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Carbon-based carbides have attracted tremendous attention for electromagnetic energy attenuation due to their adjustable dielectric properties, oxidation resistance, and good chemical stability. Herein, we reasonably regulate the growth of dopamine hydrochloride on the surface of the Mo-glycerate (Mo-GL) microsphere and then transform the resultant Mo-polydopamine (Mo-PD) microsphere into a dual-shell Mo

The physicochemical and antioxidant properties of seven carotenoids: antheraxanthin, β-carotene, neoxanthin, peridinin, violaxanthin, xanthrophyll and zeaxanthin were studied by theoretical means. Then the Optoelectronic properties and interaction of chlorophyll-carotenoid complexes are analysed by TDDFT and IGMPLOT. Global reactivity descriptors for carotenoids and chlorophyll (Chla, Chlb) are calculated via conceptual density functional theory (CDFT). The higher HOMO–LUMO (HL) gap indicated structural stability of carotenoid, chlorophyll and chlorophyll-carotenoid complexes. The chemical hardness for carotenoids and Chlorophyll is found to be lower in the solvent medium than in the gas phase. Results showed that carotenoids can be used as good reactive nucleophile due to lower µ and ω. As proton affinities (PAs) are much lower than the bond dissociation enthalpies (BDEs), it is anticipated that direct antioxidant activity in these carotenoids is mainly due to the sequential proton loss electron transfer (SPLET) mechanism with dominant solvent effects. Also lower PAs of carotenoid suggest that antioxidant activity by the SPLET mechanism should be a result of a balance between proclivities to transfer protons. Reaction rate constant with Transition-State Theory (TST) were estimated for carotenoid-Chlorophyll complexes in gas phase. Time dependent Density Functional Theory (TDDFT) showed that all the chlorophyll (Chla, Chlb)–carotenoid complexes show absorption wavelength in the visible region. The lower S1–T1 adiabatic energy gap indicated ISC transition from S1 to T1 state.

In this study, a high molecular weight arabinoxylan (AX, Mw: 694 kDa) from wheat bran was alkaline extracted and covalently linked with Catechin (CA) by free radical catalytic reaction. Comparing to AX, arabinoxylan-catechin (AX-CA) conjugates demonstrated an extra UV–vis absorption peak at 274 nm, a new FT-IR absorption band at 1516 cm−1 and new proton signals at 6.5–7.5 ppm, which all confirmed the covalently linked structure. Grafting CA onto AX not only decreased the molecular weight, thermal stability and apparent viscosity of AX, but also enhanced its inhibition effects on starch digestibility in vitro. The in vitro fermentation test with pig feces showed that the degradation & utilization rate of AX, the total short-chain fatty acid (SCFA) and acetic acid levels produced all were significantly delayed after grafting. This study provided a novel approach to synthesize AX-CA conjugates that could be a novel dietary fiber of enhanced functional/bioactive properties using in the fields of functional foods and medicine.

The degradation of paracetamol (PCT) in an aqueous medium using the Fenton and photo-Fenton reactions was investigated. The aim of this research was the development of a kinetic model based on a reaction mechanism, which includes two main intermediates of PCT degradation and the local volumetric rate of photon absorption (LVRPA). Ferrioxalate was used as a catalyst and the working pH was adjusted to 5.5 (natural pH). Experimental work was planned through a D-optimal experimental design and performed in a flat plate reactor irradiated by a solar simulator. Hydrogen peroxide (HP) concentration, reaction temperature, and radiation level were the operating parameters. The photo-Fenton reaction allowed to reach a minimum relative PCT concentration of 2.01% compared to 5.04% achieved with Fenton reaction. Moreover, the photo-Fenton system required a 50% shorter reaction time and lower HP concentration than in dark conditions (90 min and 189 mg L-1 vs. 180 min and 334 mg L-1, respectively). The experimental results were used to estimate the kinetic parameters of the proposed kinetic model employing a nonlinear, multi-parameter regression method. The values obtained from the normalized root-mean-square error (14.52, 1.96, 4.36, 13.16, and 8.72 % for PCT, benzoquinone, hydroquinone, HP, and oxalate, respectively) showed a good agreement between the predicted and experimental data.

The technology of magnetic resonance imaging is developing towards higher magnetic fields to improve resolution and contrast. However, whole-body imaging at 7 T or even higher flux densities remains challenging due to wave interference, tissue inhomogeneities, and high RF power deposition. Nowadays, proper RF excitation of a human body in prostate and cardiac MRI is only possible to achieve by using phased arrays of antennas attached to the body (so-called surface coils). Due to safety concerns, the design of such coils aims at minimization of the local specific absorption rate (SAR), keeping the highest possible RF signal in the region of interest. Most previously demonstrated approaches were based on resonant structures such as e.g. dipoles, capacitively-loaded loops, TEM-line sections. In this study, we show that there is a better compromise between the transmit signal \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\bf{B}}}_{{\bf{1}}}^{{\boldsymbol{+}}}$$\end{document}B1+ and the local SAR using non-resonant surface coils generating a low electric field in the proximity of their conductors. With this aim, we propose and experimentally demonstrate a leaky-wave antenna implemented as a periodically-slotted microstrip transmission line. Due to its non-resonant radiation, it induces only slightly over half the peak local SAR compared to a state-of-the-art dipole antenna but has the same transmit efficiency in prostate imaging at 7 T. Unlike other antennas for MRI, the leaky-wave antenna does not require to be tuned and matched when placed on a body, which makes it easy-to-use in prostate imaging at 7 T MRI., Magnetic resonance imaging of the prostate is challenging due to the trade-off between a high magnetic field and safety concern of local specific absorption rate. Here, the authors demonstrate that a leaky-wave antenna design can reduce local heating due to non-resonant radiation.

Due to the current state of ozone layer depletion and potential risk of skin cancer, researches on sustainable cellulose-based films with ultraviolet (UV) blocking capabilities has attracted widespread attention. However, pure cellulose-based film required UV absorbent to be incorporated because of its poor UV blocking ability. In this work, natural lignocellulosic nanofibril (LCNF) film was fabricated by vacuum filtration and pressing process without any complex chemical modification or adding UV absorbers. The residual lignin retained in LCNF was found to act as natural macro-molecular UV absorber. LCNF film with lignin content of 4.89–15.68% exhibited excellent thermal stability, and their UVA and UVB blocking were in the range of 81.4–99.5% and 96.7–100%, respectively. Moreover, LCNF film exhibited stable UV shielding performance under high temperature, UV irradiation, acidic or alkaline conditions, providing LCNF film with a long-term use capacity. Overall, LCNF film is more environmentally friendly and harmless, which shows high potentials in anti-counterfeiting materials, UV protection, and windshields for vehicles.

