Čerapaitė-Trušinskienė, Reda

Collagenous colitis (CC) is diagnosed histologically and is characterised by a thickened subepithelial collagen band together with inflammatory and epithelial changes. Although routine haematoxylin and eosin (H&E) staining is sufficient for diagnosis in most cases, visual assessment of the collagen band can be challenging in borderline or heterogeneous specimens. Additional stains may be required in diagnostically difficult situations.

The Killip classification is a long-established bedside tool for early haemodynamic risk stratification in ST-elevation myocardial infarction (STEMI). However, its prognostic performance in contemporary STEMI populations treated with primary percutaneous coronary intervention (PCI) remains debated. We aimed to re-evaluate the association between Killip class and in-hospital mortality in a modern STEMI cohort.

Image-guided radiotherapy (IGRT) has enhanced the precision of cancer treatment by integrating imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI) and cone-beam computed tomography (CBCT) into daily radiotherapy workflows. In head and neck cancer, where anatomical changes are common, accurate image registration between planning and treatment scans is essential to ensure dose accuracy. However, geometric distortions in CBCT (such as translation, rotation, and scaling resulting from patient positioning variations observed in daily CBCT images) can affect tumour targeting and dose delivery. This pilot study assesses a MATLAB-based image correction algorithm that uses rigid bony landmarks and point cloud registration together with spatial transformation to align CBCT with planning CT. Two head and neck cancer patients were retrospectively analysed, selected for their contrasting anatomical responses: one with substantial tumour regression and one with minimal change. Imaging was performed on the Halcyon V3.1 linear accelerator (Varian Medical Systems), with 25 daily CBCT scans per patient (85–96 slices per scan), resulting in 50 datasets for analysis. Spatial deviations were measured along the X, Y, and Z axes, and dose recalculations were performed for each treatment fraction. The correction method significantly improved spatial congruence and reduced geometric discrepancies caused by voxel spacing and acquisition parameters. Uncorrected scans showed dose deviations of up to ± 12% in organs at risk, notably the spinal cord and parotid glands. These findings demonstrate the feasibility and dosimetric relevance of automated CBCT correction in daily head and neck radiotherapy. Although limited in sample size, the study provides a detailed technical and dosimetric analysis of spatial distortions and supports future validation in larger patient cohorts.

Patient positioning, together with physical changes in soft tissues during the course of radiotherapy, significantly affects the irradiation of targeted tissues and adjacent structures. This leads to a high risk of under-dosage of the tumour and/or over-dosage of critical normal structures during the late sessions of treatment. Accurate and timely identification of irradiation-affected tissue regions is highly valuable for adaptive radiotherapy planning. We propose a method for the identification and evaluation of specific computed tomography (CT) attenuation changes that can reveal the affected tissue regions. The search for correlated CT attenuation changes in the tumour and surrounding tissues, based on principal component analysis of series of intensity values in each fixed voxel, can reveal the actual three-dimensional region of irradiation-affected tissues for radiotherapy control and replanning.

Ensuring selective irradiation of target tissues is one of the biggest challenges in radiotherapy. Methods and devices of Image-Guided Radiotherapy (IGRT) are elaborated with the aim of ensuring that the prescribed radiation dose is delivered accurately to the tumour while minimising exposure to surrounding healthy tissues. Technical solutions ensure a few-millimetre, or even sub-millimetre precision of the irradiation beam, while with currently used mechanical means of patient positioning, we can expect much bigger positioning deviations, reaching even centimetre range. Patient positioning deviation to a certain extent is related to changes in soft tissue density and volume, which change during the period of treatment. Therefore, the discovery of reliable reference structures in routinely performed daily Cone-Beam Computed Tomograms (CBCT) was one of the aims of this study. Having the reliable reference structures, we carried out the retrospective estimation of patient position deviation during the whole treatment cycle and evaluated possible dynamics of unwanted irradiation of tumour-surrounding critical organs. The study was conducted in patients with head and neck cancer treated in the Lithuanian University of Health Sciences Kaunas Clinics Affiliated Hospital of Oncology, Department of Radiotherapy. Patients’ positioning was evaluated using volumetric images obtained by the CBCT machine integrated into the Halcyon V3.1 linear accelerator (Varian Medical Systems, Palo Alto, CA, USA). Custom-made algorithms of hard tissue segmentation and actual patient position estimation were elaborated in MATLAB (MathWorks, USA) environment. The hard tissue structures in volumetric images, in particular the mandible and part of the skull, were segmented and adjusted using mathematical morphology algorithms. We found these structures as reliable reference landmarks for patient position estimation. We found the deviation of actual patient position ranging from 1 to 3,5 mm, which resulted in changes in irradiation ranging from 0,016 to 0,057 Gy/fraction in the planned target volume and in critical surrounding organs (e.g. larynx, parotid, etc.) as well. The values indicate that it can cause significant damage to the surrounding organs. In conclusion, we state that specially selected hard tissue structures can serve as reliable landmarks of patient position, while soft tissues eventually change. The development of more precise image-guided radiotherapy methods can significantly reduce the damage to tumour-surrounding organs.

