Determination of equivalent breast phantoms for different age groups of Taiwanese women: an experimental approach.

Purpose: Polymethylmethacrylate (PMMA) slab is one of the mostly used phantoms for studying breast dosimetry in mammography. The purpose of this study was to evaluate the equivalence between exposure factors acquired from PMMA slabs and patient cases of different age groups of Taiwanese women in mammography.

Methods: This study included 3910 craniocaudal screen/film mammograms on Taiwanese women acquired on one mammographic unit.

Development of an adjustable model breast for mammographic dosimetry assessment in Taiwanese women.

Objective: The currently used model breast for mammographic dosimetry assessment lacks the flexibility to change dimensions. The aim of this study was to develop an adjustable model breast for mammographic dosimetry assessment of Taiwanese women.

Materials And Methods: A retrospective review of 4226 craniocaudal (CC) views was conducted.

Quantitative ultrasound of the calcaneus in hemodialysis patients.

The aim of this study was to investigate the bone status of hemodialysis patients and identify factors that have influence on bone quality. Four hundred eighty-nine subjects (213 males and 276 females) on maintenance hemodialysis and 696 healthy subjects (309 men, 387 women) were enrolled in this study. Speed of sound (SOS), broadband ultrasound attenuation (BUA) and quantitative ultrasound index (QUI) were assessed by quantitative ultrasound (QUS) at the right calcaneus in both groups.

Biodistribution, toxicity and radiation dosimetry studies of the serotonin transporter radioligand 4-[18F]-ADAM in rats and monkeys.

Purpose: 4-[(18)F]-ADAM is a potent serotonin transport imaging agent. We studied its toxicity in rats and radiation dosimetry in monkeys before human studies are undertaken.

Methods: Single and multiple-dosage toxicity studies were conducted in Sprague-Dawley rats.

An improved synthesis of 4-[18F]-ADAM, a potent serotonin transporter imaging agent.

An improved synthesis of N,N-dimethyl-2-(2-amino-4-[(18)F]fluorophenylthio)benzylamine (4-[(18)F]-ADAM, 2) as a potent serotonin transporter (SERT) imaging agent is described. Molecular orbital (MO) calculation predicts that N,N-dimethyl-2-(2-nitro-4-trimethylammoniumtrifluoromethanesulfonylphenylthio)benzamide (8) is probably a better precursor than N,N-dimethyl-2-(2,4-dinitrophenylthio)benzylamine (1) for preparing 2. Radioligand 2 was synthesized by the reaction of either precursor 1 or precursor 8 with K[(18)F]/K(2.

Prognostic factors in women with early stage small cell carcinoma of the uterine cervix.

Small cell carcinoma of the uterine cervix (SCCUC) is an uncommon, aggressive disease accounting for less than 5% of all cervical cancers. Due to its rarity, definitive treatment strategies have not been developed. Our aim was to analyze the clinical factors, treatment modalities, sites of relapse, and overall survival of women with early stage SCCUC and thus determine prognostic factors.

Effect of cigarette smoking on bone mineral density in healthy Taiwanese middle-aged men.

The effect of cigarette smoking in relation to bone mineral density (BMD) remains inconclusive, especially in middle-aged men. This cross-sectional study was conducted to examine the effect of smoking on BMD in 837 healthy Taiwanese males (532 never-smokers, 258 current smokers, 47 former smokers; aged 46-64 yr), recruited at their routine health examination. Subjects with suspected conditions affecting bone metabolism or receiving any medications affecting bone metabolism were excluded.

Radioactivity concentrations and dose assessment for soil samples around nuclear power plant IV in Taiwan.

Activity concentrations and distributions of natural and man-made radionuclides in soil samples collected around nuclear power plant IV, Taiwan, were investigated for five years to assess the environmental radioactivity and characterisation of radiological hazard prior to commercial operation. The activity concentrations of radionuclides were determined via gamma-ray spectrometry using an HPGe detector. Data obtained show that the average concentrations of the (238)U and (232)Th series, and (40)K, were within world median ranges in the UNSCEAR report.

Micro-column solid phase extraction to determine uranium and thorium in environmental samples.

