Development of Temperature Distribution and Light Propagation Model in Biological Tissue Irradiated by 980 nm Laser Diode and Using COMSOL Simulation

Introduction: The purpose of this project is to develop a mathematical model to investigate light distribution and study effective parameters such as laser power and irradiated time to get the optimal laser dosage to control hyperthermia. This study is expected to have a positive impact and a better simulation on laser treatment planning of biological tissues. Moreover, it may enable us to replace animal tests with the results of a COMSOL predictive model.Methods: We used in this work COMSOL5 model to simulate the light diffusion and bio-heat equation of the mouse tissue when irradiated by 980 nm laser diode and the effect of different parameters (laser power, and irradiated time) on the surrounding tissue of the tumor treatment in order to prevent damage from excess heatResults: The model was applied to study light propagation and several parameters (laser power, irradiated time) and their impact on light-heat distribution within the tumor in the mouse back tissueThe best result is at laser power 0.5 W and time irradiation 0.5 seconds in order to get the maximum temperature hyperthermia at 52°C.Conclusion: The goal of this study is to simulate a mouse model to control excess heating of tissue and reduce the number of animals in experimental research to get the best laser parameters that was safe for use in living animals and in human subjects

Algorithm for Analyzing Thermal Images of Laser Irradiated Human Skin

Introduction: Tracking temporal changes of temperature during laser skin treatment plays an important role in improving the process of laser skin treatment itself. There are a number of methods to analyze temperature’s temporal dependency during laser skin treatment; some of those methods depend on imaging the skin with thermal cameras. However, the use of thermal cameras exhibits specific problems, including the ability to track laser-skin interaction spot. This paper is dedicated to solve that problem using digital image processing program coded with Matlab.Methods: The measurements were taken for 15 native Syrian subjects of different sex, age and skin tones, the treated ailment was port wine stain. The clinical work (laser exposure) was performed in Damascus University, hospital of dermatology. The treatment was observed by thermal camera and analyzed using the proposed Matlab coded tracking system.Results: For all the subjects, the treatment laser spot was tracked and the curves of skin temperature change with time where calculated by the use of the proposed algorithm, then the active time was calculated for each subject. The algorithm proved practical and robust.Conclusion: The proposed algorithm proved to be efficient and can be used to support future researchers with capability to measure the temperature with high frame rat

A Sensitive Fibre Optic Probe for Autofluorescence Spectroscopy of Oral Tongue Cancer: Monte Carlo Simulation Study

The objective of this paper is to determine the best optical probe configuration that would help to detect neoplastic lesions in oral tongue epithelial tissue. Three geometrical configurations are investigated. The first one is a single-fibre probe with different fibre diameters. The second one is a multitilted fibre probe that employs different tilting angles for emission and collection fibres. While the third one is a multidiameter probe that employs different fibre diameters and distances between the emission and the collection fibres. All probes were evaluated for their depth-limited sensitivity in the epithelium layer of the tongue. Probes that showed efficient sensitivities were then compared for their fluorescence intensities acquired from both tissue types. The sensitivity for the first two types of probes was found to be roughly comparable. However, the differentiation capability of the multitilted fibre probe between dysplastic and healthy tissue was found to be noticeably larger by 30% of that of the single-fibre probe. The third type showed more sensitivity to fluorescence emerging from deeper layers. Finally, the proposed configuration is presented and proved to achieve higher sensitivity for both superficial and deep layers

Optimized Cylindrical Diffuser Powers for Interstitial PDT Breast Cancer Treatment Planning: A Simulation Study

