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At least 199 records · Page 11Linked to original sources
PubMed1992

Knowledge-based decision support for patient monitoring in cardioanesthesia.

An approach to generating 'intelligent alarms' is presented that aggregates many information items, i.e. measured vital signs, recent medications, etc., into state variables that more directly reflect the patient's physiological state. Based on these state variables the described decision support system AES-2 also provides therapy recommendations. The assessment of the state variables and the generation of therapeutic advice follow a knowledge-based approach. Aspects of uncertainty, e.g. a gradual transition between 'normal' and 'below normal', are considered applying a fuzzy set approach. Special emphasis is laid on the ergonomic design of the user interface, which is based on color graphics and finger touch input on the screen. Certain simulation techniques considerably support the design process of AES-2 as is demonstrated with a typical example from cardioanesthesia.

Anesthesia↗
PubMed1992

3-D comparative study of proton vs. x-ray radiation therapy for rectal cancer.

To assess the usefulness of proton beams for treatment of patients with rectal cancer, we have performed comparative 3D treatment planning for proton beam and x-ray beam therapy. Three common x-ray techniques (AP-PA, 3-field, and 4-field box), a proton beam only plan, and a proton boost plan were compared. The plan which would have been treated without the aid of the 3D planning system was also simulated. Dose distributions were analyzed and dose-volume histograms computed for the target volumes and critical normal tissues. Analyses of these plans demonstrate that the proton beam techniques reduce the volume of small bowel irradiated. This may allow higher doses to be delivered to the tumor, with a probable increase in local control, or a reduction in normal tissue complications probability. All the plans developed with the 3D planning system treated significantly less bowel than the one planned without it.

Aged↗
PubMed1992

Computer systems and mechanical tools for stereotactically guided conformation therapy with linear accelerators.

An integrated system for fractionated, stereotactically guided conformation radiotherapy has been developed. The system components are a stereotactic fixation system that can be used each treatment day, a localization, and positioning unit that can be used during x-ray computer tomography, magnetic resonance imaging, positron emission tomography, and radiographical examinations as well as for treatment. Conformal precision radiotherapy is planned with a new three-dimensional treatment planning system (Voxel-Plan-Heidelberg) which comprises, among others options, a three-dimensional image correlation procedure as well as routines for the calculation of coplanar and non-coplanar irradiations with irregularly shaped fields. Two different multi-leaf collimators have been designed for precision radiotherapy in the head and neck region. A manual multi-leaf collimator is used for irradiations with stationary beams or for moving beam treatments with invariable irregularly shaped fields. This collimator system is now being used for patient treatments. The design of a computer controlled multi-leaf collimator unit for multiple fixed field irradiation techniques is discussed. All system components are aimed at conforming dose distributions for fractionated radiotherapy treatments to the target to improve sparing of adjacent normal tissues, and at achieving a sufficient geometrical accuracy in the dose application.

Computer Systems↗
PubMed1977

Radiotherapy treatment planning using the ACTA-scanner.

Computerized tomography is useful in radiotherapy treatment planning in the following ways: (1) Its image provides the most accurate possible contour of the patient and demonstrates the internal structures in their proper relation to each other. (2) The tumor and its extension are accurately demonstrated. (3) Corrections for tissue heterogeneities can be accomplished in one of two ways, either by arbitrary assignment of densities to tissues or by direct scanning with a therapy source. This latter procedure is under investigation. (4) The computer can be programmed to demonstrate summations of dose delivered from multiple fields.

Dose-Response Relationship, Radiation↗
PubMed1992

EEG-brain mapping. A method to optimize therapy in schizophrenics using absolute power and center frequency values.

In this study EEG-spectral parameters like mean alpha-power values and center frequency values are computed as maps and compared using significant probability mapping. The parameters are used to describe changes of the functional state of the brain after neuroleptic depot injection (Haldol-Decanoate) in schizophrenic patients. The absolute alpha-power increased significantly (p < 0.01), especially within the first week after injection mostly in the left hemispheric regions. The center frequency decreased most significantly (p < 0.02) between the first and second week after haldol depot injection at the right occipital regions. Both parameters are efficient to describe functional changes correlated with clinical symptomatology, even 3-5 days earlier. Thus, EEG power and center frequency mapping can be used very efficiently to estimate the optimal time between sequential neuroleptic depot injections.

Adult↗
PubMed1977

Computer-aided tumour classification and treatment selection in breast cancer.

