Optimization of the Eclipse TPS beam configuration parameters for small field dosimetry using Monte Carlo simulations and experimental measurements.

Purpose: To evaluate the impact of tuning the beam configurations parameters on the Analytical Anisotropic Algorithm (AAA) and the Acuros XB (AXB) algorithm for small fields using Monte Carlo simulations and measurements.

Methods: The TrueBeam STx with the high-definition 120 multi-leaf collimator (HD120-MLC) was modeled with Geant4 application for emission tomography (GATE) Monte Carlo platform and validated against measurements. The impact of varying the effective spot size (ESS) and dosimetric leaf gap (DLG) on AAA and AXB calculations was carried out for small MLC-fields ranging from 0.

Helical tomotherapy for post-mastectomy radiation therapy with or without breast implant: a single institution experience.

Introduction: We report on our experience of using Helical Tomotherapy (HT) in the context of post-mastectomy radiation therapy (PMRT) with or without immediate implant-based breast Reconstruction (IBR).

Material And Methods: The study included a total of 173 patients who underwent PMRT with HT between 2013 and 2015 in our institution (87 immediate breast reconstructions with retropectoral implants (IBR + ), 86 without reconstructions (IBR-)). The chest wall target volume included subcutaneous tissue and pectoralis muscle and excluded the posterior region of the implant as well as the ribs.

Field output correction factors and electron fluence perturbation of the microSilicon and microSilicon X detectors.

The aim of this study was to determine field output correction factorskQclin,Qreffclin,frefand electron fluence perturbation for new PTW unshielded microSilicon and shielded microSilicon X detectors.kQclin,Qreffclin,freffactors were calculated for 6 and 10 MV with and without flattening filter beams delivered by a TrueBeam STx. Correction factors were determined for field sizes ranging from 0.

Technical note: GAMMORA, a free, open-source, and validated GATE-based model for Monte-Carlo simulations of the Varian TrueBeam.

Purpose: Monte Carlo (MC) is the reference computation method for medical physics. In radiotherapy, MC computations are necessary for some issues (such as assessing figures of merit, double checks, and dose conversions). A tool based on GATE is proposed to easily create full MC simulations of the Varian TrueBeam STx.

A study of the interplay effect in radiation therapy using a Monte-Carlo model.

Purpose: In modulated radiotherapy, breathing motion can lead to Interplay (IE) and Blurring (BE) effects that can modify the delivered dose. The aim of this work is to present the implementation, the validation and the use of an open-source Monte-Carlo (MC) model that computes the delivered dose including these motion effects.

Methods: The MC model of the Varian TrueBeam was implemented using GATE.

Towards the standardization of the absorbed dose report mode in high energy photon beams.

The benefits of using an algorithm that reports absorbed dose-to-medium have been jeopardized by the clinical experience and the experimental protocols that have mainly relied on absorbed dose-to-water. The aim of the present work was to investigate the physical aspects that govern the dosimetry in heterogeneous media using Monte Carlo method and to introduce a formalism for the experimental validation of absorbed dose-to-medium reporting algorithms. Particle fluence spectra computed within the sensitive volume of two simulated detectors (T31016 Pinpoint 3D ionization chamber and EBT3 radiochromic film) placed in different media (water, RW3, lung and bone) were compared to those in the undisturbed media for 6 MV photon beams.

A study of the interplay effect for VMAT SBRT using a four-axes motion phantom.

Purpose: To assess the accuracy of volumetric modulated arc therapy (VMAT) stereotactic body radiation therapy (SBRT) when treating moving targets (such as lung or liver lesions), focusing on the impact of the interplay effect in the event of complex breathing motion and when a gating window is used.

Methods: A dedicated programmable motion platform was implemented. This platform can carry large quality assurance (QA) phantoms and achieve complex three-dimensional (3D) motion.

Virtual bolus for total body irradiation treated with helical tomotherapy.

Intensity-modulated radiation therapy (IMRT) for total body irradiation (TBI) is practiced in several centers using the TomoTherapy System. In this context the planning target volume (PTV) is the entire body including the skin. A safety margin in the air surrounding the body should be added to take into account setup errors.

Integration method of 3D MR spectroscopy into treatment planning system for glioblastoma IMRT dose painting with integrated simultaneous boost.

Background: To integrate 3D MR spectroscopy imaging (MRSI) in the treatment planning system (TPS) for glioblastoma dose painting to guide simultaneous integrated boost (SIB) in intensity-modulated radiation therapy (IMRT).

Methods: For sixteen glioblastoma patients, we have simulated three types of dosimetry plans, one conventional plan of 60-Gy in 3D conformational radiotherapy (3D-CRT), one 60-Gy plan in IMRT and one 72-Gy plan in SIB-IMRT. All sixteen MRSI metabolic maps were integrated into TPS, using normalization with color-space conversion and threshold-based segmentation.

[Clinical prediction rule for diagnosing deep vein thrombosis in primary care].

Patients with suspected deep vein thrombosis (DVT) are often managed on an outpatient basis by primary care physicians. International guidelines recommend anticoagulant treatment for patients with suspected DVT when diagnostic testing is delayed or when clinical probability is high. Our goal was to build a clinical prediction rule specifically for easy use in primary care to help decide about starting anticoagulant therapy while awaiting ultrasound examination.

Initial evaluation of a four-dimensional computed tomography system using a programmable motor.

A dynamic lung tumor phantom was used to investigate the geometric reconstruction accuracy of a commercial four-dimensional computed tomography (4D-CT) system. A ball filled with resin, embedded in a cork cube, was placed on a moving platform. Various realistic antero-posterior (AP) motions were programmed to reproduce the respiratory motion of a lung tumor.

Lung volume assessment for a cross-comparison of two breathing-adapted techniques in radiotherapy.

Purpose: To assess the validity of gated radiotherapy of lung by using a cross-check methodology based on four-dimensional (4D)-computed tomography (CT) exams. Variations of volume of a breathing phantom was used as an indicator.

Methods And Materials: A balloon was periodically inflated and deflated by a medical ventilator.

[Respiratory gated radiotherapy: the 4D radiotherapy].

Respiration-gated radiotherapy offers a significant potential for improvement in the irradiation of tumor sites affected by respiratory motion such as lung, breast and liver tumors. An increased conformality of irradiation fields leading to decreased complications rates of organs at risk (lung, heart..