Reproducibility and air gap pockets of 3D-printed brachytherapy applicator placement in high-dose-rate skin cancer.

BACKGROUND AND PURPOSE: This study aimed to investigate the reproducibility of a novel approach using 3D printed brachytherapy applicators for the treatment of skin cancer. Specifically, we aimed to assess the accuracy of applicator placement and to minimize the existence of air gap pockets between the applicator and the patient's skin. MATERIALS AND METHODS: A total of 20 patients plans diagnosed with skin cancer were enrolled in this study. All patients underwent high dose rate (HDR) brachytherapy. To ensure precise applicator placement, patient-specific 3D printed applicators were designed based on individual body and tumor topography, utilizing data obtained from computer tomography (CT) scans. All applicators were fabricated using fused deposition modeling technology. RESULTS: The error in applicator placement was measured and found to be less than 1.0 mm on average, with a standard deviation of 0.9 mm. Additionally, the average error in air gap pockets between the applicator and the patient's skin was 0.4 mm (standard deviation was 0.5 mm). The study demonstrated that the personalized approach of 3D printed brachytherapy applicator placement in skin cancer treatment yielded highly accurate results. The average error of less than 1.0 mm in applicator positioning and the minimal air gap pockets demonstrated the reproducibility and precision of this technique. CONCLUSION: Our study establishes the reproducibility and accuracy of 3D-printed brachytherapy applicator placement in the treatment of skin cancer. This personalized treatment approach offers a highly precise method for delivering radiation therapy, minimizing the risk to adjacent healthy tissues, and enhancing overall patient outcomes.

Brachytherapy and 3D printing for skin cancer: A review paper.

Brachytherapy is a type of radiation therapy, in which a radiation source is placed directly or close to a tumor. It is commonly used to treat skin cancer, and enables precise irradiation treatment of affected area (planning target volume - PTV) while minimizing exposure dose to surrounding healthy tissue (organs at risk - OARs). Recently, the use of 3D printing has begun revolutionizing brachytherapy, as it allows manufacturing of custom-designed applicators for unique shape of skin topography, tumor, and surrounding tissues. Outcome of the combination of 3D printing and brachytherapy has several advantages over traditional treatment planning methods. Some of the advantages are intuitive, whereas others can be concluded from a literature overview as follows: 1) Possibility of developing patient-specific applicators that precisely match the shape of tumor area; 2) Reduction of the time required for applicator production, especially when custom-made devices are needed; 3) Reduction of manufacturing costs; 4) Treatment procedures improvement; 5) Improvement of safety measures accelerated by the development of smart materials (e.g., polymer filaments with admixture of heavy elements); 6) Possibility of nearly instant adjustment into tumor treatment (applicators can be changed as the tumor is changing its shape); and 7) Applicators designed to securely fit to treatment area to hold radioactive source always in the same place for each fraction. Consequently, tumor-provided dose is accurate and leads to effective treatment. In this review paper, we investigated the current state-of-the-art of the application of 3D printing in brachytherapy. A number of existing reports were chosen and reviewed in terms of printing technology, materials used, treatment effectiveness, and fabrication protocols. Furthermore, the development of future directions that should be considered by collaborative teams bridging different fields of science, such as medicine, physics, chemistry, and material science were summarized. With the indicated topics, we hope to stimulate the innovative progress of 3D printing technology in brachytherapy.

Hall effect in electrolyte flow measurements: introduction to blood flow measurements.

The Hall effect has been applied to electrolyte flow measurement. It has been proven that Hall voltage does not depend on electrolyte concentration; however, there is a linear relationship between Hall voltage and flow velocity. Obtained results for electrolyte allow us to suppose that Hall effect can be used to determine blood flow. Research on blood will be conducted as the next step.

Analysis of the Influence of Process Parameters on the Properties of Homogeneous and Heterogeneous Membranes for Gas Separation.

Heterogeneous membranes, otherwise known as Mixed Matrix Membranes (MMMs), which are used in gas separation processes, are the subject of growing interest. This is due to their potential to improve the process properties of membranes compared to those of homogeneous membranes, i.e., those made of polymer only. Using such membranes in a process involves subjecting them to varying temperatures and pressures. This paper investigates the effects of temperature and feed pressure on the process properties of homogeneous and heterogeneous membranes. Membranes made of Pebax®2533 copolymer and containing additional fillers such as SiO2, ZIF-8, and POSS-Ph were investigated. Tests were performed over a temperature range of 25-55 °C and a pressure range of 2-8 bar for N2, CH4, and CO2 gases. It was found that temperature positively influences the increase in permeability, while pressure influences permeability depending on the gas used, which is related to the effect of pressure on the solubility of the gas in the membrane.

Material and Process Tests of Heterogeneous Membranes Containing ZIF-8, SiO2 and POSS-Ph.

