Determination of beam quality correction factors for alanine dosimetry in clinical proton beams.

Introduction: With the advent of FLASH radiotherapy, alanine dosimetry has gained attention as a promising dosimeter owing to its dose-rate independence. However, before utilized in radiotherapy, procedures for determining the absorbed dose to water using alanine under clinical proton beams must be established. This study sought to develop a formula for alanine dosimetry by deriving beam quality correction factors and validating them through Monte Carlo simulations and experimental measurements.

Evaluation of a modified formalism for precision electron beam dosimetry compared to TG-51 and TRS-398.

Purpose: This study aims to evaluate a modified formalism for electron beam reference dosimetry and to compare the results with the cases of previous protocols TG-51 and TRS-398.

Methods: Measurements were performed using three types of cylindrical chambers (TW30013, FC65-G, and A1SL) and plane-parallel chambers (PPC) (Roos, Advanced Markus, and NACP-02) with electron beams of energies 6, 12, and 18 MeV. Absorbed dose to water at the reference depths was determined following the modified formalism using different chambers and methods, including the direct application of Co calibration or cross-calibration for PPCs in a high-energy electron beam.

Generation of deep learning based virtual non-contrast CT using dual-layer dual-energy CT and its application to planning CT for radiotherapy.

This paper presents a novel approach for generating virtual non-contrast planning computed tomography (VNC-pCT) images from contrast-enhanced planning CT (CE-pCT) scans using a deep learning model. Unlike previous studies, which often lacked sufficient data pairs of contrast-enhanced and non-contrast CT images, we trained our model on dual-energy CT (DECT) images, using virtual non-contrast CT (VNC CT) images as outputs instead of true non-contrast CT images. We used a deterministic method to convert CE-pCT images into pseudo DECT images for model application.

Dual-encoder architecture for metal artifact reduction for kV-cone-beam CT images in head and neck cancer radiotherapy.

During a radiotherapy (RT) course, geometrical variations of target volumes, organs at risk, weight changes (loss/gain), tumor regression and/or progression can significantly affect the treatment outcome. Adaptive RT has become the effective methods along with technical advancements in imaging modalities including cone-beam computed tomography (CBCT). Planning CT (pCT) can be modified via deformable image registration (DIR), which is applied to the pair of pCT and CBCT.

Conversion of single-energy CT to parametric maps of dual-energy CT using convolutional neural network.

Objectives: We propose a deep learning (DL) multitask learning framework using convolutional neural network for a direct conversion of single-energy CT (SECT) to 3 different parametric maps of dual-energy CT (DECT): virtual-monochromatic image (VMI), effective atomic number (EAN), and relative electron density (RED).

Methods: We propose VMI-Net for conversion of SECT to 70, 120, and 200 keV VMIs. In addition, EAN-Net and RED-Net were also developed to convert SECT to EAN and RED.

Improvement of performance for flexible film dosimeter by incorporating additive agents.

To evaluate the reduction in energy dependence and aging effect of the lithium salt of pentacosa-10,-12-diynoic acid (LiPCDA) films with additives including aluminum oxide (AlO), propyl gallate (PG), and disodium ethylenediaminetetracetate (EDTA).. LiPCDA films exhibited energy dependence on kilovoltage (kV) and megavoltage (MV) photon energies and experienced deterioration over time.

Evaluations of patient-specific bolus fabricated by mold-and-cast method using computer numerical control machine tools†.

The patient-specific bolus fabricated by a mold-and-cast method using a 3D printer (3DP) and silicon rubber has been adopted in clinical practices. Manufacturing a mold using 3DP, however, can cause time delays due to failures during the 3D printing process. Thereby, we investigated an alternative method of the mold fabrication using computer numerical control (CNC) machine tools.

Novel tongue-positioning device to reduce tongue motions during radiation therapy for head and neck cancer: Geometric and dosimetric evaluation.

