Development of a novel 3D-printed dynamic anthropomorphic thorax phantom for evaluation of four-dimensional computed tomography.

Background And Purpose: In radiotherapy, the image quality of four-dimensional computed tomography (4DCT) is often degraded by artifacts resulting from breathing irregularities. Quality assurance mostly employ simplistic phantoms, not fully representing complexities and dynamics in patients. 3D-printing allows for design of highly customized phantoms.

An international film dosimetry intercomparison to establish a multi-center audit framework.

Background: In 2021, a Technical Meeting was hosted by the International Atomic Energy Agency (IAEA) where it was recommended that a standardized method for assessing the accuracy of film dose calculations should be established.

Purpose: To design an audit that evaluates the accuracy of film dosimetry processes. To propose a framework for identifying out-of-tolerance results and to perform an international pilot study to test the audit design.

Optimizing volumetric modulated arc therapy prostate planning using an automated Fine-Tuning process through dynamic adjustment of optimization parameters.

In radiotherapy treatment planning, optimization is essential for achieving the most favorable plan by adjusting optimization criteria. This study introduced an innovative approach to automatically fine-tune optimization parameters for volumetric modulated arc therapy prostate planning, ensuring all constraints were met. A knowledge-based planning model was invoked, and the fine-tuning process was applied through an in-house developed script.

Dosimetry and Monte Carlo modelling of the Papillon+ contact X-ray brachytherapy device.

Purpose: This study aimed to develop and validate a Monte Carlo (MC) model for the Papillon+ contact x-ray brachytherapy (CXB) device, producing 50 kilovolt (kV) X-rays, specifically focusing on its application with a 25 mm diameter rectal applicator for contact therapy.

Material And Methods: The validation process involved depth dose and transverse dose profile measurements using EBT3 gafchromic films positioned in a plastic water low energy range phantom. The half-value layer (HVL) was further measured and derived from the simulated X-ray spectra.

Automated determination of the ion-recombination correction factor (k) in ultra-high dose rate electron radiation therapy.

Background: Plane-parallel ionization chambers are the recommended secondary standard systems for clinical reference dosimetry of electrons. Dosimetry in high dose rate and dose-per-pulse (DPP) is challenging as ionization chambers are subject to ion recombination, especially when dose rate and/or DPP is increased beyond the range of conventional radiotherapy. The lack of universally accepted models for correction of ion recombination in UDHR is still an issue as it is, especially in FLASH-RT research, which is crucial in order to be able to accurately measure the dose for a wide range of dose rates and DPPs.

Early results of a remote dosimetry audit program for lung stereotactic body radiation therapy.

Background And Purpose: A dosimetry audit program based on alanine electron paramagnetic resonance (EPR) and radiochromic film dosimetry, may be a valuable tool for monitoring and improving the quality of lung stereotactic body radiotherapy (SBRT). The aim of this study was to report the initial, independent assessment of the dosimetric accuracy for lung SBRT practice using these dosimeters in combination with a novel phantom design.

Materials And Methods: The audit service was a remote audit program performed on a commercial lung phantom preloaded with film and alanine detectors.

Extended in-field and out-of-field validation of a compact Monte Carlo model of an IBA PROTEUSONE proton beam in TOPAS/GEANT4.

This study evaluates a compact Monte Carlo (MC) model of a pencil beam scanning clinical proton beam using TOPAS to estimate the dose out-of-field (OOF). Compact modelling means that the model starts from a pristine proton beam at the nozzle exit, customised based on acceptance and commissioning data, instead of modelling the full treatment head and room.: First, in-field validation tests were performed.

Optically stimulated luminescence system as an alternative for radiochromic film for 2D reference dosimetry in UHDR electron beams.

Radiotherapy is part of the treatment of over 50% of cancer patients. Its efficacy is limited by the radiotoxicity to the healthy tissue. FLASH-RT is based on the biological effect that ultra-high dose rates (UHDR) and very short treatment times strongly reduce normal tissue toxicity, while preserving the anti-tumoral effect.