In order to provide a common basis for treatment decisions and the future evaluation of breast cancer therapy, the breast cancer protocol used in our clinic was formulated for the computer. A system for the simulation of clinical reasoning was used which allows the physician to express the medical logic as a series of inferences to be confirmed or rejected on the basis of Boolean combinations of medical criteria. The system enables the physician to rearrange these criteria into a questionnaire for complete and accurate recording of patient data. These data are then fed into the computer to produce a patient status report and treatment recommendations. The data from 26 patients in various stages of breast cancer have been processed by the computer and the computer's conclusions compared to the assessment made by a junior physician in our department. In three cases the staging was not identical, in 15 cases the treatment decisions were not identical and in all cases investigations were left out by the physician. The system has been of considerable value in standardising patient examination and treatment and in training inexperienced physicians.

Breast Neoplasms↗
PubMed1992

Simultaneous high-resolution measurement of adenosine triphosphate levels and blood flow in the hamster amelanotic melanoma A-Mel-3.

BACKGROUND: Some studies suggest that nutritional blood flow and intratumor levels of high-energy phosphates such as adenosine triphosphate (ATP) affect tumor response to treatment. Reports of intratumor variabilities have shown that distribution of high-energy phosphates within experimental and human tumors is not uniform, and this variability may be related to differences in blood flow in different regions of the tumor. However, previous studies provide no insight into the intratumor relationship of these parameters. PURPOSE: To study the intratumor relationship between blood flow and ATP concentration, we have developed a method that allows simultaneous quantitation of the two variables almost at a cellular level at adjacent sites. In addition, this technique, which uses digital image processing and analysis, facilitates regional high-resolution measurements of blood flow and ATP concentrations in relation to histology. METHODS: We examined tissue samples cut in consecutive order from one representative hamster A-Mel-3 amelanotic melanoma. Specimens from the same tumor were analyzed for histological features, blood flow (measured autoradiographically by the use of [4-N-methyl-14C]iodoantipyrine), and ATP content (measured by a quantitative substrate-induced bioluminescence reaction, using single-photon imaging). The data on the three parameters were stored as digitized images, which were later transformed to reach geometric congruency. The relationship between blood flow and ATP was examined by nonlinear regression and correlation analyses. RESULTS: Regional distribution of blood flow was highly correlated with distribution of ATP within the A-Mel-3 tumor. For images of the tumor using measuring fields of approximately 20 tumor cells, the coefficient of correlation was .92 (P < .001). The relationship between the two parameters was described by a second-order function. At low blood flow values, small differences in blood flow were associated with large changes in levels of ATP, whereas at high blood flow values, differences in blood flow were associated with much smaller changes in ATP levels. CONCLUSION: This high-resolution technique may have applications in future studies investigating the relationship between tumor cell metabolism and regional blood flow and in studies aimed at identifying the locoregional target of various cancer therapies.

Adenosine Triphosphate↗
PubMed1992

Digital echocardiography in myocardial infarction.

Probably the most under-utilised application of echocardiography is in patients with coronary artery disease (CAD). This under-utilisation is striking since echocardiography can be very valuable in evaluating the natural history and therapy of CAD. One reason why echocardiography is not being utilised to its fullest is because of the reliance on videotape to record and display echocardiograms. This medium is time consuming and inconvenient for clinicians to review studies, it is not ideal for detecting subtle wall motion abnormalities, and videotape is impractical for comparing serial studies. Recording and storing echocardiograms on a digital medium overcomes these difficulties. Digital cine loops of single cardiac cycles provide great versatility. Multiple views or studies can be displayed simultaneously, subtle changes in wall motion are more easily detected and different views, or serial studies, can be readily compared. Such images can be displayed on computers on the ward or in the coronary care unit (CCU) and be available 24 hours a day, seven days a week at the convenience of the clinician. One does not need to find a recording on a two hour videotape, which may be in the ultrasound instrument, and one can view the exam in 30 sec instead of 5 to 10 min. Regional and global left ventricular function is one of the most important manifestations of CAD. With new therapeutic efforts at restoring myocardial function and limiting infarct expansion, assessing LV function is more important than ever. Digital echocardiography is an extremely practical and convenient way for clinicians to obtain this information.

Echocardiography↗
PubMed1978

Computer use in diagnosis, prognosis, and therapy.

