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Biomedical subjects

C Tillman

Publications and source records attributed to C Tillman.

9 recordsLinked to original sources
PubMed2005

Contact allergy to gold in patients with gold-plated intracoronary stents.

An increasingly common and effective method for the treatment of atherosclerotic disease in the coronary arteries is percutaneous transluminal coronary angioplasty (PTCA) and stenting. The stents are made of different metals. An increased rate of restenosis when using gold-plated stents has been shown. Contact allergy to gold is common in many countries. Recently, a study has shown an increased rate of contact allergy to nickel among patients with restenosis and a nickel-containing stent. The aims of our study were to investigate whether there was an increased rate of contact allergy to gold among patients with gold-plated stents and if this increased the risk of restenosis. 22 patients who had received a gold-plated stent were patch tested. An age- and sex-matched population of 88 patients, previously patch tested because of a suspected contact dermatitis, served as controls. In the stent group, 10/22 (45.5%) had a contact allergy to gold, in the control group 18/88 (20.5%); the difference is statistically significant (P = 0.04). There was no significant difference regarding frequency of restenosis. Our study indicates that there is a risk of sensitizing the patient when implanting a gold-plated stent. Further studies are needed to confirm these results and to evaluate whether there is an increased risk of restenosis.

Adult↗
PubMed1999

Survival of mammalian cells exposed to ultrahigh dose rates from a laser-produced plasma x-ray source.

PURPOSE: To determine whether intense laser-produced x rays have an increased radiation hazard. MATERIALS AND METHODS: Mammalian cells were exposed to x rays from a laser-produced plasma that produced ultrahigh peak absorbed dose rates, up to a factor of 10(10) higher than those produced by conventional x rays used in imaging. The cell survival was studied as a function of the absorbed dose. The survival of mammalian cells exposed to high peak absorbed dose rates with laser-produced x rays was compared with the survival of cells exposed to standard absorbed dose rates with conventional x-ray sources. Comparative survival studies were performed by using a conventional x-ray tube and a cobalt 60 source. The absorbed doses in the irradiation field were measured with thermoluminescent dosimeters. RESULTS: Cell survival following irradiation by filtered, laser-produced x rays with a high dose rate was not markedly different from the survival following irradiation by conventional sources. There was, however, a notable difference between the survival after exposure to filtered, laser-produced x rays and the survival after exposure to unfiltered laser-produced x rays. CONCLUSION: Exposure to filtered, laser-produced x rays with a high dose rate does not lead to increased harm to mammalian cells exposed in vitro compared with the harm from exposure to x rays from conventional sources, which indicates that the use of high-power laser facilities for medical imaging is justified.

Animals↗
PubMed1997

Contrast-enhanced radiography by differential absorption, using a laser-produced x-ray source.

RATIONALE AND OBJECTIVES: The authors evaluate the feasibility of differential imaging of contrast media, with division of individual pixel values obtained from digital images generated by characteristic radiation from a laser-produced plasma, bridging the K-absorption edge of the contrast agent. METHODS: Laser pulses from an ultrashort-pulse terawatt laser system were focused onto gadolinium and tantalum targets, creating a plasma from which characteristic radiation and Bremsstrahlung was emitted. The elements of the target were selected so the characteristic emission lines of one of the elements were below the K edge of the contrast agent and the emission lines of the other element above. A phantom with gadolinium and other elements in various concentrations was examined. One radiographic exposure was made using a gadolinium target source and a subsequent exposure using a tantalum source. Both images were recorded digitally and the transmission ratios calculated by division of the individual pixel values. RESULTS: When viewed separately, the two images of the test phantom appeared similar. In the differential image, only the gadolinium solutions were bright, reflecting a difference in attenuation between the two exposures. CONCLUSIONS: Element-specific radiographs can be obtained by differential imaging. When fully explored, the technique may allow for contrast-enhanced radiography with increased sensitivity and decreased contrast dose.

Animals↗
PubMed1996

Training/learning/accountability ... never ending.

Patient-focused redesign exemplifies a radical change in the patient care delivery system. The focus shifts from fragmented, centralized departmental functions to a point of service, collaborative orientation. The profundity of this shift evokes a myriad of seemingly endless learning opportunities that permeates the organization. This article offers an overview of some of these learning opportunities from global training, functional unit, and specific procedural perspectives.

Hospital Restructuring↗
PubMed1993

Generation of x rays for medical imaging by high-power lasers: preliminary results.

PURPOSE: To evaluate the use of x-ray imaging performed with a high-power laser system in biologic and medical studies. MATERIALS AND METHODS: A compact terawatt laser system based on chirped pulse amplification in titanium-doped sapphire was used. X rays were generated by irradiating a high-atomic-number target (tantalum). RESULTS: When photons with an energy below 10 keV were removed with use of 3 mm of aluminum, the half-value layer in aluminum for the remaining x rays was approximately 10 mm. The x-ray source allowed performance of biologic magnification radiography. Star-pattern tests indicated an equivalent focal spot size of less than 60 microns. Exposures of a single pulse could be obtained. The duration of a single x-ray pulse was estimated to be of the order of picoseconds. CONCLUSION: With use of subpicosecond laser pulses, x-ray generation can occur with a smaller equivalent focal spot size than with conventional x-ray sources.

Aluminum↗