Radionuclide tritium is widely used in the nuclear energy production industry and creates a threat to human health through radiation exposure. Herein, the radioactive elimination and radioprotective effect of hydrogen-rich water (HRW), a potential antioxidant with various medical applications, on tritiated water (HTO) exposure, was studied in vitro and in vivo. Results showed that intragastric administration of HRW effectively promoted the elimination of urinary tritium, decreased the level of serum tritium and tissue-bound tritium (OBT), and attenuated the genetic damage of blood cells in mice exposed to HTO (18.5 MBq/kg). Pretreatment with HRW effectively reduces tritium accumulation in HTO-treated human blood B lymphocyte AHH-1 cells. In addition, the anti-oxidative properties of HRW could attenuate the increased intracellular ROS (such as O2•-, •OH and ONOO−), resulting in reversing the exhaustion of cellular endogenous antioxidants (reduced GSH and SOD), decreasing lipid peroxidation (MDA), relieving DNA oxidative damage, and depressing cell apoptosis and cytotoxicity induced by HTO exposure. In conclusion, HRW is expected to be an effective radioactive elimination agent through the competition effect of isotope exchange or a radioprotective agent by scavenging free radicals induced by HTO exposure.

The multi-copper Laccase enzyme corresponds to one of the most investigated oxidoreductases for potential uses in xenobiotic bioremediation. In this work, we have investigated the photo-degradation process of Laccase from Trametesversicolor induced by UVB light and the influence on its activity over selected substrates. Laccase undergoes photo-degradation when irradiated with UVB light, and the process depends on the presence of oxygen in the medium. With the kinetic data obtained from stationary and time resolved measurements, a photo-degradation mechanism of auto-sensitization was proposed for the enzyme. Laccase generates singlet oxygen, by UVB light absorption, and this reactive oxygen species can trigger the photo-oxidation of susceptible amino acids residues present in the protein structure. The catalytic activity of Laccase was evaluated before and after UVB photolysis over hydroxy-aromatic compounds and substituted phenols which represent potential pollutants. The dye bromothymol blue, the antibiotic rifampicin and the model compound syringaldazine, were selected as substrates. The values of the kinetic parameters determined in our experiments indicate that the photo-oxidative process of Laccase has a very negative impact on its overall catalytic function. Despite this, we have not found evidence of structural damage by SDS-PAGE and circular dichroism experiments, which indicate that the enzyme retained its secondary structure. We believe that, given the importance of Laccase in environmental bioremediation, the information found about the stability of this kind of biomolecule exposed to UV solar irradiation may be relevant in the technological design and/or optimization of decontamination strategies.

Gold nanoparticles (AuNPs) and gold nanoclusters (AuNCs) are gaining interest in medical diagnosis and therapy as they are bio-compatible and are easy to functionalize. Their interaction with radiofrequency (RF) field for hyperthermia treatment is ambiguous and needs further investigation. A systematic study of the absorption of capacitive RF field by AuNPs and AuNCs dispersed in phosphate-buffered saline (PBS) is reported here in tissue mimicking phantom. The stability of AuNPs and AuNCs dispersed in PBS was confirmed for a range of pH and temperature expected during RF hyperthermia treatment. Colloidal gold solutions with AuNPs (10 nm) and AuNCs (2 nm), and control, i.e. PBS without nanogold, were loaded individually in 3 ml wells in a tissue phantom. Phantom heating was carried out using 27 MHz short-wave diathermy equipment at 200 and 400 W for control and colloidal gold solutions. Experiments were conducted for colloidal gold at varying gold concentrations (10-100 µg/ml). Temperature rise measured in the phantom wells did not show dependence on the concentration and size of the AuNPs. Furthermore, temperature rise recorded in the control was comparable with the measurements recorded in both nanogold suspensions (2, 10 nm). Dielectric property measurements of control and colloidal gold showed3% difference in electrical conductivity between the control and colloidal gold for both nanoparticle sizes. From the measurements, it is concluded that AuNPs and AuNCs do not enhance the absorption of RF-capacitive field and power absorption observed in the biological medium is due to the ions present in the medium.

Background In 2007, the FDA added requirements for sunscreens to be labeled "re-apply at least every 2 hours" based on very limited data. This study used hybrid diffuse reflectance spectroscopy (HDRS) to evaluate the persistence of protection by 80 minutes water-resistant sunscreen formulation with and without re-application, and with and without sweat-inducing activity over 6 hours. Methods Sunscreens were applied to subject's foreheads and backs, and they remained at rest or exercised to induce sweating in a heated environment. Efficacy of a sun protection factor (SPF 50) very water-resistant sunscreen was measured with HDRS instrumentation and ultraviolet (UV) photography to determine the sunscreen protection over time. Results The sunscreen maintained SPF 50 efficacy over 6 hours for the non-active group with a single application, and for 2 hours for the active group, dropping slowly to SPF 30 level after 6 hours of sweating. Re-application of sunscreen gave additive SPF, with two applications resulting in SPF >100 and three applications approximately SPF 150. UV photography was insensitive to the differences in protection detected with HDRS instrumentation. Conclusions Sunscreen efficacy is maintained over time in the absence of sweating or rub-off. After two hours of sweating, an 80 minutes water-resistant sunscreen does not need to be re-applied "at least every 2 hours."

Laser has been widely used in the treatment of vascular skin diseases, such as port wine stain, due to the effect of selective photothermolysis in laser on biological tissue. The 755 nm alexandrite laser was expected to achieve better curative effect than the commonly used 585 or 595 nm pulsed dye laser (PDL) because of its deeper tissue penetration. In this study, the dorsal chamber model and microscopic visualization system were used to observe morphology changes on 42 blood vessels before and after irradiation with the 755 nm laser. Results showed that thermal effects of blood vessels intensified with the increase in energy, and high energy was required to produce the same thermal effect as the extension of pulse width. Different from 595 and 1064 nm lasers, partial vessel contraction was dominant thermal effect caused by the 755 nm laser. The bleeding injury rate and thermal effect of the 755 nm laser were between those of 595 nm PDL and 1064 nm Nd:YAG laser. The simulation results proved that 595 nm PDLs were effective for small and shallow target blood vessels. The 755 nm alexandrite lasers were effective in the treatment of hypertrophic and resistant blood vessels to PDL in the skin with low or moderate melanin concentration. The 1064 nm Nd:YAG laser was effective in the treatment of deeply buried and enlarged target blood vessels in the skin with high melanin concentration. The simulation results were supported by published clinical observations.

