Eye Lens Research Articles

Seeing further into the early steps of the endangered atlantic goliath grouper (Epinephelus itajara): Eye lenses high resolution isotopic profiles reveal ontogenetic trophic and habitat shifts

Estuarine mangroves are often considered nurseries for the Atlantic Goliath grouper juveniles. Yet, the contributions of different estuarine primary producers and habitats as sources of organic matter during early ontogenetic development remain unclear. Given the species’ critically endangered status and protection in Brazil, obtaining biological samples from recently settled recruits in estuaries is challenging. In this study, we leveraged a local partnership with fishers and used stable isotope (C and N) profiles from the eye lenses of stranded individuals or incidentally caught by fishery to reconstruct the trophic and habitat changes of small juveniles. The eye lens grows by the apposition of protein-rich layers. Once these layers are formed, they become inert, allowing to make inferences on the trophic ecology and habitat use along the development of the individual until its capture. We used correlations between fish size and the entire eye lens size, along with estuarine baselines, to reconstruct the fish size and trophic positions for each of the lens layers obtained. We then used dominant primary producers and basal sources from mangrove sheltered, exposed estuarine and marine habitats to construct an ontogenetic model of trophic and habitat support changes since maternal origins. Our model revealed marine support before the juveniles reached 25 mm (standard length), followed by a rapid increase in reliance on mangrove sheltered sources, coinciding with the expected size at settlement. After reaching 60 mm, individuals began to show variability. Some remained primarily supported by the mangrove sheltered area, while others shifted to rely more on the exposed estuarine area around 150 mm. Our findings indicate that while mangroves are critical for settlement, as Goliath grouper juveniles grow, they can utilize organic matter produced throughout the estuary. This underscores the need for conservation strategies that focus on seascape connectivity, as protecting just one discrete habitat may not be sufficient to preserve this endangered species and safeguard its ecosystem functions.

Intraoperative Staff Radiation Exposure During Aortic Endovascular Procedures

The risk of radiation exposure in the surgical operating room (OR) and/or catheterization laboratory is now well established. Complex endovascular procedures often require multiple approaches and different positioning of the staff members around the patient, potentially increasing the levels of radiations exposure. Our goal was to evaluate the levels of radiation exposure of the members of the staff during endovascular aortic procedures in order to propose radioprotection optimization. We included 41 aortic endovascular procedures out of 114 procedures performed between January 12, 2014, and August 31, 2015, including 24 standard endovascular aortic aneurysm repair (EVAR), 7 EVAR with iliac branch (EVARib), 8 complex fenestrated/branched EVAR (F/B EVAR), and 2 thoracic EVAR (TEVAR). Procedures were performed in an OR equipped with a carbon fiber table and a mobile fluoroscopy C-arm. We collected the usual dosimetry data given by the C-arm as well as the patient's peak skin dose (PSD). In all staff members, radiation exposure was measured with thermoluminescent chip dosimeters placed on both temples, on posterior sides of both hands, and on both lower legs. PSD levels were low for EVAR because 24 patients had values below the reading threshold. PSD significantly increased with more complex procedures. Main operator (MO) received the higher level of irradiation on whole body, hands, and ankles. Eye lenses irradiation was higher on both assistant operators (AOs). Other members received low levels of irradiation. We found a high ranges of radiation exposure with a high risk of exposure for the AO, mainly for F/B EVAR and EVARib. Even if all personal protections are used, staff positioning is a major point that must be considered. If MO is supposed to be the most exposed to X-rays, specific conditions of positioning of the AO may be at risk of exposure.

An ultraviolet-driven rescue pathway for oxidative stress to eye lens protein human gamma-D crystallin

Human gamma-D crystallin (HGD) is a major constituent of the eye lens. Aggregation of HGD contributes to cataract formation, the leading cause of blindness worldwide. It is unique in its longevity, maintaining its folded and soluble state for 50-60 years. One outstanding question is the structural basis of this longevity despite oxidative aging and environmental stressors including ultraviolet radiation (UV). Here we present crystallographic structures evidencing a UV-induced crystallin redox switch mechanism. The room-temperature serial synchrotron crystallographic (SSX) structure of freshly prepared crystallin mutant (R36S) shows no post-translational modifications. After aging for nine months in the absence of light, a thiol-adduct (dithiothreitol) modifying surface cysteines is observed by low-dose SSX. This is shown to be UV-labile in an acutely light-exposed structure. This suggests a mechanism by which a major source of crystallin damage, UV, may also act as a rescuing factor in a finely balanced redox system.

