Monte Carlo simulation for scanning technique with scattering foil free electron beam: A proof of concept study.

This study investigated the potential of a newly proposed scattering foil free (SFF) electron beam scanning technique for the treatment of skin cancer on the irregular patient surfaces using Monte Carlo (MC) simulation. After benchmarking of the MC simulations, we removed the scattering foil to generate SFF electron beams. Cylindrical and spherical phantoms with 1 cm boluses were generated and the target volume was defined from the surface to 5 mm depth.

The influence of the dose calculation resolution of VMAT plans on the calculated dose for eye lens and optic pathway.

To investigate the effect of dose calculation grid on calculated dose-volumetric parameters for eye lenses and optic pathways. A total of 30 patients treated using the volumetric modulated arc therapy (VMAT) technique, were retrospectively selected. For each patient, dose distributions were calculated with calculation grids ranging from 1 to 5 mm at 1 mm intervals.

Quality of tri-Co-60 MR-IGRT treatment plans in comparison with VMAT treatment plans for spine SABR.

Objective: To investigate the plan quality of tri-Co-60 intensity-modulated radiation therapy (IMRT) plans for spine stereotactic ablative radiotherapy (SABR).

Methods: A total of 20 patients with spine metastasis were retrospectively selected. For each patient, a tri-Co-60 IMRT plan and a volumetric-modulated arc therapy (VMAT) plan were generated.

A comparative planning study for lung SABR between tri-Co-60 magnetic resonance image guided radiation therapy system and volumetric modulated arc therapy.

Background And Purpose: To compare the plan quality of tri-(60)Co magnetic-resonance image-guided radiation therapy (IGRT) to that of volumetric modulated arc therapy (VMAT) for lung stereotactic ablative radiotherapy (SABR).

Materials And Methods: A total of 22 patients with lung tumors located in the lower lobe were selected retrospectively. For each patient, VMAT plans with linac and intensity-modulated radiation therapy (IMRT) plans with the tri-(60)Co system were generated with prescription doses of 60Gy (daily dose=15Gy).

The effect of extremely narrow MLC leaf width on the plan quality of VMAT for prostate cancer.

Background: To investigate the effect of multi-leaf collimators (MLCs) with leaf width of 1.25 mm on the plan quality of volumetric modulated arc therapy (VMAT) for prostate cancer.

Methods: A total of 20 patients with prostate cancer were retrospectively selected.

A machine learning approach to the accurate prediction of multi-leaf collimator positional errors.

Discrepancies between planned and delivered movements of multi-leaf collimators (MLCs) are an important source of errors in dose distributions during radiotherapy. In this work we used machine learning techniques to train models to predict these discrepancies, assessed the accuracy of the model predictions, and examined the impact these errors have on quality assurance (QA) procedures and dosimetry. Predictive leaf motion parameters for the models were calculated from the plan files, such as leaf position and velocity, whether the leaf was moving towards or away from the isocenter of the MLC, and many others.

Dosimetric effects of roll rotational setup errors on lung stereotactic ablative radiotherapy using volumetric modulated arc therapy.

Objective: To evaluate the dosimetric effects of roll-rotational setup errors of stereotactic ablative radiotherapy (SABR) for lung cancer using volumetric modulated arc therapy (VMAT).

Methods: A total of 23 lung SABR cases were evaluated retrospectively. Each of the planning CT images was intentionally rotated by ±1°, ±2° and ±3°.

The effect of beam interruption during VMAT delivery on the delivered dose distribution.

Purpose: The aim of this study is to investigate the effect of beam interruptions during delivery of volumetric modulated arc therapy (VMAT) on delivered dose distributions.

Methods: Ten prostate and ten head and neck (H&N) VMAT plans were retrospectively selected. Each VMAT plan was delivered using Trilogy™ without beam interruption, and with 4 and 8 intentional beam interruptions per a single arc.

Modulation indices for volumetric modulated arc therapy.

The aim of this study is to present a modulation index (MI) for volumetric modulated arc therapy (VMAT) based on the speed and acceleration analysis of modulating-parameters such as multi-leaf collimator (MLC) movements, gantry rotation and dose-rate, comprehensively. The performance of the presented MI (MIt) was evaluated with correlation analyses to the pre-treatment quality assurance (QA) results, differences in modulating-parameters between VMAT plans versus dynamic log files, and differences in dose-volumetric parameters between VMAT plans versus reconstructed plans using dynamic log files. For comparison, the same correlation analyses were performed for the previously suggested modulation complexity score (MCS(v)), leaf travel modulation complexity score (LTMCS) and MI by Li and Xing (MI Li&Xing).

Texture analysis on the fluence map to evaluate the degree of modulation for volumetric modulated arc therapy.

Purpose: Texture analysis on fluence maps was performed to evaluate the degree of modulation for volumetric modulated arc therapy (VMAT) plans.

Methods: A total of six textural features including angular second moment, inverse difference moment, contrast, variance, correlation, and entropy were calculated for fluence maps generated from 20 prostate and 20 head and neck VMAT plans. For each of the textural features, particular displacement distances (d) of 1, 5, and 10 were adopted.

Survivors, not invaders, control forest development following simulated hurricane.

Wind disturbance profoundly shapes temperate forests but few studies have evaluated patterns and mechanisms of long-term forest dynamics following major windthrows. In 1990, we initiated a large hurricane simulation experiment in a 0.8-ha manipulation (pulldown) and 0.

A study on toxic organic emissions from batch combustion of styrene.

Results from a laboratory-scale investigation on batch combustion of styrene are reported herein. Limited quantities of waste styrene monomer are incinerated, however this monomer is, also, the primary pyrolyzate during combustion of waste polystyrene, the second most abundant polymer produced worldwide. Thus, its combustion-generated emissions are of importance to the operation of hazardous waste incinerators and municipal waste-to-energy powerplants.

Polynuclear aromatic hydrocarbon and particulate emissions from two-stage combustion of polystyrene: the effects of the secondary furnace (afterburner) temperature and soot filtration.

Laboratory experiments were conducted in a two-stage horizontal muffle furnace in order to monitor emissions from batch combustion of polystyrene (PS) and identify conditions that minimize them. PS is a dominant component of municipal and hospital waste streams. Bench-scale combustion of small samples (0.