Validation of Monte Carlo-based calculations for megavolt electron beams for IORT and FLASH-IORT.

In Intra-Operative Radiation Therapy (IORT) the tumour site is surgically exposed and normal tissue located around the tumour may be avoided. Electron applicators would require large surgical incisions; therefore, the preferred mechanism for beam collimation is the IORT cone system. FLASH radiotherapy (FLASH-RT) involves the treatment of tumours at ultra-high dose rates and the IORT cone system can also be used.

Measured, calculated, and egs_brachy I-125 dose distributions in a gold plaque for retinoblastoma treatment.

Background: This study measured and calculated dose distributions around a unique gold plaque for whole-eye radiotherapy (to treat retinoblastoma). The applicator consists of a pericorneal ring attached to the four extraocular muscles and four legs, each loaded with I-125 seeds. They are inserted beneath the conjunctiva in-between each pair of muscles and attached anteriorly to the ring.

Practical Dosimetry Considerations for Small MLC-Shaped Electron Fields at 60 cm SSD.

Superficial tumours can be treated with megavoltage electron beams. The underlying tissue can be spared through the steep dose fall-off gradients over a range of a few centimetres. An accurate Monte Carlo model for an Elekta Precise was determined and dose distribution was simulated.

The relation between XR-QA2 and RT-QA2 Gafchromicfilm optical density and absorbed dose in water produced by radionuclides.

. In this study, Monte Carlo (MC) simulations were done to relate the dose-response of the film to that in water. The effect of backscattering materials (PMMA, lead, polystyrene, and air) was investigated on its influence on film density for radionuclides including Am-241, Tc-99m, I-131, Cs-137.

Validation of a Lévy electron energy straggling model for an Elekta Synergy® linear accelerator.

Aim: In this study, an EGSnrc based Monte Carlo electron model was validated for an Elekta Synergy® 160-leaf Agility™ linear accelerator. A previously reported electron energy straggling model based on a Lévy distribution was tested against water tank measurements and a specially designed heterogeneous multi-layered phantom. This included PDD, beam profile, and relative output factor (ROF) comparison.

Dose Shadowing and Prosthesis Involvement for Megavoltage Photon Diode Dosimetry.

Aim: The aim of the study is to investigate the photon beam perturbations induced by an diode in combination with prosthesis involvement in a human-like phantom.

Materials And Methods: Beam perturbations for 6 MV and 10 MV photons caused by an EDP-20 diode in combination with prosthesis involvement were studied in a unique water-equivalent pelvic phantom, equipped with bony structures and Ti prosthesis using single fields between 2 × 2 and 15 cm × 15 cm as well as 10 MV lateral opposing fields and a four-field plan. Dose distributions were measured with Gafchromic EBT3 films with and without the diode included in the beams on the prosthesis (prosthetic fields) and non-prosthesis (non-prosthetic fields) sides of the phantom.

Set-up error validation with EPID images: Measurements vs Egs_cbct simulation.

Aim: In this study, the egs_cbct code's ability to replicate an electronic portal imaging device (EPID) is explored.

Background: We have investigated head and neck (H&N) setup verification on an Elekta Precise linear accelerator. It is equipped with an electronic portal imaging device (EPID) that can capture a set of projection images over different gantry angles.

Characterization of Nylon-12 as a water-equivalent solid phantom material for dosimetric measurements in therapeutic photon and electron beams.

The tissue- or water-equivalence of dosimetry phantoms used as substitutes for water is essential for absorbed dose measurements in radiotherapy. At our institution, a heterogeneous pelvic phantom that consists of stacked Nylon-12 layers has recently been manufactured for Gafchromic film dosimetry. However, data on the use of Nylon as tissue-mimicking media for dosimetric applications are scarce.

Multi-Energy Computed Tomography Breast Imaging with Monte Carlo Simulations: Contrast-to-Noise-Based Image Weighting.

Context: Photon-counting detectors and breast computed tomography imaging have been an active area of research. With these detectors, photons are assigned an equal weight and weighting schemes can be enabled. More weight can be assigned to lower energies, resulting in an increase in the contrast-to-noise ratio (CNR).

EGS_cbct: Simulation of a fan beam CT and RMI phantom for measured HU verification.

Introduction: A mathematical 3D model of an existing computed tomography (CT) scanner was created and used in the EGSnrc-based BEAMnrc and egs_cbct Monte Carlo codes. Simulated transmission dose profiles of a RMI-465 phantom were analysed to verify Hounsfield numbers against measured data obtained from the CT scanner.

Methods And Materials: The modelled CT unit is based on the design of a Toshiba Aquilion 16 LB CT scanner.