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Open access

Rahal Saaidi, Yassine Toufique, Abdelkrim Zeghari, Abderrahman El kharrim and Rajaâ Cherkaoui El Moursli

Abstract

We used GATE simulation to study the effect of the coincidence time window (CTW) along with the block gap and the intercrystal gap on the count rate performance and the spatial resolution of the Biograph mCT 20 Excel. We ran simulations on our local cluster to reduce computation time. The task was split into several jobs that were then triggered simultaneously on the cluster nodes. The BiographTM mCT 20 Excel was validated using the NEMA NU 2-2012 protocol. Our results showed good agreement with experimental data. The simulated sensitivity, peak true count rate, peak noise equivalent count rate (NECR), and scatter fraction showed agreement within 3.62%, 5.77%, 0.6%, and 2.69%, respectively. In addition, the spatial resolution agreed within <0.51 mm. The results showed that a decrease in the coincidence time window and the block gap and an increase in the intercrystal gap increase the count rate performance and improve the spatial resolution. The results also showed that decreasing the coincidence time window increased the NECR by 27.37%. Changing the intercrystal gap from 0 to 0.2 mm and the block gap and from 4 to 0.4 mm increased the NECR by 5.53% and improved the spatial resolution at 1 cm by 2.91% and that at 10 cm by 3.85%. The coincidence time window, crystal gap, and block gap are important parameters with respect to improving the spatial resolution.

Open access

Nikolay Uzunov, Michele Bello, Laura Melendez-Alafort and Laura De Nardo

Abstract

In recent years, there is a constantly increasing interest in the application of nanoparticles for cancer diagnosis and cancer therapy. In this respect, the most promising nano-objects at present are the gold nanoparticles. A very convenient and powerful property of these objects is their ability to increase their temperature under electro-magnetic irradiation with certain wavelength. In our research we have directed our efforts toward particular nano-objects specifically sensitive to electromagnetic radiation in the near-infrared region (NIR). In order to study the photothermic properties of the solutions of gold nanoparticles in the NIR we constructed a specific electronic setup consisting of a laser system with interchangeable laser diodes with different wavelength NIR light, a thermally-insulated cuvette-holder compartment with temperature measuring probes and a NIR spectrometer to control the stimulated fluorescence emission of the nanoparticle solutions. The temperature measurement compartment with the thermal-insulated cuvette holder was designed to maintain the solutions’ temperature at a fixed value right before the moment of laser irradiation. To maintain the measurement setup at a fixed temperature before the irradiation we used a thermal stabilized system based on two Peltier cells with electronic temperature control. The temperatures of the ambient air and the temperature of the cuvette walls were continuously measured in order to make corrections about the temperature dissipation during the irradiation.

Open access

Amin Banaei, Bijan Hashemi, Mohsen Bakhshandeh and Bahram Mofid

Abstract

Background: The relationship between the prostate IMRT techniques and patients anatomical parameters has been rarely investigated.

Objective: to evaluate various prostate IMRT techniques based on tumor control and normal tissue complication probability (TCP and NTCP) values and also the correlation of such techniques with patients anatomical parameters. Methods: Four IMRT techniques (9, 7 and 5 fields and also automatic) were planned on the CT scans of 63 prostate cancer patients. The sum of distances between the organs at risk (OARs) and target tissue and also their average joint volumes were measured and assumed as anatomical parameters. Selected dosimetric and radiobiological parameters (TCP and NTCP) values were compared among various techniques and the correlation with the above anatomical parameters were assessed using Pearsons’ correlation.

Results: High correlations were found between the dosimetric/radiobiological parameters of OARs with the joint volumes and with the distances between the OARs and target tissue in all the techniques. The TCP and complication free tumor control probability (P+) values were decreased with increasing the joint volume and decreasing the distances between the OARs and target tissue (as poly-nominal functions). The NTCP values were increased with increasing the joint volumes and decreasing the distances (3-degree poly-nominal functions). For the low percent joint volumes (<20%) and high distances (>7 cm), The TCP, NTCP and P+ showed no statistical differences between various techniques (P-value>0.07). However, 9 and 7 fields techniques indicated better radiobiological results (P-value<0.05) in almost other ranges (>20% joint volumes and <7 cm distances).

