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Biomedical subjects

G G Cox

Publications and source records attributed to G G Cox.

At least 37 records · Page 2Linked to original sources
PubMed1987

A digital radiology imaging system: description and clinical evaluation.

We have successfully interfaced an advanced microcomputer system to a 47-cm image intensifier for direct digital radiology. Our development effort has included the design and construction of hardware and the implementation of software. The system matrix (spatial resolution) is 1024 X 1024 and contrast resolution is 8 bits deep. A receiver-operator-characteristic analysis comparing conventional and digital laser chest radiographs for the detection of lung nodules demonstrated no statistical difference. Dosimetry measurements identified decreased patient dose. The intensifier-based digital imaging system is being increasingly used for a variety of examinations including IV pyelograms, all kinds of barium studies, and skeletal, trauma, and chest studies. Hard-copy laser-printed digital images with "bones black" are preferred by the radiology staff and have been well accepted by referring clinicians.

Evaluation Studies as Topic↗
PubMed1987

Digital image-management networks: problems in implementation.

The apparent advantages of a DIMS are often cited by those involved in medical information-management research. The promise of a high-speed electronic image-management system that could increase a department's patient throughput and improve patient care is most attractive. Every major manufacturer of medical imaging equipment has a group working to develop such systems. Many problems remain to be solved before such systems can be acquired, installed, and made operational. This paper has summarized the significant technical problems yet to be solved.

Archives↗
PubMed1986

Investigation of the interaction of cardiotoxic anticancer agents using the fetal mouse heart organ culture system.

The fetal mouse heart organ culture system was utilized in an effort to document and predict the potential cardiotoxic effects of ionizing radiation, Adriamycin (ADR), and Dihydroxyanthraquinone (DHAQ); alone and in combination. These antineoplastic agents have been shown to produce clinical cardiomyopathy which is often dose-limiting. Fetal mouse hearts (gestational day 17) were removed and placed in a culture system of 6-well microtiter plates. A single heart was placed in each well on a piece of aluminium mesh, above the culture medium but bathed by capillary action. The plates were then placed in a 100% oxygen environment and incubated at 37 degrees C. Treatments performed on day 1 after culture were Cs-137 irradiation (10, 20, or 40 Gy); ADR (10, 30, or 100 micrograms/ml); DHAQ (5, 20, or 50 micrograms/ml); or various combinations of drugs and radiation. Hearts were checked every day for functional activity as evidenced by continuous heart best. Untreated hearts beat rhythmically for up to 9 days (average = 6.8 days); treated hearts stopped beating between 2 and 7 days after treatment. Using this endpoint of functional retention time (FRT), dose response curves were obtained for all individual agents. Combinations of ADR and DHAQ (at concentrations that resulted in FRTs of 3.5 days) produced no greater effect than either agent alone. However, the combination of radiation (FRT = 5.3 days) with ADR, DHAQ or both drugs was more effective than was drug alone. This system may help to predict the cardiotoxic effects that result from the use of these drugs and radiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Estimating digital information throughput rates for radiology networks. A model.

The design and implementation of a digital radiology image management system requires the definition, evaluation, and comparison of appropriate measures of system performance. The mean throughput rate is an important measure of the actual performance of a finished system. The mean throughput rate identifies the transmission of digital information either in bits/second or tasks/second. It is dependent on software, database management, equipment interface designs, number of users and display stations, and communications media. The mean throughput rate can document resource allocation bottlenecks within a given system. A model for estimating the mean throughput rate and its application in helping us design our radiology digital image networks is described.

Electronic Data Processing↗
PubMed1986

Intraarterial digital subtraction arteriographic evaluation of extremity tumors: comparison with conventional arteriography.

