Photodynamic Therapy (PDT) using Aminolevulinic acid (ALA) could be an effective and minimally invasively applicable way to treat many different types of tumors without radiation and large incisions by just applying a light pulse. However the PDT process is difficult to observe, control and optimize and the dynamical relationships between the variables involved in the process is complex and still hardly understood. One of the main variables affecting the outcome of the process is the determination of the interval of time between ALA inoculation and starting of light delivery. This interval, better known as drug-light interval, should ensure that enough Protoporphyrin IX (PPIX) is located in the vicinity of functional structures inside the cells for the greatest damage during the PDT procedure. One route to better estimate this time interval would be by predicting PPIX from the dynamical changes of its precursors. For that purpose, in this work a novel optical setup (OS) is proposed for differentiating fluorescence emitted by Coproporphyrin III (CPIII) and PPIX itself in samples composed of mixed solutions. The OS is tested using samples with different concentrations in mixed solutions of PPIX and the precursor CPIII as well as with a Polymethyl methacrylate test sample as additional reference. Results show that emitted fluorescence of the whole process can be measured independently for PPIX and its precursor, which can enable future developments on PPIX prediction from the dynamical changes of its precursor for subject-dependent drug-light interval assessment.
Background: Radiation therapy using beta particles is an interesting treatment for very superficial skin lesions. Due to their low penetration in tissue and rapid dose falloff, beta particles can protect underlying bony structures and surrounding healthy tissue while irradiating the skin tumor. In the current work, a simple method for the fabrication of a radioactive patch for use in skin cancer therapy based on a beta-emitting isotope is presented. Materials and methods: The beta radiation sources were Y-90 microspheres currently used for catheter-based radioembolization of unresectable liver tumors. The microspheres were filtered through a syringe filter to trap them on the cellulose nitrate paper of the filter and create a radioactive patch. In the current study, to avoid the need for a hot laboratory, the experiment was done using nonradioactive microspheres. An optical microscope was used to verify the distribution of the particles on the filter paper. Results: Visual evaluation of the patches showed that using the proposed method, therapeutic skin patches with a fairly uniform distribution of microspheres can be created. Conclusion: The proposed simple method may be used in creating radiotherapeutic patches using Y-90 microspheres for radiation therapy of thin skin lesions located close to sensitive structures.
IntroductionContrast media injections, infusions, or experiments that require a constant volume flow close to or within a very high magnetic field like in magnetic resonance imaging (MRI) require a liquid reservoir and a power unit to deliver the fluid. However, most power units are driven by motors that are either not MRI-compatible or require external connections that restrict mobility and usage. In this paper, the development of a highly portable, lightweight, and MRI-compatible pump system is explained.MethodsThe energy required to deliver the flow is generated using a pressurized bottle concept. The valve inside the bottle is opened to create a flow which should be maintained constant. In order to find the optimal flow resistance for a constant flow rate, we created multiple setups with different flow resistance.ResultsWe measured the flow rates for different flow resistances by attaching a restring valve to the bottle. The results clearly show that high flow resistance results in lower and more constant flow rate.DiscussionThe optimal flow rate achieved using our current setup was significantly constant but not ideal. Consequently, such a pump system can be used in many medical applications like MRI-compatible contrast agent injectors.
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