Dose rate conversion coefficients for ocular contamination in nuclear medicine: A Monte Carlo simulation with experimental validation.

Since 2011, the International Commission on Radiological Protection (ICRP) has recommended an annual eye lens dose limit of 20 mSv for radiation workers, averaged over 5 years, with no year exceeding 50 mSv. However, limited research has been conducted on dose rate conversion coefficients (DCCs) for direct contamination of the eye. This study aimed to accurately determine DCCs for the eye lens and cornea for ocular contamination with radionuclides used in nuclear medicine. DCCs for 37 radionuclides used in nuclear medicine were determined using two different methods. Method 1 involved conducting Monte Carlo (MC) simulations of an ICRU cylinder to determine the absorbed dose at a depth of 3mm resulting from a point source. The accuracy of this simulation approach was validated by experimental thermoluminescent dosimeter (TLD) measurements for 18F, 68Ga, 99mTc, and 177Lu. In method 2, average DCCs were calculated for the eye lens (complete and radiosensitive parts) and the cornea for both a point source and thin surface contamination centered on the cornea using MC simulations on the adult mesh-type reference computational phantom of the eye from the ICRP (MRCP). DCCs determined from TLD measurements showed excellent agreement (deviations: +1.4%, +4.7%, -3.1%, and -2.5% for 18F, 68Ga, 99mTc, and 177Lu, respectively) compared to MC simulations of the experimental set-up. For the 37 radionuclides, DCCs of the complete eye-lens for a point source ranged from 2.53×10-7 to 4.15×10-2 mGy MBq-1 s-1 for the adult MRCPs, being substantially smaller compared to DCCs determined via MC simulations of a ICRU cylinder. In general, point source and surface contamination showed comparable DCCs for the eye lens. Radionuclides emitting low-energy beta radiation or conversion electrons (e.g., 177Lu, 99mTc) showed low DCCs as the radiation does not penetrate to the depth of the eye lens, while radionuclides emitting high-energy beta radiation (e.g., 90Y) showed high DCCs. Overall, DCCs for the radiosensitive part of the eye lens were larger (up to a factor of 3) compared to the complete eye lens. DCCs for the cornea were larger than for the eye lens with a factor that strongly depended on the emitted radiation type. Especially alpha emitters (e.g., 211At, 223Ra) showed high DCCs for the cornea because of the short range of alpha radiation, leading to local maxima in the cornea and not reaching the eye lens. DCCs at a depth of 3mm in an ICRU cylinder and adult MRCP DCCs for both the complete and sensitive parts of the eye lens and cornea were determined for 37 radionuclides having applications in nuclear medicine. These DCCs are highly useful in radiation safety assessments and radiation dose calculations in ocular contamination incidents.

Automated Compression Testing of the Ocular Lens.

The biomechanical properties of the ocular lens are essential to its function as a variable power optical element. These properties change dramatically with age in the human lens, resulting in a loss of near vision called presbyopia. However, the mechanisms of these changes remain unknown. Lens compression offers a relatively simple method for assessing the lens' biomechanical stiffness in a qualitative sense and, when coupled with appropriate analytical techniques, can help quantify biomechanical properties. A variety of lens compression tests have been performed to date, including both manual and automated, but these methods inconsistently apply key aspects of biomechanical testing such as preconditioning, loading rates, and time between measurements. This paper describes a fully automated lens compression test wherein a motorized stage is synchronized with a camera to capture the force, displacement, and shape of the lens throughout a preprogrammed loading protocol. A characteristic elastic modulus may then be calculated from these data. While demonstrated here using porcine lenses, the approach is appropriate for the compression of lenses of any species.

Entropy Tug-of-War Determines Solvent Effects in the Liquid-Liquid Phase Separation of a Globular Protein.