Teacher-guided learning, a traditional instructional approach, involves the educator leading the process through lectures, structured activities, and guided discussions. It allows immediate feedback, helping students clarify doubts and strengthen understanding in real time. Social interaction through peer discussions and collaborative tasks promotes engagement and knowledge sharing. The lecturer’s presence can also enhance motivation and accountability by encouraging consistent participation. However, this approach has limitations: its fixed pace may not suit all learners, leaving some unchallenged and others overwhelmed, and it can encourage passive learning if students rely too heavily on the instructor. In contrast, self-paced learning emphasizes learner autonomy, allowing students to control the pace, sequence, and timing of study. It offers flexibility, accommodates personal schedules, and enables learners to focus on areas of interest or difficulty. This approach fosters self-discipline, responsibility, and lifelong learning skills, while access to diverse digital resources can enhance understanding and engagement. Nonetheless, self-paced learning poses challenges, including the need for high self-motivation, risk of persistent misconceptions due to delayed feedback, limited social interaction, and difficulty organizing study without structured guidance. This study aimed to compare teacher-guided and self-paced learning, highlighting their advantages and limitations to understand how each supports learner engagement, flexibility, and academic success. Results indicated that teacher-guided learning provides structure, feedback, and social interaction but can restrict pace and active engagement. Self-paced learning offers autonomy and flexibility but requires strong self-motivation and may reduce feedback and peer support. Combining elements of both approaches may optimize learning outcomes.

Maximisation of irradiation accuracy of malignant tissues is a key challenge on the way to optimal radiotherapy. Strategies to improve irradiation accuracy should balance the expected clinical benefit against the feasibility and procedural demands of the method used. This pilot study marks an initial step toward retrospectively evaluating patient positioning accuracy, analysing CBCT images in relation to clinical outcomes, and estimating actual irradiation of target and surrounding tissues. The CBCT images were acquired from head and neck patients treated with the Halcyon V3.1 linear accelerator. The algorithms for precise alignment of images, which made it possible to estimate the detailed changes in tumour tissue density during treatment sessions were developed in the MATLAB. The recalculation of the actual dose showed that even small positioning errors can lead to significant changes in the delivered dose, especially in areas where critical organs are affected.

Vaizdais valdoma radioterapija (angl. image-guided radiotherapy) padidino gydymo tikslumą, tačiau naviko atsakas dažniausiai vertinamas tik gydymo pabaigoje. Nors kasdien atliekami kūginio pluošto kompiuterinės tomografijos tomografijos – KPKT (angl. cone beam computed tomography) vaizdai yra įprasti verifikacijai, jie retai naudojami išsamesnei analizei ar gydymo efektyvumo įvertinimui. Tai ypač svarbu galvos ir kaklo navikų atvejais, kur dažni naviko tūrio, paciento svorio ir organų padėties pokyčiai tarp frakcijų gali būti kliniškai reikšmingi [1, 2]. Nepaisant termoplastinių kaukių ir kitų imobilizavimo priemonių, pacientų padėties nuokrypiai išlieka. Be to, KPKT ir planavimo KT vaizdų registracija dažnai apsunkinama dėl skirtingų skenavimo sąlygų - pjūvių neatitikimo, poslinkių, pasukimų ar mastelio iškraipymų. Nors šie neatitikimai dažnai sunkiai pastebimi kasdienėje praktikoje, jie gali reikšmingai paveikti suplanuotą dozę, ypač esant stipriam atsakui į gydymą. Šio tyrimo tikslas – įvertinti vaizdų neatitikimų įtaką dozės nuokrypiams nuo suplanuotosios dozės, skirtingo atsako į spindulinę terapiją kontekste. Tyrimo metu buvo analizuoti LSMUL KK Onkologijos ligoninėje, linijiniu greitintuvu Halcyon V3.1 gydytų dviejų pacientų, sergančių galvos-kaklo navikais, kiekvienos procedūros metu registruoti KPKT vaizdai. Siekiant koreguoti erdvinius iškraipymus KPKT vaizduose, buvo identifikuoti kauliniai orientyrai pagal jų Hounsfieldo vieneto (HU) reikšmes ir suformuoti trimačiai taškų debesys. Duomenų registracijai naudotas MATLAB aplinkoje sukurtas algoritmas, apimantis šiuos etapus: 1) retai išdėstytų taškų debesies generavimą; 2) iteracinio artimiausio taško atitikimo algoritmo taikymą; 3) erdvinės transformacijos įgyvendinimą, pritaikant transformacijos matricą KPKT duomenims. Pakoreguoti KPKT vaizdai buvo lyginami su planavimo KT vaizdais, siekiant įvertinti anatominį atitikimą. Pacientui, kuriam stebėtas silpnesnis atsakas į spindulinį gydymą, koordinačių nuokrypių vidurkis (standartinis nuokrypis) buvo: X (šonine kryptimi) – 2,51 (1,49) mm, Y (aukščio kryptimi) – 2,13 (1,31) mm, Z (išilgine kryptimi) – 1,92 (1,22) mm. Tuo tarpu pacientui su stipriu atsaku į gydymą, vidutiniai nuokrypiai buvo žymiai mažesni: X – 0,17 (0,13) mm, Y – 0,14 (0,12) mm, Z – 0,79 (0,99) mm. Remiantis šiais duomenimis, apskaičiuota dozės neatitiktis (procentais) suplanuotai dozei (1 lentelė). Kritinių organų - seilių liaukų, stemplės, stuburo smegenų - dozių neatitikimai kai kuriais atvejais viršija 3 %., t.y. peržengė leistinas radioterapijos ribas. Tyrimas parodė, jog net minimalūs pacientų padėties pokyčiai gali turėti kliniškai reikšmingų pokyčių apšvitos dozi. Rezultatai išryškino poreikį detalesnei vaizdų analizei bei KPKT duomenų integravimui, ypač svarstant adaptyvios terapijos galimybes.