This study aimed to assess the performance of a tongue-positioning device in interfractional tongue position reproducibility by cone-beam computed tomography (CBCT). Fifty-two patients treated with radiation therapy (RT) while using a tongue positioning device were included in the study. All patients were treated with 28 or 30 fractions using the volumetric modulated arc therapy technique.

Extension of matRad with a modified microdosimetric kinetic model for carbon ion treatment planning: Comparison with Monte Carlo calculation.

Background: Treatment planning is essential for in silico particle therapy studies. matRad is an open-source research treatment planning system (TPS) based on the local effect model, which is a type of relative biological effectiveness (RBE) model.

Purpose: This study aims to implement a microdosimetric kinetic model (MKM) in matRad and develop an automation algorithm for Monte Carlo (MC) dose recalculation using the TOPAS code.

Dual imaging modality of fluorescence and transmission X-rays for gold nanoparticle-injected living mice.

Background: X-ray fluorescence (XRF) imaging for metal nanoparticles (MNPs) is a promising molecular imaging modality that can determine dynamic biodistributions of MNPs. However, it has the limitation that it only provides functional information.

Purpose: In this study, we aim to show the feasibility of acquiring functional and anatomic information on the same platform by demonstrating a dual imaging modality of pinhole XRF and computed tomography (CT) for gold nanoparticle (GNP)-injected living mice.

Performance evaluation of a visual guidance patient-controlled respiratory gating system for respiratory-gated magnetic-resonance image-guided radiation therapy.

The performance of a visual guidance patient-controlled (VG-PC) respiratory gating system for magnetic-resonance (MR) image-guided radiation therapy (MR-IGRT) was evaluated through a clinical trial of patients with either lung or liver cancer. Patients can voluntarily control their respiration utilizing the VG-PC respiratory gating system. The system enables patients to view near-real-time cine planar MR images projected inside the bore of MR-IGRT systems or an external screen.

Scanning methodology for contact lens-type ocular in vivo dosimeter (CLOD) dosimetry applying a silicone material.

Purpose: Contact lens-type ocular in vivo dosimeters (CLODs) were recently developed as the first in vivo dosimeter that can be worn directly on the eye to measure the dose delivered to the lens during radiotherapy. However, it has an inherent uncertainty because of its curved shape. Newton's ring effect inevitably occurs because the spacing between the glass window and the active layer is not constant.

3D star shot analysis using MAGAT gel dosimeter for integrated imaging and radiation isocenter verification of MR-Linac system.

Purpose: This study aims to investigate a star shot analysis using a three-dimensional (3D) gel dosimeter for the imaging and radiation isocenter verification of a magnetic resonance linear accelerator (MR-Linac).

Methods: A mixture of methacrylic acid, gelatin, and tetrakis (hydroxymethyl) phosphonium chloride, called MAGAT gel, was fabricated. One MAGAT gel for each Linac and MR-Linac was irradiated under six gantry angles.

Comparison of treatment plans between static jaw and jaw tracking techniques in postmastectomy intensity-modulated radiation therapy.

This study reports a dosimetric comparison between treatment plans using static jaw and jaw tracking techniques in intensity-modulated radiation therapy (IMRT) for postmastectomy radiation therapy (PMRT). Seventeen patients treated for left-sided breast cancer with implant-based reconstruction were subjected to IMRT plans. Another group of 22 patients treated for left-sided breast cancer without reconstruction was also subjected to IMRT plans.

Gold coated contact lens-type ocular in vivo dosimeter (CLOD) for monitoring of low dose in computed tomography: A Monte Carlo study.

Purpose: This study reports a sensitivity enhancement of gold-coated contact lens-type ocular in vivo dosimeters (CLODs) for low-dose measurements in computed tomography (CT).

Methods: Monte Carlo (MC) simulations were conducted to evaluate the dose enhancement from the gold (Au) layers on the CLODs. The human eye and CLODs were modeled, and the X-ray tube voltages were defined as 80, 120, and 140 kVp.