Liquid-liquid phase separation (LLPS) plays a key role in the compartmentalization of cells via the formation of biomolecular condensates. Here, we combined atomistic molecular dynamics (MD) simulations and terahertz (THz) spectroscopy to determine the solvent entropy contribution to the formation of condensates of the human eye lens protein γD-Crystallin. The MD simulations reveal an entropy tug-of-war between water molecules that are released from the protein droplets and those that are retained within the condensates, two categories of water molecules that were also assigned spectroscopically. A recently developed THz-calorimetry method enables quantitative comparison of the experimental and computational entropy changes of the released water molecules. The strong correlation mutually validates the two approaches and opens the way to a detailed atomic-level understanding of the different driving forces underlying the LLPS.

Basic characteristics of Vision badge and its performance as an eye lens dosimeter for endoscopists

Vision badge is an eye lens dosimeter to measure H p(3). This study aimed to evaluate the basic characteristics of the Vision badge and its performance as an eye lens dosimeter for endoscopists by phantom study. Energy dependence was evaluated by changing the tube voltage to 50 kV (effective energy of 27.9 keV), 80 kV (32.2 keV), and 120 kV (38.7 keV). Dose linearity was evaluated by changing the number of irradiation to 1, 5, and 40 times, which corresponded to 0.53, 5.32, and 21.4 mGy. Batch uniformity was evaluated by calculating the coefficient of variation of H p(3) obtained from 10 Vision badges. Angular dependence was evaluated at 0° (perpendicular to the incident direction of x-rays), 30°, 60°, 75°, and 90°. The Vision badge and optically stimulated luminescence (OSL) dosimeter were attached to the inside of the radioprotective glasses, worn on the endoscopist phantom, and the H p(3) obtained from both dosimeters were compared. The H p(3) obtained from the Vision badge with 38.7 keV was 3.8% higher than that with 27.9 keV. The Vision badge showed excellent linearity (R 2 = 1.00) with the air kerma up to 21.4 mGy. The coefficient of variation of the H p(3) for 10 Vision badges was 3.47%. The relative dose of the Vision badge decreased as the angle increased up to 75°, but increased at 90°. The H p(3) obtained by the OSL dosimeter and the Vision badge were decreased as the endoscopist phantom was turned away from the patient phantom. The H p(3) that was obtained by the Vision badge was 35.5%–55.0% less than that obtained by the nanoDot. In conclusion, the Vision badge showed specific angular dependence due to its shape, but satisfactory basic properties were exhibited for all characteristics. In phantom study, the Vision badge showed generally similar trends with the OSL dosimeter.

IJCM_248A: Visual health related to quality of life and visual acuity in cataract patients advised for surgery: A hospital-based cross-sectional study

Background: Vision plays a pivotal role in daily activities, and its impairment, often caused by cataracts, significantly impacts the quality of life. Cataracts, characterized by cloudiness or opacity in the eye lens, contribute significantly to visual impairment, especially in individuals over 60 years. The prevalence of cataract-induced blindness in India is alarmingly high, with 80.1% of blindness and 58% of senile cataract cases attributed to this condition. Objectives: To assess the impact of cataract surgery on the visual health- related quality of life (VHRQoL) among patients. Methodologyology: This hospital-based cross-sectional study was conducted at Government Wenlock Hospital and KMC Mangalore Attavar, hospitals affiliated to Kasturba Medical college, Mangalore. The study included cataract patients, both preoperative and postoperative, excluding those with other eye-related disorders. Non-probability (purposive) sampling was employed, determining a sample size of 60 based on a 95% confidence level and 62% prevalence of cataract. Results: Patients undergoing cataract surgery exhibited notable improvements in general vision, ocular pain, mental health, and near activities. Enhanced role performance, social life, and reduced dependency were observed. Post-operative visual acuity improved, especially for pre-operative values below 6/18. VFQ-J11 revealed significant associations in 4 out of 7 domains, surpassing VFQ-25 (2 out of 12), making VFQ-J11 a preferred tool for assessing pre- operative and post-operative patients. Conclusion: The cataract surgery leads to an overall enhancement in the quality of life for the majority of patients, with a moderate correlation between VHRQoL improvement and visual acuity.