Boron neutron capture therapy (BNCT) is an emerging radiation treatment modality, exhibiting the potential to selectively destroy cancer cells. Currently, BNCT is conducted using a nuclear reactor. However, the future trend is to move toward an accelerator-based system for use in hospital environments. A typical BNCT radiation field has several different types of radiation. The beam quality should be quantified to accurately determine the dose to be delivered to the target. This study utilized a tissue equivalent proportional counter (TEPC) to measure microdosimetric and macrodosimetric quantities of an accelerator-based neutron source. The micro- and macro-dosimetric quantities measured with the TEPC were compared with those obtained via the the particle and heavy ion transport code system (PHITS) Monte Carlo simulation. The absorbed dose from events >20 keV/μm measured free in air for a 1-h irradiation was calculated as 1.31 ± 0.02 Gy. The simulated result was 1.41 ± 0.07 Gy. The measured and calculated values exhibit good agreement. The relative biological effectiveness (RBE) that was evaluated from the measured microdosimetric spectrum was calculated as 3.7 ± 0.02, similar to the simulated value of 3.8 ± 0.1. These results showed the PHITS Monte Carlo simulation can simulate both micro- and macro-dosimetric quantities accurately. The RBE was calculated using a single-response function, and the results were compared with those of several other institutes that used a similar method. However, care must be taken when using such a single-response function for clinical application, as it is only valid for low doses. For clinical dose ranges (i.e., high doses), multievent distribution inside the target needs to be considered.

This study explores the application of synchrotron radiation and conventional microcomputed tomography (SR-µCT and C-µCT, respectively) in evaluating bone-biopsy specimens. Bone-biopsy specimens were obtained using a trephine bur during bone-graft removal for implant placement six months after performing a maxillary sinus bone-graft procedure. Image data of specimens were obtained using SR-µCT and C-µCT. SR-µCT was performed using the 6C biomedical imaging beamline at the Pohang Accelerator Laboratory with a monochromatic X-ray beam of 23 keV, and C-µCT was performed using a table-top CT scanner (Skyscan 1272). Reconstruction images obtained using the two methods were qualitatively compared with 2D images evaluated under 3D visualization. The SR-µCT images, especially of the new-bone–graft–woven-bone formation, were less noisy and sharper than the C-µCT images. To evaluate the new-bone–graft–woven-bone formation, only the SR-µCT images showed areas of new bone (NB) formation with bone substitute (BS; Bio-Oss) and woven bone (WB) contact, and correctly visualized true 3D structures of bone formation. Hence, µCT techniques are non-destructive and can provide detailed images of bone biopsy. In particular, SR-µCT can be used to obtain improved image quality with contrast of NB, BS and WB, demonstrating a level of detail comparable with bone formation. SR-µCT could be an unbiased 3D alternative for imaging WB formation and for high-throughput analysis.

The intended purpose of UV-absorbing contact lenses is to protect the cornea and posterior ocular structures from UV-induced damage. Few studies report conjunctival effects of UV-absorbing contact lens materials. The purpose of this study was to evaluate conjunctival ultraviolet autofluorescence (UVAF) for contact lens wearers of UV-absorbing and minimally UV-absorbing materials.Forty-four volunteers enrolled in the cross-sectional study. Three groups were recruited; non-contact lens wearers (n = 15), minimally UV-absorbing contact lens wearers (n = 15), and UV-absorbing contact lens wearers (n = 14). Ocular sun exposure was calculated using self-reported measures. Conjunctival UVAF images of temporal and nasal conjunctiva, acquired using a Nikon D7000 camera system adapted with appropriate flash and filter system, were analyzed using ImageJ. A sub-group of participants including only subjects with measurable UVAF was analyzed.No significant differences were present between groups found similar for age, gender, and ocular sun exposure. The area of UVAF significantly increased following lens removal for UV-absorbing contact lens wearers compared with non-contact lens wearers. Furthermore, for contact lens wearers compared with non-lens wearers, area of UVAF was significantly greater between right and left eyes (p = .04 minimally UV-absorbing, p = .01 UV-absorbing), and between nasal (p = .046 minimally UV-absorbing, p = .01 UV-absorbing), and temporal (p = .01 UV-absorbing) areas. However, no significant difference was found between contact lens wearers of the two groups. No difference was found between nasal and temporal UVAF regions during contact lens wear (p = .28) or after lens removal (p = .16) (Mann-Whitney U).Contact lens materials have conjunctival effects, with increased UVAF in both UV-absorbing and minimally UV-absorbing contact lens wearers compared with non-lens wearers. UV-absorbing and minimally UV-absorbing contact lens materials appear to influence nasal and temporal areas of the ocular surface equally.

Chromium exists in several oxidation states, with the trivalent state (Cr(III)) being the dominant naturally occurring form. Chromium in other oxidation states tends to be converted to the trivalent oxide in the natural environment and in biological systems. Chromium(III) has been shown to be an essential nutrient for humans and several non-human species. Chromium(VI), the second most stable form of chromium, is an important environmental contaminant that is mostly of industrial origin and is associated with lung cancer and nose tumours in chromium workers. This paper proposes a biokinetic model for chromium that addresses the distinctive behaviours of Cr(III) and Cr(VI) following uptake to blood of an adult human. The model is based on biokinetic data derived from relatively short-term studies involving administration of chromium tracers to adult human subjects or laboratory animals, supplemented with data on the long-term distribution of chromium in adult humans as estimated from autopsy measurements. The model is part of a comprehensive update of biokinetic models of the International Commission on Radiological Protection, used to project or evaluate radiation doses from occupational intake of radionuclides.

