Audit of radiation dose delivered in time-resolved four-dimensional computed tomography in a radiotherapy department.

Introduction: To review the dose delivered to patients in time-resolved computed tomography (4D CT) used for radiotherapy treatment planning.

Methods: 4D CT is used at Peter MacCallum Cancer Centre since July 2007 for radiotherapy treatment planning using a Philips Brilliance Wide Bore CT scanner (16 slice, helical 4D CT acquisition). All scans are performed at 140 kVp and reconstructed in 10 datasets for different phases of the breathing cycle.

Online kidney position verification using non-contrast radiographs on a linear accelerator with on board KV X-Ray imaging capability.

The kidneys are dose-limiting organs in abdominal radiotherapy. Kilovoltage (kV) radiographs can be acquired using on-board imager (OBI)-equipped linear accelerators with better soft tissue contrast and lower radiation doses than conventional portal imaging. A feasibility study was conducted to test the suitability of anterior-posterior (AP) non-contrast kV radiographs acquired at treatment time for online kidney position verification.

Smokers as a high-risk group: data from a screening population.

Goal: To determine the number of pack-years exposure associated with a 2-fold increase risk for significant colorectal neoplasia and to examine the risk of smoking in younger patients.

Background: Cigarette smoking has been shown to be a significant risk factor for colorectal neoplasia and may be used to stratify patients for screening or triaging of screening resources. However, more information is needed regarding the amount of exposure required to significantly increase by 2-fold an individual's risk for colorectal neoplasia.

Body mass index: a marker for significant colorectal neoplasia in a screening population.

Background And Aims: Although some studies suggest a positive association between increasing body mass index (BMI) and risk for colorectal neoplasia, the impact on screening has not been examined. We performed a cross-sectional study to examine the association of BMI and colorectal neoplasia in a screening population.

Methods: Data collected for 2493 patients presenting for screening colonoscopy included known risk factors for colorectal neoplasia, demographic information, and lifestyle factors.

Perinatal HIV counseling and rapid testing in Tijuana, Baja California, Mexico: seroprevalence and correlates of HIV infection.

Objective: To evaluate the acceptance of counseling and rapid HIV testing and to determine the associated risk factors for HIV infection in pregnant women in Baja California, Mexico.

Methods: Pregnant women attending Tijuana General Hospital who consented to participate in the study had blood drawn for a rapid HIV test (Determine HIV-1/2; Abbott Diagnostics, North Chicago, IL). A confirmatory enzyme immunoassay and Western blot were performed and demographic and risk factor data were obtained.

Prevalence and risk of colorectal neoplasia in consumers of alcohol in a screening population.

Background And Aims: Although studies suggest a positive association between alcohol consumption and risk for colorectal neoplasia, the impact on screening has not been fully examined. It is also unclear whether all types of alcohol are associated with an increased risk. We performed a cross-sectional study to examine the impact of regular alcohol consumption on the detection of significant colorectal neoplasia in a screening population.

Predictors of proximal neoplasia in patients without distal adenomatous pathology.

Background: Previous colorectal cancer screening studies have observed that some patients may have advanced proximal neoplasia without distal findings. Since these studies have included only gender, age, and family history as risk factors, they are limited in their ability to identify predictors of isolated proximal neoplasia.

Methods: Data were collected from the charts of 1,988 patients who presented for colonoscopy.

Prevalence of colorectal neoplasia in smokers.

Objectives: Smoking has been linked with colorectal neoplasia. Previous colonoscopy screening studies have omitted smoking and have examined only gender, age, and family history. Our aim was to use a screening population to measure the prevalence of neoplasia in smokers, the anatomic location of these lesions, and the strength of this association relative to other risk factors.

Mechanism of Amine-Catalyzed Ester Formation from an Acid Chloride and Alcohol.

Stopped-flow FT-IR spectroscopy has been used to study the amine-catalyzed reactions of benzoyl chloride with either butanol or phenol in dichloromethane at 0 degrees C. There is a paucity of detailed rate information available in the literature for this process. Our goal was to determine whether amine catalysis operated by a nucleophilic-, specific-base-, or general-base-catalyzed mechanism.