Microdensitometry using a slide projector

We have evaluated a simple microdensitometer concept by Stanton et al. for measurements of dose distributions with high spatial resolution. A magnified image of the film is created by a slide projector and its light intensity measured with a photomultiplier with a small aperture. The projector is placed on a movable stage to allow scanning of the film. A resolution of 17 micron (full width at half maximum of the line spread function) was achieved in the film plane.     

Automatic film-badge reading system for personnel dosimetry

A system has been developed to rapidly read and evaluate film badges worn by personnel occupationally exposed to ionising radiation. The developed films are inserted one at a time into the film badge reader and an identification number entered on a keyboard. An optoelectronic system measures the light transmission through the significant film areas and passes this information to a minicomputer for dose calculation and record keeping. The calculated dose is fed back to the reader for display. A paper-tape punch may be used with the film badge reader to allow subsequent offline computer processing. This system offers considerable time saving over more conventional manual techniques.     

Preprocessor Adapts Cardiovascular Signals to a Minicomputer

A laboratory-developed analog signal processor, driven by a conventional polygraph recorder and associated signal conditioning devices, provides automatic heart beat-by-heart beat preprocessing of various cardiovascular functions for input to a laboratory-type minicomputer. The technique of preprocessing individual functions, integrated with the minicomputer system which includes an A/D converter and teletype as input-output peripherals, provides a low-cost data acquisition and reduction system for the on-line computation and analysis of cardiovascular functions in experimental research applications. Such preprocessing more efficiently uses the minicomputer's memory to handle large amounts of information since the digitized data is in the form of one data sample, per function, per heart beat. Preprocessing analog data provides a low density data format and simplified software programs that are ideally suited for the utilization of a minicomputer in this on-line application.     

Mining knowledge for HEp-2 cell image classification

HEp-2 cells are used for the identification of antinuclear autoantibodies (ANAs). They allow for recognition of over 30 different nuclear and cytoplasmic patterns, which are given by upwards of 100 different autoantibodies. The identification of the patterns has recently been done manually by a human inspecting the slides with a microscope. In this paper, we present results on the analysis and classification of cells using image analysis and data mining techniques. Starting from a knowledge acquisition process with a human operator, we developed an image analysis and feature extraction algorithm. The collection of the dataset was done based on an expert's image reading and based on the automatic extracted features. A dataset containing 132 features for each entry was set up and given to a data mining algorithm to find out the relevant features among this large feature set and to construct the classification knowledge. The classifier was evaluated by cross validation. The results gave the expert new insights into the necessary features and the classification knowledge and show the feasibility of an automated inspection system.     

A comparative study of mobile electronic data entry systems for clinical trials data collection

PURPOSE: To determine the speed, accuracy, ease of use, and user satisfaction of various electronic data entry platforms for use in the collection of mammography clinical trials data. METHOD AND MATERIALS: Four electronic data entry platforms were tested: standalone personal digital assistant (PDA), Tablet PC, digitizer Tablet/PDA Hybrid (DTP Hybrid), and digital pen (d-pen). Standard paper data entry was used as control. Each of five radiologist readers was assigned to enter interpretations for 20 screening mammograms using three out of the five data entry methods. Assistants recorded both start and stop data entry times of the radiologists and the number of help requests made. Data were checked for handwriting recognition accuracy for the d-pen platform using handwriting verification software. A user satisfaction survey was administered at the end of each platform reading session. RESULTS: Tablet PC and d-pen were statistically equivalent to conventional pen and paper in initial data entry speed. Average verification time for d-pen was significantly less than secondary electronic data entry of paper forms (p-value <0.001). The number of errors in handwriting recognition for d-pen was less than secondary electronic data entry of the paper forms data. Users were most satisfied with Tablet PC, d-pen, and conventional pen and paper for data entry. CONCLUSIONS: Tablet PC and d-pen are equally fast and easy-to-use data entry methods that are well tolerated by radiologist users. Handwriting recognition review and correction for the d-pen is significantly faster and more accurate than secondary manual keyboard and mouse data entry.     