The objective of this study is to investigate the need for detailed classification of skin colors through the quantification of skin color and light absorbance differences. Skin color is one of the most important factors in dermatological laser treatments. Dermatological laser treatments are currently performed based on the experience and judgment of the doctor with the Fitzpatrick scale. However, the Fitzpatrick scale and the doctor's experience were not quantified assessment methods for skin color classification and laser parameters selection. Improper selection of laser irradiating parameters can lead to undesirable tissue effects and treatment outcomes. We analyzed the correlations between absorbance and quantified colors using skin phantoms to identify that using the Fitzpatrick scale in dermatological treatments have limitations. Absorbance differences for different skin colors are measured at 532 nm with a custom-built system for radiant power measurements using skin phantoms fabricated with nine different colors. Some correlations between the color and absorbance agree with the Fitzpatrick scale. Generally, absorbance for the bright colored phantoms is lower than that for the darker colored phantoms. However, some phantoms fabricated with bright colors exceptionally have higher absorbance than those with darker colors. This means that for conventional standards, the Fitzpatrick scale may not always be accurate at 532-nm lights. Through these experiments, we demonstrate the need for a reliable classification standard for skin colors based on quantification of the skin colors and absorbance differences for each skin color as an alternative to the Fitzpatrick scale, which has limitations at certain wavelengths.

The 3D printing of fluorescent materials could help develop, validate, and translate imaging technologies, including systems for fluorescence-guided surgery. Despite advances in 3D printing techniques for optical targets, no comprehensive method has been demonstrated for the simultaneous incorporation of fluorophores and fine-tuning of absorption and scattering properties. Here, we introduce a photopolymer-based 3D printing method for manufacturing fluorescent material with tunable optical properties. The results demonstrate the ability to 3D print various individual fluorophores at reasonably high fluorescence yields, including IR-125, quantum dots, methylene blue, and rhodamine 590. Furthermore, tuning of the absorption and reduced scattering coefficients is demonstrated within the relevant mamalian soft tissue coefficient ranges of 0.005–0.05 mm−1 and 0.2–1.5 mm−1, respectively. Fabrication of fluorophore-doped biomimicking and complex geometric structures validated the ability to print feature sizes less than 200 μm. The presented methods and optical characterization techniques provide the foundation for the manufacturing of solid 3D printed fluorescent structures, with direct relevance to biomedical optics and the broad adoption of fast manufacturing methods in fluorescence imaging.

Orientador: Fernando Cendes Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas Resumo: Esse trabalho foi realizado para avaliar as doses de radiação absorvidas em exames de tomografia computadorizada em um hospital geral que atende uma grande população no Brasil. O FDA (Food and Drug Administration) considera que exames de CT com a absorção de uma dose efetiva de 10 mSv podem ser associados com um aumento na probabilidade de desenvolver um câncer fatal na proporção de 1/2000. Foram revisados 1352 relatórios de exames de tomografia computadorizada, provenientes de dois aparelhos, um com 16 e outro com 64 detectores. No aparelho de 16 detectores doses absorvidas ? 10 mSv foram observadas em 182 casos de um total de 326 pacientes (56%), enquanto no aparelho de 64 detectores essas doses foram observadas em 517 casos de um total de 996 pacientes (52%). Doses absorvidas > 100 mSv foram observadas em 16% de todos pacientes. Em ambos aparelhos , exames de abdome e de tórax + abdome apresentaram doses significantemente maiores que nos exames de pescoço, cabeça e tórax. Exames de abdome e tórax + abdome realizados com espessura de 1,25 mm no tomógrafo de 16 detectores e com 1,0 mm no aparelho de 64 detectores mostraram uma significante redução da dose absorvida em comparação com os mesmos tipos de exame realizados com espessura de 0,5 mm no aparelho de 64 detectores. Os exames de tórax realizados com espessura de 1,25 mm no tomógrafo de 16 detectores também mostraram uma significante diminuição da dose absorvida em comparação ao mesmo tipo de exame realizado no aparelho de 64 detectores com cortes de 0,5 mm. O aumento da espessura dos cortes tomográficos não causou uma significativa alteração na qualidade das imagens. Em conclusão, exames de tomografia computadorizada são frequentemente associados com altas doses de radiação absorvida indicando que os protocolos de exames devem ser reavaliados. Para exames de tomografia de abdome e de tórax + abdome , o aumento da espessura dos cortes pode proteger os pacientes de altas doses de radiação desnecessárias Abstract: This study was conducted to evaluate the absorbed radiation doses in CT examinations in a general hospital that serves a large population in Brazil. The Food and Drug Administration (FDA) considers that CT examination with an effective dose of 10 mSv may be associated with an increase in the possibility of fatal cancer of around 1/2000. CT examinations of 1352 patients performed in two types of CT equipment (with 16 and 64 detectors) were reviewed. In the 16 detector CT scanner, an absorbed dose ?10 mSv was detected in 182 out of 326 patients (56%) whereas in the 64 detector CT scanner, in 517 out of 996 (52%). Absorbed dose > 100 mSv was seen in 16% of all patients. In both CT scanners, examinations of abdomen and thorax+ abdomen presented an absorbed dose significantly higher than neck, head and thorax. Examinations of abdomen and thorax+ abdomen performed with slices of 1,25 mm in the 16 detector CT scanner and with 1,0 mm in the 64 detector CT scanner showed a significant reduction of the absorbed dose in comparison to the same type of examination with slices of 0.5 mm in the 64 detector CT scanner. The examinations of thorax performed with slices of 1,25 mm in the 16 detector scanner also showed a significant reduction of the absorbed dose in comparison to the examinations performed with slices of 0,5 mm in the 64 detectors scanner. The increase of the slice thickness did not lead to noticeable alteration of the image quality. In conclusion, CT examinations were often associated with high doses of absorbed radiation indicating that the protocols of the examinations should be reevaluated. For CT examinations of abdomen and thorax+abdomen, the increase of the slice thickness can protect patients from unnecessarily high doses of radiation Doutorado Fisiopatologia Médica Doutor em Ciências

Avoiding damage of the endothelial cells, especially in thin corneas, remains a challenge in corneal collagen crosslinking (CXL). Knowledge of the riboflavin gradients and the UV absorption characteristics after topical application of riboflavin in concentrations ranging from 0.1% to 0.5% could optimize the treatment. In this study, we present a model to calculate the UV-intensity depending on the corneal thickness. Ten groups of de-epithelialized porcine corneas were divided into 2 subgroups. Five groups received an imbibition of 10 min and the other five groups for 30 min. The applied riboflavin concentrations were 0.1%, 0.2%, 0.3%, 0.4% and 0.5% diluted in a 15% dextran solution for each subgroup. After the imbibition process, two-photon fluorescence microscopy was used to determine fluorescence intensity, which was compared to samples after saturation, yielding the absolute riboflavin concentration gradient of the cornea. The extinction coefficient of riboflavin solutions was measured using a spectrophotometer. Combining the obtained riboflavin concentrations and the extinction coefficients, a depth-dependent UV-intensity profile was calculated for each group. With increasing corneal depth, the riboflavin concentration decreased for all imbibition solutions and application times. The diffusion coefficients of 10 min imbibition time were higher than for 30 min. A higher RF concentration and a longer imbibition time resulted in higher UV-absorption and a lower UV-intensity in the depth of the cornea. Calculated UV-transmission was 6 percentage points lower compared to the measured transmission. By increasing the riboflavin concentration of the imbibition solution, a substantially higher UV-absorption inside the cornea is achieved. This offers a simple treatment option to control the depth of crosslinking e.g. in thin corneas, resulting in a lower risk of endothelial damage.

