Imaging

DIP, Health Informatics, PACS

DIP

Digital Image Processing

PACS

Picture Archiving & Communication Systems

Image processing

manipulating an image to enhance the image/extract useful information from it

Analog

Continuous-tone images produced by analogue optic + electronic devices that vary continuously over all dimensions of the image

For an analogue image to be processed or displayed by a computer, first its converted into a computer-readable form (digital format)

Screen/Film Radiography

process of taking image and processing for result

A digital image

matrix of many small bits- pixels (picture elements)

Each pixel is represented by a numerical value

The pixel value is related to the brightness/colour we see when the digital image is converted into an analogue image for display and viewing

DIP

use of a digital computer to process digital images through an algorithm

development of DIP affected by

-Computers development
-Mathematic algorithms development
- demand for a wide range of applications in environment, agriculture, military, industry and medical science

Computer language

Binary: 1 or 0 (on or off, black or white)

Bit: binary digit

limitations- the range of values that can be written with a specific number of bits is limited

Binary values-

The number of bits that have been made available in the digital system to represent each pixel in the image

4 bits- limited to 16 different values (brightness levels or shades of grey)

Digital Image Post-Processing

Film-based radiology is now obsolete,
all imaging modalities produce digital images that can be post-processed/ manipulated with relative ease

Main aim in rad imaging is to alter/change an image to enhance diagnostic interpretation

Pre-Processing vs post-Processing

pre-processing operations apply appropriate corrections to the raw data

Post-processing intends to change the image contrast, reduce image noise and enhance the sharpness to enhance diagnostic interpretation

post-processing varies between modalities

CR and DR

-Grey scale processing
-Spatial filtering
-Dynamic range control

Fluoroscopy

-Digital subtraction angiography (DSA)
-Subtraction of images out of a sequence
-Grey scale processing
-Temporal frame averaging
-Edge enhancement

CT

-Image plane reformatting
-Windowing
-Region of interest (ROI)
-3D volume rendering
--Multi-planar reformatting (MPR)
-Maximum Intensity Projection (MIP)

Imaging Processing Algorithms

Point processing operations e.g., grey scale processing (windowing, image subtraction, and temporal averaging)

Local processing operations (such as spatial filtering, edge enhancement, and smoothing)

Global operations such as the Fourier Transform (FT)

Grey scale processing

Contrast stretching, Contrast enhancement, Histogram modification, Histogram stretching + Windowing (most commonly used across all modalities)

LUT

LUT= numerical info/ enhancing image contrast
Lookup tables are pre-calculated data (numeric info) stored in the computer: used to substitute new values for each pixel during the processing

Dynamic Range

Digital radiographic detectors have wide exposure latitude
The latitude (or dynamic range) is the range of receptor exposures over which an image and contrast will be formed

Exposure index

EI is the measure of the amount of exposure received by the IR
-provides useful feedback to the rad about the accuracy of the exposure utilised
-Vendor specific but there is an international standard for EI

Image Windowing

windowing is a way of adjusting the brightness and contrast of an image to visualise specific anatomy

selecting a segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of grey) range from white to black

Spatial Frequency Processing

Series of different algorithms used to post-process the image:

Edge enhancement-sharpness
Unsharp Masking- uses DSA to sharpen
Smoothing/blurring- reduce noise/graininess

Geometrical Processing

Techniques allowing user to change the position/orientation of pixels in the image rather than the contrast/brightness of the pixels--> enhanced diagnosis

Image Reconstruction (CT)

-Multiplanar Reformatting (MPR)
-Maximum Intensity Projection (MIP)
-Volume Rendering/3D Reconstruction

Digital Breast Tomosynthesis - DBT

Imaging technique that allows a volumetric reconstruction of the whole breast from a finite number of low-dose two-dimensional projections obtained by different X-ray tube angles

Why health informatics?

Healthcare generates a vast amount of data that needs to be used, organised, stored, communicated and managed efficiently

Data

facts, observations or measurements (e.g., pts BP is 120/80mmHg)

Information

the relationships between data (eg pt's BP is considered high as its been greater than 135/95mmHg on 3 separate occasions)

Knowledge

application of information (eg pts BP has now measured 125/85mmHG + is now under control)

Digital data

Computers only work with digital data.
info 1st turned into a digital signal either: 'on' or 'off'
computer processor -collection of switches
Transistors= switches which can either be on or off
Info from input devices must be digitised so the info can be processed.

Digital Data Organisation - Databases

An organised collection of data stored and accessed electronically from a computer system/A Database Management System (DBMS) is the software that interacts with end users, applications, and the database itself to capture and analyse the data

Information Sharing

-Internet
-A global system of interconnected computer networks to communicate between networks and devices

Computer Networks

Allows different computers to share resources and exchange information

Info systems

An integration of components for collection, storage and processing of data

Health Information Systems- HIS

System designed to collect, store, manage and transmit healthcare data
tasks such as booking in pts + appointment scheduling
Manage a pt's electronic record + Analyse data to support healthcare policy decisions

Data analytics

Help gather, compile and analyse health data to help manage population health, reduce healthcare costs and improve patient care

Collaborative care

When patients need treatments from different healthcare providers, exchange of information between HIS, allow healthcare facilities to access common health records

cost control

Using digital networks to exchange healthcare data creates efficiencies and cost savings

Population health management

Aggregate pt data, analyse it and identify trends in populations. Clinical decision support systems can use data to help diagnose individual patients and treat them

Health Information Systems (HIS)

Main hospital system where pt is registered and is connected to all other systems. Manages all pt data

Radiology Information System (RIS)

System for the electronic management of imaging departments. Manages pt scheduling, resource management, examination performance tracking, reporting, results distribution etc.

