Search PubMed⌕ Search

Biomedical subjects

P Bloch

Publications and source records attributed to P Bloch.

At least 55 records · Page 3Linked to original sources
PubMed1989

[Massive hemobilia caused by erosion of the hepatic artery by cholelithiasis with cholecysto-duodenal fistula].

The authors present a case of gastrointestinal haemorrhage due to erosion of the hepatic artery by a gallstone trapped in the neck of the gallbladder. The unusual feature of this case resides in the exteriotisation of this haemorrhage via two anatomical routes: in the form of heamobilia via the common bile duct and in the form of gastrointestinal haemorrhage via a cholecysto-duodenal fistula. Haemostasis was achieved by ligation of the hepatic artery after failure of direct repair.

Aged↗
PubMed1989

Integrated magnetic resonance and 31p spectroscopy.

Magnetic resonance imaging (MRI) has proven to be a powerful tool for accurate assessment of the anatomical extent of head and neck neoplasms. The ability to localize precisely defined volumes of interest within tissue with measurement of multinuclear magnetic resonance spectra (1H and 31P) has provided a basis for integrating spectroscopy into the clinical MRI examination. This technique which offers a means for noninvasive monitoring of relative concentrations of mobile metabolites at specific regions within a tumor is discussed. Examples of data obtained from integrated MRI/MRS studies for representative head and neck lesions are presented. The potential role of integrated MRI/MRS to monitor the response of neoplasms to therapy is reviewed.

Carcinoma, Squamous Cell↗
PubMed1988

Portal radiographs: digital enhancement of contrast.

The quality of low-contrast portal radiographs for radiation therapy can be improved with electronic contrast enhancement. After the image is copied digitally with a laser scanner microdensitometer into 4,096 gray-scale levels (12 bits) and 1,686 X 2,048 pixels, a special software package permits linear, logarithmic, exponential, or sigmoid transformations of the optical density. The precise representation of the portal image can then be interactively adjusted to emphasize the desired anatomy. Clinical examples demonstrate the value of the digital enhancement approach.

Radiographic Image Enhancement↗
PubMed1987

Practice of 3-dimensional treatment planning at the Fox Chase Cancer Center, University of Pennsylvania.

The use of 3-dimensional (3-D) dose distributions and dose-volume histograms in radiation therapy treatment planning is illustrated on a patient with a head and neck tumor. The patient was immobilized in a rectangular tissue compensation bolus box. The treatment was planned with a 14 MeV D-T derived fast neutron therapy beam. The isodose distributions and the dose-volume histograms at multiple adjacent levels are used to evaluate the adequacy of coverage of target volumes and the doses to the normal tissues. Such dose-volume histograms are useful and practical in summarizing the dose distribution throughout the irradiated volume, assessing the degree of uniformity of the dose distribution within the target volume, quantifying the amount of normal tissue irradiated, and evaluating rival treatment plans for both particle and nonparticle beams.

Fast Neutrons↗
PubMed1987

Rapid three-dimensional treatment planning: I. Ray-tracing approach to primary component dose calculations.

Algorithms for fully three-dimensional divergent-beam radiotherapy treatment planning have been developed to achieve very high sampling of dose in heterogeneous (inhomogeneous density) tissue throughout an arbitrarily oriented patient volume, in clinically acceptable times of calculation. Dose is calculated at points along numerous rays which sample each beam. To display the dose distribution, the calculated dose values for each beam are interpolated onto rectilinear grids of (arbitrary) parallel planes, scaled for beam weight and finally merged with the weighted dose contributions of other beams. In this paper we describe and demonstrate the algorithm for the primary component of the three-dimensional photon dose distribution delivered to a patient.

Clinical Trials as Topic↗
PubMed1986

An x-ray fluorescence technique to measure in situ the heavy metal burdens of persons exposed to these elements in the workplace.

Assays of hair and body fluid concentrations may be valuable measurements of acute exposure to a heavy metal, but they do not provide insight into the total heavy metal intake when the intake is low and chronic. The use of an x-ray fluorescence technique (XRF) enables measurement of the long-term retention of various heavy metals in select tissues in vivo. XRF was used to measure the mercury content of head and bone tissue in 298 dentists with long-term exposure to mercury-containing amalgams. It was also used to evaluate the lead burden of persons suspected of having elevated lead exposure at the workplace, and to assay the lead levels in urban and rural children. These studies indicated that the x-ray fluorescence method of assaying heavy metals in vivo is noninvasive, safe, rapid, and sensitive to levels of many heavy metals that accumulate in human tissues.

Adult↗
PubMed1985

A clinically operational method for three-dimensional dose calculations.

Three-dimensional dose calculations can now be performed for both photon and neutron beam therapy in reasonable times on a minicomputer. The method described is a scatter-air ratio-tissue-air ratio (SAR-TAR) model which, for any beam, finds the correct depth at each point in a patient even when the beam passes obliquely through more than one transverse section of the patient. Scatter dose is determined by performing a Clarkson integration over both angle and radial distance, with the correct depth of the beam calculated at both accumulation and scatter points. Doses are computed and displayed over a 0.33 cm sampling grid superimposed on each transverse CT slice used in treatment planning. Dose-volume histograms are made for the entire patient volume and for internal organs and target volumes outlined by the physician. The clinical efficacy of the method in therapy planning is demonstrated and a comparison is made between this method and single section two-dimensional methods.

Breast Neoplasms↗
PubMed1985

[Osteonecrosis of the femur head caused by sickle cell anemia in Benin. Epidemiologic and radiologic aspects].

The author reports 19 aseptic necrosis of the femoral head, due to sickle cell anemia, collected in 14 black people native from Benin. Sickle cell anemia is the most frequent etiology of osteonecrosis there. They are generally observed between 10 and 30 years of age. A systematic and complete study of the radiological signs has been carried out. The peculiar severity of the disease in black Africa is related to the chronicity of the sickling disorder, the delay brought to the diagnostic, the lack in therapeutic media.

Adolescent↗
PubMed1984

[Osteonecrosis of the femoral head of sickle-cell origin. Apropos of 19 cases observed during a year in Benin. Proposal for radiologic classification].

The author reports 19 aseptic necrosis of the femoral head, due to sickle-cell anemia, collected in 14 black people native from Benin. Sickle-cell anemia is the most frequent etiology of osteonecrosis there. They are generally observed between 10 and 30 years of age. A systematic and complete study of the radiological signs has been carried out. The peculiar severity of the disease in black Africa is related to the chronicity of the sickling disorder, the delay brought to the diagnostic, the lack in therapeutic media. A six stage X-ray classification is argued because of the most severe aspects.

Adolescent↗
PubMed1982

Neurophysiological and neuropsychological function in mercury-exposed dentists.

In a study of the relation between cumulative exposure to mercury and chronic health impairment 298 dentists had their mercury levels measured by an X-ray fluorescence technique. Electrodiagnostic and neuropsychological findings in the dentists with more than 20 micrograms/g tissue mercury levels were compared with those of a control group consisting of dentists with no detectable mercury levels. 30% of the 23 high mercury dentists had polyneuropathies. No polyneuropathies were detected in the control group. The high mercury group had mild visuographic dysfunction; they also had more symptom-distress than did the control group. These findings suggest that the use of mercury as a restorative material is a health risk for dentists.

Adult↗