Purpose To investigate inter‐subject variability of B 1 +, SAR and temperature rise in a database of human models using a local transmit array for 7 T cardiac imaging. Methods Dixon images were acquired of 14 subjects and segmented in dielectric models with an eight‐channel local transmit array positioned around the torso for cardiac imaging. EM simulations were done to calculate SAR distributions. Based on the SAR distributions, temperature simulations were performed for exposure times of 6 min and 30 min. Peak local SAR and temperature rise levels were calculated for different RF shim settings. A statistical analysis of the resulting peak local SAR and temperature rise levels was performed to arrive at safe power limits. Results For RF shim vectors with random phase and uniformly distributed power, a safe average power limit of 35.7 W was determined (first level controlled mode). When RF amplitude and phase shimming was performed on the heart, a safe average power limit of 35.0 W was found. According to Pennes' model, our numerical study suggests a very low probability of exceeding the absolute local temperature limit of 40 °C for a total exposure time of 6 min and a peak local SAR of 20 W/kg. For a 30 min exposure time at 20 W/kg, it was shown that the absolute temperature limit can be exceeded in the case where perfusion does not change with temperature. Conclusion Safe power constraints were found for 7 T cardiac imaging with an eight‐channel local transmit array, while considering the inter‐subject variability of B 1 +, SAR and temperature rise., 14 subject specific dielectric body models were constructed based on dixon MRI scans. SAR and thermal simulations were performed in all these for a 7T body array of 8 fractionated dipole antennas to find distributions of peak SAR and temperature. Based on our model database, safe power limits were found for 7T cardiac imaging, while considering inter‐subject variation of SAR, temperature and B1+.

Background and objectives Optical properties characterize light propagation in turbid media, such as tissue. Recovery of optical properties is of great importance in a wide variety of biomedical applications, including both therapeutic treatments and diagnosis. Most of the available methodologies are well established, however, these are not optimized for real-time measurements. Study design/materials and methods Optical properties are recovered using the Inverse Adding Doubling program from reflectance measurements measured with an integrating sphere and light in the visible range. A user-friendly interface was programmed in Visual Studio and the libraries of a particular spectrophotometer were used. To achieve real-time measurements, a parallel computing routine was implemented, splitting the whole spectra in threads to be computed independently. Several tests using living tissue and inorganic materials were carried out to validate the proposed algorithm. Results Recovery of absorption/scattering coefficient spectrum in the visible range with high precision in a couple of seconds was achieved, demonstrating its capabilities for real-time monitoring in biomedical applications. The absorption coefficient spectrum shows the expected characteristics according to the different melanin and blood concentration of various volunteers, also showing the expected changes during a thermoregulation process. Conclusions A real-time monitoring of optical properties algorithm was developed, including parallel computing and a user-friendly interface. The proposed algorithm would be of help in biomedical applications, where real-time monitoring optical properties is required. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Purpose: Estimation of energy absorption buildup factors (EABFs) of some human tissues for photon energies commonly used in brachytherapy (BT) and external beam radiotherapy (EBRT).Methods: A five ...

The incorporation of 2,2,2-trichloroethanol in polyacrylamide gels allows for fluorescent visualization of proteins following electrophoresis. Ultraviolet-light exposure, in the presence of this trichlorinated compound, results in a covalent modification of the tryptophan indole ring that shifts the fluorescent emission into the visible range. Based on this principle, we used 2,2,2-trichloroethanol to develop a microplate format protein quantification assay based on the fluorescent signal generated by modified proteins. We also demonstrated a specific fluorescent emission of 2,2,2-trichloroethanol-labeled protein at 450 nm, with a 310 nm excitation, resulting from modification of both tryptophan and tyrosine residues. Following optimization, this protein quantification assay displayed superior sensitivity when compared to UV absorbance at 280 nm (A280), and enabled quantification beyond the linear range permitted by the Bradford method. This 100 μL assay displayed a sensitivity of 10.5 μg in a range up to at least 200 μg. Furthermore, we extended the utility of this method through the development of a 20 μL low-volume assay, with a sensitivity of 8.7 μg tested up to 100 μg, which enabled visualization of proteins following SDS-PAGE. Collectively, these results demonstrate the utility of 2,2,2-trichloroethanol-based protein quantification and demonstrates the protein visualization in polyacrylamide gels based on 2,2,2-trichloroethanol-labeling pre-electrophoresis.

Objective: To measure the doses of occupational radiation to which a physician who performs orthopedic surgery of the foot and ankle using a fluoroscopy device is exposed during work and to compare those doses with the values provided in the current legislation and propose measures of radioprotection. Methods: Thermoluminescent dosimetry (TLD) was used to measure radiation in critical target areas (whole-body, lens, thyroid, right and left hands) of the surgeon’s body during all the surgical procedures performed by him between 12/19/2017 and 2/5/2018. From the mean dose values obtained for the procedures, the dose of annual radiation exposure was estimated for each of the regions analyzed and compared with the current legislation. Results: The estimate of the annual radiation dose received by the surgeon to the chest region, above the lead apron, was 5 times higher than that established by the national legislation. However, considering the use of the lead apron, the dose was acceptable. Estimates of equivalent doses for the limbs and thyroid had results within the levels required by the current legislation. The equivalent dose for the lens, on the other hand, was 4 times higher than that established by the legislation. Conclusion: During the workday, the foot and ankle orthopedic surgeon is exposed to doses of radiation higher than those considered acceptable. The data corroborate the need to wear radiological protective clothing, especially a lead apron and goggles. Level of Evidence IV; Prognostic Study; Case Series.