Conventional arteriography and intraarterial digital subtraction arteriography (IADSA) were compared in 36 patients with primary bone or soft-tissue tumors of the extremities. The sensitivity of IADSA was at least equal to conventional arteriography for demonstrating normal or abnormal major arteries and feeding arteries, equal to or superior for depicting tumor stains or draining veins, but slightly inferior for revealing minute tumor vessels. An increase of the matrix size from 256 X 256 to 512 X 512 improved these sensitivities. IADSA with 15% diatrizoate contrast material eliminated the contrast material-induced pain in all patients. With a computer-controlled iris setting, an average of 5 minutes of procedure time and 1.7 R of radiation (0.44 mC kg) per examination could be saved. IADSA reduced the cost of an examination by an average of $67. The results indicate that IADSA was diagnostic in all instances and can replace conventional arteriography for the evaluation of extremity tumors.

Angiography↗
PubMed1986

Computer networks for image management in radiology: an overview.

Currently, images obtained from digital radiographic modalities are archived and managed as analog images recorded on radiographic film. An alternative for total image management is a computer-based digital network. General design considerations for a digital image network are reviewed, and estimates of important system parameters are determined.

Computers↗
PubMed1986

Digital image management: networking, display, and archiving.

The requirements for implementing a radiology imaging network are similar to those for local area networks now being designed for other purposes to manage large data films. A radiology department serving a 500-bed hospital generates about 927 megabytes of digitally formatted data per working day. These data are expected to be on line for the patient's hospitalization period. The retrieval rate of these data among the interactive diagnosis display stations requires data throughput rates of between 2 and 5 megabits per second. This throughput rate requires signaling rates of between 20 and 50 megabits per second. Analog hard-copy generation of the images on the network is required by the referring physician for selected images that support the consultation report. Digital laser recorders using paper may be quite satisfactory. Long-term archiving must be low in cost and requires a database scheme capable of managing more than a terabyte of image data. Radiology networks must be required to bridge with other hospital information systems.

Computers↗
PubMed1985

Comparison of single, fractionated and hyperfractionated irradiation on the development of normal tissue damage in rat lung.

The effect of fractionated thoracic irradiation on the development of normal tissue damage in rats was compared to that produced by single doses. Animals received a single dose of 15 Gy, 30 Gy in 10 daily fractions of 3 Gy each (fractionation), or 30 Gy in 30 fractions of 1 Gy each 3 times a day (hyperfractionation). The treatments produced minimal lethality since a total of only 6 animals died between days 273 and 475 after the initiation of treatment, with no difference in survival observed between the control and any of the 3 treated groups. Despite the lack of lethality, evidence of lung damage was obtained by histological examination. At times less than 180 days after treatment, the lungs of animals receiving a single dose of 15 Gy displayed more severe changes than did animals from either fractionation group. At longer times after treatment (days 261 and 475), the histological appearances within each group were changed, collagen deposits and fibrosis being the most significant observations. Animals that had received either single doses or fractionated doses had more of the pulmonary parenchyma involved than did animals that had received hyperfractionated doses. We conclude that, in the rat lung model, a total radiation dose of 30 Gy fractionated over 14 days produces no more acute lethality nor damage to lung tissue than does 15 Gy delivered as a single dose. However, long-term effects as evidenced by deposits of collagen and development of fibrosis are significantly reduced by hyperfractionation when compared to single doses and daily fractionation.

Animals↗
PubMed1985

Analog image recording using a laser printer and paper system.

This article describes a method for generating gray scale analog hard copy images on ordinary paper using a laser printer system. Operation of the computer-controlled laser printer is described. The cost of the laser printer/paper technology is estimated and compared with the cost of multiformat camera/conventional film systems. Results of an initial clinical evaluation of laser printed paper images are presented.

Angiography↗
PubMed1984

Interaction of radiation, dihydroxyanthraquinone, and adriamycin on the induction of acute lethality in mice.

