Modeling of the metallic port in breast tissue expanders for photon radiotherapy

The purpose of this study was to model the metallic port in breast tissue expanders and to improve the accuracy of dose calculations in a commercial photon treatment planning system (TPS). The density of the model was determined by comparing TPS calculations and ion chamber (IC) measurements. The model was further validated and compared with two widely used clinical models by using a simplified anthropomorphic phantom and thermoluminescent dosimeters (TLD) measurements. Dose perturbations and target coverage for a single postmastectomy radiotherapy (PMRT) patient were also evaluated. The dimensions of the metallic port model were determined to be 1.75 cm in diameter and 5 mm in thickness. The density of the port was adjusted to be 7.5 g/cm3 which minimized the differences between IC measurements and TPS calculations. Using the simplified anthropomorphic phantom, we found the TPS calculated point doses based on the new model were in agreement with TLD measurements within 5.0% and were more accurate than doses calculated based on the clinical models. Based on the photon treatment plans for a real patient, we found that the metallic port has a negligible dosimetric impact on chest wall, while the port introduced significant dose shadow in skin area. The current clinical port models either overestimate or underestimate the attenuation from the metallic port, and the dose perturbation depends on the plan and the model in a complex way. TPS calculations based on our model of the metallic port showed good agreement with measurements for all cases. This new model could improve the accuracy of dose calculations for PMRT patients who have temporary tissue expanders implanted during radiotherapy and could potentially reduce the risk of complications after the treatment

Aspects of Pacemakers

Outstanding steps forward were made in the last decades in terms of identification of endogenous pacemakers and the exploration of their controllability. New "artifical" devices were developed and are now able to do much more than solely pacemaking of the heart. In this book different aspects of pacemaker - functions and interactions, in various organ systems were examined. In addition, various areas of application and the potential side effects and complications of the devices were discussed

CT Scanning

Since its introduction in 1972, X-ray computed tomography (CT) has evolved into an essential diagnostic imaging tool for a continually increasing variety of clinical applications. The goal of this book was not simply to summarize currently available CT imaging techniques but also to provide clinical perspectives, advances in hybrid technologies, new applications other than medicine and an outlook on future developments. Major experts in this growing field contributed to this book, which is geared to radiologists, orthopedic surgeons, engineers, and clinical and basic researchers. We believe that CT scanning is an effective and essential tools in treatment planning, basic understanding of physiology, and and tackling the ever-increasing challenge of diagnosis in our society

Surgical Ophthalmic Oncology

Designed as an easy-to-use, practical guide to tumors of the eye, lids, and orbit, this Open Access book comprehensively addresses surgical treatment and management of diseases related to ophthalmic oncology. Surgical Ophthalmic Oncology: A Collaborative Open Access Reference is an ideal reference for general ophthalmologists, surgeons, fellows and trainees around the world who encounter these diseases in the care of their patients. Notably, this book includes considerations for those ophthalmologists offering subspecialty care in environments with limited access to advanced technology and instrumentation. Individual chapters address diagnostic indications, pre-operative and post-operative concerns, and provide detailed explanations of surgical techniques required to manage various eye cancer ailments with help of ample illustrations. High-quality videos included throughout the book provide readers with the opportunity to review surgical steps in real-time as a learning tool. Chapters thoroughly cover tumors of eyelid, cornea and conjunctiva, orbit as well as intraocular tumors, while later chapters discuss ophthalmic radiation therapy. The book concludes with a section on ophthalmic pathology which details essential guidelines on relevant aspects from specimen collection and transport, to interpretation of the pathology report. Surgical Ophthalmic Oncology: A Collaborative Open Access Reference is a unique and necessary valuable resource for ophthalmologists, trainees, and related medical professionals working in underserved areas in providing quality care for patients suffering from ocular cancers. ; Open Access text that discusses Preferred Practice Guidelines for common surgeries performed on tumors of the eye and adnexa Written for general ophthalmologists providing oncology care and specialists practicing in areas with limited access to advanced technology and instrumentation Includes chapters on eyelid tumors, conjunctival and corneal tumors, intraocular tumors, brachytherapy, and ocular pathology Each chapter includes extensive color pictures and relevant video to assist the clinician in the various surgical procedures discusse

