Analog to Digital Converters (ADCs) :Analog to Digital Converters (ADCs)


Analog to Digital Converters (ADCs) :Analog to Digital Converters (ADCs) Output from scintillation camera provides three signals for each gamma ray scintillation effect The X and Y signal represents the location of the gamma ray interaction in the detector The Z signal measures the gamma ray energy


Analog to Digital Converters (ADCs) :Analog to Digital Converters (ADCs) These three signals are analog and must be converted into numbers to be transferred into the computer The camera interface uses two (ADCs) to digitize the X and Y signals. Voltage pulses are converted using a successive approximation technique. The incoming pulse is compared with the largest bit in the digital world to represent the data. If the pulse is larger than this most significant bit, the bit is set to 1.


Analog to Digital Converters (ADCs) :Analog to Digital Converters (ADCs) Each bit in the digital representation, from the largest to the smallest, is tested against the incoming voltage until the last bit has been set. The resulting digital value is the closest digital approximation to the input analog signal. Successive approximation ADCs are very fast, and camera position signals are digitized to an accuracy much finer than that of the image matrix into which de image data is stored.


Analog to Digital Converters (ADCs) :Analog to Digital Converters (ADCs) In modern scintillation camera the computer interfaces directly with the camera, and there is no separate noncomputerized operating console for the camera. In these cameras the X, Y and Z signals are digitized, in addition to other inputs such as electro cardiograms (EKG) used in in gated cardiac studies


Analog to Digital Converters (ADCs) :Analog to Digital Converters (ADCs) ADCs are so fast that there is no loss in storing counts waiting for them to transform electronic pulses into the digital format. Once the digitized information comes through the camera interface, the DMA transmits data directly to its assigned memory location without interrupting the activities of the CPU.


Questions (Imre Beliczay) :Questions (Imre Beliczay) 1. Analog digital converters _______ information digitize 2. X and Y signals represent the _______ of gamma ray interaction in the detector location 3. Z signal measures the gamma ray ____ Energy 4. If the pulse is larger than the most significant bit, the bit is set to __ a. 2 b. 1 c. 1 ½ d. 4 5. In modern scintillation cameras the computer interfaces directly with the _______ camera


Environmental factors for computers :Environmental factors for computers by: Yasnhai Diaz


Quality assurance :Quality assurance Imaging computers required a certain environmental criteria to ensure reliable performance. - temperature -humidity -electromagnetic fields - power - cleanliness


Temperature :Temperature A critical factor in prolonging the life of your computer is the temperature of the components. Components that run hot die young; those that stay cool last a much longer time. Good operating temperature for a PC is about 60 to 75 degrees Fahrenheit.


Humidity :Humidity PCs are not as sensitive to humidity as they are to temperature changes, but they are still affected by it. Computers prefer moderate range of humidity. Keep PC away from places that may get it wet. Also don't use the computer case as a drink holder. Extreme humidity can cause corrosion and condensation in the computer.


Electromagnetic fields :Electromagnetic fields All electronic devices give off electromagnetic emissions. This is radiation that is a byproduct of electrical or magnetic activity. The emissions from one device can interfere with other devices, causing potential problems. Interference can lead to data loss and picture quality degradation on monitors.


Power Supply :Power Supply The power supply is responsible for powering every device in your computer; if it has a problem or is of low quality you may experience many difficulties that you may not realize are actually the fault of the electrical system. Uninterruptible power supply system prevent voltage spikes from damaging the computer.


Cleanliness :Cleanliness Computers operate best when they are used in a clean environment, and when they are cleaned regularly. Dust and dirt create problems with power supplies, circuit boards and in particular with hard drives. Most sensitive areas of imaging computers are protected by air filters over the cooling fans. Air filters should be cleaned monthly.


Questions :Questions List environmental factors for computers. -temperature, humidity, electromagnetic fields, power supplies and cleanliness. 2. Good operating temperature for a PC is about___ to ______ degrees Fahrenheit. - 60 to 75 TRUE/FALSE 3. Interference can lead to data loss and picture quality degradation on monitors. - TRUE 4. Dust and dirt create problems with power supplies, circuit boards and in particular with hard drives. -TRUE 5. Extreme humidity can not cause corrosion and condensation in the computer. - FALSE


Slide 16:THE END


Operating Systems :Operating Systems By Fernando


What is an Operating System? :What is an Operating System? If you have a computer, then you have heard about operating systems. Any desktop or laptop PC that you buy normally comes pre-loaded with Windows XP. Macintosh computers come pre-loaded with OS X. Many corporate servers use the Linux or UNIX operating systems. The operating system (OS) is the first thing loaded onto the computer.