Picture Archiving and Communication System (PACS)

A system connected to various imaging modalities that allows storage, viewing, manipulation and sharing of diagnostic images and reports

Electronic Health Record (EHR)

A longitudinal record of a patient's health and healthcare from cradle to grave (it is not associated with just one institution)

Electronic Patient Record (EPR)

A longitudinal record of a pts heath provided mainly by one institution (typically this relates to the healthcare provided by 1 hospital or a GP)

Electronic Medical Record (EMR)

An electronic record of an episode of medical care, whether inpatient, outpatient, A&E etc.

Interoperability

Characteristic of a system whose interfaces are completely able to work with other systems, at present or the future, in either implementation or access, without restrictions

Interoperability standards

Integrating the Healthcare Enterprise (IHE)-non-profit organisation: improve the way computer systems in healthcare share information

use of established standards such as DICOM and HL7 to address specific clinical needs in support of optimal patient care

HL7 (Health Level 7)

International standards for transfer of clinical and administrative messaging data between software applications used by various healthcare providers- ‘layer 7’ in the OSI model

DICOM

Digital Imaging and Communications in Medicine- international standard to transmit, store, retrieve, print, process and display medical imaging information (medical jpeg/png)

Unique Identifiers (UID)

An identifier that is guaranteed to be unique among all identifiers used for those objects (in a database) and for a specific purpose

Terms, Codes and Classifications

Healthcare organisations often use different software and different terminologies/terms to record health information

E.g., 1 doc records a 'chest infection', other recorda it as 'upper-respiratory infection' so the 2 systems might not be able to match the info
needs to be a commonality to the way illnesses are described/ An agreed set of terms to describe illnesses, pathologies and conditions

SNOMED CT (Systemised Nomenclature of Medicine – Clinical Terms)

A systematically organised computer processable collection of medical terms providing codes, terms, synonyms, definitions used in clinical documentation and reporting
Considered to be the most comprehensive multilingual clinical healthcare terminology in the world- Provides clinical IT systems a single shared language, which makes exchanging information between systems easier,

ICD 11 (International Classification of Diseases version 11)

medical classification list by World Health Organization (WHO)
contains codes for diseases, signs and symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or diseases

Terminology server

A terminology server transforms the way in which data is captured, shared and analysed across healthcare, meaning more effective, efficient and safer decision-making

Clinical Decision Support System (CDSS)

A health info tech system- provides clinicians with knowledge and person-specific info, intelligently filtered/presented at appropriate times, to enhance health and health care

Links health observations with health knowledge to influence health choices by clinicians for improved health care

Picture

any medical image acquired through the various imaging modalities (DR, fluoro, US, CT, MRI, RNI, mammo etc.)

Archiving

storage of images (short + long term) via image archive servers, VNA or cloud based solutions

Communication

images need to be shared and visualised both internally within the organisation (hospital) and externally with other organisations

System

All the various components are connected, user can access the images via an application program

PACS

A computerised means of replacing the roles of conventional radiological film: images are acquired, stored, transmitted, and displayed digitally/allows the digital images generated by imaging modalities to be visualised, shared and stored. Revolutionised the practice of radiology/medical imaging + rad profession

VNA and Cloud Storage

Most healthcare organisations looking for a new PACS installations or upgrades will opt for a VNA and/or cloud storage solutions

Vendor Neutral Archive

Application that stores medical images in a standard format with a standard interface. Images stored in VNA can be accessed through any workstation, irrespective of the vendor

Advantages of VNA

PACS features can often vary between individual vendors, even if images are stored in the standard DICOM format. Despite the brand of software, VNA’S open on anything and file can be accessed on anything

VNA function

When image is stored in PACS, several ‘tags’ are added which vary between vendors, so final medical image file may open on other applications

VNA ‘uncouples’ the pure DICOM image from the surrounding fluff, ensuring that the image is standardised and compatible with all workstations

VNA allows healthcare providers to migrate from 1 vendor to another without worrying about imaging data loss

Web based PACS VS Client based PACS

systems used by rads

HIS, RIS + PACS

Display Moniter

Flat panel liquid crystal displays (LCDs) are the main types of monitors used offering high spatial resolution, low distortion, high luminance and high contrast ratios

Medical monitors

must allow custom measurement and adjustment of their colour and grayscale tonal representations to allow for calibration towards recognised reference standards (DICOM GSDF)

DICOM viewer

Within a hospital environment, PACS workstations are utilised to review radiographic images and examinations/ essential to view dicoms as they wont open on MACS/WINDOWS

Managing PACS

-Radiology Systems Manager
-PACS Manager
-PACS Administrator
-IT Support
-Vendor/Service Provider Support