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Biomedical subjects

D Paix

Publications and source records attributed to D Paix.

At least 19 recordsLinked to original sources
PubMed2004

A CMOS image sensor method of focal spot size measurement.

A phosphor opto-coupled monochrome CMOS image sensor with a slit diaphragm was used to investigate focal spot characteristics. Images were captured during x-ray exposure with a triggered frame grabber and subsequently enhanced. Dimensions of the focal spot width (1.39mm) and length (1.92mm) were determined from the focal spot intensity profiles and their corresponding Full Width at Half Maxima (FWHM) in two orthogonal orientations. The CMOS image sensor measurements demonstrated differences in the measured width and length dimensions when compared to film measurements. The obtained nominal focal spot values however showed that image-sensor determined focal spot dimensions agreed with the direct film and film-screen methods when based on the AS/NZS defined nominal focal spot values. The CMOS image sensor tested appears to lack the measurement accuracy required for the measurement of small focal spot sizes due in part to its limited camera sensitivity.

Equipment Design↗
PubMed1994

Calibration of a cadmium IVNAA system.

An in vivo neutron activation analysis (IVNAA) system for the measurement of cadmium in the human liver and kidney was calibrated using cadmium doped liver and kidney phantoms in a water tank. The effect on the number of cadmium gammas detected with changes in organ position and cross-organ interference was assessed. The lower limits of detection were found to be 12 mg cadmium in the kidney and 7 ppm cadmium in the liver. This system was compared to five others using a performance index which considers equipment specifications and dose to the subject, and was found to rank second best for the liver measurements and second worst for the kidney measurements. The results from the organ position studies showed that the depth of the organs in the body has a great effect on the results, and differences between systems could be partially due to differences in calibration geometry.

Cadmium↗
PubMed1993

Alpha radiation detection using silicon memory chips--preliminary studies.

Alpha radiation dosage is an important occupational health factor in the mining of uranium and mineral sands. Alpha radiation induced errors in the data of silicon based memory chips provide the foundation for a new type of sensor, with the potential for affordable and prompt measurement of personal alpha doses. With particular reference to Dynamic Random Access Memories (DRAM) this paper introduces the operating principle of a memory based radiation sensor, which is the error mechanism in silicon integrated circuits.

Humans↗
PubMed1992

Response of air, silicon and dosimetric films to x-ray spectra of various qualities.

Calculations have been performed of the kerma to radiographic film and to silicon from a number of x-ray spectra generated at 30 to 140 kV with tungsten and molybdenum targets. These results have been compared with the air-kerma values due to the same beams. It is concluded that both film and silicon can be used as practical dosemeters with an accuracy of +/- 5 to 15%, provided that correction factors are applied based on the generating potential or preferably the beam quality, expressed as half-value thickness.

Air↗
PubMed1983

Speeds of film-screen combinations for radiography.

Values of Ex, the exposure required to yield a net optical density of 1.0, were determined for 12 blue- and nine green-sensitive film types used with 11 blue- and eight green-emitting screen types respectively. The measurements were made using x-rays generated at 80 kVp and 200 mA, under conditions simulating clinical procedures. To examine reciprocity law failure many of the determinations were repeated under similar conditions but at 15 mA. The values of Ex obtained at 15 mA were 6% to 93% greater than those at 200 mA.

Radiographic Image Enhancement↗
PubMedDate not supplied

Repair of distal biceps tendon rupture: a new technique using the Endobutton.

The authors describe a technique with a single anterior incision and fixation with an internal button, the Endobutton. The procedure is performed through a 5-cm transverse skin incision, and the tendon is sutured to the Endobutton with 2 number 5 Ethibond sutures. Surgical repair in the depths of the muscular forearm is not required, because the tendon is simply sutured external to the wound. The Endobutton delivers and locks the tendon into a hole in the radial tuberosity. The Endobutton technique was used in 12 patients who were allowed early active mobilization. All were satisfied, returned to activities, and regained grade 5 strength. Average flexion was from 5 degrees to 146 degrees with 81 degrees supination and 80 degrees pronation. No neurovascular complications or synostosis occurred. In cadaveric studies the average distance from the biceps tendon were ulnar artery 6 mm, median nerve 12 mm, and posterior interosseous nerve 18 mm. The average distance from the posterior interosseous nerve to a Steinman pin advanced through the proximal radius was 14 mm. This technique is a safe and effective method of repair of distal biceps tendon avulsion that allows active mobilization with minimal risk of complication.

Adult↗