Biomedical subjects

N Blais

Publications and source records attributed to N Blais.

At least 19 recordsLinked to original sources

PubMed1994

Radiation doses to patients in neurointerventional procedures.

PURPOSE: To evaluate stochastic and deterministic risks associated with neurointerventional procedures for the patient. METHODS: Eight neurovascular interventional procedures were evaluated to determine the entrance skin dose and effective dose for the patient. Dosimetry was done with thermoluminescence dosimeters. The highest dose on the patient's head was recorded as the maximum entrance skin dose. The equivalent dose was obtained by conversion of the dose-area product using published conversion tables. RESULTS: The maximum entrance skin dose varied from 129 to 1335 mGy. The mean effective dose was 1.67 mSv with a range of 0.44 to 3.44 mSv. No deterministic effect has been encountered. Stochastic risk linked to the highest effective dose value was approximately one death by fatal cancer for every 6000 procedures, according to the new International Commission on Radiological Protection coefficient. CONCLUSIONS: Because no deterministic effect has been detected, and stochastic risks were very low, radiation hazard to the patient is a minor consideration in deciding whether to undertake a neurointerventional procedure.

Adult↗

PubMed1992

The mass angular scattering power method for determining the kinetic energies of clinical electron beams.

A method for determining the kinetic energy of clinical electron beams is described. The method is based on the measurement in air of the spatial spread of a pencil electron beam which is produced from the broad clinical electron beam. As predicted by the Fermi-Eyges theory, the dose distribution measured in air on a plane, perpendicular to the incident direction of the initial pencil electron beam, is Gaussian. The square of its spatial spread is related to the mass angular scattering power which in turn is related to the kinetic energy of the electron beam. The measured spatial spread may thus be used to determine the mass angular scattering power, which is then used to determine the kinetic energy of the electron beam from the known relationship between mass angular scattering power and kinetic energy. Energies obtained with the mass angular scattering power method agree with those obtained with the electron range method. The angular scattering power method is relatively cumbersome, but allows us to determine the kinetic energies of electron beams from first principles, in contrast to the empirical methods based on range measurements in water.

Electrons↗

PubMed1990

Decreased necessity for dialysis with loop diuretic therapy in hemolytic uremic syndrome.

High dose loop diuretic therapy was administered at time of admission to hospital or at time of diagnosis to 54 patients with childhood hemolytic uremic syndrome. Forty-one patients maintained a diuresis sufficient to avoid the necessity for dialysis. When compared to an earlier time period the dialysis rate fell from 82% to 24% with furosemide therapy. Though a change in disease severity may explain the decrease in necessity for dialysis, a salutary effect of furosemide therapy may also be responsible.

Blood Urea Nitrogen↗

PubMed1989

Hemolytic uremic syndrome: glomerular filtration rate, 6 to 11 years later measured by 99mTc DTPA plasma slope clearance.

Thirty-seven patients who had been discharged from hospital six to eleven years after an acute episode of hemolytic uremic syndrome were studied. Glomerular filtration rates were measured by plasma slope clearance using 99mTc DTPA. Eleven patients had GFRs below 60 ml/min/1.73 m2. Hemolytic uremic syndrome may result in an appreciable deterioration in GFR undectable by routine laboratory tests and without clinical signs.

Acute Disease↗

PubMed1987

Phantom equivalent thicknesses in diagnostic radiology.

Some measurements in diagnostic radiology must be done with phantoms. The most frequently used phantoms are water, plexiglass, aluminium and copper. It is interesting to know the equivalent thicknesses between these phantoms in order to be able to relate these values to real anatomical organs of known thicknesses. The use of antiscatter grids, the choice of intensifier screens, the beam size and in general the scattering parameters considerably change the equivalent thicknesses. Many situations have been simulated by the Monte Carlo method and equivalent thicknesses are presented.

Humans↗

PubMed1976