Computers are used to influence diagnostic and therapeutic decisions. The computer's information-handling capabilities allow it to serve as a reliable extension of the physician's memory and expander of the physician's information and synthesized knowledge resources. Computers have been used to facilitate decisions through organization of patient data, improved classification of patients, decision analysis in clinical settings, and simulation of expert clinical reasoning. Computer programs are more successful in narrow, constrained, single arenas of medicine with much underlying pathophysiologic understanding and where decisions are based largely on hard laboratory data. New models of synthetic reasoning that simulate expert clinical behavior show promise of supporting complicated decisions concerning problems of multiple diseases. All systems are confronted by problems of consensus and authority of the underlying information used.

Computers↗
PubMed1992

Radiographic methods in the evaluation of periodontal therapy.

Radiographic methods are commonly utilized to assess periodontal bone changes in clinical trials. Radiographs are unique as a data source in that they provide a permanent visual record of the bone support and allow for linear, area, and volume measurements of periodontal lesions. The major limiting factors in the use of radiographic outcomes measures are geometric distortion and radiographic processing errors. The use of standardized methods and computer algorithms has reduced the effect of these errors on data from radiographs. Radiographic analysis in clinical trials is largely done in digital format by indirect digitizing film with a video camera. Direct digital detectors are now available for intra-oral use. The use of a direct detector eliminates the need for film processing and allows for dose reduction. The detectors currently available are limited in size and resolution. Subtraction radiography allows for area and volume estimates of bone gain or loss. The subtraction methods are highly precise, but are also technically exacting and labor intensive. The clinical trial hypothesis, size, length, and accuracy required should be the final consideration in choosing a radiographic method.

Alveolar Bone Loss↗
PubMed1975

[Marker-evidence for documentation and evaluation of findings and treatment in fractures of the facial skull].

A special form is presented by means of which clinical findings and therapy of fractures of the visceral cranium are documented in such a way that the data can be fed into a computer and be evaluated. Like similar forms for cheilognathopalatoschisis and tumors of the jaw and face area the present form is meant for a special field or specific problems and is not to replace the traditional case history.

Diagnosis, Computer-Assisted↗
PubMed1979

[A computer-controlled monitoring and therapy system for shock compensation in severe burns (author's transl)].

A computer-controlled control loop for the automatic diagnosis of shock and infusion therapy is reported. External information (off-line) and vital parameters measured with serial devices (on-line) are used by the computer for the automatic control of infusion pumps. By this method the critical shock phase could be prevented in five seriously burned patients. The construction of the system also permits its use in other shock conditions.

Blood Pressure↗
PubMedDate not supplied

Investigating the potential of three-dimensional treatment planning.

3-D treatment planning has received a great deal of attention in the radiation therapy community over the last several years. This new technology makes use of the continuous improvements in computer hardware and graphics capabilities, along with major improvements in treatment planning software, to provide a fully three dimensional simulation of the patient, radiation beams, and dose distributions which are used for radiation therapy of various cancers. With these capabilities, the physician and treatment planner may now optimize the radiation beams used to treat the patient much more effectively than in the past, when only a limited description of the patient, beams, and doses was available. This paper describes several of the new capabilities of these 3-D planning systems, some research studies which are currently being performed to evaluate the usefulness of the new technology, and finally some of the costs associated with its implementation.

Computer Simulation↗
PubMedDate not supplied

[Computerized planning of radiotherapy].

The hypophysis was studied by MR tomography in 148 patients with the most prevalent diseases of the hypothalamohypophyseal system and in 13 ones with primary hypothyrosis. The findings evidence a great variety of changes in the MRT picture in the examinees. The method permits a reliable diagnosis of hypophyseal macroadenoma and of an 'empty' sella turcica. Qualitative and quantitative criteria for MRT diagnosis of these conditions are suggested. The diagnostic value of MRT for the detection of macroadenomas is still to be researched. The method was effectively used for a dynamic follow-up of the hypophyseal status in the course of pathogenetic therapy; the formation of an 'empty' sella turcica is possible against the background of dopamine agonist therapy and substitution therapy of primary hypothyrosis.

Adolescent↗
PubMed1992

[Conformal technics by the movement of bars in pendular fields. 1. Prototype realization and the possible applications].