Lens Cytoskeleton: An Update on the Etiopathogenesis of Human Cataracts.

A cataract is a loss of the transparency of a normal crystalline lens. Multiple factors, including age as the major risk factor for cataracts, can disturb the transparency of the crystalline lens due to cumulative damage from environmental insults to proteins, particularly crystallins. Lens proteins do not turnover, and crystallins undergo extensive post-translational modifications (PTMs) with age in order to interact with each other and maintain their soluble basis for lens transparency. These PTMs include truncation, oxidation, deamidation, acetylation, phosphorylation, and glycosylation. Cataract formation, apart from protein PTMs, involves protein crosslinking, protein insolubilization, and aggregation. Oxidation is a key feature in age-related cataract formation. Due to the role of genetic and environmental factors, as well as its variable clinical presentation, we consider cataracts to be a multifactorial disease. The preliminary results of our study indicate that proteins implicated in the pathway of a structural constituent of the eye lens (BFSP1, BFSP2, CRYAA, CRYAB, CRYBA, CRYBB, CRYGC, CRYGD, CRYGS, KRTs, and VIM), together with AQP1 and AQP5, may also be involved in lens aging.

Disease-related non-muscle myosin IIA D1424N rod domain mutation, but not R702C motor domain mutation, disrupts mouse ocular lens fiber cell alignment and hexagonal packing.

The mouse ocular lens is an excellent vertebrate model system for studying hexagonal cell packing and shape changes during tissue morphogenesis and differentiation. The lens is composed of two types of cells, epithelial and fiber cells. During the initiation of fiber cell differentiation, lens epithelial cells transform from randomly packed cells to hexagonally shaped and packed cells to form meridional row cells. The meridional row cells further differentiate and elongate into newly formed fiber cells that maintain hexagonal cell shape and ordered packing. In other tissues, actomyosin contractility regulates cell hexagonal packing geometry during epithelial tissue morphogenesis. Here, we use the mouse lens as a model to study the effect of two human disease-related non-muscle myosin IIA (NMIIA) mutations on lens cellular organization during fiber cell morphogenesis and differentiation. We studied genetic knock-in heterozygous mice with NMIIA-R702C motor domain or NMIIA-D1424N rod domain mutations. We observed that while one allele of NMIIA-R702C has no impact on lens meridional row epithelial cell shape and packing, one allele of the NMIIA-D1424N mutation can cause localized defects in cell hexagonal packing. Similarly, one allele of NMIIA-R702C motor domain mutation does not affect lens fiber cell organization while the NMIIA-D1424N mutant proteins disrupt fiber cell organization and packing. Our work demonstrates that disease-related NMIIA rod domain mutations (D1424N or E1841K) disrupt mouse lens fiber cell morphogenesis and differentiation.

Marfan Syndrome with Atypical Pneumonia: A Case Report

Marfan syndrome (MFS) is an autosomal dominant systemic disorder of the connective tissue. Children impacted by the MFS carry the mutation in one of their two alleles of the gene that codes the connective tissue protein fibrillin-1 (FBN-1). MFS influences their effects upon most organs and tissues, in particular the skeleton, lungs, eyes, heart, and the large blood vessel that distributes blood from the heart to the reminder of the physique. A case report of MFS with atypical pneumonia has been reported with positive Steinberg sign, thumb sign and wrist sign. Existence of long legs with the positive Walker Murdoch sign. There were no complications such as an aortic aneurysm, ocular lens luxation, or mitral valve prolapse were remarked. Since the patient was lacking such complications based on MFS, he was treated only for atypical pneumonia. Keywords: Marfan Syndrome, Fibrillin-1, Thoracic Aortic Aneurysm or Dissection, Ectopia Lentis

The Effect of Lens Shape, Zonular Insertion and Finite Element Model on Simulated Shape Change of the Eye Lens

The process of lens shape change in the eye to alter focussing (accommodation) is still not fully understood. Modelling approaches have been used to complement experimental findings in order to determine how constituents in the accommodative process influence the shape change of the lens. An unexplored factor in modelling is the role of the modelling software on the results of simulated shape change. Finite element models were constructed in both Abaqus and Ansys software using biological parameters from measurements of shape and refractive index of two 35-year-old lenses. The effect of zonular insertion on simulated shape change was tested on both 35-year-old lens models and with both types of software. Comparative analysis of shape change, optical power, and stress distributions showed that lens shape and zonular insertion positions affect the results of simulated shape change and that Abaqus and Ansys show differences in their respective models. The effect of the software package used needs to be taken into account when constructing finite element models and deriving conclusions.