Dose calculation of 3D printing lead shield covered by biocompatible silicone for electron beam therapy.

This study aims to calculate the dose delivered to the upstream surface of a biocompatible flexible absorber covering lead for electron beam treatment of skin and subcutaneous tumour lesions for head and neck. Silicone (Ecoflex™ 00-30, Smooth-On, Easton, PA, USA) was used to cover the lead to absorb backscattered electrons from lead. A 3D printer (Zortrax M300, Zortrax, Olsztyn, Poland) was used to fabricate the lead shield.

Europium-Diethylenetriaminepentaacetic Acid Loaded Radioluminescence Liposome Nanoplatform for Effective Radioisotope-Mediated Photodynamic Therapy.

Photodynamic therapy (PDT) is an effective anticancer strategy with a higher selectivity and fewer adverse effects than conventional therapies; however, shallow tissue penetration depth of light has hampered the clinical utility of PDT. Recently, reports have indicated that Cerenkov luminescence-induced PDT may overcome the tissue penetration limitation of conventional PDT. However, the effectiveness of this method is controversial because of its low luminescence intensity.

Dose perturbation and inhomogeneity of multi-arrays of I seed-loaded stent for treatment of portal vein tumor thrombosis.

Purpose: To investigate the dosimetry of I seed-loaded stent system currently used for an adjuvant treatment of portal vein tumor thrombosis (PVTT).

Methods: The stent system consisted of an inner metallic stent and outer seed-loaded capsules. Four arrays of I seeds were attached longitudinally to the outer surface of the stent at 90° separation.

Dynamic In Vivo X-ray Fluorescence Imaging of Gold in Living Mice Exposed to Gold Nanoparticles.

Dynamic in vivo biodistribution of gold nanoparticles (GNPs) in living mice was first successfully acquired by a pinhole X-ray fluorescence (XRF) imaging system using polychromatic X-rays. The system consisted of fan-beam X-rays to stimulate GNPs and a 2D cadmium zinc telluride (CZT) gamma camera to collect K-shell XRF photons emitted from the GNPs. 2D XRF images of kidney slices of three Balb/C mice were obtained within 2 minutes of irradiation per slice.

Computational Modeling and Clonogenic Assay for Radioenhancement of Gold Nanoparticles Using 3D Live Cell Images.

Radioenhancement of gold nanoparticles (GNPs) has shown great potential for increasing the therapeutic efficiency of radiotherapy. Here we report on a computational model of radiation response, which was developed to predict the survival curves of breast cancer cells incubated with GNPs. The amount of GNP uptake was estimated using inductively coupled plasma-mass spectroscopy, and the three-dimensional (3D) intracellular distribution of GNPs was obtained using optical diffraction tomography.

Pinhole X-ray fluorescence imaging of gadolinium and gold nanoparticles using polychromatic X-rays: a Monte Carlo study.

This work aims to develop a Monte Carlo (MC) model for pinhole K-shell X-ray fluorescence (XRF) imaging of metal nanoparticles using polychromatic X-rays. The MC model consisted of two-dimensional (2D) position-sensitive detectors and fan-beam X-rays used to stimulate the emission of XRF photons from gadolinium (Gd) or gold (Au) nanoparticles. Four cylindrical columns containing different concentrations of nanoparticles ranging from 0.

Evaluation of the microscopic dose enhancement for nanoparticle-enhanced Auger therapy.

The aim of this study is to investigate the dosimetric characteristics of nanoparticle-enhanced Auger therapy. Monte Carlo (MC) simulations were performed to assess electron energy spectra and dose enhancement distributions around a nanoparticle. In the simulations, two types of nanoparticle structures were considered: nanoshell and nanosphere, both of which were assumed to be made of one of five elements (Fe, Ag, Gd, Au, and Pt) in various sizes (2-100 nm).