Bare Bones :Bare Bones Not all computers have operating systems. The computer that controls the microwave oven in your kitchen, for example, doesn't need an operating system. It has one set of tasks to perform, very straightforward input to expect (a numbered keypad and a few pre-set buttons) and simple, never-changing hardware to control. Instead, the computer in a microwave oven simply runs a single hard-wired program all the time. All desktop computers have operating systems. The most common are the Windows family of operating systems developed by Microsoft, the Macintosh operating systems developed by Apple and the UNIX family of operating systems. There are hundreds of other operating systems available for special-purpose applications, including specializations for mainframes, robotics, manufacturing, real-time control systems and so on.


What does it do :What does it do At the simplest level, an operating system does two things: It manages the hardware and software resources of the system. In a desktop computer, these resources include such things as the processor, memory, disk space, etc. (On a cell phone, they include the keypad, the screen, the address book, the phone dialer, the battery and the network connection.) It provides a stable, consistent way for applications to deal with the hardware without having to know all the details of the hardware.


What Kinds Are There :What Kinds Are There Real-time operating system (RTOS) - Real-time operating systems are used to control machinery, scientific instruments and industrial systems. An RTOS typically has very little user-interface capability, and no end-user utilities, since the system will be a "sealed box" when delivered for use. A very important part of an RTOS is managing the resources of the computer so that a particular operation executes in precisely the same amount of time every time it occurs. In a complex machine, having a part move more quickly just because system resources are available may be just as catastrophic as having it not move at all because the system is busy. Single-user, single task - As the name implies, this operating system is designed to manage the computer so that one user can effectively do one thing at a time. The Palm OS for Palm handheld computers is a good example of a modern single-user, single-task operating system. Single-user, multi-tasking - This is the type of operating system most people use on their desktop and laptop computers today. Microsoft's Windows and Apple's MacOS platforms are both examples of operating systems that will let a single user have several programs in operation at the same time. For example, it's entirely possible for a Windows user to be writing a note in a word processor while downloading a file from the Internet while printing the text of an e-mail message. Multi-user - A multi-user operating system allows many different users to take advantage of the computer's resources simultaneously. The operating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn't affect the entire community of users. Unix, VMS and mainframe operating systems, such as MVS, are examples of multi-user operating systems.


Questions :Questions All computers have operating systems? All desktops have operating systems? What are the 4 types of operating systems? What is the bare bone of an operating system? Name one company that makes an operating system.


Differentiate between high-level and machine code programs :Differentiate between high-level and machine code programs Arvin Torcuator


High-Level Programming Language :High-Level Programming Language a programming language that is more abstract, easier to use, or more portable across platforms. such languages often abstract away CPU operations such as memory access models and management scope. “high-level language” does not imply that the language is superior to low-level programming language but rather refers to the higher level of abstraction from machine language.


Three models of execution for modern high-level languages: :Three models of execution for modern high-level languages: Interpreted – are read and then executed directly, with no compilation storage. Compiled – are transformed into an executable form before running. There are two types of compilation: Intermediate representations – when a language is compiled to an intermediate representation, that representation can be optimized or saved for later execution without the need to re-read the source file. When the intermediate representation is saved it is often represented as byte code. Machine code generation – some language compile directly into machine code. Virtual machines that execute byte code directly or transform it further into machine code have blurred the once clear distinction between intermediate representation and truly compiled languages. Translated – a language may be translated into a low-level programming language for which native code compilers are already widely available. The C programming language is a common target for such translators.


Machine Code Programs :Machine Code Programs the elemental language of computers, consisting of a stream of 0’s and 1’s. the output of any programming language analysis and processing. instructions at this level are extremely basic and performs only the most rudimentary tasks. assembly language programs are written in short, very specific tasks. simple instructions are followed one at a time to fetch instructions, decide on the operation to be performed, get values from memory, move these values to locations where operations can be performed, and so on.


Machine Code Instructions :Machine Code Instructions the “words” of a machine instructions are patterns of bits with different patterns corresponding to different commands to the machine. Every CPU model has its own machine code, or instruction set. For example: If CPU A understands the full language of CPU B it is said that A is compatible with B. CPU B may not be compatible with CPU A, as A may know a few codes that B does not After you write a program, your source language statements are compiled or assembled into output. This machine code is stored as an executable file until someone tells the computer’s operating system to run it. The computer’s microprocessor reads in and handles a certain number 0’s and 1’s at a time. For example: it may be designed to read 32 binary digits at a time. Because it is designed to know how many bits tell it what operation to do, it can look at the right sequence of bits and perform the next operation. Then it reads the next instruction, and so on.