Heterogeneous membranes made of a polymer matrix and containing nano-metric fillers in their structure may present improved physicochemical and process properties compared to homogeneous membranes made only of polymer materials. Membranes made of a PEBAX®2533 block copolymer were tested with fillers such as ZIF-8, SiO2 and POSS-Ph being dosed to them. The material analysis and process tests indicate that these nanomaterials can be used as fillers for heterogeneous membranes. Chemometric analyses determined the influence of individual fillers on selected physicochemical properties of the materials which were used to produce the membranes. For specific concentrations of these fillers, improvement in the permeability and selectivity of the membranes, or at least in one of these parameters, was achieved. The greatest increase in permeability against the homogeneous membrane was obtained for membranes containing 10 wt% ZIF-8 (for CO2, an increase of 2.07 times; for CH4, 2.36 times; for N2, 3.08 times). In turn, the greatest increase in selectivity was obtained for the CO2/CH4 mixture for the membrane containing 5 wt% SiO2 (1.15 times), and for the CO2/N2 mixture for the membrane containing 2 wt% POSS-Ph (1.21 times).

Novel PVDF-PEG-CaCO3 Membranes to Achieve the Objectives of the Water Circular Economy by Removing Pharmaceuticals from the Aquatic Environment.

In the aquatic environment, substances of pharmacological origin are common contaminants. The difficulty of removing them from water is a problem for the implementation of a circular economy policy. When recycling water, an effort should be made to remove, or at least, minimize the presence of these substances in the water. Porous membranes with a new functionality consisting in their adsorption capacity towards pharmaceutical substances have been developed. A Polyvinylidene Fluoride (PVDF) membrane with Calcium Carbonate (CaCO3) nanoparticles as an adsorbent was prepared. By implementing an integrated filtration-adsorption process using sulphadiazine, as a representative of pharmacological substances, 57 mg/m2 of adsorption capacity has been obtained, which is an improvement in adsorption properties of more than 50 times that of a commercial membrane. At the same time the membrane permeability is 0.29 m3/(h·m2·bar), which means that the membrane's permeability was improved by 75%.

Modification of Ceramic Membranes with Carbon Compounds for Pharmaceutical Substances Removal from Water in a Filtration-Adsorption System.

The aim of this work is to develop a new type of carbon-ceramic membranes for the removal of pharmaceutical substances from water. The membranes were prepared by the chemical modification method using an organosilicon precursor-octadecyltrichlorosilane (ODTS). Graphene oxide, multi-walled carbon nanotubes with carboxylic groups, and single-walled carbon nanotubes were used in the modification process. The filtration properties and adsorption properties of the developed membranes were tested. In order to characterize the membrane, the water permeability, the change of the permeate flux in time, and the adsorbed mass of the substance were determined. Additionally, the surface properties of the membranes were characterized by contact angle measurements and porosimetry. The antibiotic tetracycline was used in the adsorption tests. Based on the results, the improved adsorption properties of the modified membrane in relation to the unmodified membrane were noticed. Novel ceramic membranes modified with MWCNT are characterized by 45.4% removal of tetracycline and permeate flux of 520 L·h·m-2·bar-1. We demonstrated the ability of modified membranes to adsorb pharmaceuticals from water streams that are in contact with the membrane. Novel membranes retain their filtration properties. Therefore, such membranes can be used in an integrated filtration-adsorption process.

Capillary Sensor for Detection of Amphetamine Precursors in Sewage Water.

This paper deals with the problem of detecting benzyl methyl ketone (BMK), which is a precursor of amphetamine that can be synthesized in home labs. The focus of our work was to identify an improvement for the analysis of sewage introduced into the municipal sewage system. The sensors used to detect BKM in these systems are often clogged and therefore cannot function properly. In this article, a new method of detecting BMK and other chemicals in wastewater is presented. A system containing capillary polypropylene, hydrophobized with polysiloxane coating fibers was prepared. These solutions were used for continuous online measurements by ion mobility spectrometry. The use of pipes with a polysiloxane coating reduces the permeation of water and significantly increases the BMK permeation due to its high solubility in the polymer.

Determination of urethral catheter surface lubricity.

Device for in-vitro measurement of static and kinetic friction coefficient of catheter surface was developed. Tribometer was designed and constructed to work with exchangeable counter-faces (polymers, tissue) and various types of tubes, in wet conditions in order to mimic in-vivo process. Thus seven commercially available urethral catheters, made from vinyl polymers, natural latex with silicone coating, all-silicone or hydrogel coated, and one made from polyvinylchloride with polyurethane/polyvinylpyrrolidone hydrogel coating obtained in our laboratory, were tested against three various counter faces: polymethacrylate (organic glass), inner part of porcine aorta and porcine bladder mucosa. Additionally, the hydrophility/hydrophobity of tested catheters was stated via water wetting contact angle measurement. Super-hydrophilic biomaterials revealed low friction on tissue and hydrophobic counter-face; slightly hydrophobic showed higher friction in both cases, while more hydrophobic manifested low friction on tissue but high on hydrophobic polymer. The smoothest friction characteristic was achieved in all cases on tissue counter-faces. The measured values of the static coefficient of friction of catheters on bladder mucosa counter-face were as follows: the highest (0.15) for vinyl and siliconised latex catheters and 3 folds lower (0.05) for all-silicone ones. Hydrogel coated catheters exhibited the lowest static and kinetic friction factors.