Surgical Ophthalmic Oncology

Designed as an easy-to-use, practical guide to tumors of the eye, lids, and orbit, this Open Access book comprehensively addresses surgical treatment and management of diseases related to ophthalmic oncology. Surgical Ophthalmic Oncology: A Collaborative Open Access Reference is an ideal reference for general ophthalmologists, surgeons, fellows and trainees around the world who encounter these diseases in the care of their patients. Notably, this book includes considerations for those ophthalmologists offering subspecialty care in environments with limited access to advanced technology and instrumentation. Individual chapters address diagnostic indications, pre-operative and post-operative concerns, and provide detailed explanations of surgical techniques required to manage various eye cancer ailments with help of ample illustrations. High-quality videos included throughout the book provide readers with the opportunity to review surgical steps in real-time as a learning tool. Chapters thoroughly cover tumors of eyelid, cornea and conjunctiva, orbit as well as intraocular tumors, while later chapters discuss ophthalmic radiation therapy. The book concludes with a section on ophthalmic pathology which details essential guidelines on relevant aspects from specimen collection and transport, to interpretation of the pathology report. Surgical Ophthalmic Oncology: A Collaborative Open Access Reference is a unique and necessary valuable resource for ophthalmologists, trainees, and related medical professionals working in underserved areas in providing quality care for patients suffering from ocular cancers. ; Open Access text that discusses Preferred Practice Guidelines for common surgeries performed on tumors of the eye and adnexa Written for general ophthalmologists providing oncology care and specialists practicing in areas with limited access to advanced technology and instrumentation Includes chapters on eyelid tumors, conjunctival and corneal tumors, intraocular tumors, brachytherapy, and ocular pathology Each chapter includes extensive color pictures and relevant video to assist the clinician in the various surgical procedures discusse

Advancing fluorescent contrast agent recovery methods for surgical guidance applications

Fluorescence-guided surgery (FGS) utilizes fluorescent contrast agents and specialized optical instruments to assist surgeons in intraoperatively identifying tissue-specific characteristics, such as perfusion, malignancy, and molecular function. In doing so, FGS represents a powerful surgical navigation tool for solving clinical challenges not easily addressed by other conventional imaging methods. With growing translational efforts, major hurdles within the FGS field include: insufficient tools for understanding contrast agent uptake behaviors, the inability to image tissue beyond a couple millimeters, and lastly, performance limitations of currently-approved contrast agents in accurately and rapidly labeling disease. The developments presented within this thesis aim to address such shortcomings. Current preclinical fluorescence imaging tools often sacrifice either 3D scale or spatial resolution. To address this gap in high-resolution, whole-body preclinical imaging tools available, the crux of this work lays on the development of a hyperspectral cryo-imaging system and image-processing techniques to accurately recapitulate high-resolution, 3D biodistributions in whole-animal experiments. Specifically, the goal is to correct each cryo-imaging dataset such that it becomes a useful reporter for whole-body biodistributions in relevant disease models. To investigate potential benefits of seeing deeper during FGS, we investigated short-wave infrared imaging (SWIR) for recovering fluorescence beyond the conventional top few millimeters. Through phantom, preclinical, and clinical SWIR imaging, we were able to 1) validate the capability of SWIR imaging with conventional NIR-I fluorophores, 2) demonstrate the translational benefits of SWIR-ICG angiography in a large animal model, and 3) detect micro-dose levels of an EGFR-targeted NIR-I probe during a Phase 0 clinical trial. Lastly, we evaluated contrast agent performances for FGS glioma resection and breast cancer margin assessment. To evaluate glioma-labeling performance of untargeted contrast agents, 3D agent biodistributions were compared voxel-by-voxel to gold-standard Gd-MRI and pathology slides. Finally, building on expertise in dual-probe ratiometric imaging at Dartmouth, a 10-pt clinical pilot study was carried out to assess the technique’s efficacy for rapid margin assessment. In summary, this thesis serves to advance FGS by introducing novel fluorescence imaging devices, techniques, and agents which overcome challenges in understanding whole-body agent biodistributions, recovering agent distributions at greater depths, and verifying agents’ performance for specific FGS applications

Single-cell tracking of therapeutic cells using Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry

Cellular therapy is emerging as a clinically viable strategy in the field of solid organ transplantation, where it is expected to reduce the dependency on conventional immunosuppression. This has produced a demand for highly sensitive methods to monitor the persistence and tissue distribution of administered cells in vivo. However, tracking cells presents significant challenges. In many cases transplanted cells are autologous with the immune system of the transplant recipient, and hence are invisible to typical methods of detection. To enable their differentiation, the cells must be labelled with a suitable, non-toxic and long lifetime label, prior to their administration to patients. In addition, administered cells represent only a small fraction of the recipient’s endogenous cells, which necessitates the use of an extremely sensitive detection method. Laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) is an exquisitely sensitive analytical technique, capable of imaging trace elements in complex samples, at high spatial resolution. [Continues.