QUESTIONS: :QUESTIONS: _______ a programming language that is more abstract, easier to use, or more portable across platforms. Answer: High-Level Programming Language _______ are read and then executed directly, with no compilation storage. Answer: Interpreted _______ are transformed into an executable form before running. Answer: Compiled _______ a language may be translated into a low-level programming language for which native code compilers are already widely available. Answer: Translated _______ simple instructions are followed one at a time to fetch instructions, decide on the operation to be performed, get values from memory, move these values to locations where operations can be performed, and so on. Answer: Machine Code Programs


Programming Languages :Programming Languages By Ignacio


Machine-oriented language :Machine-oriented language Information understood by computers is all written in a series of zeros and ones This form of instructions is machine language Instructions at this level are extremely basic and are used to carry out the most basic of features


High-level programming languages :High-level programming languages This form of programming is written in actual words An editor is a program that allows keyboard entry of written material that will become the program Two classifications of high-level languages are: interpreted and complied An interpreted language program is carried out line by line Complied language is translated all at one time into machine language


Beginners All-purpose Symbolic Instruction Code :Beginners All-purpose Symbolic Instruction Code BASIC is an example of an interpreted language To write a program in BASIC the lines of instructions are numbered and preformed according to that line number BASIC is used in Nuclear Medicine to perform elementary processing functions quickly


FORTRAN :FORTRAN Formula translation is a powerful language for performing computations dealing with large amounts of numeric information and complex calculations FORTRAN is widely used in nuclear medicine systems for all types of applications When writing a FORTRAN program the lines that define variables, input, and print data must deal with strict syntax rules for FORTRAN to understand them


Other high-level programming languages :Other high-level programming languages COBOL: used to permit easy handling of textual data with relatively basic requirements for complex numeric calculations Pascal: uses a top-down logic of programming, in which the main objectives are defined as modules and details are in each module C: uses a wide variety of functions to perform many tasks that with other languages can be performed only with assembly code routines


Questions :Questions Machine language is written how? As a series of zeros and ones Two classifications of high-level languages are what? interpreted and complied languages BASIC is an example of what language? An interpreted language What program is widely used in nuclear medicine? FORTRAN Name some other high-level programming languages. COBOL, Pascal, and C


Digital Storage of Images :Digital Storage of Images By Chinyere Millington


Digital Image Storage :Digital Image Storage Capturing images from the scintillation camera first requires the conversion of analog x, y, and z pulses into digital information. Digitization is accomplished by the analog-to-digital converters (ADCs) to provide a quantitative location of a scintillation event.


Digital Image Storage :Digital Image Storage The digital location information locates the appropriate pixel into which the gamma event can be recorded. Scintillation events are stored in the proper pixel locations until the acquisition time has elapsed, or until the selected number of counts (count density) has been reached.


Digital Image Storage :Digital Image Storage , Therefore an image is represented as an array or matrix of pixels. Most computer systems allow for a selection of matrices. Eg 64*64, 128*128, 256*256, or 512*512 matrices. Figure 1: An image — an array or a matrix of pixels arranged in columns and rows.


Digital Image Storage :Digital Image Storage The image density for each pixel is determined by the number of gamma-ray counts stored within a pixel. A pixel able to contain only 1 byte of information allows storage of 256 different numbers, ie 0 to 255.


Digital Image Storage :Digital Image Storage If the counts per pixel reach a maximum of 255, pixel rollover may occur, where pixel value goes back to 0. On some systems pixel rollover is prevented by retaining the maximum however, counts above 255 are not recorded and quantitative information is lost. Figure 2: Each pixel has a value from 0 (black) to 255 (white). The possible range of the pixel values depend on the colour depth of the image, here 8 bit = 256 tones or greyscales.


Digital Image Storage :Digital Image Storage On some computers systems dynamic, gated, or SPECT image files must be stored in sequential data blocks. If many image files have to be acquired, there may not be enough sequential data blocks of available storage, and data acquisition will not be allowed until the necessary space is available. Significant file space might be required when using multidetector SPECT cameras.


Digital Image Storage :Digital Image Storage Most newer computer systems do not require continuous blocks of space. Information from one image file can be distributed and stored into many groups of blocks spread throughout the system.


Digital Image StorageQuestions :Digital Image StorageQuestions Digitization of scintillation camera images is accomplished by ----------. Answer: ADCs (analog-to-digital converters) True/ False A pixel able to contain 1 byte of information allows for storage of 256 different numbers. Answer: true Define pixel rollover. Answer: Pixel rollover occurs when the maximum counts per pixel is reached, allowing pixel value to go back to 0.


Digital Image Storage Questions :Digital Image Storage Questions True/False Computer systems which do not require storage in continuous blocks cannot acquire large image files until appropriate space is available. Answer: false - systems that require data be stored in continuous (or sequential) data blocks, cannot acquire images until the necessary space is available. An image is represented as an ------------------- of pixels. Answer: array or matrix