Extraction chromatographic separation techniques based on U/TEVA and TEVA resins were utilized to separate uranium and thorium isotopes in complex matrices from environmental samples. This approach has the advantages of ease of quantitative analysis, small sample size, an absence of mixed waste solvents, complete separation of U/Th isotopes, acceptable chemical yields and good energy resolution in the alpha spectrum. The procedure for analyzing alpha-emitting isotopes of uranium and thorium in geothermal water from Peito, Taiwan, is illustrated in detail.

On-line enhancement and separation of nanoparticles using capillary electrophoresis.

We describe a rapid, simple, and highly efficient capillary electrophoresis (CE)-based method for the analysis of nanoparticles (NPs). In this study, we used the reversed electrode polarity stacking mode (REPSM) of CE to assess the feasibility of enhancing the detection of Au NPs and Au/Ag NPs, optimizing parameters such as the length of time for which the REPSM was applied, the concentrations of the buffer and the sodium dodecylsulfate (SDS) surfactant, and the pH. Under the optimized on-line enhancement conditions [buffer: SDS (40 mM) and 3-cyclohexylamino-1-propanesulfonic acid (CAPS; 10 mM) at pH 10.

Analytical separation of Au/Ag core/shell nanoparticles by capillary electrophoresis.

This paper demonstrates that capillary electrophoresis (CE) can be employed for characterizing the sizes of a series of Au/Ag core/shell nanoparticles (NPs). We effected the CE separation of Au/Ag core/shell NPs using a mixed buffer of sodium dodecyl sulphate (SDS) (40 mM) and 3-(cyclohexylamino)propanesulfonic acid (10 mM) at pH 9.7 and an applied voltage of 20 kV.

A positron emission tomography/computed tomography (PET/CT) acquisition protocol for CT radiation dose optimization.

Background: In current combined positron emission tomography/computed tomography (PET/CT) systems, high-quality CT images not only increase diagnostic value by providing anatomic delineation of hyper- and hypometabolic tissues, but also shorten the acquisition time for attenuation correction compared with standard PET imaging. However, this technique potentially introduces more radiation burden to patients as a result of the higher radiation exposure from CT.

Methods: In this study, the radiation doses delivered from typical germanium-based and CT-based transmission scans were measured and compared using an anthropomorphic Rando Alderson phantom with insertions of thermoluminescent dosimeters.

Combining optical lithography with rapid microwave heating for the selective growth of Au/Ag bimetallic core/shell structures on patterned silicon wafers.

We demonstrate a novel approach for the production of patterned films of nanometer-sized Au/Ag bimetallic core/shell nanoparticles (NPs) on silicon wafers. In this approach, we first self-assembled monodisperse Au NPs, through specific Au..

Studying the size/shape separation and optical properties of silver nanoparticles by capillary electrophoresis.

This paper describes the feasibility of employing capillary electrophoresis (CE) to separate silver particles in nanometer regimes. We have found that the addition of an anionic surfactant, sodium dodecyl sulphate (SDS), to the running electrolyte prevents coalescence of the silver particles during the process, which improves the separation performance; the concentration of SDS required for optimal silver nanoparticle separation is ca. 20 mM.

Three-dimensional conformal radiation therapy for unresectable hepatocellular carcinoma patients who had failed with or were unsuited for transcatheter arterial chemoembolization.

Background: The purpose of our study was to evaluate the outcome of unresectable hepatocellular carcinoma (HCC) patients, who had either failed with or were unsuited for transcatheter arterial chemoembolization (TACE), treated with three-dimensional conformal radiation therapy (3DCRT) and to determine the prognostic outcome factors.

Methods: From September 1999 to March 2003, 44 patients with unresectable HCC underwent 3DCRT. Thirty-seven patients were male and seven female.

Correlation between temporal response of fMRI and fast reaction time in a language task.

Correlation between behavioral parameters and fMRI responses can provide an advanced understanding of the neuronal processes. A lexical decision task was employed to examine the correlation between the reaction time (RT) and the temporal parameters in event-related BOLD responses. Word frequency was manipulated in the experiment.

Temporal resolving power of perfusion- and BOLD-based event-related functional MRI.

