This PDF file contains the front matter associated with SPIE Proceedings Volume 12823, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Significance: Oral squamous cell carcinoma (OSCC) has an exceptionally high rate of incidence and mortality in India, with 15 cases per 100,000 people and over 70,000 deaths annually. The problem is exacerbated due to insufficient medical infrastructure for widescale screening and oncology care, particularly in rural regions. New technologies are urgently needed to detect oral cancer and provide timely treatment at the point of care. This work draws upon previous development and clinical validation of low-cost hardware for photodynamic therapy (PDT) treatment of oral lesions combined with an intraoral probe for cancer screening, incorporated here into an integrated theranostic device for image-guided PDT. Aim: This study aimed to validate technical performance of a novel hand-held smartphone-coupled intraoral device designed for simultaneous imaging and photodynamic therapy (PDT) of oral lesions. The imaging and PDT light delivery capabilities of the handheld system were evaluated using tissue phantoms containing protoporphyrin IX (PpIX) and a mouse model of OSCC photosensitized using 5-aminolevulinic acid (ALA)-induced PpIX. Approach: The probe’s built-in multi-channel fluorescence and polarized white light imaging capabilities were evaluated using tissue phantoms with TiO₂ and controlled PpIX concentrations. In-vivo testing was performed using mice with subcutaneous TR146 OSCC implants before and after administering ALA, and again to assess photobleaching after light delivery (a total of 100J/cm² at 635nm from the integrated diode laser). Results: Quantification of fluorescence images generated using the device showed that the PpIX signal scaled linearly with concentration, and the extent of photobleaching increased with increasing PDT dose as expected. In murine xenografts, PDT treatment delivered through the intraoral probe reduced tumor volume significantly in comparison to untreated control animals. Conclusion: Our findings demonstrate the effectiveness of a low-cost handheld device for simultaneous quantitative imaging of PpIX fluorescence and image-guided PDT in vivo. The integration of intraoral imaging and image-guided treatment into the same handheld device paves the way for a streamlined approach to cancer screening and early intervention with PDT at the point of care.

Photodynamic therapy (PDT) is a promising cancer treatment modality that involves the administration of a photosensitizing agent followed by light activation at a specific wavelength. Upon activation, the photosensitizer generates reactive oxygen species, including singlet-state oxygen ([¹O₂]), which causes cellular damage leading to cancer cell death. Direct detection of singlet-state oxygen constitutes the holy grail dosimetric method for type II PDT, a goal that can be quantified using multispectral singlet oxygen dosimetry (MSOLD). The optical properties of tissues, specifically their scattering and absorption coefficients, play a crucial role in determining how light interacts within a medium. Variations in these optical properties can significantly impact various aspects, including the distribution of treatment laser, the generation of singlet oxygen, and the detection of singlet oxygen signals using the MSOLD device. In this study, we have investigated the influence of optical properties variation on the spatial distribution of treatment laser energy in tissue simulated phantom and the distribution of generated singlet oxygen signals using Monte Carlo simulations (MC). Additionally, we conducted a comparative analysis by examining singlet oxygen signals generated by Photofrin in MeOH, as detected by an InGaAs spectrometer in vitro, and compared these results to our Monte Carlo simulations. The experimental findings validate the accuracy of our Monte Carlo simulations, further affirming the robustness of our research. Our research advanced the comprehension of singlet oxygen generation and enhanced the accuracy of singlet oxygen detection using the MSOLD device, especially when optical properties undergo changes.