Alanine/EPR dosimetry for mailed intercomparison at ocular proton therapy facilities-preliminary results for three centres for irradaitions at CCB IFJ PAN eyeline.

Quality control of therapeutic photon beams in the form of postal dose audits based on passive dosemeters is widely used in photon radiotherapy. On the other hand, no standardised dosimetry audit programme for proton centres has been established in Europe so far. We evaluated alanine/EPR dosimetry systems developed at the Istituto Superiore di Sanità (Italy), the Hasselt Universiteit (Belgium) and the Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences (Poland) for their applicability as a potential tool for routine mailed dose audits of passively scattered therapeutic proton beams.

Treatment verification in high dose rate brachytherapy using a realistic 3D printed head phantom and an imaging panel.

Purpose: Even though High Dose Rate (HDR) brachytherapy has good treatment outcomes in different treatment sites, treatment verification is far from widely implemented because of a lack of easily available solutions. Previously it has been shown that an imaging panel (IP) near the patient can be used to determine treatment parameters such as the dwell time and source positions in a single material pelvic phantom. In this study we will use a heterogeneous head phantom to test this IP approach, and simulate common treatment errors to assess the sensitivity and specificity of the error-detecting capabilities of the IP.

TOPAS simulations of the response of a mini-TEPC: benchmark with experimental data.

. Microdosimetry offers a fast tool for radiation quality (RQ) verification to be implemented in treatment planning systems in proton therapy based on variable LET or RBE to move forward from the use of a fixed RBE of 1.1.

Dual-energy CT evaluation of 3D printed materials for radiotherapy applications.

. There is a continuous increase in 3D printing applications in several fields including medical imaging and radiotherapy. Although there are numerous advantages of using 3D printing for the development of customized phantoms, bolus, quality assurance devices and other clinical applications, material properties are not well known and printer settings can affect considerably the properties (e.

Point scintillator dosimetry in ultra-high dose rate electron "FLASH" radiation therapy: A first characterization.

FLASH radiation therapy is a novel technique combining ultra-high dose rates (UHDR) with very short treatment times to strongly decrease normal tissue toxicity while preserving the anti-tumoral effect. However, the radiobiological mechanisms and exact conditions for obtaining the FLASH-effect are still under investigation. There are strong indications that parameters defining the beam structure, such as dose per pulse, instantaneous dose rate and pulse repetition frequency (PRF) are of importance.

A deep learning and Monte Carlo based framework for bioluminescence imaging center of mass-guided glioblastoma targeting.

Bioluminescence imaging (BLI) is a valuable tool for non-invasive monitoring of glioblastoma multiforme (GBM) tumor-bearing small animals without incurring x-ray radiation burden. However, the use of this imaging modality is limited due to photon scattering and lack of spatial information. Attempts at reconstructing bioluminescence tomography (BLT) using mathematical models of light propagation show limited progress.

Brachytherapy treatment verification using gamma radiation from the internal treatment source combined with an imaging panel-a phantom study.

Brachytherapy has an excellent clinical outcome for different treatment sites. However,treatment verification is not performed in the majority of hospitals due to the lack of proper monitoring systems. This study investigates the use of an imaging panel (IP) and the photons emitted by a high dose rate (HDR)Ir source to track source motion and obtain some information related to the patient anatomy.

Validation of TOPAS MC for modelling the efficiency of an extended-range coaxial p-type HPGe detector.

TOPAS MC software was used to model the efficiency of a coaxial p-type HPGe detector, type GX9023 from Canberra. The model was validated by comparing experimental efficiencies with efficiencies calculated by TOPAS MC simulations. Three different geometries of radionuclide sources, placed at different heights from the detector endcap, were used to validate the model.

Characterization of passive dosimeters in proton pencil beam scanning - A EURADOS intercomparison for mailed dosimetry audits in proton therapy centres.

