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Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 793 records · Page 44Linked to original sources
PubMed1981

New procedure on making a thumb--one-stage reconstruction with free neurovascular flap and iliac bone graft.

A new method for reconstruction of an amputated thumb with a free neurovascular flap and an iliac bone graft in one stage is described. The method consists of four operative steps: (1) preparation of the recipient hand, (2) elevation of a free dorsalis pedis flap, (3) iliac bone graft, and (4) transfer of the flap with microvascular anastomoses. Four successful results with this operation are presented. The method, which reconstructs the thumb in a single operation, is suitable for patients who refuse other reconstructive methods which sacrifice uninjured digits or toes.

Adult↗
PubMed1981

Analysis of recorded image noise in nuclear medicine.

The concepts of autocovariance function and Wiener spectrum have been applied to describe the recorded image noise in nuclear medicine. They were derived as functions of the expected detected count density and the detector and exposure point spread functions. It was shown that the detector system affects only the noise magnitude, whereas the recorder system affects both noise magnitude and texture. In experimental studies, the autocovariance function and Wiener spectrum of recorded image noise were measured by one-dimensional time-series analysis. Due to the non-linearity of the recording film, the best agreement between the theoretical predictions and the experimental results is found when the detected count density is sufficiently high and the size of the exposure spot is sufficiently large for the density fluctuations in the recorded noise image to be relatively low.

Models, Theoretical↗
PubMed1981

Spontaneous rupture of the spleen in acute myeloid leukemia.

The results of an autopsy of an 80-year-old Japanese male with acute myeloid leukemia who died of spontaneous rupture of the spleen are reported. The patient was admitted because of anorexia, fatigue, weight loss, and multiple skin eruptions. Hematological examinations indicated a rapid increase in myeloblasts. The patient collapsed on the 28th hospital day, immediately after complaining of severe epigastralgia and vomiting. He died ten hours later. The autopsy revealed extensive leukemic infiltration of the bone marrows, spleen, lymph nodes, skin, and other internal organs. The spleen was enlarged and was ruptured in places at the hilar portion. Massive intraperitoneal hemorrhage from the rupture was the direct cause of death. The mechanisms of splenic rupture are discussed.

Aged↗
PubMed1981

Monte Carlo simulation studies of backscatter factors in mammography.

Experimentally determined backscatter factors in mammography can contain significant systematic errors due to the energy response, dimensions, and location of the dosimeter used. In this study, the Monte Carlo method was applied to simulate photon-scattering in tissue-equivalent media and to determine backscatter factors without the interference of a detector. The physical processes of measuring backscatter factors with a lithium fluoride thermoluminescent dosimeter (TLD) and an "ideal" tissue-equivalent detector were also simulated. Computed results were compared with the "true" backscatter factors and with measured values reported by other investigators. It was found that the TLD method underestimated backscatter factors in mammography by as much as 10% at high energies with TLD-100 (3.2- x 3.2- x 0.89-mm3) crystals.

Mammography↗
PubMed1981

Effect of crossover exposure on radiographic image quality of screen-film systems.

Modulation transfer functions (MTFs), Wiener spectra, and H & D curves of conventional and anticrossover screen-film systems were measured in an evaluation of the potential clinical use of anticrossover systems. The relative speed of anticrossover (3M) systems was reduced by 40%, compared with conventional (Kodak OG) systems. The anticrossover system improved both resolution and noise properties of screen-film systems (55% improvement of MTF at 2 cycles/mm and 40% reduction of radiographic mottle at low spatial frequencies) in a way that a combination of slow, sharp screens with conventional film may not accomplish, even when the speeds of different systems are matched. Detail visibility, in phantom images and radiographs of the hand, was considerably enhanced with anticrossover film compared with that of conventional film.

Humans↗
PubMed1980

Evaluation of absorbed dose in mammography: monte carlo simulation studies.

Computer programs for calculation of the backscatter factor and absorbed dose in breast phantoms are developed based on Monte Carlo simulation. Rad/roentgen conversion factors are calculated for water, fat, a mixture of 50% water and 50% fat, and lucite irradiated with monoenergetic and polyenergetic x rays from a tungsten or molybdenum anode x-ray tube. These factors can be used to estimate skin dose, average depth dose, or average integral dose in a breast when the beam quality, exposure in air at the skin position, and composition of the breast are known. Calculated backscatter factors are considerably greater than measured values reported previously.

Breast↗
PubMed1980

Relative efficiencies of energy to photographic density conversions in typical screen-film systems.

This study compared the speeds of six typical screen-film systems and the energy absorbed by their screen pairs as a function of incident x-ray energy. Three of the screen-film systems studied had calcium fungstate phosphors, one contained barium strontium sulfate, and two were composed of a mixture of lanthanum oxysulfide with larger amounts of gadolinium oxysulfide. A source of monoenergetic radiation was used for measurement of the relationship between these two quantities as a function of keV. With certain exceptions, the speeds of screen-film systems act in a manner similar to that which would be predicted if only the energy absorption properties of their screens were considered.

Models, Theoretical↗
PubMed1980

Isolation and properties of sialodacryoadenitis virus of rats.

Pathogenic agents were isolated from affected salivary glands of rats with sialodacryoadenitis (SDA) by means of intercerebral inoculation to newborn mice and inoculation to primary rat kidney cell cultures. The properties of these isolates, irrespective of the isolation techniques, were in general agreement with that of SDA virus strain 681, and they were identified as SDA virus. In addition to the known properties, following characteristics were noticed: (1) Particles of SDA virus bore two different long and short surface projections. (2) Some antigenic differences were observed between the present isolate 930-10 and the strain 681. (3) It was suggested that SDA virus grew better at 35 degrees C than at 31 degrees, 33 degrees, 37 degrees or 39 degrees C. (4) SDA virus did not propagate in DBT cells.

Animals↗
PubMed1980

Pathological observations on natural cases of sialodacryoadenitis of rats.

Pathological observations were carried out on 100 male rats of Sprague-Dawley strain obtained from 5 outbreaks of sialodacryoadenitis (SDA). In accordance with clinical and macroscopic findings, principal microscopic changes were found in the salivary (submaxillary and parotid) and Harderian glands. Lesions observed in these different glands were essentially similar to each other, and characterized by degenerative changes in the epithelial cells of the ducts and acini associated with marked and extensive serous inflammation in the interstice. Furthermore, squamous metaplasia of the ductal epithelia was a common feature to these glands in the late stage of the disease. Some differences, however, were detected between the changes of the salivary glands and those of the Harderian glands. Firstly, the ductal epithelial cells were affected at first and the acinous epithelial cells were damaged only secondarily in the active inflammatory process in the salivary glands, while both ductal and acinous epithelial cells were involved equally in the primary lesion in the Harderian glands. Secondly, the increase in connective tissue elements in the reparatory process was extremely marked in the Harderian glands as compared with the salivary glands. Consequently, in the lesion of Harderian glands in the late stage, original construction was almost indiscernible, and the ducts and acini were only recognized as disseminated islets in actively proliferated connective tissue elements.

Animals↗
PubMed1979

Plasma branched-chain amino acids in cold- and heat-acclimatised rats.

The concentrations of plasma branched-chain amino acids, valine, isoleucine and leucine, were significantly elevated in cold-acclimatised rats, while these values were significantly reduced in heat-acclimatised rats, in both 2-week and 4-week temperature acclimatisation.

Acclimatization↗