Using time domain OCT and gelatin-based skin phantom as training tools for venipuncture

The College of Science Physics Department invited the academic community to a lecture entitled Using Time Domain OCT and Gelatin-based Skin Phantom as Training Tools for Venipuncture by Dr. Paulito F. Mandia. Abstract: Optical coherence tomography (OCT) is a non-invasive imaging modality developed in the early 1990’s for retinal imaging. Further modifications allowed OCT’s to be used on other parts of the human body, and non-medical areas as well. Timedomain OCT (TD-OCT) basically is a Michelson interferometer with a low-coherence light source which enables noninvasive, cross-sectional visualization of the sample. In this paper, the researchers used the TDOCT system, which uses a rotating reference mirror. Using this system in conjunction with fabricated skin phantoms, students of venipuncture can hone their skills on skin phantoms before practicing on actual persons. This helps in mitigating the potential risks inherent to the performance of invasive procedures such as venipuncture. Furthermore, the skin phantom is chiefly composed of gelatin with latex tubing used to imitate the veins. Such materials are cheap and readily available, allowing multiple phantoms to be fabricated easily. Preliminary results showed that OCT is a promising tool in imaging the tissue phantom and thus can be utilized for venipuncture training

Time-domain optical coherence tomography system for determining the extinction coefficient and refractive index of gelatin-based skin phantoms

Optical Coherence Tomography (OCT) is a non-invasive, non-destructive optical imaging technique that uses a low coherence interferometer to obtain real-time cross-sectional images and three-dimensional images of a biological tissue sample. OCT is notably used in biomedical applications including ophthalmology and dermatology. Aside from generating cross-sectional images of the sample, axial scans can also provide additional information about its optical properties such as extinction coefficient (EC) and refractive index (RI). This study determines the EC and RI of gelatin-based skin phantoms using a portable time-domain (TD) – OCT system. The gelatin-based skin phantoms were fabricated with varying concentrations of titanium dioxide (TiO2). By changing the proportion of the gelatin powder and TiO2, skin phantoms can then be fabricated to mimic various skin conditions, both pathologic and non-pathologic. The performance of the constructed portable TD-OCT system was also evaluated. The OCT system has an SNR ranging from 30.04 dB to 42.73dB. The depth profile produced by the OCT is accurate as indicated by the distance measurement conducted. The OCT system was capable of generating B-scans, but the long acquisition times prevent it from obtaining B-scans for in vivo studies or for samples with volatile components. Results of the study found a negligible correlation of EC with TiO2 concentration. Whereas, the RI had a very strong correlation with TiO2 concentration. The median EC values of the phantoms ranged from 4.29/mm to 8.48/mm. Samples of porcine skin were also studied for EC, and the median values ranged from 2.45-6.33. Literature showed that epidermis can have EC of 1.64-7.3/mm. For RI of the phantoms, values ranged from 1.32 to 1.48, while studies on human participants showed that human skin has RI values of 1.34-1.56. Based on EC and RI, it is feasible to fabricate phantoms mimicking human and porcine skin

Elemental distribution and source analysis of atmospheric aerosols from Meycauayan, Bulacan, Philippines

One of the industrialized cities in the Philippines is Meycauayan, Bulacan. This study reports the elemental distribution and source apportionment in eight varying land cover-land use type sampling points located along the Marilao-Meycauayan- Obando Rivers System. Elemental analysis was conducted using a scanning electron microscope coupled with energy dispersive x-ray. Cu, Pb, Zn, Cr, Mn, As, Cd, Co, Fe, Ni, Ti, and V concentrations were determined using Inductively Coupled Plasma Mass Spectrometry, and Hg concentrations by Mercury analyzer. Principal component analysis (PCA), hierarchical cluster analysis (HCA), and Pearson's r correlation were used to analyze different sources of heavy metals and its corresponding land use-land cover type. The aerosol samples showed the presence of heavy metals Pb and Hg, elements that were also detected in trace amounts in the water measurements. Concentrations of heavy metals such as Cu, Fe, Pb, Zn, V, Ni, and As found in the atmospheric aerosols and urban dusts were attributed to anthropogenic sources such as residential, commercial and industrial wastes. Other source of aerosols in the area were traffic and crustal emissions in Meycauayan. Using HCA, there are 3 clusters observed based on the similar sets of heavy metals: (1) AQS1 (Caingin), AQS2 (Banga), and AQS8 (Malhacan); (2) AQS3(Calvario), AQS4 (Camalig), and AQS5(Langka); (3) AQS1(Sto Nino-Perez), and (AQS7) (Sterling). These groups are related based on different land use setting such as residential/commercial, agricultural, and commercial/industrial areas. Our study recommends the need to address heavy metal pollution in Meycauayan in support to the ongoing implementation of laws and regulations by the local and private sectors