The lack of mailed dosimetry audits of proton therapy centres in Europe has encouraged researchers of EURADOS Working Group 9 (WG9) to compare response of several existing passive detector systems in therapeutic pencil beam scanning. Alanine Electron Paramagnetic Resonance dosimetry systems from 3 different institutes (ISS, Italy; UH, Belgium and IFJ PAN, Poland), LiF:Mg, Ti (MTS-N) and LiF:Mg, Cu, P (MCP-N) thermoluminescent dosimeters (TLDs), GD-352M radiophotoluminescent glass dosimeters (RPLGDs) and AlO:C optically stimulated dosimeters (OSLDs) were evaluate. Dosimeter repeatability, batch reproducibility and response in therapeutic Pencil Beam Scanning were verified for implementation as mail auditing system.

Use of a Luciferase-Expressing Orthotopic Rat Brain Tumor Model to Optimize a Targeted Irradiation Strategy for Efficacy Testing with Temozolomide.

Glioblastoma multiforme (GBM) is a common and aggressive malignant brain cancer with a mean survival time of approximately 15 months after initial diagnosis. Currently, the standard-of-care (SOC) treatment for this disease consists of radiotherapy (RT) with concomitant and adjuvant temozolomide (TMZ). We sought to develop an orthotopic preclinical model of GBM and to optimize a protocol for non-invasive monitoring of tumor growth, allowing for determination of the efficacy of SOC therapy using a targeted RT strategy combined with TMZ.

Advanced design, simulation, and dosimetry of a novel rectal applicator for contact brachytherapy with a conventional HDR Ir source.

Purpose: Dose escalation yields higher complete response to rectal tumors, which may enable the omission of surgery. Dose escalation using 50 kVp contact x-ray brachytherapy (CXB) allow the treatment of a selective volume, resulting in low toxicity and organs-at-risk preservation. However, the use of CXB devices is limited because of its high cost and lack of treatment planning tools.

Mechanical evaluation of the Bravos afterloader system for HDR brachytherapy.

Purpose: The Bravos afterloader system was released by Varian Medical Systems in October of 2018 for high-dose-rate brachytherapy with Ir sources, containing new features such as the CamScale (a new device for daily quality assurance and system recalibration), channel length verification, and different settings for rigid and flexible applicators. This study mechanically evaluated the Bravos system precision and accuracy for clinically relevant scenarios, using dummy sources.

Methods And Materials: The system was evaluated after three sets of experiments: (1) The CamScale was used to verify inter- and intra-channel dwelling variability and system calibration; (2) A high-speed camera was used to verify the source simulation cable movement inside a transparent quality assurance device, where dwell positions, dwell times, transit times, speed profiles, and accelerations were measured; (3) The source movement inside clinical applicators was captured with an imaging panel while being exposed to an external kV source.

A novel rectal applicator for contact radiotherapy with HDR Ir sources.

Purpose: Dose escalation to rectal tumors leads to higher complete response rates and may thereby enable omission of surgery. Important advantages of endoluminal boosting techniques include the possibility to apply a more selective/localized boost than using external beam radiotherapy. A novel brachytherapy (BT) rectal applicator with lateral shielding was designed to be used with a rectoscope for eye-guided positioning to deliver a dose distribution similar to the one of contact x-ray radiotherapy devices, using commonly available high-dose-rate Ir BT sources.

Online pretreatment verification of high-dose rate brachytherapy using an imaging panel.

Brachytherapy is employed to treat a wide variety of cancers. However, an accurate treatment verification method is currently not available. This study describes a pre-treatment verification system that uses an imaging panel (IP) to verify important aspects of the treatment plan.

Dose distribution for gynecological brachytherapy with dose accumulation between insertions: Feasibility study.

Purpose: For gynecological treatments, it is standard to acquire CT images and preferably also MR images before each treatment to calculate the dose of the day. The dose of the complete treatment is calculated by adding the dose metrics of each fraction. It makes the conservative assumption that the same part of the organs at risk always receives the highest dose.