The present study describes the preparation and characterization of composite films from bacterial cellulose produced by Komagataeibacter xylinus combined with poly(vinyl alcohol) and chitosan. The unique bacterial cellulose structure provides an expanded surface area with high porosity, easing the combination with other soluble polymers by dipping. This blending method effectively reinforces the bacterial cellulose structure. Toughness, puncture strength, water solubility, and swelling degree were measured to assess the effect of poly(vinyl alcohol) and chitosan on the analyzed properties. The morphology and optical and thermal properties were evaluated by scanning electron microscopy, UV-vis spectral analysis, thermogravimetry, and differential scanning calorimetry, respectively. Results showed that the films have good UV-barrier properties and high thermal stability. Toughness values ranged from 0.26 to 7.18 MJ/m3, burst strength ranged from 58.88 to 3234.62 g, and distance to burst ranged from 0.39 to 3.24 mm. Poly(vinyl alcohol) affected the water solubility and increased the swelling degree.

We report a novel label-free quantitative detection of human performance "stress" biomarkers in different body fluids based on optical absorbance of the biomarkers in the ultraviolet (UV) region. Stress biomarker (hormones and neurotransmitters) concentrations in bodily fluids (blood, sweat, urine, saliva) predict the physical and mental state of the individual. The stress biomarkers primarily focused on in this manuscript are cortisol, serotonin, dopamine, norepinephrine, and neuropeptide Y. UV spectroscopy of stress biomarkers performed in the 190-400 nm range has revealed primary and secondary absorption peaks at near-UV wavelengths depending on their molecular structure. UV characterization of individual and multiple biomarkers is reported in various biofluids. A microfluidic/optoelectronic platform for biomarker detection is reported, with a prime focus toward cortisol evaluation. The current limit of detection of cortisol in sweat is ∼200 ng/mL (∼0.5 μM), which is in the normal (healthy) range. Plasma samples containing both serotonin and cortisol resulted in readily detectable absorption peaks at 203 (serotonin) and 247 (cortisol) nm, confirming feasibility of simultaneous detection of multiple biomarkers in biofluid samples. UV spectroscopy performed on various stress biomarkers shows a similar increasing absorption trend with concentration. The detection mechanism is label free, applicable to a variety of biomarker types, and able to detect multiple biomarkers simultaneously in various biofluids. A microfluidic flow cell has been fabricated on a polymer substrate to enable point-of-use/care UV measurement of target biomarkers. The overall sensor combines sample dispensing and fluid transport to the detection location with optical absorption measurements with a UV light emitting diode (LED) and photodiode. The biomarker concentration is indicated as a function of photocurrent generated at the target wavelength.

Neutron fields produced by an accelerator-driven neutron source are generally mixed radiation fields that consist of fast neutrons and gamma rays. To estimate the biological effects of fast neutrons precisely, the gamma ray dose contamination must be evaluated in neutron fields. In this work, we developed a discrimination technique for absorbed doses (60Co gamma-ray equivalent) of fast neutrons and gamma rays using an ionization chamber. The filter thickness dependences of the absorbed doses of fast neutrons and gamma rays are different for a given filter material. Thus, the absorbed doses of each type of radiation were distinguished by fitting the dose attenuation curve, which was measured with an ionization chamber and attenuation filters, with a two-component exponential function. The absorbed dose of fast neutrons and gamma rays with no attenuation filter was evaluated from the y-intercept of the fitting function. This technique was demonstrated in two neutron fields produced by 4 MeV proton and deuteron bombardment of a 9Be target. The thicknesses of the polyethylene attenuation filters were 0–350 mm. The dose attenuation coefficients of fast neutrons obtained by the two-component exponential fitting function for the 9Be(p,n)9 and 9Be(d,n) reactions showed differences of 1.5 and 1.7%, respectively, from the reference measurements using a CR-39 plastic nuclear track detector. The absorbed dose contributions of gamma rays in neutrons fields of the 9Be(p,n)9B and 9Be(d,n) reactions were evaluated as 30.2 ± 3.24% and 20.4 ± 5.16%, respectively, without polyethylene filters.

Visualization of tumor vessels/metastasis and cerebrovascular architecture is vitally important for analyzing pathological states of brain diseases and a tumor’s abnormal blood vessels to improve cancer diagnoses. In vivo fluorescence imaging using second near-infrared emission beyond 1500 nm (NIR-IIb) has emerged as a next generation optical imaging method with significant improvement in imaging sensitivity and spatial resolution. Unfortunately, a highly biocompatible probe capable of generating NIR-IIb emission with sufficient brightness and uniformed size is still scarce. Here, we have proposed the poly(acrylic acid) (PAA)-modified NaLnF4:40Gd/20Yb/2Er nanorods (Ln = Y, Yb, Lu, PAA-Ln-NRs) with enhanced downshifting NIR-IIb emission, high quantum yield (QY), relatively narrow bandwidth (∼160 nm), and high biocompatibility via Ce3+ doping for high performance NIR-IIb bioimaging. The downshifting emission beyond 1500 nm is improved by 1.75–2.2 times with simultaneously suppressing the upconversion (UC) p...

Multifunctional nanomaterials that have integrated diagnostic and therapeutic functions and low toxicity, and can enhance treatment efficacy through combination therapy have drawn tremendous amounts of attention. Herein, a newly developed multifunctional theranostic agent is reported, which is PEGylated W-doped TiO2 (WTO) nanoparticles (NPs) synthesized via a facile organic route, and the results demonstrated strong absorbance of these WTO NPs in the second near-infrared (NIR-II) window due to successful doping with W. These PEGylated WTO NPs can absorb both NIR-II laser and ionizing radiation, rendering them well suited for dual-modal computed tomography/NIR-II photoacoustic imaging and synergistic NIR-II photothermal/radiotherapy of tumors. In addition, the long-term in vivo studies indicated that these PEGylated WTO NPs had no obvious toxicity on mice in vivo, and they can be cleared after a 30-day period. In summary, this multifunctional theranostic agent can absorb both NIR-II laser and ionizing radiation with negligible toxicity and rapid clearance, therefore it has great promise for applications in imaging and therapeutics in biomedicine.