Background. Educational simulation using synthetic organ phantoms becomes very popular in training of wide range medical professionals. However, in some cases only specially processed natural hard tissue preparations could help to gain particular valuable skills for future practices. One of major features of such preparations is translucency enabling comprehensive control of the educational process, e.g., instrument manipulations. Aim. The aim of this study was to elaborate a method for evaluation of optical properties of the preparations enabling assessment of its suitability and optimisation of the preparation process. Methods. This particular study was designed to compare optical properties of natural teeth preparations made using two chemical methods – a) the traditional, using methyl ester of salicylic acid, giving satisfactory results, but toxic, vs b) using benzyl benzoate and benzyl alcohol, from the first impression giving also satisfactory results, but being much less toxic. Translucent light images of 32 teeth were captured using a collimated white light source and a digital camera (C-P8, Optika, Italy), with the teeth positioned on a dental glass slab. A small piece of prosthodontic impression material (A-silicone Elite Transparent, Zhermack, Italy) was placed nearby to normalise exposure and white balance across all images. The optical properties of tooth translucency were analysed using custom-made image processing algorithms in the MatLab environment. The algorithm segmented the apical part of each tooth using superpixel technique. Optical properties of segmented apical part of each tooth were estimated in HSV colour scheme. Results. We did not find any statistical difference in optical properties of apical parts prepared by both methods. Statistical analysis (Mann–Whitney U test, p > 0.2) showed no significant difference in hue, saturation, nor in value between the two groups. Conclusions. The optical properties of the translucent teeth prepared by both methods were similar, so we advise to use less toxic method using benzyl benzoate and benzyl alcohol. The principle of evaluation of optical properties could be used also for assessment of other tissues and other processing methods.

Welcome to the captivating realm where the principles of physics intersect with the intricacies of medicine, providing deep insights into the workings of the human body and revolutionizing diagnostics and therapeutic approaches. This interdisciplinary journey will take you on a multi-faceted voyage of discovery, from the fundamental mechanics of bodily functions to the intricate interplay of light and matter and the profound effects of ionizing radiation in healthcare. At the center of this convergence is the application of fundamental physical concepts to decipher the complex relationships of human physiology. From the mechanics of body movement and function - exploring phenomena such as vibrations, sound waves and the propagation of acoustic signals - to eluci¬dating the molecular interactions and behavior of fluids in the human system, this journey reveals the underlying physical principles that govern not only a marvel of biological engineering but also a realm governed by the immutable laws of physics. As we venture further into the field of optics, we encounter a variety of phenomena ranging from the propagation of light waves to the intricate mechanisms of vision. The study of optics in medicine encompasses a variety of topics, including the nature of light, the principles of refraction and dispersion, the mechanisms of visual perception, and the construction and function of optical instruments such as lenses, microscopes, refractometers and polarimeters. By unravelling the mysteries of the interactions between light and matter, physicists and physicians alike are gaining invaluable insights into the diagnosis and treatment of various eye diseases, paving the way for better patient care and improved clinical outcomes. This book also covers the field of ionizing radiation - a powerful tool of modern medicine with profound implications for diagnosis and treatment. From the discovery of X-rays by Wilhelm Com-ad Roentgen to the ground-breaking advances in radiation oncology, the use of ionizing radiation has revolutionized medical imaging, cancer treatment and many other areas of healthcare. By elucidating the mechanisms of interaction between radiation and matter and quantifying the dosimetric properties of different radiation sources, physicists and radiation oncologists play a crucial role in optimizing treatment protocols, minimizing radiation exposure and ensuring the safety and efficacy of clinical interventions. Recognizing the diverse backgrounds and interests of our readership, this comprehensive learning resource has been carefully crafted to appeal to stu-dents from a broad spectrum of the health sciences. Whether you are a bud-ding physician, a curious biologist or a budding medical physicist, this book will serve as an introduction to the fascinating intersection of physics and medicine. Through a successful blend of theoretical foundations, practical applications, and hands-on laboratory exercises, students will not only be able to understand the intricate nuances of physics in healthcare but also to apply this knowledge in a variety of clinical and research situations.