Effect of radioprotective curtain length on the scattered dose rate distribution and endoscopist eye lens dose with an over-couch fluoroscopy system

Sufficient dose reduction may not be achieved if radioprotective curtains are folded. This study aimed to evaluate the scattered dose rate distribution and physician eye lens dose at different curtain lengths. Using an over-couch fluoroscopy system, dH*(10)/dt was measured using a survey meter 150 cm from the floor at 29 positions in the examination room when the curtain lengths were 0% (no curtain), 50%, 75%, and 100%. The absorbed dose rates in the air at the positions of endoscopist and assistant were calculated using a Monte Carlo simulation by varying the curtain length from 0 to 100%. The air kerma was measured by 10 min fluoroscopy using optically stimulated luminescence dosimeters at the eye surfaces of the endoscopist phantom and the outside and inside of the radioprotective goggles. At curtain lengths of 50%, 75%, and 100%, the ratios of dH*(10)/dt relative to 0% ranged from 80.8 to 104.1%, 10.5 to 61.0%, and 11.8 to 24.8%, respectively. In the simulation, the absorbed dose rates at the endoscopist’s and assistant’s positions changed rapidly between 55 and 75% and 65% and 80% of the curtain length, respectively. At the 0%, 50%, 75%, and 100% curtain lengths, the air kerma at the left eye surface of the endoscopist phantom was 237 ± 29, 271 ± 30, 37.7 ± 7.5, and 33.5 ± 6.1 μGy, respectively. Therefore, a curtain length of 75% or greater is required to achieve a sufficient eye lens dose reduction effect at the position of the endoscopist.

Staring X-ray backscatter imaging based on ultra-high aspect ratio lobster eye lens.

In contrast to conventional X-ray imaging systems, the lobster eye lens, serving as a pivotal component for X-ray focusing, presents the potential for downsizing X-ray backscatter imaging systems. This study reports the successful implementation of a pioneering non-contact staring X-ray backscatter imaging experiment, with the target positioned 1.5 meters away from the system and employing a tube voltage of 60 kV for the X-ray light source. The system is built upon a novel high aspect ratio (500) meridian lobster eye lens, employing a laboratory low illuminance desktop light source and a commercial X-ray detector to achieve high-resolution focused imaging of hard X-rays. Point spread function testing and a series of imaging experiments were carried out to assess the resolution and optimal imaging photon energy of the proposed system. Furthermore, according to the characteristics of the point spread function of the cross image of the lobster eye lens, we proposed an image processing algorithm. The experimental results demonstrate that, after processing, the Structural Similarity (SSIM) Index of the backscatter image and the ground truth image can be improved from an average of 0.0526 to 0.5758. Our research significantly contributes to the advancement of a new generation of X-ray backscatter imaging systems.

Comprehensive simulation and analysis of lobster eye micro-pore optics imaging in the hard X-ray band

The lobster eye lens uses square channels to reflect and converge light. It has no fixed optical axis and possesses advantages such as a broad field of view (FOV) and no chromatic aberration. Moreover, lobster eye lenses based on microporous optics manufacturing technology have been successfully applied to the spatial detection of soft X-ray spectra. Based on the penetrability of hard X-rays, lobster eye lenses can detect the perspective of hidden targets, which can be applied to fields such as safety inspection and industrial flaw detection. This study proposes an algorithm for comprehensive analysis of the imaging ability of a hard X-ray lobster eye lens, focusing on the stray rays transmitted by high-penetration X-rays. The simulation results showed that the point-spread function of the off-axis FOV is different. With the increase in the photon energy, the enhanced superposition effect of the cross-arm decreases the image contrast. Both the simulated and experimental images show that the image contrast decreases as the photon energy increases. The image contrast can be improved by adding more Pb to the materials used to create the lobster eye lens owing to the strong attenuation ability of Pb to X-rays. These results can contribute to the improvement of lobster eye lenses in X-ray backscatter imaging.

