Well calculated is better than quickly calculated: Comparison of Pencil beam and Monte Carlo algorithms according to the number of lesions and fractionation in radiosurgery of multiple brain metastases.

Purpose: In this work we compared pencil beam (PB) and Monte Carlo (MC) algorithms in single isocenter plans of multiple brain metastases radiosurgery (SIMM-SRS) plans using the quality indices reported for SRS.

Method: The plans were evaluated concerning the prescribed dose, fractions and the number of metastases. The quality indices studied were mean dose (D), D95, Paddick conformity index (PCI), Radiation Therapy Oncology Group (RTOG) homogeneity (HI) and quality of coverage indices (Q), gradient index (GI), efficiency index for targets (Gη) and organs at risk (OARη) and V-V for brain.

Assessment of PTV margin adequacy for single isocenter multiple brain metastases using genetic algorithms.

. To study the impact on dose coverage and the dose to the healthy tissue applying optimized margins in single isocenter multiple brain metastases radiosurgery (SIMM-SRS) in linac machine based on setup rotations/translations induced errors calculated by a genetic algorithm (GA).The following quality indices of SIMM-SRS were analyzed for 32 plans (256 lesions): Paddick conformity index (PCI), gradient index (GI), maximum (D) and mean (D) doses, local and global Vfor the healthy brain.

Use of genetic algorithm for PTV optimization in single isocenter multiple metastases radiosurgery treatments with Brainlab Elements™.

Purpose: To optimize PTV margins for single isocenter multiple metastases stereotactic radiosurgery through a genetic algorithm (GA) that determines the maximum effective displacement of each target (GTV) due to rotations.

Method: 10 plans were optimized. The plans were created with Elements Multiple Mets™ (Brainlab AG, Munchen, Germany) from a predefined template.

A novel and fast methodology to calculate doses in LDR brachytherapy.

We present the concept of a new methodology for faster simulation of the doses in brachytherapy with permanent implants, based on the knowledge of the seeds arrangement, adding previously simulated doses in an equivalent medium in terms of the atomic composition of the organ in question. To perform the doses calculations we use Monte Carlo simulations. We simulated a cylindrical I-125 seed and compared our results against published data.

Comparison between measured and calculated dynamic wedge dose distributions using the anisotropic analytic algorithm and pencil-beam convolution.

We used the two available calculation algorithms of the Varian Eclipse 7.3 three-dimensional (3D) treatment planning system (TPS), the anisotropic analytic algorithm (AAA) and pencil-beam convolution (PBC), to compare measured and calculated two-dimensional enhanced dynamic wedge (2D EDW) dose distributions, plus implementation of the dynamic wedge into the TPS. Measurements were carried out for a 6-MV photon beam produced with a Clinac 2300C/D linear accelerator equipped with EDW, using ionization chambers for beam axis measurements and films for dose distributions.

Commissioning and quality assurance for intensity modulated radiotherapy with dynamic multileaf collimator: experience of the Pontificia Universidad Católica de Chile.

The objective of this paper is to present our experience in the commissioning and quality assurance (QA) for intensity modulated radiotherapy (IMRT) using dynamic multileaf collimator (dMLC), sliding window technique. Using Varian equipment solution, the connectivity and operation between all IMRT chain components was checked. Then the following test were done: stability of leaf positioning and leaf speed, sensitivity to treatment interruptions (acceleration and deceleration), evaluation of standard field patterns, stability of dMLC output, segmental dose accuracy check, average leaf transmission, dosimetric leaf separation, effects of lateral disequilibrium between adjacent leaves in dose profiles and multiple carriage field verification.

Hospital discharge of patients with thyroid carcinoma treated with 131I.

Unlabelled: A dose limit-based criterion was proposed to authorize hospital discharge of thyroid carcinoma patients treated with 131I. Evaluation of accumulated doses to determine the effective half-life, the expected accumulated dose at 1 m, and the hospitalization time was performed to ensure that the dose limit was satisfied for each patient. Situations involving different dose limits and occupancy factors were analyzed.