Effect of Shields in Radiation Dose and Secondary Biological Risk of Gonads in Lumbosacral Digital and Computerized Radiography.

Background: The purpose of this study was to evaluate the effect of shields in imposed radiation dose to gonads in anterior-posterior (AP) and lateral views of lumbosacral radiography using digital radiography (DR) and computerized radiography (CR) methods. Materials and Methods: Sixty patients who were suspected to AP and lateral view of lumbosacral radiography were included in this study. The patients were exposed with and without shields which have 0.25 mm thickness. This study also compared the imposed dose to gonads for one and two plates of shields with none shields situation. Measurement of the radiation dose was performed using thermo luminescence dosimeters on the surface of the gonads. Furthermore, the absolute and excess relative risk (ERR) of biological abnormalities was estimated in the above-mentioned method using the BEIR VII model. Results: The mean dose of the DR method (10.14 ± 0.27) for the AP view was significantly lower than CR (32.43 ± 0.17) with and without shields. In addition, the imposed dose to gonads in the lateral view of DR (6.41 ± 0.47) was lower compared to CR (9.38 ± 0.14). Furthermore, the mean imposed dose to gonads for one and two pate shields of DR was lower than CR. Moreover, the excess relative risk to gonads in the AP for DR was lower compared to CR in all mentioned situations. Conclusion: Lumbosacral radiography is suggested to be performed by DR systems, due to the lower imposed dose and ERR to the gonads. Moreover, using shields may lead to decrease of scatter rays and also ERR of the gonads.

A novel design of high performance and robust ultra-low power SRAM cell based on memcapacitor.

The present paper proposes a six-FinFET two-memcapacitor (6T2MC) non-volatile static random-access memory (NVSRAM). In this design, the two memcapacitors are used as non-volatile memory elements. The proposed cell is flexible against data loss when turned off and offers significant improvement in read and write operations compared to previous NVSRAMs. The performance of the new NVSRAM design is evaluated in terms of read and write operation at particular nanometric feature sizes. Moreover, the proposed 6T2MC cell is compared with 8T2R, 8T1R, 7T1R, and 7T2R cells. The results show that 6T2MC has a 5.50% lower write delay and 98.35% lower read delay compared to 7T2R and 7T1R cells, respectively. The 6T2MC cell exhibits 38.86% lower power consumption and 23.80% lower leakage power than 7T2R and 7T1R cells. The proposed cell is significantly improved in terms of HSNM, RSNM, and WSNM compared to 8T2R, 8T1R, 7T2R, and 7T1R cells, respectively. Important cell parameters, such as power consumption, data read/write delay, and SNM, are significantly improved. The superior characteristics of FinFET over MOSFET and the combination of this technology with memcapacitors lead to significant improvement in the proposed design.

Improving the Security and Confidentiality in the Internet of Medical Things Based on Edge Computing Using Clustering.

Families, physicians, and hospital environments use remote patient monitoring (RPM) technologies to remotely monitor a patient's vital signs, reduce visit time, reduce hospital costs, and improve the quality of care. The Internet of Medical Things (IoMT) is provided by applications that provide remote access to patient's physiological data. The Internet of Medical Things (IoMT) tools basically have a user interface, biosensor, and Internet connectivity. Accordingly, it is possible to record, transfer, store, and process medical data in a short time by integrating IoMT with the data communication infrastructure in edge computing. (Edge computing is a distributed computing paradigm that brings computation and data storage closer to the sources of data. This is expected to improve response times and save bandwidth. A common misconception is that edge and IoT are synonymous.) But, this approach faces problems with security and intrusion into users' medical data that are confidential. Accordingly, this study presents a secure solution in order to be used in the IoT infrastructure in edge computing. In the proposed method, first the clustering process is performed effectively using information about the characteristics and interests of users. Then, the people in each cluster evaluated by using edge computing and people with higher scores are considered as influential people in their cluster, and since users with high user interaction can publish information on a large scale, it can be concluded that, by increasing user interaction, information can be disseminated on a larger scale without any intrusion and thus in a safe way in the network. In the proposed method, the average of user interactions and user scores are used as a criterion for identifying influential people in each cluster. If there is a desired number of people who are considered to start disseminating information, it is possible to select people in each cluster with a higher degree of influence to start disseminating information. According to the research results, the accuracy has increased by 0.2 and more information is published in the proposed method than the previous methods.

An inter-comparison between accuracy of EGSnrc and MCNPX Monte Carlo codes in dosimetric characterization of intraoperative electron beam.