Voice-activated retrieval of mammography reference images

We undertook this project to integrate context sensitive computer-based educational and decision making aids into the film interpretation and reporting process, and to determine the clinical utility of this method as a guide for further system development. An image database of 347 digital mammography images was assembled and image features were coded. An interface was developed to a computerized speech recognition radiology reporting system which was modified to translate reported findings into database search terms. These observations were used to formulate database search strategies which not only retrieved similar cases from the image database, but also other cases that were related to the index case in different ways. The search results were organized into image sets intended to address common questions that arise during image interpretation. An evaluation of the clinical utility of this method was performed as a guide for further system development. We found that voice dictation of prototypical mammographic cases resulted in automatic retrieval of reference images. The retrieved images were organized into sets matching findings, diagnostic hypotheses, diagnosis, spectrum of findings or diagnoses, closest match to dictated case, or user specified parameters. Two mammographers graded the clinical utility of each form of system output. We concluded that case specific and problem specific image sets may be automatically generated from spoken case dictation. A potentially large number of retrieved images may be divided into subsets which anticipate common clinical problems. This automatic method of context sensitive image retrieval may provide a “continuous’; form of education integrated into routine case interpretation.     

Microcomputer assistance in clinical monitoring of intracranial pressure

Intracranial-pressure (i.c.p.) monitoring has been shown to provide valuable information in the care of patients suffering acute head injury. Continuous recording of i.c.p. is essential due to the rapidly changing characteristics that are encountered, but this produces an overwhelming quantity of data when performed for several days. Methods of data reduction are therefore desirable to aid identification of significant features, and may even reveal aspects of the i.c.p. which are not apparent from the raw data. This paper describes a bedside microcomputer-based monitoring system which automatically acquires i.c.p. data, and periodically compresses them into histograms of pressure. The histograms are displayed to the nursing staff. The microcomputer forms one limb of a distributed computer network which centralises major computing resources on a minicomputer. Both primary and processed i.c.p. data are transmitted to the minicomputer for storage and offline investigation.     

A liquid ionisation detector for digital radiography of therapeutic megavoltage photon beams

Experiments with an ionisation detector were performed in order to determine whether it was possible to obtain high energy photon beam images for radiotherapy treatment verification. A small prototype detector with a field of view of 78 mm X 78 mm and constructed from printed circuit boards was used. The imaging area was a matrix ionisation chamber, filled with air or liquid (2,2,4-trimethylpentane). A minicomputer was used to control the data acquisition electronics and to reconstruct and restore the images. The images were displayed on a viewing console for computed tomography images. The liquid filled detector with a front-rear board separation of 1.0 mm gave the best results. The spatial resolution was about 3.8 mm with a density resolution of 0.5% for a data acquisition time of 120 s. Comparison of the liquid detector images with corresponding metal screen-film detector images showed that the image qualities were the same. An important advantage of the ionisation detector image is that grey scale modification, sharpening and smoothing by digital processing can easily be performed.     

Computer analysis of frequency spectrum of a phonothyreogram

An analysis of phonothyreograms and phonocardiograms was made with the aid of an ND minicomputer and a CYBER 73 computer system using an electrocardiogram signal as a reference time signal. Programs were written to estimate the power spectral density function of these signals. In patients with Graves' disease and those with nodular goiter the intrinsic thyroid murmur was found to differ from the sound transmitted from the heart in healthy subjects by a large contribution of frequencies in the 250–750 Hz range, this factor being particularly pronounced in patients with Graves' disease.     

