returns control to embedded controller 40 for determination of the line count and the current position of the scan.

According to a second approach, image input device 26 can be configured to provide first input data representative of only the diagnostic portion of the scan line. This approach relies heavily on the pixel count maintained by field programmable gate array 38. If the line count maintained by embedded controller 40 indicates that the next scan line contains a diagnostic portion of the image, the embedded controller activates field programmable gate array 38 to generate second input data to address second output data in image data memory device 32 sufficient to drive the formation of the non- diagnostic portion of the scan line in left border region 16. As field programmable gate array 38 addresses each pixel in the scan line, the pixel count is incremented. When the pixel count indicates the end of the non-diagnostic portion of the scan line in left border region 16, field programmable gate array 38 sends a start-of-line signal to image input device 26.

The image input device 26 responds to the start- of-line signal by sending first input data representative of the diagnostic portion 12 of the scan line. The first input data is referenced to the first output data in the first memory of image data memory device 32 and used to drive imaging module 34 to form the diagnostic portion. During formation of the diagnostic portion, field programmable gate array 38 receives the pixel strobe signal from image input device 26 and uses the pixel strobe signal to increment the pixel count and control the output of image data memory device 32. When the pixel count indicates the end of diagnostic portion 12 of the scan line, field programmable gate array 38 again takes over, generating second input data to address second output data in image data memory device 32 sufficient to drive the formation of the non-diagnostic portion of the scan line in right border region 20. According to this second approach, field programmable gate array 38 effectively "patches" together second output data representative of left border region 16, first output data representative of diagnostic portion 12, and second output data representative of right border region 20. When the pixel count indicates the end of the scan line, field programmable gate array 38 returns control to embedded controller 40 to process the next scan line. After forming the scan lines containing diagnostic portion 12, field programmable gate array 38 and embedded controller 40 cooperate to form lower border region 18. To form lower border region 18, field programmable gate array 38 again generates second input data to address second output data in the second memory of image data memory device 32. The second output data addressed by field programmable gate array 38 is representative of an appropriate scan line in lower border region 18, and is used to drive imaging module 34 to form a visible representation of the scan line. When the line count indicates the last scan line and the pixel count indicates the last pixel in the last scan line, image data controller 36 sends a signal to image input device 26 indicating availability for the next imaging operation.

Having described the exemplary embodiments of the invention, additional advantages and modifications will readily occur to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. Therefore, the specification and examples should be considered exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

Claims

What is claimed is;

1. A medical image output device comprising: an imaging module for forming a visible representation of an image on imaging media; and an image data controller for selectively driving the imaging module based on one of first input data corresponding to a diagnostic portion of the image and second input data corresponding to a non-diagnostic portion of the image, wherein the imaging module thereby forms a visible representation of the image that combines both the diagnostic portion and the non-diagnostic portion of the image.

2. The medical image output device of claim 1, further comprising: a first memory storing first output data addressable by the first input data; and a second memory storing second output data addressable by the second input data, wherein the image data controller selectively addresses the first memory with the first input data to access the first output data, and selectively addresses the second memory with the second input data to access the second output data, the image data controller selectively driving the imaging module with one of the first output data and the second output data to form a visible representation of the image that combines both the diagnostic portion and the non-diagnostic portion of the image.

3. The medical image output device of claim 2, wherein the first memory and the second memory reside in a common memory device.

4. The medical image output device of claim 1, wherein the imaging module scans a beam of radiation across the imaging media in a plurality of scanned lines, each of the scanned lines including a plurality of scanned pixels, and wherein the image data controller includes: a line counter for counting a number of the scanned lines; and a pixel counter for counting a number of the scanned pixels within each of the scanned lines, the image data controller selectively driving the imaging module based on one of the first input data and the second input data according to the number of scanned lines counted by the line counter and the number of scanned pixels counted by the pixel counter.

5. The medical image output device of claim 4, further comprising: a first memory storing first output data addressable by the first input data; and a second memory storing second output data addressable by the second input data, wherein the image data controller selectively addresses the first memory with the first input data to access the first output data, and selectively addresses the second memory with the second input data to access the second output data, wherein the first input data is received from an image input device, and wherein the image data controller generates the second input data according to the number of scanned lines counted by the line counter and the number of scanned pixels counted by the pixel counter, thereby addressing a portion of the second output data corresponding to a region of the image indicated by the number of scanned lines and the number of scanned pixels.

6. The medical image output device of claim 5, wherein the first memory and the second memory reside in a common memory device.

7. The medical image output device of claim 5, wherein the imaging module comprises a scanning laser module, and the imaging media comprises radiation- sensitive media, the scanning laser module scanning a laser beam across the radiation-sensitive media to expose pixels on the radiation-sensitive media with exposure values indicated by the first output data and the second output data, thereby forming the visible representation of the image.

8. The medical image output device of claim 1, wherein the image data controller generates the second input data to address a same portion of the second output image data for a plurality of different scan lines.

9. The medical image output device of claim 1, wherein the non-diagnostic portion of the image comprises border regions of the image disposed about a periphery of the diagnostic portion of the image.

10. A medical image output method comprising the steps of: driving an imaging module to form a visible representation of an image on imaging media; and selectively driving the imaging module based on one of first input data corresponding to a diagnostic portion of the image and second input data corresponding to a non-diagnostic portion of the image. wherein the imaging module thereby forms a visible representation of the image that combines both the diagnostic portion and the non-diagnostic portion of the image.

11. The medical image output method of claim 10, further comprising the steps of: storing first output data addressable by the first input data in a first memory; storing second output data addressable by the second input data in a second memory; selectively addressing the first memory with the first input data to access the first output data, and selectively addressing the second memory with the second input data to access the second output data; and selectively driving the imaging module with one of the first output data and the second output data to form a visible representation of the image that combines both the diagnostic portion and the non- diagnostic portion of the image.

12. The medical image output method of claim 11, wherein the first memory and the second memory reside in a common memory device.

13. The medical image output method of claim 1, wherein the imaging module scans a beam of radiation across the imaging media in a plurality of scanned lines, each of the scanned lines including a plurality of scanned pixels, and wherein the method further comprises the steps of: counting a number of the scanned lines; counting a number of the scanned pixels within each of the scanned lines; selectively driving the imaging module based on one of the first input data and the second input data according to the number of scanned lines and the number of scanned pixels.

14. The medical image output method of claim 13, further comprising the steps of: storing first output data addressable by the first input data in a first memory; storing second output data addressable by the second input data in a second memory; selectively addressing the first memory with the first input data to access the first output data, and selectively addressing the second memory with the second input data to access the second output data; receiving the first input data from an image input device; and generating the second input data according to the number of scanned lines and the number of scanned pixels, thereby addressing a portion of the second output data corresponding to a region of the image indicated by the number of scanned lines and the number of scanned pixels.

15. The medical image output method of claim 14, wherein the first memory and the second memory reside in a common memory device.

16. The medical image output method of claim 14, wherein the imaging module comprises a scanning laser module, and the imaging media comprises radiation- sensitive media, the scanning laser module being driven to scan a laser beam across the radiation- sensitive media to expose pixels on the radiation- sensitive media with exposure values indicated by the first output data and the second output data, thereby forming the visible representation of the image.

17. The medical image output method of claim 10, further comprising the step of generating the second input data to address a same portion of the second output image data for a plurality of different scan lines.

18. The medical image output method of claim 10, wherein the non-diagnostic portion of the image comprises border regions of the image disposed about a periphery of the diagnostic portion of the image.

19. An apparatus for practicing the method of any of claims 1-18.