John Stratakis

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The purpose of this study was to determine the gonadal dose, effective dose and relevant radiogenic risks associated with pediatric patients undergoing voiding cystourethrography (VCUG). Exposure parameters were monitored in 118 consecutive children undergoing VCUG. The entrance surface dose (ESD) was determined by thermoluminescent dosimeters (TLDs). For(More)
BACKGROUND Symptomatic choledocholithiasis can be treated during pregnancy. Conceptus doses ranged from 0.1 mGy to 3 mGy in previous studies. OBJECTIVE The objectives of the current study were to investigate whether the conceptus dose may exceed the threshold of 10 mGy in the case of a pregnant patient undergoing ERCP, and to provide data for the accurate(More)
z overscanning in multidetector (MD) helical CT scanning is prerequisite for the interpolation of acquired data required during image reconstruction and refers to the exposure of tissues beyond the boundaries of the volume to be imaged. The aim of the present study was to evaluate the effect of z overscanning on the patient effective dose from helical MD CT(More)
The aim of the current study was to (a) provide normalized dose data for the estimation of the radiation dose from upper gastrointestinal tract contrast (UGIC) studies carried out to infants and (b) estimate the average patient dose and risks associated with radiation from UGIC examinations performed in our institution. Organ and effective doses, normalized(More)
This paper presents a computerized method for the selection of an irregular region of interest (ROI) in broadband ultrasound attenuation (BUA) images. A region growing algorithm searches an initial region in the posterior part of the calcaneus until the pixel with the lowest attenuation value is found; this is the starting seed. Then, the algorithm(More)
PURPOSE To estimate radiation dose and associated risks after fluoroscopically guided percutaneous transhepatic biliary (PTB) drainage and stent implantation procedures. MATERIALS AND METHODS Organ and effective doses, normalized to dose-area product (DAP), were estimated for PTB procedures with use of a Monte Carlo transport code and an adult(More)
The objective of this study was to estimate the radiation dose and associated risks resulting from fluoroscopically guided percutaneous transluminal angioplasty with or without stent placement in the abdominal region. Average examination parameters for renal and aortoiliac procedures were derived using data from 80 consecutive procedures performed in our(More)
Our aim in the present study was to investigate the effects of initial electron beam characteristics on Monte Carlo calculated absorbed dose distribution for a linac 6 MV photon beam. Moreover, the range of values of these parameters was derived, so that the resulted differences between measured and calculated doses were less than 1%. Mean energy, radial(More)
The objective of the present work was to provide precise effective and organ dose data for radiographic examinations of the skull performed on pediatric patients. To accomplish this, the MCNP4C2 transport code was utilized and 18 mathematical anthropomorphic phantoms, representing ages from a newborn child to a 17-year-old adolescent, were developed. Three(More)
PURPOSE The aim of this study was to determine occupational dose levels for projections commonly used in fluoroscopically guided percutaneous transhepatic biliary (PTB) drainage and stent placement procedures. METHODS Exposure data from 71 consecutive PTB examinations were analyzed to determine average examination parameters for biliary drainage and stent(More)