Lecture 7_Digital Image Acquisition.pptx

for information management team

1. ECU-M 213: HEALTH INFORMATICS Topic: Digital Image Acquisition By: Patience A. Jaffu Bsc Maths , CSC( Mak 2012) and MHI( Mak 2020)

2. Digital Imaging Definition: Computerized management of imaging data and related information, extending from patient demographic information and referral data to reports, statistics and image diagnosis, review and distribution through tele -radiology platforms Digital imaging offers many advantages over conventional film based imaging, the most compelling/ of which is the ability to store, retrieve, distribute and review images at any time and in any location which is appropriately networked.

3. PACS/RIS Digital images are typically managed in a dedicated image network and database known as a picture archiving and communications system (PACS), whereas all other patient information is typically recorded in a Radiology Information System (RIS). Proper integration of the RIS and PACS can provide productivity improvements in radiology departments resulting in, for instance, faster study turnaround times for patients and clinicians.

4. PACS/RIS While it is entirely feasible to organize and manage a digital imaging service using a PACS alone, the absence of a RIS will mean significant limitations. Lack of integration with hospital information systems Difficulties with the consistency of patient identification Difficulties in the management of multimodality and multiservice imaging data over time Patient and room scheduling Radiology workload balancing Automatic scheduling of patient lists on imaging equipment due to variable time required for the examination, insurance authorization verifications etc

5. PACS/RIS It is very difficult to manage image data for the same patient across more than one imaging center without a RIS to match patient and image data and without the ability to merge the patient image data. RIS allows for much more effective design of workflow, improves efficiency and reduces the chance of redundant data entry, duplicates and incorrect patient data entry.

6. DICOM Digital Imaging and Communications in Medicine is the standard for the communication and management of medical imaging information and related data. It consists of a standard image format as well as a network communications protocol. Compliance with this standard enables an open architecture for imaging systems, bridging hardware and software entities and allowing interoperability for the transfer of medical images and associated information between disparate systems.

7. DICOM DICOM format includes a File header information relevant to the image, such as matrix size or number of rows and columns, pixel size, and grayscale bit depth, as well as information about the imaging device and technique, Patient demographic data such as name, date of birth, and so on, are also included in the image header

8. Prior to DICOM The acquisition of digital image data and relevant information was extremely difficult, often requiring separate hardware devices and software programs for different vendors’ products, and even for different models of devices made by the same manufacturer. Most of the major manufacturers of imaging devices currently comply with the DICOM standard, thus greatly facilitating an open systems architecture consisting of multivendor devices.

9. Prior to DICOM Manufacturers developed practical solutions for transferring, storing and remotely displaying images electronically. These were initially in a proprietary form, and different systems would not communicate (or were not interoperable). One could, for example, equip an entire hospital with X ray, computed tomography (CT) and magnetic resonance imaging (MRI) acquisition devices as well as a PACS and review workstations, but only if everything was purchased from one vendor, or if custom interfaces were developed for each acquisition device.

10. DICOM This approach was neither scalable nor affordable , and the need to develop open standards to promote interoperability between equipment from different manufacturers quickly became acute. A key feature of DICOM that distinguished it from other standards was the use of evolving computer networks and Internet technology and protocols. Today, the use of DICOM is ubiquitous, and no manufacturer would be able to market a device that did not conform to the standard.

11. DIGITAL IMAGE ACQUISITION Image acquisition is the first point of data entry into a PACS, and as such, errors generated here can propagate throughout the system, adversely affecting clinical operations.

12. Typical PACS Workflow As already noted, a PACS should interface with both the HIS and RIS. Typically, the patient is identified in the HIS and an order created that is sent to the RIS via an HL7 protocol (HL7 and its members provide a framework and related standards for the exchange, integration, sharing, and retrieval of electronic health information). Orders will go to the imaging device via the DICOM protocol and the image is created in DICOM format and sent to the PACS server. Images are stored on the image archive, and the reading physician (radiologist) is notified of a pending study. The study is then read by the radiologist at a computer workstation using high-resolution monitors and viewing software available from a variety of different vendors.

13. Image Processing and Image Analysis Image Processing: Image processing comprises a wide range of methods that act on an image to generate another image. The aim of the changes made by these methods is generally to improve the visibility of the characteristics and details of the images , or to facilitate the analysis of these images, or even to improve image quality for printing purposes . Image Analysis Image analysis makes it possible to obtain digital data from images, using a combination of image processing techniques and measurements. These quantified data can then be analysed statistically for decision-making purposes and graphic representations.

14. Image Compression Image compression is a process which on implementation gives output which is often smaller in size but looks similar to the original. Image compression involves a process to give out a compact representation of an image, in turn reducing the image storage and transmission requirements. There is a limit beyond which an image can not be compressed more without loosing information. It allows modifying the bit structure of data in a way that consumes a minimum amount of space on the disk. It also helps to send data or files quickly over the network. Despite the increase in capacities of computer hard discs and bandwidths for network, image compression is becoming necessary to meet growing needs for storage and transmission.

15. Types of Image Compression Lossy compression: A  compression  technique that decompresses data back to its original form without any loss. The decompressed file and the original are identical. Lossy compression is commonly used to compress multimedia data such as audio, video, and images. It is used in applications such as streaming media and internet telephony. Even though it causes data loss and degradation, lossy compression is used in data communication to reduce transmission time and to reduce storage space.

16. Types of Image Compression 2. Lossless Compression Techniques It is also known as entropy coding as it uses decomposition techniques to minimize loopholes/redundancy. The original image can be perfectly recovered from the compressed image, in lossless compression techniques. These do not add noise to the signal.

17. Lossless compression Lossless compression reduces the original data size but it does not minimize the quality. Lossless compression rewrites the original file data in an efficient manner. Lossless compression does not reduce the quality of the original data. Therefore, the resulting file has some amount of storage.

18. Compression is achieved by the removing one of the following redundancy: 1. Coding 2. Inter-pixel 3. Perceptual Read more about these

19. Descriptors of digital image quality Explain the following terms and how they affect image quality Detective Quantum Efficiency Spatial Resolution and Contrast Resolution Image Segmentation Contrast enhancement Assignment for presentation on: Next week : Test will be in 2 weeks time