Conclusion: Based on our results, it would be possible to compare radiobiological effects of various common IMRT techniques and choose the best one regarding to patients anatomical parameters derived from the CT scans.

Open access

Farshid Mahmoudi, Mozafar Naserpour, Zahra Farzanegan and Amirhossein Davudian Talab

Abstract

Introduction: Since the CT operators play an important role in the diagnosis and treatment of diseases and exposing the patients to radiation exposure, they must be aware of all CT parameters which affect the image quality and patient dose and update their knowledge in parallel with the progresses in CT technology. Therefore, the knowledge of radiographers and CT technologists regarding the CT parameters was assessed in this study to identify and resolve any potential deficiencies.

Material and methods: This study was conducted in 2018 among 113 radiographers and 103 CT technologists in Khuzestan province using a three-part questionnaire containing demographic characteristics, general opinion on CT scan dose and questions assessing technologists’ knowledge of CT exposure parameters. Data were analyzed using SPSS software.

Results: Total knowledge scores of radiographers and CT technologists about CT exposure parameters were 36 and 42, respectively. The highest knowledge score among technologist was the knowledge of changing parameters based on patient characteristics and the lowest was in the field of awareness of noise index and diagnostic reference levels.

Conclusion: Total knowledge scores of radiographers and CT technologists about different scan parameters affecting dose and image quality was very low. Reviewing and updating the content of academic education and holding retraining courses are suggested.

Open access

Daryoush Khoramian, Soroush Sistani and Peyman Hejazi

Abstract

Objective: The literature has approved that the use of the concept of diagnostic reference level (DRL) as a part of an optimization process could help to reduce patient doses in diagnostic radiology comprising the Computed Tomography (CT) examinations. There are four public/governmental CT centers in the province (Semnan, Iran) and, to our knowledge, after about 12 years since the launch of the first CT scanner in the province there is no dosimetry information on those CT scanners. The aim of this study was to evaluate CT dose indices with the aim of the establishment of the DRL for head, chest, cervical spine, and abdomen-pelvis examinations.

Methods: Scan parameters of 381 patients were collected during two months from 4 CT scanners. The CT dose index (CTDI) was measured using a calibrated ionization chamber on two cylindrical poly methyl methacrylate (PMMA) phantoms. For each sequences, weighted CTDI (CTDIw), volumetric CTDI (CTDIv) and dose length product (DLP) were calculated. The 75th percentile was proposed as the criterion for DRL values.

Results: Proposed DRL (CTDIw, CTDIv, DLP) for the head, chest, cervical spine, and abdomen-pelvis were (46.1 mGy, 46.1 mGy, 723 mGy × cm), (13.8 mGy, 12.0 mGy, 377 mGy × cm), (40.0 mGy, 40.0 mGy, 572 mGy × cm) and (14.9 mGy, 12.1 mGy, 524 mGy × cm), respectively.

Conclusion: Comparison with the others results from the other countries indicates that the head, chest and abdomen-pelvis scans in our region are lower or in the range of the other studies investigated in terms of dose. In the case of cervical spine scanning it’s necessary to review and regulate scan protocols to reach acceptable dose levels.

Open access

Habib E. Ashoor and Khalil Ebrahim Jasim

Abstract

The behaviour of light interaction with biological tissue is determined by micro-optical parameters: refractive index (n), absorption coefficient (µa), scattering coefficient (µs), and anisotropy (g). The goal of this study is to measure the optical properties of normal whole blood using He-Ne laser (wavelength 632.8 nm).