Photodynamic therapy (PDT) is employed following surgical resection to address microscopic residual malignant pleural mesothelioma. The generation of singlet oxygen during PDT induces the death of cancer cells. Precise dosimetry plays a pivotal role in ensuring treatment efficacy. This study sought to model the distribution of reacted singlet oxygen ([¹O₂]_rx) on the surface of the pleural cavity using patient-specific data acquired in a clinical setting for Photofrin-mediated PDT. Cavity geometry was obtained using an infrared camera-based navigation system during surgery, and Photofrin concentration was measured using a multi-fiber contact probe. Light fluence was calculated based on the cavity geometry and the position of the treatment wand. The COMSOL Multiphysics software simulated the distribution of [¹O₂]_rx using the measured geometry, Photofrin concentration, and light fluence data. Models comparing homogeneous and heterogeneous Photofrin uptake were examined, revealing that [¹O₂]_rx increased proportionally to the Photofrin concentration in both scenarios. The aim of this research is to account for heterogeneity and optimize treatment outcomes by incorporating real patient data into the model. Monitoring under- and over-exposed regions could potentially enhance treatment efficacy. The findings demonstrate the feasibility of employing explicit dosimetry for pleural PDT. Future investigations will concentrate on real-time modeling through the integration of patient data obtained during treatment. Explicit dosimetry holds the potential to provide accurate dosing, thereby maximizing treatment effectiveness and improving patient outcomes. This patient-specific modeling approach could be extended to PDT in other anatomical locations where a reconstructed treated cavity is available.

Direct detection of singlet-state oxygen ([¹O₂]) is a crucial objective in type II photodynamic therapy (PDT), achievable through the implementation of multispectral singlet oxygen dosimetry (MSOLD). To accurately assess the amount of reactive singlet oxygen, the Singlet Oxygen Explicit Dosimetry (SOED) model was developed, incorporating parameters such as light fluence rate, photosensitizer concentration, and ground-state oxygen concentration. This study focuses on comparing the results obtained from MSOLD and SOED by measuring the singlet oxygen signal via a commercial InGaAs spectrometer and subsequently calculating reactive singlet oxygen based on the SOED theory. A continuous-wave laser emitting at 630nm is employed to excite Protoporphyrin IX (PPIX) in methanol, varying the concentration from 10mg/kg to 100mg/kg. Utilizing the Singular Value Decomposition (SVD) algorithm, the measured singlet oxygen spectrum is fitted to extract the singlet oxygen signal. To simulate clinical PDT scenarios, real-time singlet oxygen spectra are collected over 1200 seconds, employing a 1.5mm diameter optic fiber for signal collection. Ground-state oxygen concentration is measured using a commercial oxygen probe while the laser is inactive, and photosensitizer concentration is assessed via a custom-made contact probe. Additionally, the fluence rate of the laser is measured using an isotropic detector. The Reactive Singlet Oxygen is then calculated using the SOED model, incorporating the photosensitizer concentration, oxygen concentration, and photon fluence rate. Detailed comparisons between MSOLD and SOED results are presented, offering valuable insights into the accuracy and reliability of both methods in quantifying singlet-state oxygen during PDT.

This study presents our implementation of a multi-channel device for continuous singlet oxygen luminescent dosimetry (CSOLD) signal acquisition using multiple InGaAs detectors connected to individual narrow band filters (1200 nm, 1240 nm, 1250 nm, 1270 nm, and 1300 nm) during PDT. An algorithm is developed to extrapolate various components from the raw multi-channel data.

Intraoperative photodynamic therapy (PDT) has proven effective in treating malignant pleural mesothelioma. Achieving uniform light dose delivery is vital for its efficiency. Currently, eight light detectors are placed inside the pleural cavity to monitor light distribution. To enhance this process, an updated navigation system, combined with a novel scanning system, has been developed to provide real-time guidance to physicians during pleural PDT, thereby improving light delivery. The scanning system incorporates two handheld three-dimensional (3D) scanners, enabling rapid and precise capture of the pleural cavity's surface topography before PDT. This allows for identification of the target surface for real-time calculation of light fluence distribution during treatment. An algorithm has been devised to further process the scanned volume, facilitating continuous tracking of the light source position within the pleural cavity throughout the treatment process. During PDT, real-time 3D and 2D visualizations of the light source position, scanned pleural cavity, and light fluence distribution across the entire cavity's surface are displayed, providing physicians with invaluable guidance to enhance overall treatment efficiency. To validate the system, phantom studies were conducted using three newly 3D-printed lung phantoms of varying volumes based on individual CT scans. A set of liquid tissue-simulating phantoms with different combinations of optical properties (μ_a, μ_s') was utilized for improved clinical simulation. These lung phantoms, designed to mimic surgical conditions, feature side openings similar to the actual surgery and are treated with eight isotropic detectors fixed on the inner surface at positions predetermined by the physician.

