Dosimetry

INTRODUCTION: Tuberculosis remains one of the top ten causes of mortality globally. Children accounted for 12% of all TB cases and 18% of all TB deaths in 2022. Paediatric TB is difficult to diagnose with conventional laboratory tests, and chest radiographs remain crucial. However, in low-and middle-income countries with high TB burden, the capacity for radiological diagnosis of paediatric TB is rarely documented and data on the associated radiation exposure limited. METHODS: A multicentre, mixed-methods study is proposed in three countries, Mozambique, South Africa and Spain...

Modern radiotherapy techniques have advanced and become more sophisticated. End-to-end 3D verification of the complex radiotherapy dose distribution in an anthropomorphic phantom can ensure the accuracy of the treatment delivery. The phantoms commonly used for dosimetry are homogeneous solid water phantom which lacks the capability to measure the 3D dose distribution for heterogeneous tissues necessary for advanced radiotherapy techniques. Therefore, we developed an end-to-end 3D radiotherapy dose verification system based on MAX-HD anthropomorphic phantom (Integrated Medical Technologies Inc...

Monte Carlo simulations using patient CT images as input are the gold standard to perform patient-specific dosimetry. However, in standard clinical practice patient's CT images are limited to the reconstructed CT scan range. In this study, organ dose calculations were performed with ImpactMC for chest and cardiac CT using whole-body and anatomy-specific voxel models to estimate the accuracy of CT organ doses based on the latter model. When the 3D patient model is limited to the CT scan range, CT organ doses from Monte Carlo simulations are the most accurate for organs entirely in the field of view...

PURPOSE: Calculation of the uncertainty of the individual time-integrated activity coefficient (TIACs) is desirable in molecular radiotherapy. However, the calculation of TIAC's uncertainty in single-time-point (STP) method has never been reported in the literature. This study presents a method based on the Bayesian fitting (BF) to calculate the standard deviation (SD) of individual TIACs in the STP dosimetry. METHODS: Biokinetic data of 177 Lu-DOTATATE in kidneys were obtained from PMID33443063...

BACKGROUND: Vitiligo is characterized by depigmented patches resulting from loss of melanocytes. Phototherapy has emerged as a prominent treatment option for vitiligo, utilizing various light modalities to induce disease stability and repigmentation. AIMS AND METHODS: This narrative review aims to explore the clinical applications and molecular mechanisms of phototherapy in vitiligo. RESULTS AND DISCUSSION: The review evaluates existing literature on phototherapy for vitiligo, analyzing studies on hospital-based and home-based phototherapy, as well as outcomes related to stabilization and repigmentation...

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PURPOSE: To provide an understanding of current FLI techniques, and their potential to improve dosimetry and outcomes for lung cancer patients receiving radiation therapy (RT). METHODS: EMBASE, PubMed, and Cochrane Library were searched from 1990 until April 2023. Articles were included if they reported on FLI in one of: techniques, incorporation into RT planning for lung cancer, quantification of RT-related outcomes for lung cancer patients. Studies involving all RT modalities, including stereotactic body radiotherapy and particle therapy, were included...

INTRODUCTION: The currently available dosimetry techniques in computed tomography can be inaccurate which overestimate the absorbed dose. Therefore, we aimed to provide an automated and fast methodology to more accurately calculate the SSDE using D_w obtained by using CNN from thorax and abdominal CT study images. METHODS: The SSDE was determined from the 200 records files. For that purpose, patients' size was measured in two ways: a) by developing an algorithm following the AAPM Report No...

This work investigates the feasibility of yeast-based impedance measurements for retrospective dosimetry applications. The local environment around yeast cells in a previously developed film-badge was modeled using Geant4. A greater dose response was observed when yeast cells were surrounded by an aluminum-polymer structure, which acted as a conversion layer. Bench-top experiments were conducted using a jar-based dosimeter design that directly combined a finely-ground aluminum conversion medium with yeast powder...

This study aimed to investigate the airborne exposure to aerosols according to the particle size distribution of three different spray types ( nano-nozzled spray gun , low-temperature steam spray , and fogger ) and compare the concentrations of inhaled aerosols between children and adults. Airborne aerosols released from three products were observed using size-segregated particle measurements, and particle concentrations deposited in the respiratory tracts of adults and children were estimated using multi-path particle dosimetry lung deposition models...

AIM: The use of stereotactic body radiation therapy (SBRT) is an increasing trend in the country. The aim of this study is to gain knowledge on patterns of quality assurance (QA) and treatment planning (TP) aspects with respect to SBRT. MATERIALS AND METHODS: A questionnaire with multiple choice was designed to determine practices of SBRT covering areas such as years of experience, type of linear accelerator, tumor-motion strategies, calculation algorithm used in the TP system (TPS), the protocol used for small field dosimetry, the detector used for small field dosimetry and QA, respiratory management during delivery...

