Search PubMed⌕ Search

Biomedical subjects

A Pilot

Publications and source records attributed to A Pilot.

8 recordsLinked to original sources
PubMed1997

The determination of dose characteristics of ruthenium ophthalmic applicators using radiochromic film.

Ruthenium ophthalmic applicators are energetic beta ray sources, supplied in several shapes and dimensions, and used in intraocular tumor therapy. Because of their small dimensions, the determination of dosimetric characteristics represents a technical challenge. We developed a semiautomatic method to define surface dose, dose distribution, and percentage depth dose of such applicators using radiochromic dosimetric media. These detectors consist of a thin (7 microns) radiation sensitive layer on polyester base (100 microns total thickness) changing color as a function of radiation exposure. Transmission images of exposed films were then grabbed with a TV-digitizer system to obtain a gray-level image from which dosimetric characteristics such as isodose distribution, dose values, and homogeneity of nuclide distribution were derived. Good agreement between experimental results and Monte Carlo simulation performed using the GEANT 3 code, appear to be a confirmation of the validity of the method. Moreover while manufacturer specifications of absolute and relative dose rates present a standard deviation error of +/- 30% on dose rate and +/- 6% on accuracy of relative dose values, the proposed method reduces the errors to +/- 10% and +/- 4%, respectively.

Beta Particles↗
PubMed1993

A personal dosimeter prototype for static magnetic fields.

A personal dosimeter prototype, for static magnetic fields with three Hall probes, has been designed and built to provide a reliable instrument for long-term analysis. The probe output signals, proportional to the magnetic flux density components of the vector B, are filtered, sampled, and stored in a buffer memory sufficient to cover a whole worker shift. The data sampling rate is high enough to record the operator movements within the fringes of the magnetic field. The content of the buffer memory is then transferred on a personal computer and registered on individual dosimetric cards. The data can be used for personal exposure monitoring.

Electromagnetic Fields↗
PubMed1984

[Development of a method for the quantitative evaluation of the regional kinetics of the left ventricle].

Segmental wall motion abnormalities of the left ventricle frequently occur in ischemic heart disease. An objective, quantitative method is required to ensure the reproducibility of the assessment of left ventricular regional function, especially in evaluating the changes induced by diagnostic and therapeutic interventions. In 32 normal subjects we obtained 30 degrees right anterior oblique left ventriculograms and developed a method based on the following observations. The method should reflect the symmetric uniform motion of the left ventricular silhouette. Only actual contractile motion should be taken into account; therefore, rotatory and translational motion should be compensated for. Passive systolic movement of aortic and mitral valves accounts for the contraction of neighbouring myocardial segments. Left ventricular wall excursion is most often measured by a coordinate system: since the cavity of the left ventricle becomes relatively longer during systole, left ventricular walls contract neither toward a single central point nor toward the long axis; therefore the appropriate origin of the coordinate system will be a segment. Furthermore, as more elongated left ventricular end-diastolic silhouettes appear to show a greater extent of systolic lengthening (we show evidence of this), the length of the segment must be related to the end-diastolic shape. The basic steps of the method are: 1) identification of a symmetry line, from the aortic mid-point to the apex, by connecting the mid-point of 19 diameters perpendicular to the long axis; 2) roto-translation of the end-systolic silhouette so that the end-systolic apex and aortic mid-point lie on the symmetry line.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart↗
PubMed1977

[Use of common glass in radiation protection].

The X-ray absorption meter (Diagnostic energy between 20-60 Kev) of common place-glass has been studied. The possibility of replacing lead glass with a reinforced type, also very cheap, has been examined.

Absorption↗