"Exposing" the exposure index: Navigating between image quality and radiation dose.

Introduction: Deep knowledge of the properties and importance of the Exposure Index (EI) is crucial for delivering high-quality digital radiography images. This study aims to assess the EI on chest posterior anterior (PA) radiographic projection, demonstrating its correlation with parameters, such as body mass index (BMI), source-to-object distance (SOD), age, gender, and patient entrance skin dose (ESD).

Methods: The study population included 805 patients who underwent a routine PA chest projection.

The role of F-FDG PET/CT imaging in paediatric Langerhans disease: Case report.

Langerhans cell histiocytosis (LCH) is a haematological disorder, affecting single or multiple organs, characterized by abnormal proliferation of Langerhans cells in children. Accurate tumour delineation (number of lesions, organs involved) is crucial for staging/re-staging, and follow-up (response to therapy). Conventional imaging techniques (computed tomography (CT), magnetic resonance imaging (MRI)) have been employed for initial diagnosis, staging and assessment of response to therapy focusing on the healing effect therapeutic protocols have on the disease.

Dose optimization of 2D X-ray image acquisition protocols in image-guided radiotherapy.

Purpose: In contemporary radiotherapy, patient positioning accuracy relies on kV imaging. This study aims at optimizing planar kV image acquisition protocols regarding patient dose without degrading image quality.

Materials And Methods: An image quality test-object was placed in-between PMMA plates, suitably arranged to model head or pelvis.

A novel rice hull - microalgal biorefinery for the production of natural phenolic compounds comprising of rice hull acid pretreatment and a two-stage Botryococcus braunii cultivation process.

Recently, the rising demand of the industry for natural phenolic antioxidant compounds has turned to the study of microalgae as potential sources. Yet, more economic substrates for microalgal cultivation are sought to lower production costs. To this end, the present work deals with the utilization of rice hull hydrolysate (RHH) as substrate for microalgae Botryococcus braunii through a novel two-stage cultivation system.

Exploring radiographers' perceptions and knowledge about patient lead shielding: a cross-sectional study in Greece and Cyprus.

The present study aimed to explore radiographers' knowledge, clinical practice and perceptions regarding the use of patient lead shielding in Greece and Cyprus. Qualitative data were analyzed using conceptual content analysis and through the classification of findings into themes and categories. A total of 216 valid responses were received.

Analysis of radiomic features derived from post-contrast T1-weighted images and apparent diffusion coefficient (ADC) maps for breast lesion evaluation: A retrospective study.

Introduction: Breast cancer is the most common malignancy among women, and its diagnosis relies on medical imaging and the invasive, uncomforted biopsy. Recent advances in quantitative imaging and specifically the application of radiomics has proved to be a very promising technique, facilitating both diagnosis and therapy. The purpose of this study is to assess radiomic features derived from post-contrast T1w Magnetic Resonance Imaging (MRI) sequences and Apparent Diffusion Coefficient (ADC) maps for the evaluation of breast pathologies.

Failure modes in stereotactic radiosurgery. A narrative review.

Objectives: Stereotactic radiosurgery (SRS) refers to an advanced radiotherapy technique that requires a high level of precision and accuracy and a flawless workflow. Failures within the SRS process can lead to serious consequences due to high doses delivered per treatment. This narrative review aimed to identify the riskiest failure modes (FMs) and the stages at which they occur in the SRS process, as well as the strategies applied to mitigate the risks.

Identification and Characterization of Circular RNAs As a New Class of Putative Biomarkers in Human Blood.

Covalently closed circular RNA molecules (circRNAs) have recently emerged as a class of RNA isoforms with widespread and tissue specific expression across animals, oftentimes independent of the corresponding linear mRNAs. circRNAs are remarkably stable and sometimes highly expressed molecules. Here, we sequenced RNA in human peripheral whole blood to determine the potential of circRNAs as biomarkers in an easily accessible body fluid.

Circular RNAs in the Mammalian Brain Are Highly Abundant, Conserved, and Dynamically Expressed.