Impact of digital radiography on clinical workflow

It is commonly accepted that digital radiography (DR) improves workflow and patient throughput compared with traditional film radiography or computed radiography (CR). DR eliminates the film development step and the time to acquire the image from a CR reader. In addition, the wide dynamic range of DR is such that the technologist can perform the quality-control (QC) step directly at the modality in a few seconds, rather than having to transport the newly acquired image to a centralized QC station for review. Furthermore, additional workflow efficiencies can be achieved with DR by employing tight radiology information system (RIS) integration. In the DR imaging environment, this provides for patient demographic information to be automatically downloaded from the RIS to populate the DR Digital Imaging and Communications in Medicine (DICOM) image header. To learn more about this workflow efficiency improvement, we performed a comparative study of workflow steps under three different conditions: traditional film/screen x-ray, DR without RIS integration (ie, manual entry of patient demographics), and DR with RIS integration. This study was performed at the Cleveland Clinic Foundation (Cleveland, OH) using a newly acquired amorphous silicon flat-panel DR system from Canon Medical Systems (Irvine, CA). Our data show that DR without RIS results in substantial workflow savings over traditional film/screen practice. There is an additional 30% reduction in total examination time using DR with RIS integration.     

Mini-micro-mainframe computer marriage: Combining technologies in a radiology results reporting system

The minicomputer-based information system in the Department of Radiology at the Medical College of Georgia Hospital and Clinics was placed in service in February, 1982. This system represents a sizable investment in minicomputer hardware in addition to more than 6 years of software customization. One serious deficiency in the original system was the lack of a radiology results reporting facility. Several options were considered to provide the department with this capability. The most obvious option was retiring the existing system and replacing it with one of a number of commercial products already offering results reporting. In-house development of a reporting facility lent itself more readily to microcomputers than to the existing minicomputer system. Due to system customization, economic and time constraints, it was decided to merge an in-house developed microcomputer-based report module into our existing minicomputer system. The minicomputer was able to communicate with and transfer files to and from both micro and mainframe systems. Combining technologies allowed us to continue taking advantage of our sizable investment in money, time, and customization while providing a microcomputer-based report module. Radiology reports are now typed on microcomputer word processors and bulk transferred to the minicomputer. The minicomputer provides access to both unapproved and approved reports on system terminals throughout the department. It also enhances reports by merging patient demographics and registration information. Using existing communications facilities to the hospital mainframe system, reports are provided throughout the institution.     

Fully 3D Monte Carlo reconstruction in SPECT: a feasibility study

In single photon emission computed tomography (SPECT) with parallel hole collimation, image reconstruction is usually performed as a set of bidimensional (2D) analytical or iterative reconstructions. This approach ignores the tridimensional (3D) nature of scatter and detector response function that affects the detected signal. To deal with the 3D nature of the image formation process, iterative reconstruction can be used by considering a 3D projector modelling the 3D spread of photons. In this paper, we investigate the value of using accurate Monte Carlo simulations to determine the 3D projector used in a fully 3D Monte Carlo (F3DMC) reconstruction approach. Given the 3D projector modelling all physical effects affecting the imaging process, the reconstruction problem is solved using the maximum likelihood expectation maximization (MLEM) algorithm. To validate the concept, three data sets were simulated and F3DMC was compared with two other 3D reconstruction strategies using analytical corrections for attenuation, scatter and camera point spread function. Results suggest that F3DMC improves spatial resolution, relative and absolute quantitation and signal-to-noise ratio. The practical feasibility of the approach on real data sets is discussed.     

Automatic read-out device for ultraviolet-radiation polymer-film dosimeters

An automatic device for measuring the optical absorbance of polymer film used as an ultravioletradiation dosimeter is described. The automated mechanics are based on a commercial slide projector. The ultraviolet radiation is generated by a tungsten quartz-halogen bulb. The optical absorbance is determined by analogue logarithmic circuitry and the resultant value displayed on a digital panel meter. A digital printer or paper-tape punch may be used for hard-copy output. An uncertainty in measurement of 1% is obtained. The device temperature stability is such that this uncertainty can be maintained for analogue circuit temperatures of 20–40°C.     

Generation of pseudorandom numbers

Computational studies requiring the generation of pseudorandom numbers are becoming increasingly common. These include Monte Carlo methodologies and studies which require the addition of "random" noise to more structured data. Although well-established random number generators exist, many of these are not suitable for implementation on micro- or minicomputer systems. An algorithm for an additive generator that can be used on any computer system is described. The performance of this algorithm as implemented on a microcomputer system is discussed. Extensive testing of the statistical behavior of the resulting number sequence was performed. The algorithm appears to be an appropriate one for a variety of applications.     