Two types of dose were proposed for use in the treatment planning of boron neutron capture therapy (BNCT) for expressing its high relative biological effectiveness (RBE). On one hand, the RBE-weighted dose is the sum of the absorbed doses weighted by fixed RBE for each dose component of BNCT. On the other hand, photon-isoeffective dose is the photon dose to give the same biological effect calculated considering the dose dependence of RBE and the synergetic effect between different types of radiation. In this study, the depth distributions of the two types of dose in a phantom placed at an accelerator-based BNCT field were calculated using Particle and Heavy Ion Transport code System, PHITS, coupled with an extended stochastic microdosimetric kinetic model. Compared with the corresponding RBE-weighted dose, the calculated photon-isoeffective dose was larger at lower absorbed dose and was smaller at higher absorbed dose, primarily due to the consideration of the dose dependence of RBE. In addition, our calculation revealed that the large variance of the intercellular 10B concentration greatly reduces the photon-isoeffective doses. These results suggest that the considerations of the dose dependence of RBE as well as the intercellular heterogeneity in 10B distribution are indispensable for the precise estimate of the biological effect of BNCT.

Purpose: Design and characterization of a radiation biodosimetry device are complicated by the fact that the requisite data are not available in the intended use population, namely humans e...

For nanoshell-assisted optical detection of cancers, gold shell, silica core (gold-silica) nanoshells are engineered to be the exogenous contrast agent. This work has performed systematic numerical parametric study to investigate the nonlinear dependences of the hemisphere diffuse reflectance on gold-silica nanoshells, laser irradiance, and hosting biology tissue. Planar phantom based tissue models have been constructed as platforms for study. The radiant transport equation (RTE) has been applied to mathematically describe the interactions among laser lights, hosting tissues, and hosted nanoshells. The diffuse reflectance signal under various combinations of parametric conditions has been computed and analyzed. Parametric parameters whose effects on the diffuse reflectance signal have been investigated are: (1) optical properties of a nanoshell generic, (2) nanoshell volume fraction, which is an indicator of nanoshell accumulation in the target tissue site, (3) the width of irradiating laser beam, and (4) thickness of the tissue slab. Seven nanoshell generics have been tested as the exogenous contrast agent including the R[50, 10] (radius of silica core is 50 nm and thickness of gold shell is 10 nm), R[55, 25], R[40, 15], R[40, 40], R[104, 23], R[75, 40] and R[154, 24] nanoshells. It has been found the R[55, 25] nanoshell works best as the exogenous contrast agent, the R[75, 40] and R[104, 23] nanoshells show good potentials as well while the R[50, 10] and R[40, 15] nanoshells should be avoided for diagnostic usage. The practice of neglecting the absorption characteristic of the exogenous contrast agent, which is quite common among the bio-nano community, has been proven to end up with an over-prediction of the effectiveness of the exogenous contrast agent. Such practice therefore is not well justified and should be avoided in future research. Interactions among laser lights, the tissue and nanoshells are highly nonlinear, demonstrated by that nanoshell generics with totally different optical properties might have similar effects on the diffuse reflectance signal and vice versa. Prior to any bench experiment, preliminary numerical investigation as this work has showcased is highly recommended.

Multiphoton microscopy has recently passed the milestone of its first 30 years of activity in biomedical research. The growing interest around this approach has led to a variety of applications from basic research to clinical practice. Moreover, this technique offers the advantage of label-free multiphoton imaging to analyze samples without staining processes and the need for a dedicated system. Here, we review the state of the art of label-free techniques; then, we focus on two-photon autofluorescence as well as second and third harmonic generation, describing physical and technical characteristics. We summarize some successful applications to a plethora of biomedical research fields and samples, underlying the versatility of this technique. A paragraph is dedicated to an overview of sample preparation, which is a crucial step in every microscopy experiment. Afterwards, we provide a detailed review analysis of the main quantitative methods to extract important information and parameters from acquired images using second harmonic generation. Lastly, we discuss advantages, limitations, and future perspectives in label-free multiphoton microscopy.

The activity of radioiodine (131I) used in adjuvant therapy for thyroid cancer ranges between 30 mCi (1.1 GBq) and 150 mCi (5.5 GBq). Dosimetry based on Marinelli's formula, taking into consideration the absorbed dose in the postoperative tumour bed (D) should systematise the determination of 131I activity. Retrospective analysis of 57 patients with differentiated thyroid cancer (DTC) after thyreidectomy and adjuvant 131I therapy with the fixed activity of 3.7 GBq. In order to calculate D from Marinelli's formula, the authors took into account, among other things, repeated dosimetry measurements (after 6, 24, and 72 h) made during scintigraphy and after administration of the therapeutic activity or radioiodine. In 75% of the patients, the values of D were > 300 Gy (i.e. above the value recommended by current guidelines). In just 16% of the patients, the obtained values fell between 250 and 300 Gy, whereas in 9% of the patients, the value of D was

Sono-photodynamic therapy is a promising anticancer technique based on the combination of sonodynamic and photodynamic therapy to improve the cancer treatment effectiveness. This study was aimed at analyzing the effects of the sono-photodynamic (SPD) activity on protoporphyrin IX (PpIX) solution and PpIX-loaded rat liver. In vitro, PpIX 5 μM solutions were irradiated with light (635 nm, 30-50 mW/cm2), ultrasound (1 MHz, 1-2 W/cm2) and both. The PpIX absorption spectra recorded over exposure time revealed that the PpIX decay rate induced by SPD activity (combined irradiation) was approximately the sum of those induced by photodynamic and sonodynamic activity. In vivo, rats were intraperitoneally injected with 5-aminolevulinic acid at the dose of 500 mg/kg weight. After 3 h of injection, the PpIX-loaded livers were irradiated with light (635 nm, 180 ± 9 J/cm2), ultrasound (1.0 MHz, 770 ± 40 J/cm2) and both using a single probe capable of illuminating and sonicating the liver simultaneously. After 30 h, the liver damage induced by each protocol was analyzed histologically. It was found that a greater necrosis depth was induced by the SPD activity. These results suggest that the SPD activity could improve the PpIX decay rate and have greater scope than photodynamic or sonodynamic activity. Further studies should be performed to gain a better understanding of this protocol.