Functional magnetic resonance imaging (fMRI) based on both perfusion and blood oxygenation level-dependent (BOLD) contrasts has been widely applied in spatiotemporal mapping of the human brain function. Temporal resolving power of fMRI is limited by the smoothed hemodynamic response function dispersed from the neuronal activity. In this study, temporal modulation transfer functions were utilized to quantify the resolving powers of perfusion and BOLD fMR signals in time domain.

Radiation exposure during transmission measurements: comparison between CT- and germanium-based techniques with a current PET scanner.

In positron emission tomographic (PET) scanning, transmission measurements for attenuation correction are commonly performed by using external germanium-68 rod sources. Recently, combined PET and computed tomographic (CT) scanners have been developed in which the CT data can be used for both anatomical-metabolic image formation and attenuation correction of the PET data. The purpose of this study was to evaluate the difference between germanium- and CT-based transmission scanning in terms of their radiation doses by using the same measurement technique and to compare the doses that patients receive during brain, cardiac and whole-body scans.

Study of induced thermoluminescence in CVD diamond film by low-energy X-rays.

For diamond film the one-hit model that is used to interpret low-energy X-ray thermoluminescence (TL) will require some modifications. After the films were irradiated with a superficial X-ray machine with different peak voltages, a two-compartment model with three parameters, the target size, the microscopic saturation factor and the high-LET saturation factor, was used to more precisely describe the TL response to X-ray with energies down to 10 kV. The microdosimetric distribution was calculated using single-event Monte Carlo code developed by authors together with EEDL cross-section data library.

Indoor light on thermoluminescence of CVD diamond film used as a high-energy photon dosimeter.

The effect of light on polycrystalline diamond film that was produced by chemical vapor deposition and is used as a thermoluminescent dosimeter should be considered, although some researchers have indicated that such an effect was theoretically unlikely to happen. A 15 min exposure to a normal desk light bulb induces significant thermoluminescence (TL) comparable to a 0.5 Gy exposure to high-energy photons.

Accuracy of the convolution/superposition dose calculation algorithm at the condition of electron disequilibrium.

Using Monte Carlo simulation and the convolution/superposition algorithm, this work examines percent depth dose curves of the central axis in an acrylic phantom (20 x 20 x 20 cm(3)) with variously sized air cavities (20 x 20 x 1.0, 20 x 20 x 2.0, 20 x 20 x 3.

The effect of a metal hip prosthesis on the radiation dose in therapeutic photon beam irradiations.

Prostate and cervical cancer patients are often treated with external X-ray beams of bi-lateral incidence. Such treatment may incur some dose effect that cannot be predicted precisely in commercial treatment planning systems (TPS) for patients having undergone total hip replacement. This study performs a Monte Carlo (MC) simulation and an analytical calculation (convolution superposition algorithm which is implemented in ADAC TPS) of a 6 MV, 5 x 5 cm2 X-ray beam incident into water with the existence of hip prosthesis, e.

Fabry-perot-type antireflective coating for deep-ultraviolet binary photomask applications.

We demonstrate an antireflective coating structure, which is based on the three-layer metal interference called the Fabry-Perot structure, for a deep-ultraviolet binary mask. The antireflective coating structure is composed of a metal-oxide-metal stack. By addition of different optimized structures, reflectances of less than 1.

Monte Carlo simulation of surface percent depth dose.

This work studied the surface percent depth dose of 6 and 15 MV X-rays, 10 x 10 cm2 and 20 x 20 cm2 fields by Monte Carlo simulation. The OMEGA/BEAM code, an EGS4 user code developed by the NRCC, was used. The linac, Siemens PRIMUS, was accurately modeled according to the ion chamber and CEA film measurement, and the phase space data generated from this linac were collected to simulate dose distribution in water.

Surface dose with grids in electron beam radiation therapy.

This investigation attempts to solve the problem of the lack of skin-sparing effect in electron radiation therapy and to increase the tolerance of skin to radiation using the grid technique. Electron grid therapy involves the mounting of a Cerrobend grid in the electron cone. Film dosimetry was employed to measure the relative surface dose and the percentage depth dose profile of electron grid portals.