The acute lethality induced by combinations of radiations, Dihydroxyanthraquinone (DHAQ), and Adriamycin (ADR) was investigated in mice. Whole-body irradiation produced acute lethality, with an LD-50/30 of approximately 6.5 Gy. ADR and DHAQ produced LD-50/30's of 14 and 4 mg/kg, respectively. When 10 mg/kg doses were fractionated into 5 X 2 mg/kg daily doses, both drugs were equally or more efficient at producing mortality, 90% by day 30. When 4 Gy radiation was combined with 5 mg/kg ADR or 5 mg/kg DHAQ, a response no greater than that produced by drug alone was obtained. However, when 5 mg/kg ADR was administered concomitantly with 5 mg/kg DHAQ, there was a less-than-additive induction of lethality, resulting in only 21% mortality by day 30. Since this response is similar to that seen after ADR only, it would appear that the DHAQ-induced toxicity was protected against. Less-than-additive effects were also observed for combinations of 5 mg/kg ADR with either 2.5 or 10 mg/kg DHAQ; and combinations of 10 mg/kg ADR with either 2.5 or 5 mg/kg DHAQ. If ADR and DHAQ (at doses of 5 mg/kg) were combined but with a 1 day interval between drugs, the protective effect was lost and animals died earlier than after either agent alone. At present, no definite explanation is available for this unusual protective effect of ADR against acute lethality induced by DHAQ.

Animals↗
PubMed1984

Ultrastructural evidence of cardiac damage resulting from thoracic irradiation and anthracyclines in the rat.

The effects of radiation combined with Adriamycin (ADR) or Dihydroxyanthraquinone (DHAQ, NSC 279836) on the induction of cardiomyopathy in the rat were investigated using electron microscopy. Rats were treated with ADR or DHAQ at 2.5, 5.0, or 10 mg/kg ip; thoracic irradiation at 12, 15, 18, 21, or 24 Gy of 25 MV X rays; or a combination of either drug at 5.0 mg/kg plus 15 Gy X rays. Survival times were observed to be linear, inverse functions of the dose of drug or radiation received. Combinations of ADR plus radiation produced an increased lethality while the combination of DHAQ and radiation produced similar lethality as DHAQ alone. Even for treatments that resulted in animal lethality, there was little histological evidence of abnormality observed in heart tissues by light microscopy. On the other hand, electron microscopic examination of cardiac tissues demonstrated dramatic decreases in mitochondrial number and destruction of mitochondrial structure. The treatments could be arranged in order of increasing severity of the damage produced as follows: 5 mg/kg ADR, 15 Gy X ray, 5 mg/kg DHAQ, 5 mg/kg ADR + 15 Gy X ray, 24 Gy X ray, and 5 mg/kg DHAQ + 15 Gy X ray. In several cases, mitochondrial abnormalities were sufficient so as to allow cardiomyopathy to be cited as the cause of death. These results indicate that electron microscopy can be used to document cellular changes that may only be functionally expressed as long-term normal tissue damage or animal lethality. The finding that DHAQ can produce significant cardiotoxicity, and that this cardiotoxicity is enhanced by concomitant thoracic irradiation, suggest caution while this drug is being investigated for clinical use.

Animals↗
PubMed1984

Renal cell carcinoma--angioinfarction.

In our experience the mortality rate in 46 patients who underwent angioinfarction for renal cell carcinoma was 4 per cent. Fever, ileus and leukocytosis were noted in 86 to 90 per cent of our patients. The use of absolute ethanol as a medium for renal infarction was associated with a significant incidence of damage to other organs. A 30 per cent decrease in tumor volume following angioinfarction using absorbable gelatin sponge and Gianturco coils was noted in 75 per cent of the patients. There was no evidence of metastatic tumor reduction and we could not document any significant decrease in operative time or blood loss. It would appear that there is some increased survival rate in patients with metastasis who are given adjuvant immune ribonucleic acid therapy. However, the numbers in our series are not significant to draw any definite conclusion. It is apparent that patients treated with infarction, delayed nephrectomy and medroxyprogesterone acetate did not have any significant survival over those treated with palliative nephrectomy or chemotherapy. The macrophage maturation assay may be useful during clinical followup.

Adenocarcinoma↗