Demands for chemical-free treatments for controlling insect pests are increasing worldwide. One such treatment is microwave heating; however, two critical issues arise when using microwaves as a heat source: intensive labor and excessive energy-consumption. Optimization is thus required to reduce energy consumption while effectively killing insects. Currently, the lethal effect of microwaves on insects is considered to be due to the temperature of the irradiated materials. This study examines how the conditions of irradiation, such as resonance or traveling mode, changed the conversion of electromagnetic energy into heat when 2.45 GHz microwaves penetrated the body of the termite, C. formosanus. Our results indicated that it is possible to heat and kill termites with microwaves under resonance condition. Termites were however found to be very tolerant to microwave irradiation as the permittivity of the insect was low compared with other reported insects and plants. Electron spin resonance revealed that termites contained several paramagnetic substances in their bodies, such as fe 3+ , cu 2+ , Mn 2+ , and organic radicals. Interestingly, irradiation with traveling microwaves hardly produced heat, but increased the organic radicals in termite bodies indicating non-thermal effects of microwaves. The use of electromagnetic waves such as microwaves and radio frequency waves (RF) for pest control through heating is not fundamentally new and was first tested and reported in the 1930s 1. These authors reported a possible mechanism through body water contents and biological factors 2 ; however, results were speculative. RF can penetrate non-metal substances efficiently, and thus, high-water content products like fruits tend to be treated with RF. Microwaves are also effective for producing heat energy in a short time and are thus applied to low-water content products such as rice or cereals 3-6. Many reports support the use of microwaves in controlling pests including termites 7-14. Although microwaves allow efficient and rapid heating deep inside treated materials, the high-energy consumption required for optimal results is a major drawback 15,16. Microwave heating has been traditionally used in the spot control of dry wood termites as they are classified as a single-piece infester of timbers 17. However, this treatment method has had mixed results and some damage to test boards was noted 10. Microwave heating has been characterized as a non-chemical method for insect control. Its mode-of-action is based on the dielectric heating and conversion of absorbed electromagnetic energy to thermal energy throughout the irradiated substrate 17. An advantage of microwave irradiation is the rapid temperature increase in the interior of the irradiated material regardless of its thermal conduction properties. Energy consumption for heat treatments has the potential to be considerably reduced when using microwaves 4. During the last decade, several studies have supported the efficiency of microwave heating of wood 18-25 and wood-invading insects 7,10,11,26. However, some other studies reported reduced or no lethal impact on pests 24,27,28. According to Nakai et al. 27 , direct exposure of the termite body to microwave radiation did not show a lethal effect. The high temperature of the timber obtained through microwave irradiation killed wood pests 24,28. To be lethal, the complete heating of the relevant material is required up to a minimum temperature of 55 °C for a duration of at least 60 min. Owing to the low heat conductivity of wood, the heating of its interior is relatively time intensive. However, in the treatment of agricultural products, pest insects generally die in much shorter time frame 2,29. It may be possible that factors; Demands for chemical-free treatments for controlling insect pests are increasing worldwide. One such treatment is microwave heating; however, two critical issues arise when using microwaves as a heat source: intensive labor and excessive energy-consumption. Optimization is thus required to reduce energy consumption while effectively killing insects. Currently, the lethal effect of microwaves on insects is considered to be due to the temperature of the irradiated materials. This study examines how the conditions of irradiation, such as resonance or traveling mode, changed the conversion of electromagnetic energy into heat when 2.45 GHz microwaves penetrated the body of the termite, C. formosanus. Our results indicated that it is possible to heat and kill termites with microwaves under resonance condition. Termites were however found to be very tolerant to microwave irradiation as the permittivity of the insect was low compared with other reported insects and plants. Electron spin resonance revealed that termites contained several paramagnetic substances in their bodies, such as Fe3+, Cu2+, Mn2+, and organic radicals. Interestingly, irradiation with traveling microwaves hardly produced heat, but increased the organic radicals in termite bodies indicating non-thermal effects of microwaves.

Animal models of total-body irradiation (TBI) are used to elucidate normal tissue damage and evaluate the efficacy of medical countermeasures (MCM). The accuracy of these TBI models depends on the reproducibility of the radiation dose-response relationship for lethality, which in turn is highly dependent on robust radiation physics and dosimetry. However, the precise levels of radiation each organ absorbs can change dramatically when different photon beam qualities are used, due to the interplay between their penetration and the natural variation of animal sizes and geometries. In this study, we evaluate the effect of varying the radiation energy, namely cobalt-60 (Co-60); of similar penetration to a 4-MV polyenergetic beam), 6 MV and 15 MV, in the absorbed dose delivered by TBI to individual organs of eight Göttingen minipigs of varying weights (10.3-24.1 kg) and dimensions (17.5-25 cm width). The main organs, i.e. heart, lungs, esophagus, stomach, bowels, liver, kidneys and bladder, were contoured by an experienced radiation oncologist, and the volumetric radiation dose distribution was calculated using a commercial treatment planning system commissioned and validated for Co-60, 6-MV and 15-MV teletherapy units. The dose is normalized to the intended prescription at midline in the abdomen. For each animal and each energy, the body and organ dose volume histograms (DVHs) were computed. The results show that more penetrating photon energies produce dose distributions that are systematically and consistently more homogeneous and more uniform, both within individual organs and between different organs, across all animals. Thoracic organs (lungs, heart) received higher dose than prescribed while pelvic organs (bowel, bladder) received less dose than prescribed, due to smaller and wider separations, respectively. While these trends were slightly more pronounced in the smallest animals (10.3 kg, 19 cm abdominal width) and largest animals (20 kg, ∼25 cm abdominal width), they were observed in all animals, including those in the 9-15 kg range typically used in MCM models. Some organs received an average absorbed dose representing80% of prescribed dose when Co-60 was used, whereas all organs received average doses of87% and93% when 6 and 15 MV were used, respectively. Similarly, average dose to the thoracic organs reached as high as 125% of the intended dose with Co-60, compared to 115% for 15 MV. These results indicate that Co-60 consistently produces less uniform dose distributions in the Göttingen minipig compared to 6 and 15 MV. Moreover, heterogeneity of dose distributions for Co-60 is accentuated by anatomical and geometrical variations across various animals, leading to different absorbed dose delivered to organs for different animals. This difference in absorbed radiation organ doses, likely caused by the lower penetration of Co-60 and 6 MV compared to 15 MV, could potentially lead to different biological outcomes. While the link between the dose distribution and variation of biological outcome in the Göttingen minipig has never been explicitly studied, more pronounced dose heterogeneity within and between organs treated with Co-60 teletherapy units represents an additional confounding factor which can be easily mitigated by using a more penetrating energy.