The growing interest for conformal radiotherapy originates from the need of giving the prescribed dose to the target volume, by sparing, at the same time, surrounding healthy tissues and organs. More dose to the target volume with respect to the healthy tissues always increases the curative possibilities of the treatment. However, the development of conformal techniques implies an increased complexity of the treatment and the solution of many technical and dosimetric problems. In our Institute we are developing new conformal techniques, based on the use of moving bars driven by a computer-controlled system in arc therapy. This paper refers to the conclusion of the preliminary part of our work: a movement (translating or rotating) of bars in arc therapy seems to have good chances to tailor dose distribution in a relatively simple way. We realized two mechanical systems driven by computer for translating and rotating movements of a bar. The two techniques have been tested by TLD and film dosimetry on acrylic phantoms. We present the results of these tests, and describe technical problems and the clinical possibilities of this method.

Equipment Design↗
PubMed1992

True three-dimensional dose computations for megavoltage x-ray therapy: a role for the superposition principle.

The objective of radiation therapy is to concentrate a prescribed radiation dose accurately within a target volume in the patient. Major advances in imaging technology have greatly improved our ability to plan radiation treatments in three dimensions (3D) and to verify the treatment geometrically, but there is a concomitant need to improve dosimetric accuracy. It has been recommended that radiation doses should be computed with an accuracy of 3% within the target volume and in radiosensitive normal tissues. We review the rationale behind this recommendation, and describe a new generation of 3D dose algorithms which are capable of achieving this goal. A true 3D dose calculation tracks primary and scattered radiations in 3D space while accounting for tissue inhomogeneities. In the past, dose distributions have been computed in a 2D transverse slice with the assumption that the anatomy of the patient dose not change abruptly in nearby slices. We demonstrate the importance of computing 3D scatter contributions to dose from photons and electrons correctly, and show the magnitude of dose errors caused by using traditional 2D methods. The Monte Carlo technique is the most general and rigorous approach since individual primary and secondary particle tracks are simulated. However, this approach is too time-consuming for clinical treatment planning. We review an approach that is based on the superposition principle and achieves a reasonable compromise between the speed of computation and accuracy in dose. In this approach, dose deposition is separated into two steps. Firstly, the attenuation of incident photons interacting in the absorber is computed to determine the total energy released in the material (TERMA). This quantity is treated as an impulse at each irradiated point. Secondly, the transport of energy by scattered photons and electrons is described by a point dose spread kernel. The dose distribution is the superposition of the kernels, weighted by the magnitude of the TERMA impulse for all interaction sites. In this review, we demonstrate the capabilities of the superposition method, particularly for situations of charged particle disequilibrium, and we report on the progress made by several research groups in adapting this method to clinical treatment planning. In the future, the superposition method will have a significant role in dose optimization for conformal irradiation techniques because of its close correspondence to image reconstruction by filtered back-projection.

Image Processing, Computer-Assisted↗
PubMed1975

[The effectiveness of treatment for breast cancer patients].

The study of late results of treatment in 1166 patients with breast cancer permitted to find the percentage of a 5-year survival to be equal to 55.58, 37.93% of patients survived for 10 years, 28.25% -- for 15 years. In the first stage a 5-year survival was 87.20%, while in the second and third -- 57.7% and 31.56% of patients survived for 5 years, accordingly. The modern methods of radiotherapy (radiosurgical method, interstitial gamma therapy with Au-198 granules, distance grammatherapy on the machine LUCH) enhanced the efficacy of therapeutic measures in patients with widespread breast cancer. A complex diagnosis -- cytology, non-contrast mammography and mathematical analysis by means of a computer contributes to recognition of early forms of breast cancer.

Adenocarcinoma↗
PubMed1978

Enlarged acid-base and blood gas calculations by electronical data computing in the blood gas laboratory.

A rapid anaysis of parameters of the acid-base equilibrium and blood gases during open heart surgery and emergency therapy is absolutely necessary. Computing of the several parameters of the acid-base status by slide rules or nomograms is time consuming and can be shortened by computer applications. The central blood gas laboratory consists of a blood gas analyzer for PO2, PCO2 and pH, an electronic desktop calculator, a four color X-Y-plotter and two data lines to the cardiac surgery unit and to the intensive care unit. The time needed for computing and feedback of the parameters could be decreased to one quarter. In addition to numerical data printout, a graphical representation of the several parameters is possible on a X-Y-plotter and includes the Rahn-Fenn-O2-CO2-Diagram with venous admixture, ventilation perfusion ratio, alveolar dead space ventilation and the standard and actual oxygen dissociation curve as well as the pH/HCO3- Acid-Base nomogram. Furthermore, a computer diagnosis of the actual disturbances can be plotted.

Acid-Base Equilibrium↗