Assessment of Setup Accuracy Using Anatomical Landmarks for Breast and Chest Wall Irradiation With Surface Guided Radiation Therapy.

Purpose: This study aimed to determine setup accuracy using anatomic landmarks for breast irradiation with and without surface guided radiation therapy (SGRT) and assess setup time with SGRT.

Methods And Materials: This study included 115 patients with 1945 treatment fractions. Patients were treated with 4 techniques: tangents, tangents using deep-inspiration breath hold, and tangents with regional nodal irradiation with and without deep-inspiration breath hold.

Three-Dimensional Dosimetry for Radiation Safety Estimates from Intrathecal Administration.

Intrathecal administration is of growing interest for drug delivery, and its utility is being increasingly investigated through imaging. In this work, the 3-dimensional Voxel-Based Internal Dosimetry Application (VIDA) and 4D Extended Cardiac Torso Phantom (XCAT) were extended to provide radiation safety estimates specific to intrathecal administration. The 3-dimensional VIDA dosimetry application Monte Carlo simulation was run using a modified XCAT phantom with additional and edited cerebrospinal fluid (CSF) regions to produce voxel-level absorbed dose per unit cumulated activity maps for 9 selected source regions.

Realistic phantoms to characterize dosimetry in pediatric CT.

Background: The estimation of organ doses and effective doses for children receiving CT examinations is of high interest. Newer, more realistic anthropomorphic body models can provide information on individual organ doses and improved estimates of effective dose.

Materials And Methods: Previously developed body models representing 50th-percentile individuals at reference ages (newborn, 1, 5, 10 and 15 years) were modified to represent 10th, 25th, 75th and 90th height percentiles for both genders and an expanded range of ages (3, 8 and 13 years).

Two Realistic Beagle Models for Dose Assessment.

Previously, the authors developed a series of eight realistic digital mouse and rat whole body phantoms based on NURBS technology to facilitate internal and external dose calculations in various species of rodents. In this paper, two body phantoms of adult beagles are described based on voxel images converted to NURBS models. Specific absorbed fractions for activity in 24 organs are presented in these models.

Patient-specific dose calculations for pediatric CT of the chest, abdomen and pelvis.

Background: Organ dose is essential for accurate estimates of patient dose from CT.

Objective: To determine organ doses from a broad range of pediatric patients undergoing diagnostic chest-abdomen-pelvis CT and investigate how these relate to patient size.

Materials And Methods: We used a previously validated Monte Carlo simulation model of a Philips Brilliance 64 multi-detector CT scanner (Philips Healthcare, Best, The Netherlands) to calculate organ doses for 40 pediatric patients (M:F = 21:19; range 0.

VIDA: a voxel-based dosimetry method for targeted radionuclide therapy using Geant4.

We have developed the Voxel-Based Internal Dosimetry Application (VIDA) to provide patient-specific dosimetry in targeted radionuclide therapy performing Monte Carlo simulations of radiation transport with the Geant4 toolkit. The code generates voxel-level dose rate maps using anatomical and physiological data taken from individual patients. Voxel level dose rate curves are then fit and integrated to yield a spatial map of radiation absorbed dose.

Cyclo-oxygenase-2 inhibition and endothelium-dependent vasodilation in younger vs. older healthy adults.

Aim: A major feature of endothelial dysfunction is reduced endothelium-dependent vasodilation, which in ageing may be due to decreased production of endothelial prostacyclin, or nitric oxide (NO), or both.

Method: We tested this hypothesis in 12 younger (age 18-38 years, six women) and 12 older healthy adults (age 55-73 years, six post-menopausal women). Endothelium-dependent vasodilation was assessed by the forearm vascular conductance (FVC) response to intra-arterial acetylcholine (ACh) (0.

Dietary sodium influences the effect of mental stress on heart rate variability: a randomized trial in healthy adults.

Background: Dietary sodium influences intermediate physiological traits in healthy adults independent of changes in blood pressure. The purpose of this study was to test the hypothesis that dietary sodium affects cardiac autonomic modulation during mental stress.

Method: In a prospective, randomized cross-over design separated by 1 month between diets, 70 normotensive healthy young adults (F/M: 44/26, aged 18-38 years) consumed a 5-day low (10 mmol/day), normal (150 mmol), and high (400 mmol) sodium diet followed by heart rate variability (HRV) recordings at rest and during 5-min computerized mental arithmetic.

Sex differences in salt sensitivity to nitric oxide dependent vasodilation in healthy young adults.

Dietary sodium and blood pressure regulation differs between normotensive men and women, an effect which may involve endothelial production of nitric oxide (NO). Therefore, we tested the hypothesis that differences in the NO component of endothelium-dependent vasodilation between low and high dietary sodium intake depend on sex. For 5 days prior to study, healthy adults consumed a controlled low-sodium diet (10 mmol/day, n = 30, mean age ± SE: 30 ± 1 yr, 16 men) or high-sodium diet (400 mmol/day, n = 36, age 23 ± 1 yr, 13 men).

Prolonged NO treatment decreases alpha-adrenoreceptor agonist responsiveness in porcine pulmonary artery due to persistent soluble guanylyl cyclase activation.

A cultured porcine pulmonary artery (PA) model was used to examine the effects of prolonged nitric oxide (NO) treatment on the response of this vessel to acutely applied NO and to the alpha-adrenoreceptor agonist phenylephrine. Two-hour treatment with the NO donor (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NO) decreased both NO and phenylephrine responsiveness. Twenty-four-hour treatment with DETA-NO resulted in a further reduction in NO responsiveness but no further reduction in phenylephrine responsiveness.