High dose rate (HDR) brachytherapy procedures for cervical cancer require multiple applicator insertions for multiple (typically 5) fractions of a single plan, which carries a risk for variability in applicator position between fractions. Due to applicator displacement relative to patient anatomy, the dose to nearby organs-at-risk (OARs) may vary significantly from one fraction to the next. The purpose of this study was to evaluate the effect of changes in HDR tandem and ring (T&R) applicator position on doses to nearby OARs and to present a quick and simple method to estimate doses to OARs inter-fractionally without having to perform a re-plan...

Glass dosimeters are very useful and convenient detection elements in radiation dosimetry. In this study, this glass dosimeter was applied to a BNCT treatment field. Boron Neutron Capture Therapy (BNCT) is a next-generation radiation therapy that can selectively kill only cancer cells. In the BNCT treatment field, both neutrons and secondary gamma-rays are generated. In other words, it is a mixed radiation field of neutrons and gamma-rays. We thus proposed a novel method to measure only gamma-ray dose in the mixed field using two RPLGD (Radiophoto-luminescence Glass Dosimeter) and two sensitivity control filters in order to control the dose response of the filtered RPLGD to be proportional to the air kerma coefficients, even if the gamma-ray energy spectrum is unknown...

Necrobiosis Lipoidica (NL) is a dermatological condition characterized by the development of granulomatous inflammation leading to the degeneration of collagen and subsequent formation of yellowish-brown telangiectatic plaques usually localized on the pretibial skin of middle-aged females. Due to its rarity and unclear etiopathogenesis, therapeutic options for NL are not well-standardized. Among them, photodynamic therapy (PDT) is an emerging tool, although its efficacy has primarily been evaluated in single case reports or small case series...

Background/Objectives : Recurrent aphthous stomatitis (RAS) is one of the most common oral mucosal lesions and a very debilitating lesion, especially in paediatric and adolescent patients. The current pharmacotherapy offers a pain relief but not without side effects, and therefore photobiomodulation (PBM) can be an alternative therapy. To the authors' best knowledge, no published study has explored the efficacy of λ 980 nm laser PBM in the management of all RAS subtypes in paediatric and adolescent patients, and therefore, this prospective observational clinical study was conducted to bridge this gap by evaluating λ 980 nm laser PBM efficacy in symptomatic RAS management in paediatric and adolescent patients...

Methodologies across the dispersion preparation, characterization, and cellular dosimetry of hydrophilic nanoparticles (NPs) have been developed and used extensively in the field of nanotoxicology. However, hydrophobic NPs pose a challenge for dispersion in aqueous culture media using conventional methods that include sonication followed by mixing in the culture medium of interest and cellular dosimetry. In this study, a robust methodology for the preparation of stable dispersions of hydrophobic NPs for cellular studies is developed by introducing continuous energy over time via stirring in the culture medium followed by dispersion characterization and cellular dosimetry...

This work aims to investigate the clinical feasibility of deep learning-based synthetic CT images for cervix cancer, comparing them to MR for calculating attenuation (MRCAT). Patient cohort with 50 pairs of T2-weighted MR and CT images from cervical cancer patients was split into 40 for training and 10 for testing phases. We conducted deformable image registration and Nyul intensity normalization for MR images to maximize the similarity between MR and CT images as a preprocessing step. The processed images were plugged into a deep learning model, generative adversarial network...

68 Ga-labeled nanobody (68 Ga-NC-BCH) is a single-domain antibody-based PET imaging agent. We conducted a first-in-humans study of 68 Ga-NC-BCH for PET to determine its in vivo biodistribution, metabolism, radiation dosimetry, safety, and potential for quantifying claudin-18 isoform 2 (CLDN18.2) expression in gastrointestinal cancer patients. Methods: Initially, we synthesized the probe 68 Ga-NC-BCH and performed preclinical evaluations on human gastric adenocarcinoma cell lines and xenograft mouse models...

BACKGROUND: Erythropoietic protoporphyria (EPP) causes painful light sensitivity, limiting quality of life. Our objective was to develop and validate a wearable light exposure device and correlate measurements with light sensitivity in EPP to predict and prevent symptoms. METHODS: A wearable light dosimeter was developed to capture light doses of UVA, blue, and red wavelengths. A prospective observational pilot study was performed in which five EPP patients wore two light dosimeters for 3 weeks, one as a watch, and one as a shirt clip...

Microplastics (MPs) and nanoplastics (NPs) pollution has emerged as a significant and widespread environmental issue. Humans are inevitably exposed to MPs and NPs via ingestion, inhalation, and dermal contacts from various sources. However, mechanistic knowledge of their distribution, interaction, and potency in the body is still lacking. To address this knowledge gap, we have undertaken the task of elucidating the toxicokinetic (TK) behaviors of MPs and NPs, aiming to provide mechanistic information for constructing a conceptual physiologically based toxicokinetic (PBTK) model to support in silico modeling approaches...