Circular RNAs (circRNAs) are an endogenous class of animal RNAs. Despite their abundance, their function and expression in the nervous system are unknown. Therefore, we sequenced RNA from different brain regions, primary neurons, isolated synapses, as well as during neuronal differentiation.

circBase: a database for circular RNAs.

Recently, several laboratories have reported thousands of circular RNAs (circRNAs) in animals. Numerous circRNAs are highly stable and have specific spatiotemporal expression patterns. Even though a function for circRNAs is unknown, these features make circRNAs an interesting class of RNAs as possible biomarkers and for further research.

Blood velocity pulse quantification in the human conjunctival pre-capillary arterioles.

Axial red blood cell velocity pulse was quantified throughout its period by high speed video microcinematography in the human eye. In 30 conjunctival precapillary arterioles (6 to 12 microm in diameter) from 15 healthy humans, axial velocities ranged from 0.4 (the minimum of all the end diastolic values) to 5.

The importance of the accuracy of image registration of SPECT images for 3D targeted radionuclide therapy dosimetry.

In this paper, the importance of the accuracy of image registration of time-sequential SPECT images for 3D targeted radionuclide therapy dosimetry is studied. Image registration of a series of SPECT scans is required to allow the computation of the 3D absorbed dose distribution for both tumour sites and normal organs. Three simulated 4D datasets, based on patient therapy studies, were generated to allow the effect of mis-registration on the absorbed dose distribution to be investigated.

A generalized 4D image registration scheme for targeted radionuclide therapy dosimetry.

An iterative, generalized four-dimensional (4D) method is presented in this paper that allows simultaneous registration of a series of single-photon emission computed tomography (SPECT) scans acquired in the course of a radionuclide therapy or pretherapy tracer study. The method combines temporal information with voxel-based similarity criteria to carry out simultaneous registration of the SPECT scans. A polynomial function was fitted to the maximum counts of each tumor site over the 4D study.

A novel four-dimensional image registration method for radionuclide therapy dosimetry.

A novel method for registering sequential SPECT scans (4DRRT) is described, whereby all sequential scans acquired in the course of a therapy or a pre-therapy tracer study may be registered in one pass. The method assumes that a monoexponential decay function can be fitted to the series of sequential SPECT scans. Multiple volumes, presenting with different decay rates, are fitted with different mono-exponential functions.

Absorbed dose ratios for repeated therapy of neuroblastoma with I-131 mIBG.

Patients undergoing targeted radionuclide therapy (TRT) may receive a series of two or more treatment administrations at varying intervals. However, the level of activity administered and the frequency of administration can vary widely from centre to centre for the same therapy. Tumour dosimetry is seldom employed to determine the optimum treatment plan mainly due to the potential inaccuracies of image quantification.

RMDP: a dedicated package for 131I SPECT quantification, registration and patient-specific dosimetry.

The limitations of traditional targeted radionuclide therapy (TRT) dosimetry can be overcome by using voxel-based techniques. All dosimetry techniques are reliant on a sequence of quantitative emission and transmission data. The use of (131)I, for example, with NaI or mIBG, presents additional quantification challenges beyond those encountered in low-energy NM diagnostic imaging, including dead-time correction and additional photon scatter and penetration in the camera head.

Automated CT marker segmentation for image registration in radionuclide therapy.

In this paper a novel, automated CT marker segmentation technique for image registration is described. The technique, which is based on analysing each CT slice contour individually, treats the cross sections of the external markers as protrusions of the slice contour. Knowledge-based criteria, using the shape and dimensions of the markers, are defined to enable marker identification and segmentation.

An automated technique for SPECT marker-based image registration in radionuclide therapy.

An automated technique for marker-based image registration in radionuclide therapy is described. This technique is based on localization of the centroids of external markers and on establishing correspondence between the individual markers of the two studies to be registered. Localization of the centroids of markers relies on segmenting the markers using iterative thresholding.