Purpose. It is well known that interstitial photodynamic therapy (iPDT) of large tumors requires effective planning to ensure efficient delivery of therapeutic dose to the target tumors. This should be achieved in parallel with minimal damage to the nearby intact tissues. To that end, clinical iPDT can be attained using cylindrical diffusing optical fibers (CDFs) as light sources. In this work, we optimize output CDF powers in order to deliver a prescribed light dose to a spherical volume such as a tumor node. Methods. Four CDFs are placed vertically inside the tumor node. The fluence rate is calculated using the diffusion equation. Therapeutic target dose is (20-50) J·cm-2. The optical properties (μa=0.085 cm−1, μs′=16 cm−1) of a breast tumor and the treatment time of 150 sec are used to calculate the fluence rate. Results. For four CDFs, the therapeutic target dose (20-50) J·cm-2 is delivered to more than 90%. This is the ratio of the total points that receive the target dose in proportion to the total points in the volume of the node of 3 cm in diameter, whereas, in larger nodes, the ratio is decreased to approximately 67%. Five CDFs are required to improve this ratio by more than 10%. Conclusion. Optimizing delivered powers enables the distribution of the therapeutic dose uniformly in the medium. In addition, this simulation study represents an essential part of a development dosimetry system for measuring and controlling the optical dose in the breast tumors

Effect of Absorption and Scattering on Fluorescence of Buried Tumours

Fluorescence spectroscopy is widely used for biomedical optical diagnosis and surgical resection of tumours. This work investigates laser-induced fluorescence spectroscopy of fluorescence inclusions that are embedded in turbid media. 405 nm laser diode is used for exciting buried protoporphyrin- (PpIX) based inclusions in brain-like optical phantoms. Effects of scattering and absorption of the turbid medium on the recorded fluorescence signal and depth-resolved fluorescence were studied. Results show that optical properties of the surrounding turbid medium influence the intensity of the fluorescence signal. Absorption coefficient of the surrounding medium is the major contributor to the fluorescent signal. Analysis of the recorded fluorescence spectra shows that the effect of absorption coefficient is larger than the effect of scattering coefficient on the fluorescence intensity by nearly fivefold. The findings indicate that the fluorescence signal could be used as a biomarker of optical property variations through different stages of malignancy. This can enhance the detectability of malignant tissue for diagnostic and surgical purposes as well

Theoretical investigation of BODIPY based compounds as photosensitizers in photodynamic therapy

1040-1046In this work we carried out theoretical evaluation of the potential use of BODIPY and related compounds as photosensitizer in photodynamic therapy (PDT). Five compounds bearing the chromophore of 4,4-difluoro-4-bora-3a,4a-diazas- indacene (BODIPY) with substituent elements from the fourth column in the periodic table (Si-Ge-Sn-Pb) have been investigated. In the present study the density functional theory and its time dependent extension TD-DFT have been used to calculate the energy of ground, singlet-triplet excited states and energy for E s1 , E T2 o S o S The electronic absorption spectra, transition dipole moments (TDM) for spin-allowed S0→Sn and other properties have been calculated. The results of this work show that among the studied compounds, PM-Sn is potentially the best option for photosensitizer in PDT

Optical properties in the visible range of two different India ink used as biological phantoms

The optical characteristics of two different brands of India ink, Parker Quink and Pelikan, as an absorber used in preparation a tissue-simulating phantom, have been investigated at visible wavelength range. For this purpose, a single integrating sphere system and a spectrophotometric transmission spectroscopy have been used to estimate the radiometric characteristics. Then, inverse adding-doubling algorithm was implemented to retrieve the optical coefficients of pure ink samples. Parker ink's absorption behavior turned out to incompatible with Pelikan over the present wavelength range. Furthermore, scattering property of both two brands has been exhibited and the albedo was calculated. Parker albedo showed a decremental behavior with wavelength and varied between 0.381 and 0.13. A structural profile of albedo was found for Pelikan, which varied between 0.366 and 0.03. This discrepancy might be explained by the variety of two brands composition besides experimental errors. Furthermore, Parker ink absorption variation turned out to be in correspondence to several tissues' absorption feature over broad wavelength ranges. Finally, Parker ink could be regarded as a better candidate to mimic absorption property for several tissues

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research