BACKGROUND: Ionometric dosimetry in IOERT is a complicated process, due to the sophisticated beam setup and the necessity for dedicated protocols for ion chamber response correction. On the other hand, the Monte Carlo (MC) technique can easily overcome such limitations and be considered as an alternative dosimetry approach. This paper presents a comparative analysis of two widely used MC codes, EGSnrc and MCNPX, for intraoperative electron beam dosimetry. METHOD: The head of LIAC12, a dedicated IOERT accelerator, was modeled by both mentioned MC codes. Then, the percentage depth dose (PDD) curves, transverse dose profiles (TDPs), and output factor (OF) values were accordingly calculated within the water phantom. To realize the accuracy of MC codes in dosimetric characterization of intraoperative electron beam, their results were finally compared with those measured by corresponding ionometric dosimetry for all forms of electron energy/applicator size. RESULTS: A good agreement was observed between the simulated and measured PDDs/TDPs for both considered MC codes, such that the calculated gamma index values were always lower than unity for both considered MC codes. Nevertheless, the lower gamma index values were found in the case of the EGSnrc code. The maximum difference between the measured and calculated OF was obtained as 2.3% and 3.1% for EGSnrc and MCNPX code, respectively. CONCLUSIONS: Although both studied MC codes showed compatible results with the measured ones, EGSnrc code has superior accuracy in this regard and can be considered as a more reliable toolkit in Monte Carlo-based commissioning of dedicated IOERT accelerators.

Detection of nucleobases on borophene nanosheet: A DFT investigation.

In this paper, we present a computational study investigating the electronic properties of DNA nucleobases (Adenine, Guanine, Cytosine and Thymine) on χ3 borophene using a combination of density functional theory (DFT) and non-equilibrium Green's function (NEGF) formalism.The adsorption energy, equilibrium distance, net charge of transfer, and density of states (DOSs) are obtained at different molecule orientations and selective positions.The most stable geometries of DNA molecules on χ3 borophene are also determined.By using (NEGF) formalism, the electronic transmission and electrical current are calculated separately as a function of applied bias voltage for each nucleobase. We find that attaching this molecule to borophene changes the electrical conductivity.Results indicate the strong potential of borophene in adsorption of the DNA molecules, meaning this two-dimensional material could be a suitable candidate for future DNA sequencing devices.

Lomustine Loaded Superparamagnetic Iron Oxide Nanoparticles Conjugated with Folic Acid for Treatment of Glioblastoma Multiforma (GBM).

This study aimed to improve delivery of lomustine as a chemotherapeutic agent and to increase its uptake by U87-MG cancer cells via synthesizes LN-FA-PG-SPIONs (lomustine loaded polyglycerol coated superparamagnetic iron oxide nanoparticles conjugated with folic acid). Nanoparticles were synthesized by thermal decomposition method and characterized using TEM (transmission microscope), FTIR (Fourier transform infrared spectroscopy), and VSM (vibrating sample magnetometer). Lomustine release from nanoparticles was determined by dialysis-bag diffusion technique. Nanoparticles cytotoxicity was evaluated by MTT assay. Mean size of SPIONs and FA-PG-SPIONs (PG-SPIONs conjugated with folic acid) were 7.1 ± 1.13 nm and 25.1 ± 3.94 nm, respectively. Based on FTIR spectra SPIONs were successfully coated by polyglycerol and conjugated with folic acid. Lomustine encapsulation efficiency was 46 ± 6.8 %. SPIONs were cytotoxic on U87-MG cells at concentration above 100 ug/ml (p < 0.05) but PG-SPIONs do not reduce viability significantly (p > 0.05). Conjugation of folic acid with PG-SPIONs increased nanoparticles uptake by U87-MG cells (p < 0.05). We concluded that however FA-PG-SPIONs are proposed as a useful tracer for diagnostic and treatment of GBM but their drug delivery properties for lomustine is not satisfactory and more researches are necessary with this regard.

All-optical Fredkin gate using photonic-crystal-based nonlinear cavities.

An all-optical Fredkin gate was proposed and designed. The Fredkin gate is a reversible logic gate. For designing the proposed structure we used three different optical nonlinear resonators. The wide-bandwidth resonators do not have switching functionality. However, the proposed resonator was modified to act as an optical switch in the horizontal direction. The final structure was designed using four wide-band resonators, twelve sharp resonators, and four nonlinear ring resonators. Simulation results show that the maximum rise time for the proposed structure is about 5 ps.

Evaluation of the Lung Dose in Three-dimensional Conformal Radiation Therapy of Left-Sided Breast Cancer: A Phantom Study.

BACKGROUND: Three-dimensional 3D-CRT: conformal radiation therapy is a selective modality in many radiotherapy centers for the treatment of breast cancer. One of the most common side effects of this method is radiation lung injury. Considering such an injury, lung dose deserves to be studied in depth. METHODS: Computed tomography scan of a node-positive left-sided breast cancer woman was used for generating a thorax phantom. Ten thermoluminescent dosimeters (TLDs) were distributed evenly in the left lung of the phantom, and the phantom was scanned. The optimal plan, including supraclavicular and tangential fields, was created by the treatment planning system (TPS). The results of TLD dose measurements at the selected points in the phantom were compared to TPS dose calculations. RESULTS: Lung doses calculated by TPS are significantly different from those measured by the TLDs (P = 0.007). The minimum and maximum differences were -0.91% and 4.46%, respectively. TLDs that were on the inner margin of the lung and breast tissue showed higher dose differences than the TLDs in the lung. CONCLUSION: The results of this study showed that TPS generally overestimated doses compared to TLD measurements due to incorrect beam modeling caused by contaminated electrons in the lung.

