Journal of Medical Signals and Sensors
Volume:5 Issue: 2, Apr-Jun 2015

In previous editorials[1,2] we explained about available fields of Inter-Disciplinary Researches (IDRs) in Iran,[2] professional, organizational, cultural obstacles, and required polices for development of IDRs in Iran.[1] In this editorial, I want to discuss about one of the IDR fields in Iran that seems to have more available conditions for marketing comparing to other interdisciplinary areas.

In recent years, demand for biological sensors which are capable of fast and accurate detection of minor amounts of pathogens inreal‑time form has been intensified. Acoustic wave (AW) devices whose performance is determined by mass sensitivity parametersand quality factor are used in biological sensors as platforms with high quality. Yet, current AW devices are facing many challengessuch as the low value of their quality factor in practical applications and also their difficulty to use in liquids. The main focus of this articleis to study on the magnetostrictive sensors which include milli/microcantilever (MSMC) type. In comparison with AW devices, MSMChas a lot of advantages; (1) its actuation and sensing unit is wirelessly controlled. (2) Its fabrication process is easy. (3) It works wellin liquids. (4) It has a high‑quality factor (in the air > 500). Simulation results demonstrate that the amount of quality factor depends onenvironment properties (density and viscosity), MSMC geometry, and its resonant behavior of harmonic modes.

The improvement of high-through-put gene profiling based microarrays technology has provided monitoring the expression value of thousands of genes simultaneously. Detailed examination of changes in expression levels of genes can help physicians to have effi cient diagnosing, classification of tumors and cancer’s types as well as effective treatments. Finding genes that can classify the group of cancers correctly based on hybrid optimization algorithms is the main purpose of this paper. In this paper, a hybrid particle swarm optimization and genetic algorithm method are used for gene selection and also artificial neural network (ANN) is adopted as the classifier. In this work, we have improved the ability of the algorithm for the classification problem by finding small group of biomarkers and also best parameters of the classifier. The proposed approach is tested on three benchmark gene expression data sets: Blood (acute myeloid leukemia, acute lymphoblastic leukemia), colon and breast datasets. We used 10-fold cross-validation to achieve accuracy and also decision tree algorithm to find the relation between the biomarkers for biological point of view. To test the ability of the trained ANN models to categorize the cancers, we analyzed additional blinded samples that were not previously used for the training procedure. Experimental results show that the proposed method can reduce the dimensional of the data set and confirm the most informative gene subset and improve classification accuracy with best parameters based on datasets.

Aorta is formed in a dynamic environment which gives rise to imbalances between many forces that tend to extend the diameter and length. Furthermore, internal forces tend to resist this extension. Impedance tomography can show this imbalance to stimulate the stenosis of aortic valve, growth of the elastic, collagen and to effectively reduce the stresses in the underlying tissue. In blood flow, auscultation noises occurred and in the echocardiography decrease in left ventricular ejection speed can be observed. In this paper, we have modeled an aorta based on anatomical studies to simulate natural, 20% and 30% stenosis as usual heart disease to early diagnosis. Valve deformation causes different impedance tomography in 3D mesh of aorta as blood pressure. Remodeling of aorta and its flow is found when a cylindrical slice of the fully retracted blood aorta is cut longitudinally through the wall.

Geant4 is an open source simulation toolkit based on C++, which its advantages progressively lead to applications in research domains especially modeling the biological effects of ionizing radiation at the sub-cellular scale. However, it was shown that Geant4 does not give a reasonable result in the prediction of antiproton dose especially in Bragg peak. One of the reasons could be lack of a reliable physic model to predict the final states of annihilation products like pions. Since most of the antiproton deposited dose is resulted from high-LET nuclear fragments following pion interaction in surrounding nucleons and we tried to reproduce depth dose curves of most probable energy range of pions and neutron particle using Geant4. We consider this work one of the steps to understand the origin of the error and finally verification of Geant4 for antiproton tracking. Geant4 toolkit version 9.4.6.p01 and Fluka version 2006.3 were used to reproduce the depth dose curves of 220 MeV pions (both negative and positive) and 70 MeV neutrons. The geometry applied in the simulations consist a 20 × 20 × 20 cm3 water tank, similar to that used in CERN for antiproton relative dose measurements. Different physic lists including Quark-Gluon String Precompound (QGSP)_Binary Cascade (BIC)_HP, the recommended setting for hadron therapy, were used. In the case of pions, Geant4 resulted in at least 5% dose discrepancy between different physic lists at depth close to the entrance point. Even up to 15% discrepancy was found in some cases like QBBC compared to QGSP_BIC_HP. A significant difference was observed in dose profiles of different Geant4 physic list at small depths for a beam of pions. In the case of neutrons, large dose discrepancy was observed when LHEP or LHEP_EMV lists were applied. The magnitude of this dose discrepancy could be even 50% greater than the dose calculated by LHEP (or LHEP_EMV) at larger depths. We found that effect different Geant4 physic list in reproducing depth dose profile of the beam of pions was not negligible. Because the discrepancies were pronounced in smaller depth and also regarding the contribution of pions in deposited dose of a beam of antiproton, further investigation on choosing most suitable and accurate physic list for this purpose should be done. Furthermore, this study showed careful attention must be paid to choose the appropriate Geant4 physic list for neutron tracking depending to the applications criteria. We failed to find any agreement between results from Geant4 and Fluka to reproduce depth dose profile of pion with the energy range used in this study