Optical development in the murine eye lens of accelerated senescence-prone SAMP8 and senescence-resistant SAMR1 strains

The eye lens is responsible for focusing objects at various distances onto the retina and its refractive power is determined by its surface curvature as well as its internal gradient refractive index (GRIN). The lens continues to grow with age resulting in changes to the shape and to the GRIN profile. The present study aims to investigate how the ageing process may influence lens optical development. Murine lenses of accelerated senescence-prone strain (SAMP8) aged from 4 to 50 weeks; senescence-resistant strain (SAMR1) aged from 5 to 52 weeks as well as AKR strain (served as control) aged from 6 to 70 weeks were measured using the X-ray interferometer at the SPring-8 synchrotron Japan within three consecutive years from 2020 to 2022. Three dimensional distributions of the lens GRIN were reconstructed using the measured data and the lens shapes were determined using image segmentation in MatLab. Variations in the parameters describing the lens shape and the GRIN profile with age were compared amongst three mouse strains. With advancing age, both the lens anterior and posterior surface flattens and the lens sagittal thickness increase in all three mouse strains (Anterior radius of curvature increase at 0.008 mm/week, 0.007 mm/week and 0.002 mm/week while posterior radius of curvature increase at 0.002 mm/week, 0.007 mm/week and 0.003 mm/week respectively in AKR, SAMP8 and SAMR1 lenses). Compared with the AKR strain, the SAMP8 samples demonstrate a higher rate of increase in the posterior curvature radius (0.007 mm/week) and the thickness (0.015 mm/week), whilst the SAMR1 samples show slower increases in the anterior curvature radius (0.002 mm/week) and its thickness (0.013 mm/week). There are similar age-related trends in GRIN shape in the radial direction (in all three types of murine lenses nr2 and nr6 increase with age while nr4 decrease with age consistently) but not in the axial direction amongst three mouse strains (nz1 of AKR lens decrease while of SAMP8 and SAMR1 increase with age; nz2 of all three models increase with age; nz3 of AKR lens increase while of SAMP8 and SAMR1 decrease with age). The ageing process can influence the speed of lens shape change and affect the GRIN profile mainly in the axial direction, contributing to an accelerated decline rate of the optical power in the senescence-prone strain (3.5 D/week compared to 2.3 D/week in the AKR control model) but a retardatory decrease in the senescence-resistant strain (2.1 D/week compared to the 2.3D/week in the AKR control model).

The Relationship between Diabetes Mellitus with Senile Cataracts

A cataract is any condition of cloudiness of the eye lens (lens opacity) caused by denaturation of lens proteins, lens hydration, or both. Senile cataract refers to cataracts suffered by patients aged > 50 years. Cataract is a multifactorial disease. About 90% of cataract incidence is related to age. Other factors such as radiation exposure, trauma, medicine, or the presence of systemic disorders are also involved in diabetes melitus. The study’s goal was to analyze the relationship between diabetes mellitus and the incidence of senile cataract. The research was carried out using an analytical observational method and utilized a case-control study approach with individual matching. The data was taken from the medical record installation at the Eye Clinic of SMEC Samarinda with a purposive sampling method. The sample in this study included patients with eye disorders or diseases.The patients with a cataract diagnosis were involved as the case group, while non-cataract patients as the control group. All patients were received treatment at the SMEC Samarinda Eye Clinic in the period January to December 2021 and already met the research sample criteria. The data then tested using the Chi-Square test with a significance value of p <0.05, which was considered significant. A total of 334 samples were obtained, consisting of 167 case samples and 167 control samples. The results indicated that there was a relationship between diabetes mellitus and senile cataract (p = 0.000) with an odds ratio (OR) value of 3.150. It can be concluded that diabetes mellitus had a relationship with the incidence of senile cataract, since patients with diabetes mellitus were 3.150 times more at risk of suffering senile cataracts than non-diabetics patients.