Sonophotodynamic therapy (SPDT) is a non-invasive anticancer therapeutic technique that relies on the interaction of two external energy sources, low-intensity ultrasound, and visible light, with a sonophotoactive molecule and the molecular oxygen present in the medium. This interaction induces both mechanical effects (e.g., generation of microjets, and shock waves) and chemical effects (e.g., generation of reactive oxygen species (ROS)), leading to antitumor responses in deeper body regions. Protoporphyrin IX (PpIX), Methylene Blue (MB), and Chlorin e6 (Ce6) are well-known organic molecules that can be activated with light and ultrasound, making them promising candidates as sonophotosensitizers for SPDT. However, there are few studies about the ROS promoted by such sensitizers during a sonophotodynamic activity. So, this study aims to assess the singlet oxygen and hydroxyl radical production for photodynamic, sonodynamic, and sonophotodynamic activity employing PpIX, MB, and Ce6 as sensitizers. For this purpose, DPBF and APF, chemical probes highly sensitive to ¹O₂ and •OH, respectively, were used. The probe+sensitizer solutions were exposed to light (630nm, 12mW/cm2), ultrasound (1Mhz, 1.5W/cm2, 50%) and a combination of both sources. The generation of ¹O₂ and •OH was detected by monitoring the absorption spectrum of the DPBF+sensitizer solution and the fluorescence spectrum of the APF+sensitizer solution, respectively, during the irradiation time. The quantification of ¹O₂ and •OH generation was carried out by calculating the DPBF decay constant and the fluorescence rate constant of fluorescein (fluorescent product generated by the interaction of APF with •OH), respectively. Contrary to studies with light, it was observed that DPBF was degraded, and fluorescein generation increased with ultrasound irradiation, even in the absence of the sensitizer. This has been attributed to a sonochemical reaction whereby •OH molecules can be generated. Therefore, this effect was subtracted from the ¹O₂ quantification calculations. The DPBF decay constant promoted by a sonophotodynamic activity using PpIX was slightly higher than photodynamic activity. The fluorescein fluorescence constant induced by the three molecules was significantly higher under the sonophotodynamic activity. These results suggest that PpIX is an efficient sonophotosensitizer for ¹O₂ generation, while the three studied molecules were efficient for •OH generation under the sonophotodynamic activity. Also, the •OH generation could be the predominant action mechanism during a sonophotodynamic activity. However, further research is needed to thoroughly understand these results.

The application of Photodynamic (PDT) for malignant pleural mesothelioma (MSM) is complex due to post-surgery alteration. To address this issue of calculating dose for complex anatomical geometries, our study utilized advanced digital technologies to construct and analyze 3D models of the human lung pleural cavity. This study aims to support a translational model that will eventually enhance PDT dose delivery while minimizing effects on surrounding healthy tissues. The pleural cavity geometries were digitally extracted from medical CT scans, transformed into stereolithography (STL) files, and 3D-printed using acrylic resins. Three volumes corresponding to small, medium, and large patient sizes were prepared. Each model was asymmetrically coated with non-reflective adhesive paper to mimic realistic conditions. Data capture utilized a single handheld scanning device operating at distances to accommodate generalized and refined detail capture. This approach enabled the precise capture of internalized cavity shapes and critical asymmetries. Medical CT validated all 3D printed models. The results confirmed the precise generation and capture of multiple asymmetric 3D human cavity models in actual size. The proposed workflow shows potential for clinicians to accurately map post-surgical pleural cavity changes, thereby improving PDT light dose delivery. This could enhance treatment efficacy and patient outcomes, underlining the potential of digital technology in advancing precision oncology and integration into future clinical practice.