The refractive index is measured using the traveller microscope. The integrating sphere method is used to measure the macro-optical parameters: total diffusive reflectance, transmittance, and collimated transmittance at wavelength 632.8 nm. The macro-optical parameters are fed to Inverse Adding Doubling (IAD) theoretical technique, to estimate the micro-optical parameters (µs, µa, g). An alternative practical method is used to measure the g value based on utilising the goniometric table. The study reveals that the refractive index (n) equals 1.395±0.0547, absorption coefficient (µa) equals 2.37 mm−1, scattering coefficient (µs) equals 55.69 mm−1, and anisotropy (g) equals 0.82.

In conclusion, these findings approved, in general, the applicability of the suggested experimental set up. The set up depend on using three devices: the integrating sphere method to estimate (µs, µa, g), traveller microscope (n) and goniometer (g).

Open access

F. Allama, N. Gherraf, Y. Nicolas, T. Toupance and D. Khatmi

Abstract

The present work deals with the synthesis of multichromophores which strongly absorb the solar spectrum to functionalize the nanoparticle oxide semiconductor used in the hybrid cells. At first, we developed a material that forms a chromophore triphenodioxazine. We obtained some triphenodioxazines with high yields up to 70 percent. On the other hand, we have carried out many tests such as UV-Visible, Cyclic voltammetry for our molecules to check their electronic and optical properties. The results confirmed that these chromophores meet the criteria for use in photovoltaic cells. Finally, we have successfully realized photovoltaic cells with triphenodioxazine. The findings were very interesting since the photovoltaic conversion efficiencies ranged from 4.30% to 6.30%. The new synthesis strategy of these chromophores opens a way for the development of organic materials used for photovoltaics.

Open access

Abdelali Merah, Abdenabi Abidi, Hana Merad, Noureddine Gherraf, Mostepha Iezid and Abdelghani Djahoudi

Abstract

Interest in nanomaterials, especially metal oxides, in the fight against resistant and constantly changing bacterial strains, is more and more expressed. Their very high reactivity, resulting from their large surface area, promoted them to the rank of potential successors of antibiotics.

Our work consisted of the synthesis of zinc oxide (ZnO) and copper oxide (CuO) in the nanoparticle state and the study of their bactericidal effect on various Gram-negative and Gram-positive bacterial strains.

The nanoparticles of metal oxides have been synthesized by sol-gel method. Qualitative analysis and characterization by UV / Visible and infrared spectrophotometry and X-ray diffraction confirmed that the synthetic products are crystalline. The application of the Scherrer equation allows to determine the size of the two metal oxides, namely: 76.94 nm for ZnO and 24.86 nm for CuO.

The bactericidal effect of ZnO and CuO nanoparticles was tested on Gram-positive bacteria (Staphylococcus aureus, Staphylococcus hominis, Staphylococcus haemolyticus, Enterococcus facials) and Gram-negative bacteria (Escherichia coli, Schigella, Klepsiella pneumoniae and Pseudomonas aeruginosa). The results indicate that the tested metal oxides nanoparticles have an effect that varies depending on bacterial species. Indeed, Gram-positive bacteria show greater sensitivity to ZnO nanoparticles whereas Gram-negative bacteria are more sensitive to CuO nanoparticles.

Open access

Abdelwahab Belkassam, Amar Zellagui, Noureddine Gherraf, Guido Flamini, Pier Luigi Cioni, Khellaf Rebbas and Tahar Smaili

Abstract

The essential oils obtained by hydrodistillation of aerial parts of Centaurea dimorpha Viv. were analyzed by means of gas chromatography-mass spectrometry (GC-MS). The main constituents were Caryophyllene oxide (09.88%), limonene (5.73%), tetradecanoic acid (5.68%), spathulenol (5.44%), methyl hexadecanoate (4.45%), and α-pinene (03.08%). To our best knowledge this is the first study of essential oils from the aerial parts of Centaurea dimorpha growing in Algeria. Moreover the essential oil and methanolic extract were screened for their possible in vitro antioxidant activity by DPPH free radical-scavenging test. The findings showed that the percentage inhibition is 10.67 and 77.01 respectively at a concentration of 1mole/L.