Comparing Gaussian and Bessel-Gauss beams for translating ultrafast laser ablation towards soft tissue surgery

The goal of this research was to further improve existing ultrafast laser surgery techniques. To do so, different beam shapes (Bessel-Gauss and Gaussian) were compared for performing ultrashort picosecond pulsed surgery on various soft biological tissues, with the goal of minimising collateral thermal damage. Initially, theoretical modelling was performed using OpticStudio to test axicons of various conical angles. A 20° axicon was selected, but unfortunately early tests on murine intestinal tissue indicated a lack of sufficient intensity to achieve plasma-mediated ablation of the tissue with the 6ps input pulses of 85 µJ energy. Subsequently, a reimaged setup was designed in OpticStudio to demagnify the beam by a factor of 1.4x. The ability of this demagnified Bessel-Gauss beam to perform plasma-mediated ablation of murine intestinal tissue was confirmed through histological analysis. Another setup was also designed to produce a Gaussian beam of equivalent spot size. These beams were then tested on porcine intestinal tissue using lower pulse repetition rates of 1, 2 and 3 kHz, with optimal ablation and thermal damage margins of less than 20 µm (confirmed through histological analysis) being achieved with the Bessel-Gauss beam for spatial pulse overlaps of 70%, while for the Gaussian beam the prominence of cavitation bubble formation at both 2 and 3 kHz inhibited the respective ablation processes at this same spatial pulse overlap. As the numbers of passes were increased, the Bessel-Gauss beam also showed a trend of increased ablation depths. This was attributed to its large depth of focus of over 1 mm, compared to the theoretical 48 µm depth of focus for the Gaussian beam. After characterisation of fixated, non-ablated porcine intestine sample surfaces to quantify the inhomogeneity, another set of ablation trials was performed at higher pulse repetition rates (5, 10 and 20 kHz) to test more clinically viable processes. For the Bessel-Gauss beam, spatial pulse overlaps of up to around 50% at 5, 10 and 20 kHz offered excellent thermal confinement (with damage margins of < 30 µm, < 50 µm and < 25 µm respectively) and shape control, but at 70% and greater pulse overlaps the ablated feature became hard to control despite good thermal confinement (< 40 µm). The Gaussian beam, while having the advantage of achieving plasma formation at lower input pulse energies, was again found to be more prone to undesirable cavitation effects. Cavitation bubbles were observed in the histology images for spatial pulse overlaps as low as 15% for 5 kHz and 30% for both 10 and 20 kHz. From the histology images it is clear to see that these effects became more pronounced as the pulse repetition rate was increased. Conversely, the more consistent spot size of the Bessel-Gauss beam across its longer focal depth resulted in a higher tolerance to cavitation bubble formation. This was also demonstrated by high-speed videos of the beams being scanned across porcine skin samples. This could be significant as it may allow for higher ablation rates. In addition, it could ease the design constraint of the maximum speed at which the beam can be scanned at the distal end of an endoscopic device. Despite this, both beams were able to achieve distinct ablation with high thermal confinement for certain parameters. This work further highlights fibre-delivered ultrashort laser pulses as a promising alternative to existing endoscopic tumour resection techniques, which carry a higher risk of bowel perforation.James Watt Scholarshi

Photosensitizing effects of chlorin e6 - Polyvinylpyrrolidone for fluorescence guided photodynamic therapy of cancer

Ph.DDOCTOR OF PHILOSOPH

Nanostructural Materials with Rare Earth Ions: Synthesis, Physicochemical Characterization, Modification and Applications

This Special Issue of "Nanostructural Materials with Rare Earth Ions: Synthesis, Physicochemical Characterization, Modification and Applications" is related to studies of nanometer-sized materials doped and co-doped with rare earth ions and the creation of periodically ordered nanostructures based on single nanoparticles. A small particle size implies a high sensitivity and selectivity. These new effects and possibilities are mainly due to the quantum effects resulting from the increasing ratio of surface-to-volume atoms in low-dimensional systems. An important factor in this context is the design and fabrication of nanocomponents displaying new functionalities and characteristics for the improvement of existing materials, including photonic materials, conductive materials, polymers and biocomposites. With this concept in mind, the aim of the Special Issue is to publish research on innovative materials and their applications.Topics to be covered in this Special Issue include, but are not limited to, the following: Technology and applications of nanomaterials with rare earth ions; Advanced physicochemical properties, characterization and modification of nanomaterials with rare earth ions; Novel active materials, especially organic and inorganic materials, nanocrystalline materials, nanoceramics doped and co-doped with rare-earth ions with bio-related and emerging applications; Magnetic properties of nano-sized rare-earth compounds; Applications of nano-sized rare-earth-doped and co-doped optical materials