Dental Cone-Beam Computed Tomography: Are the Eye Lens and Thyroid at Risk?

Background: The purpose of this study was to assess radiation dose to the eye lens (EL) and thyroid gland (TG) from 22 protocols used in maxillofacial imaging with cone-beam computed tomography (CBCT).Methods and Results: NanoDot optically stimulated luminescence dosimeters were used to assess scattered radiation to the EL and TG using a phantom. The dosimeters were secured at four sites around areas of interest. Mean eye radiation dose was significantly associated with field of view (FOV) size (r=0.830, P<0.001). Meanwhile, the mean thyroid radiation dose was found to be significantly associated only with exposure time (r=0.464, P=0.030). Mandible centralization was observed to be the most significant predictor for a greater effective thyroid dose; mandible FOV centralization had 0.236 odds of a higher thyroid dose than maxilla FOV centralization.Conclusion: FOV size significantly impacted EL dose. Thyroid exposure was affected by FOV centralization and exposure time. Centering the FOV on the mandible resulted in a greater effective dose due to the proximity of the TG to the primary beam.

Fast and Mobile Cataract Detection by Applying Line Laser Eye Illumination

Cataract is observed when the eye lens becomes opaque. This condition causes blurred vision and is the main cause of blindness worldwide. Cataract diagnosis is usually performed during ophthalmologist examination using a slit lamp, which requires expertise, is expensive and bulky. In this study, we present a small handheld illumination setup for cataract detection. Ex-vivo porcine eyes are investigated to determine whether colored line lasers, 450 nm (blue), 520 nm (green) and 650 nm (red), which shine obliquely into the eye, are principally suited for detection of the Y shaped suture cataract and of cold cataract, respecting exposure limits of EU guideline 2006/25/EC. Camera images of the cataract exhibited good results under illumination with all line lasers. Observations with the physician’s eye led to an even better diagnosis of cataract. Generally, green laser light illumination was the best choice for cataract detection. With red laser light illumination it was also possible, but least suitable for this purpose. With this method, line lasers are a good choice for cataract identification, as cataract can be detected quickly and without much effort. This type of line laser illumination of the eye is safe and both types of cataract are detectable with all wavelengths. For the human eye, a further development of this system is conceivable.

On the gamma radiation response of commercially available 3D printing materials for medical dosimetry

3D printing technology has rapidly spread for decades, allowing the fabrication of medical implants and human phantoms and revolutionizing healthcare. The objective of this study is to evaluate some radiological properties of commercially available 3D printing materials as potential tissue mimicking materials. Among fifteen materials, we compared their properties with nine human tissues. In all materials and tissues, exposure and energy absorption buildup factors were calculated for photon energies between 0.015 and 15 MeV and penetration depths up to 40 mean free path. Furthermore, the Geant4 Monte Carlo toolkit (version 10.5) was used to simulate their percentage depth dose distributions. In addition, equivalent atomic numbers, effective atomic numbers, attenuation coefficients, and CT numbers have been examined. All parameters were considered in calculating the average relative error (σ), which was used as a statistical comparison tool. With σ between 6 and 7, we found that Polylactic Acid (PLA) was capable of simulating eye lenses, blood, soft tissue, lung, muscle, and brain tissues. Moreover, Polymethacrylic Acid (PMAA) material has a σ value of 4 when modeling adipose and breast tissues, respectively. Aside from that, variations in 3D printing materials’ infilling percentage can affect their CT numbers. We therefore suggest the PLA for mimicking soft tissue, muscle, brain, eye lens, lung and blood tissues, with an infill of between 92.7 and 94.3 percent. We also suggest an 89 percent infill when simulating breast tissue. Furthermore, with a 96.7 percent infill, the PMAA faithfully replicates adipose tissue. Additionally, we found that a 59 percent infill of Fe-PLA material is comparable to cortical bone. Due to the benefits of creating individualized medical phantoms and equipment, the results might be seen as an added value for both patients and clinicians.