Numerous studies are underway to identify an effective dynamic therapy against cutaneous melanoma. Dynamic therapy is based on the interaction of an external energy source and a molecule sensitive to this energy, which triggers a series of reactions resulting in tumor cell death. The adequate distribution and concentration of the sensitizer in tumor cells can lead to obtaining the expected anticancer effects. Protoporphyrin IX (PpIX) is a well-known endogenous sensitizer. Its accumulation in target cells can reach photosensitizing concentrations by the exogenous application of its precursor, 5-aminolevulinic acid (ALA). This study aimed to find an effective protocol for ALA delivery that induces a higher sensitizing PpIX deposition in murine cutaneous melanoma tumors. For this purpose, melanoma-bearing mice were subjected to five different protocols of ALA delivery: topical administration MAL cream (20% w/w methyl aminolevulinate hydrochloride, incubation time: 12h), intratumoral ALA injection (dose: 200mg/Kg b.w., incubation time: 2 h), and intraperitoneal ALA injection (dose: 200mg/Kg b.w., incubation time: 3, 4, 5h). The amount of PpIX extracted from the melanoma tumors (B16F10) was compared with that extracted from a non-melanoma tumor model (A431) where the PpIX accumulation was induced by a clinical protocol of ALA delivery commonly applied for photodynamic therapy. The detection and quantification of PpIX were carried out by applying Steady-state fluorescence spectroscopy (SSFS) by in vivo and in vitro measurements, with the latter involving a chemical extraction method. In vitro measurements showed that the PpIX concentration extracted from the melanoma tumor was greater by intraperitoneal (3h) (0.31±0.05μM) and intratumoral (0.39±0.17μM) protocols. Through the topical protocol, it was possible to avoid the healthy region sensitization, and the concentration of PpIX extracted from the melanoma tumor (0.15±0.04μM) was almost the same amount as that generated by the clinical protocol (0.18±0.05μM). The results suggested that a photosensitive amount of PpIX can be synthesized within the melanoma tumor by the intratumoral, intraperitoneal (3h) protocols.

In this study, we present the evaluation in fibroblast cells of photosensitizers semi-synthesized derived from chlorophyll a (as described in literature). The process began with the extraction of methyl-pheophorbide a (1), which was then reacted with primary aliphatic amines (butylamine, hexylamine, and octylamine) to yield molecules 2 to 4. Additionally, purpurin-18 methyl ester (5) was obtained through the oxidation of methyl pheophorbide a (1). By adding different aliphatic amines (butylamine, hexylamine, and octylamine) into the anhydride ring of 5, products 6 to 8 were obtained. Compounds 2-4 and 6-8 exhibited absorption bands around 660nm. The effectiveness of photosensitizers relies on their ability to selectively target damaged cells without harming healthy cells. Therefore, an evaluation of photosensitizers (2- 4, 6-8, and chlorin-e6) against HFF-1 fibroblast cells was performed. Testing two different concentrations (1 and 10μM), it was observed that, under dark conditions, the photosensitizers were primarily non-toxic as they did not significantly reduce cell viability and were close to the control group's viability. Furthermore, the impact of photodynamic therapy (PDT) on cell viability was analyzed by using a light fluence of 30J/cm². The lower polarity of the compounds (more lipophilic) improved the efficiency of the photosensitizers. In conclusion, this study highlights the successful development of cost-effective photosensitizers with potential applications in PDT. The evaluation against HFF-1 fibroblast cells showed promising results, indicating these photosensitizers could be further investigated for the selective treatment of damaged cells without causing harm to healthy cells.