11 research outputs found
Evaluation of the impact of intraocular lens Tecnis Z9000 misalignment on the visual quality using the optical eye modeling
Purpose: The aim of this study was to investigate the effect of misalignment (tilt & decentration) of IOLs in cataract surgery using Liu-Brennan optical eye model in a simulation. Methods: A phantom with the real eye parameters -Liu-Brennan model- and Tecnis Z9000 IOL were used for simulation. Results: Results showed that with 0.4 mm decentration and more the modulation transfer function (MTF) and contrast were reduced continuously in the ±X Axes. IOL decentration in ±Y axes showed a symmetrical reduction of MTF and contrast and increasing the decentration. In the ±X and ±Y axes the 8° IOL tilt has no significant effect on the MTF and contrast of the eye. Conclusion: It can be said that the decentration of Tecnis Z9000 IOL in the ±X and ±Y axes will reduce the optical quality of the person, specially for decentration more than 0.4 mm this effect is very significant. Therefore using the compensation methods for improvement of the optical quality is essential. But up to 8° IOL tilt in vertical and horizontal axes have no significant effect on the visual quality of the patient. © 2013 by the Iranian Society of Ophthalmology
Studies of antibacterial effects of synthesized silver nanoparticles using a novel thermotolerant Isoptericola variabilis sp. IRSH1 against Staphylococcus aureus and Pseudomonas aeruginosa
Background: Silver nanoparticles can consider as an alternative source for some antibiotic usages due to those effective antibacterial activity and eco-friendly characteristics.
Objective: This in vitro study was done to evaluate the inhibitory effect of extracellular synthesized of silver nanoparticles using inexpensive cellulosic materials and supernatant culture of Isoptericola variabilis sp. IRSH1 against Staphylococcus aureus and Pseudomonas aeruginosa.
Methods: Silver nanoparticles were produced by extracellular biosynthesis using supernatant culture of a novel thermotolerant Isoptericola variabilis sp.IRSH1 and characterized. The antibacterial activities of the synthesized silver nanoparticles were examined by the standard Kirby-
Bauer disc diffusion method against Staphylococcus aureus and Pseudomonas aeruginosa on
Muller-Hinton agar plates.
Findings: The silver nanoparticles were produced with an average size of 77 nm and 0.29 polydispersity index (PDI). The inhibition zones of AgNPs (1000 μg/ml) were 10 mm and 11 mm against Staphylococcus aureus and Pseudomonas aeruginosa respectively.
Conclusion: The biosynthesized AgNPs has good antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. The results indicate Pseudomonas aeruginosa is more sensitive to silver nanoparticles.
Keywords: Nanotechnology, Metallic nanoparticle, Anti-bacterial agents, Staphylococcus aureus, Pseudomonas aeruginos
Evaluation of silicon and 10% bismuth shield with variable thickness compared with constant thickness on the dose reduction and image quality during chest CT examination
One of the best methods to reduce the breast radiation dose in chest CT scan exam is using the bismuth shield. Due to the fact that, in CT scan tests, the breast dose is higher in the central axis of body than other sides, so the bismuth shield with variable thickness (outer half 1 mm thick and inner half 2 mm thick) is designed in this study. The objective of this study is to investigate in effectiveness of silicon and 10% bismuth composite shied with variable thickness on reducing radiation dose and image quality parameters in chest CT scan test compare to 1 mm and 2 mm of fixed thickness shield. Physical chest phantom underwent chest CT scan without or with bismuth shields with thickness of 1 mm, 2 mm, and variable in 90, 120 and 140 kVp in inactive TCM mode. Dosimetry was performed by using TLD, and image quality was evaluated quantitatively (by drawing the ROI in the identical images like image j, calculation of noise, CT number, SNR and CNR) and qualitatively (by two expert radiologists). Designed bismuth shield with unsteady thickness in inner and outer side compare to 1 mm and 2 mm thickness shields is presented in 120 kVp, has a significant difference in the amount of breast dose reduction (19% reduction), as well as in 140 kVp, all these three bismuth shields resulted in a significant dose reduction almost in the same similarity. At 120 kVp, the bismuth shield with variable thickness lead to a significant change in CT numbers in the heart and lungs, but it does not have a remarkable effect on other image quality parameters. The bismuth shield with variable thickness can lead to a better effectiveness in reducing breast dose without any side effect on image quality at 120 kVp, which requires further studies in this field
Utility of Quantitative 3D SPECT/CT Imaging in Patient Specific Internal Dosimetry of 153-Samarium with GATE Monte Carlo Package
Practical nuclear medicine and utility of phantoms for internal dosimetry: XCAT compared with Zubal
Projected future risk of leukemia and brain tumors from unnecessary brain CT scans: a multi-center study in Iran
Introduction: Computer Tomography (CT) scans can deliver a relatively high radiation dose to the patient, therefore radiation protection for this modality is paramount. The present study determined the frequency of no abnormality detected (NAD) brain CT scans and probability of cancer induction in different age groups and genders. Methods: In this study, brain CT reports were used to identify any findings as abnormality detected (AD) and others as NAD. Then probability of future leukemia and brain cancer was estimated for different age and gender groups. Results: On average, in 65% of the cases the results were NAD (56% and 76% among males and females, respectively). Among children, 79% of the reports were NAD. The total number of projected brain cancers was 1.8 and 1.3 for males and females, respectively. The number of projected leukemia cases was 0.75 and 0.7 for males and females, respectively. For pediatric patients, brain CT scans can lead to leukemia cases about 4.5 times more often than adults. Conclusion: Brain CT scans can lead to additional cases of brain cancer and leukemia. A significant fraction of brain CTs were NAD (non-pathologic) and could practically be replaced by other radiation-free imaging modalities, especially in pediatric and young patients
Radiation exposure of interventional cardiologists for different types of procedures in catheterization lab, is it more concern about extremities?
Introduction: Angiography and angioplasty expose cardiologists to a high level of X-ray comparing other radiographic methods, due to the high dose of radiation and the presence of the physician beside the patient bed during the procedure. Therefore, this study was designed to measure the absorbed dose in some important organs and extremities in cardiologists during different angiography and angioplasty procedures in catheterization lab. Methods: The entrance skin dose and extremity absorbed dose of the physicians in 100 angiography and angioplasty procedures were measured by TLD chips. The points on the physicians’ body, which were measured in this study, included: thyroid, right and left chest, right and left wrists, and left leg. The correlation of entrance skin dose in these six points to the exposure parameters is also evaluated. Results: The left leg has maximum dose and maximum correlation with total DAP for all three physicians in all procedure types. There was a weak correlation between left wrist absorbed dose and number of views among three physicians. Also, the maximum annual absorbed dose of the physicians in the left leg was lower than 150 mSv. Conclusion: According to the results of this study, it can be stated that periodic leg and hand dosimetry during operation is necessary for interventional cardiologists. Results also showed that, regardless of the type of procedure, the characteristics of device output, especially DAP, have a direct role in the absorbed dose of the organs and extremities, especially those outside the shield