The cancer of oral cavity is related to lesions of mucous membrane of tongue and gum that can be treated with radiation therapy. A lateral photon field can be used to treat this kind of tumor, which has a side‑effect on normal tissue in the opposite side of the oral cavity. In this study the dosimetric effect of the various shields in oral cavity is evaluated. In this study, a special phantom similar to the structure of oral cavity with capability of film dosimetry was designed and constructed. The various shield slabs were made of five materials: Lead, Plexiglas, Acrylic resin, Silicon and Plaster. For irradiation, Cobalt 60 (60Co) and 6 MV photon beams were used. The film dosimetry before and after the shield was performed using GAFCHROMIC EBT2 films. The film before the shield measures the magnitude of backscattering radiation from the shield. The prescribed dose was 150 cGy. Results showed that 3 cm of the lead in both energies had the maximum absorption of radiation. The absorbed dose to opposite side of shield for 6 MV photon beams and 60Co were 21 and 32 cGy, respectively. The minimum attenuation on radiation was observed in silicon shield for which the dose of opposite side were 116 and 147 cGy for 6 MV and 60Co respectively. The maximum backscattered dose was measured 177 cGy and 219 cGy using 3 cm thickness of lead, which was quite considerable. The minimum backscattering where for acrylic resin 101 and 118 cGy for 6 MV and cobalt. In this study, it was concluded that the amount of backscattering for 3 cm Lead shield is quite considerable and increases the dose significantly. A composite layer of shield with 1–2 cm lead and 1 cm acrylic resin can have the protective effect and low backscattering radiation at the same time.

The application of low-frequency ultrasound for transdermal delivery of insulin is of particular public interest due to the increasing problem of diabetes. The purpose of this research was to develop an air ultrasonic ceramic transducer for transdermal insulin delivery and evaluate the possibility of applying a new portable and low-cost device for transdermal insulin delivery. Twenty-four rats were divided into four groups with six rats in each group: one control group and three experimental groups. Control group (C) did not receive any ultrasound exposure or insulin (untreated group). The second group (T1) was treated with subcutaneous insulin (Humulin® R, rDNA U-100, Eli Lilly and Co., Indianapolis, IN) injection (0.25 U/Kg). The third group (T2) topically received insulin, and the fourth group (T3) received insulin with ultrasound waves. All the rats were anesthetized by intraperitoneal injection of ketamin hydrochloride and xylazine hydrochloride. Blood samples were collected after anesthesia to obtain a baseline glucose level. Additional blood samples were taken every 15 min in the whole 90 min experiment. In order for comparison with changes in blood glucose levels, the data were corrected by subtracting the baseline glucose for each rat from each blood glucose level at any time. The statistical multiple comparison (two-sided Tukey) test showed a signifi cant difference between transdermal insulin delivery group (T2) and subcutaneous insulin injection group (T1) during 90 min experiment (P = 0.018). In addition, the difference between transdermal insulin delivery group (T2) and ultrasonic transdermal insulin delivery group (T3) was signifi cant (P = 0.001). Results of this study demonstrated that the produced low-frequency ultrasound from this device enhanced the transdermal delivery of insulin across hairless rat skin.

In radiation cancer treatments، the most of the side effects could be minimized using a proper dosimeter. Gel dosimeter is the only three‑dimensional dosimeter and magnetic resonance imaging (MRI) is the gold standard method for gel dosimeter readout. Because of hard accessibility and high cost of sample reading by MRI systems، some other alternative methods were developed. The optical computed tomography (OCT) method could be considered as the most promising alternative method that has been studied widely. In the current study، gel dosimeter scanning using a prototype optical scanner and validation of this optical scanner was performed. Optical absorbance of the irradiated gel samples was determined by both of conventional spectrophotometer and the fabricated OCT system at 632 nm. Furthermore، these irradiated vials were scanned by a 1. 5 T MRI. The slope of the curves was extracted as the dose‑response sensitivity. The R2‑dose sensitivity measured by MRI method was 0. 1904 and 0. 113 for NIPAM and PAGAT gels، respectively. The optical dose sensitivity obtained by conventional spectrophotometer and the fabricated optical scanner was 0. 0453 and 0. 0442 for NIPAM gels and 0. 0244 and 0. 0242 for PAGAT gels، respectively. The scanning results of the absorbed dose values showed that the new OCT and conventional spectrophotometer were in fair agreement. From the results، it could be concluded that the fabricated system is able to quantize the absorbed dose values in polymer gel samples with acceptable accuracy.