Clinical assessment of Hokkaido University PACS

The paper describes the hardware and software used in the Hokkaido University picture archiving and communication system (HUPACS), which has been in use for the past two years. An evaluation of the system is also included. Fuji computed radiography completely replaces conventional X-ray radiographs, and 10∶1 data compression is routinely employed. The PACS LAN is connected to the hospital information system through the main-frame computer and it is linked, not only to the radiology department, but also to the outpatient clinics. Image data have been steadily stored in the optical disc library, which contains more than 200 000 images. The original image can be accessed within 1 min. Image quality on a cathode ray tube (CRT) is clinically acceptable. Nevertheless, the transfer time of a newly made image is prolonged in some cases, during periods of heavy usage of the system. During scheduled radiology conferences, image reading tends to take more time on a CRT than on film. An improvement in the ease of operation of the workstations is necessary for full acceptance of CRT diagnoses. Generally speaking, however, HUPACS is working well and is appreciated by most of the clinicians.     

An interactive computer based editing system for physiological data

A prerequisite to the automatic analysis of biological data of all kinds requires that a considerable degree of pre-processing be performed to enhance interesting features and remove artefacts.

This paper describes an interactive computer based system which allows efficient semi-automatic preprocessing by means of a light pen. The system itself is at present implemented on an IBM 1800 computer, with 16K words of core, but given the necessary peripherals, could be made available on a much smaller machine.     

A Fortran program for fast and compact processing of clinical radiotherapy data

A set of Fortran IV programs have been developed to enable a patient registry to operate on a minicomputer of a type frequently used for treatment planning within radiotherapy departments. The system is both comprehensive and flexible, allowing the efficient storage of clinical data in the form of coded units. The coding format used enables inexperienced operators to enter, or extract data from the system with the minimum of keyboard operations.     

人体器官的计算机三维重建及显示

本研究应用国内计算机的设备条件,采用体素表示的表面显示法,对人体肾脏、颅及腰椎的CT图象进行了计算机三维重建和显示。对新鲜离体肾脏标本先行包埋、低温冰冻,横断连续切割和撮影,然后再行轮廓描绘并将图象输入计算机;另外选择颅和腰椎横断面的CT图象,同样输入机内。在Vax-11/730主机,S-600图象处理系统下,用FORTRAN 77编制成软件包,实现在彩色监视器的屏幕上,对上述器官进行了三维重建和显示。重建后的器官可按需要进行不同角度的旋转、剖割和透明处理。图象逼真,富有立体感。本研究为解剖学的教学和科研,为CT诊断等提供了一种新颖的、有价值的显像手段。     

Tomogram reconstruction in desired plane based on serial tomograms

Computer synthesis of an image from tomograms is described. Several ultrasonic cardiograms are taken at every 5 or 2.5 mm from the anterior chest wall, digitized by a flying-spot-scanner and stored on a magnetic disk. Looking at a border-lined tomogram displayed on a CRT, the operator specifies the cross section that he wants displayed. A minicomputer retrieves from the disk the data corresponding to the desired section and displays the sectional image on the CRT. A feature of the computer synthesis is that the tomogram at any angle can be obtained using 3-dimensional information. The method can therefore display a 2-dimensional echocardiogram at a plane parallel to the chest wall in spite of the proximity of the lungs to the heart.     

A video interface for behavioural recordings with applications

An interface which can transmit information from a TV camera to a minicomputer is described. The interface delivers addresses significant for the position of an animal in an observation arena. These addresses are then treated by a minicomputer assembler program. In our application, the length of visiting (duration), frequency of visits and latency of first visit to a specified field are recorded, together with an activity variable. The high IR sensitivity of the camera makes it possible to record the position of the animal relative to certain environmental objects under conditions of dimmed light.