Relationship between Dilution Magnification of Non-Ionic Iodinated Contrast Medium and Amplification Effect of Radiation Dose.

Objective: Neuroendovascular treatments are less invasive than surgical clipping. However, the number of fluoroscopy runs may be greater when a contrast medium is used than when routine angiography is performed. Several recent studies have suggested that an iodinated contrast medium causes an increase in the radiation dose.

Contrast enhancement efficacy of iodinated contrast media: Effect of molecular structure on contrast enhancement.

Purpose: To investigate the contrast enhancement in DSA images based on the X-ray absorption characteristics of iodinated contrast media.

Methods: We have derived a new formula of predicting the pixel value ratio of two different contrast media and designate it as "Contrast Enhancement Ratio (CER)". In order to evaluate the accuracy of CER, we have evaluated the relationship between CER and pixel value ratio for all combinations of eleven iodinated contrast media.

Dose reduction and image quality in CT angiography for cerebral aneurysm with various tube potentials and current settings.

Objectives: The purpose of this study is to investigate the image quality on both axial and three-dimensional CT angiograms of the brain at various tube potentials and currents, and to propose the use of descriptors for evaluating the image quality of three-dimensional CT angiograms using entropy analysis.

Methods: A head phantom was used as a target object. Axial CT and three-dimensional CT angiograms were obtained at various effective milliampere-second values (49-350 mAs) and tube potentials (80-140 kVp) with a 64-row detector CT scanner.

Evaluation of patient dose for barium enemas and CT colonography in Japan.

The objective of this study was to assess patient doses for examinations of the lower digestive tract (barium enemas and CT colonography) in Japan. These doses were evaluated from in-phantom dose measurements using a dosemeter-implanted anthropomorphic phantom and from the knowledge of procedures of these examinations. For barium enemas, the doses, which were the sums of doses for various projections in the procedure, were separately derived for fluoroscopy and for analogue and digital radiography.

Evaluation of exposure dose to patients undergoing catheter ablation procedures--a phantom study.

The aim of this study was to evaluate entrance skin dose (ESD), organ dose and effective dose to patients undergoing catheter ablation for cardiac arrhythmias, based on the dosimetry in an anthropomorphic phantom. ESD values associated with mean fluoroscopy time and digital cine frames were in a range of 0.12-0.

Comparative evaluation of organ and effective doses for paediatric patients with those for adults in chest and abdominal CT examinations.

Patient doses in paediatric and adult CT examinations were investigated for modern multislice CT scanners by using specially constructed in-phantom dose measuring systems. The systems were composed of 32 photodiode dosemeters embedded in various tissue and organ sites within anthropomorphic phantoms representing the bodies of 6-year-old children and adults. Organ and the effective doses were evaluated from dose values measured at these sites.

Organ and effective dose evaluation in diagnostic radiology based on in-phantom dose measurements with novel photodiode-dosemeters.

Organ and the effective doses of patients undergoing clinical X ray examinations of chest and abdomen were evaluated with an anthropomorphic phantom and a new dosimetry system. The system was comprised of 34 pin photodiode dosemeters placed in/on particular tissues or organs of the anthropomorphic phantom, where the tissues and organs are defined by the International Commission on Radiological Protection (ICRP) to estimate the effective doses. Dosemeter signals were acquired on a personal computer directly, and converted into absorbed doses, from which the organ and the effective doses were evaluated on the computer.

[Evaluation of the effectiveness of gonad protection in diagnostic radiology].

In the present study we describe the evaluation of the effectiveness of gonad protection in diagnostic radiology based on the measurement of organ and the effective doses with and without lead clothing to gonads. We devised in-phantom dosimetry system and measured organ and effective doses in x-ray radiography and CT examinations with the new dosimetry system. From the data of organ and the effective doses we assessed the effectiveness of radiological protection by the use of lead clothing to gonads.

An in-phantom dosimetry system using pin silicon photodiode radiation sensors for measuring organ doses in x-ray CT and other diagnostic radiology.

A dosimetry system using commercially available pin silicon photodiodes as the sensor is evaluated for in-phantom dose measurements in x-ray CT and other diagnostic radiology. System sensitivity measured as a function of the effective energy of x rays was between 0.37 and 0.

Monosialoganglioside containing cationic liposomes with a cationic cholesterol derivative promote the efficiency of gene transfection in mammalian culture cells.

We have studied the effects of monosialoganglioside (GM1)-containing cationic liposomes with a cationic cholesterol on the liposome-mediated gene transfection into mammalian culture cells. The results showed that both cationic liposomes with either a cationic cholesterol derivative of a hydrophobic amino head group (I) and a hydrophilic amino head group (II) promoted the transfection of luciferase plasmids (pGL3) into HeLa and CHO-K1 cells more than the control cationic liposomes without GM1. In addition, we found that cationic liposomes with a cationic cholesterol derivative (II) were about ten times as effective as that by commercially available cationic liposome Lipofectin.

Membrane fusion plays an important role in gene transfection mediated by cationic liposomes.

By confocal laser scanning microscopy (CLSM) we have studied the membrane fusion between cationic liposomes and the endosome membranes involved in gene transfection mediated by cationic liposomes. Antisense oligonucleotides were transferred by cationic liposomes with a cationic cholesterol derivative, cholesteryl-3beta-carboxyamidoethylenedimethylamine (I). Cationic liposomes were made by a mixture of the derivative I and DOPE.

Atomic force microscopy for studying gene transfection mediated by cationic liposomes with a cationic cholesterol derivative.

Atomic force microscopy (AFM) was used for studying gene transfection mediated by cationic liposomes which contain a cationic cholesterol derivative with a different spacer arm. Cationic liposomes were made by a mixture of one of eight cationic cholesterol derivatives and 1,2-dioleoyl-sn-glycero-3-phosphatidyl ethanolamine (DOPE). AFM images showed that vesicles made of the liposome/DNA complex had various diameters depending on each cationic cholesterol derivative with a different spacer arm.

Effect of zeta potential of cationic liposomes containing cationic cholesterol derivatives on gene transfection.

Cationic liposomes are known to be useful tools for gene transfection. However, the relation between transfection efficiency and physicochemical properties of liposomes has not been well understood. Here, we synthesized eight cationic derivatives of cholesterol which contain a tertiary amino head group with a different spacer arm.

Manipulation of a single cell with microcapillary tubing based on its electrophoretic mobility.

Manipulation of a single cell of spherical shape, approximately 5-10 microns in diameter, was performed with capillary tubing and an electrostatic field. A single cell migrates with its electrophoretic mobility into capillary tubing against the flow of electroosmosis coming out of the capillary. After trapping the cell in the capillary, it is pulled out into the other microreservoir with the application of a reverse electric voltage.