Changes in lung volume parameters regarding the received dose in the lobes of the lungs after locoregional radiotherapy of breast cancer.

AIM: The purpose of this study was to evaluate ΔLVP and correlate them with MLD and V20 in the lobes of the lung. BACKGROUND: Radiation-induced lung injury after breast irradiation is controversial. The incidence of such an injury could have negative consequences on breast cancer patients. MATERIALS AND METHODS: Twenty-three women treated with Breast-conserving surgery, chemotherapy, and locoregional RT underwent body plethysmography pre-RT and 3 and 6 months post-RT. Statistical analysis was used to evaluate ΔLVP over time and relate them with MLD, V20, age, and concurrent hormonal therapy. RESULTS: LVP decreased after 3 months and then showed a slight improvement by returning partially to their pre-RT values after 6 months. The mean ΔLVP was -0.64% for one Gy increase of MLD and -0.34% for one percent increase of V20 after 3 months. After 6 months, only ΔVC showed 0.45% reduction with MLD in the upper lobe. Finally, there was no significant correlation between ΔLVP with respect to age and concurrent hormonal therapy. CONCLUSIONS: The results of this study showed that lung volume changes were not a cause for concern in breast cancer patients. There are three reasons to support this conclusion. Lung volume changes and percentage reductions in LVP for each Gy increase of MLD and each percentage increase of V20 in each lobe were small; patients were asymptomatic during the follow-up period; and LVP showed partial improvements after 6 months.

Evaluation of image quality and radiation dose in low tube voltage coronary computed tomography angiography.

BACKGROUND: Coronary computed tomography angiography (CCTA) is an important modality in diagnosis of coronary artery disease (CAD). Owing to the fact that computed tomography (CT) examinations are performed using ionizing radiation; applying radiation dose-reduction strategies seems to be necessary. Lowering tube voltage (in kV) according to the patient's body mass index (BMI) or weight is an approach that is investigated by many researchers. The goal of this study was to evaluate the impact of low tube voltage CCTA on radiation dose and image quality in order to decrease radiation dose in selected patients who meet inclusion criteria of the introduced protocol. METHODS: Patients with clinical indications of CCTA who met inclusion criteria were classified in two groups randomly. Imaging of two groups was performed using 120 kV and 100 kV, respectively. Subjective and objective parameters of image quality and radiation dose of two groups were measured. Afterward, data were analyzed by appropriate statistical tests using SPSS software. RESULTS: While differences in image quality between two groups were not significant, radiation dose of patients who underwent 100 kV CCTA was significantly lower than the other group. Effective doses (EDs) of first and second groups were 22.30 ± 5.48 mSv and 13.82 ± 2.00 mSv, respectively (P < 0.001). CONCLUSION: Lowering tube voltage in non-obese patients is an effective and practical approach to radiation dose reduction without missing image quality that should be considered especially for female patients.

Radiobiological Evaluation of Three Common Clinical Radiotherapy Techniques Including Combined Photon-Electron, Tangential Beams and Electron Therapy in Left-Sided Mastectomy Patients.

BACKGROUND: The aim of this study was radiobiological evaluation of different radiotherapy (RT) techniques, namely, combined photon-electron, two tangential photon beams, and electron therapy which are commonly used for treatment of mastectomy patients. MATERIALS AND METHODS: The mentioned techniques were planned on the computed tomography (CT) images of a chest phantom, using TiGRT treatment planning system (TPS). The TPS dose calculations were verified using Thermo Luminescence dosimeters (TLD) measurements. Dose-volume histogram (DVH) of the plans was generated in the TPS, and also tumor control probability (TCP) and normal tissue complication probability (NTCP) values were calculated using DVH data for each technique. For TCP and NTCP modeling, Poisson Linear-Quadatric (PLQ) and Lyman-Kutcher-Burman (LKB) models were used, respectively. RESULTS: The TCPs for the chest wall, internal mammary nodes, supraclavicular nodes, and axilla for the combined photon-electron was 90%, 90%, 90%, and 65%, respectively, which was higher compared to tangential beams (up to 11%, 11%, 5%, and 5%, respectively) and the electron therapy (up to 11%, 11%, 33%, and 23%, respectively) Whereas the NTCPs of the tangential beams for ipsilateral and contralateral lungs, heart, and chest wall-lung interface was 4%, 1%, 3%, and 5.6%, respectively. These NTCP values were considerably lower than electron therapy (up to 42%, 66%, and 40% and 30%, respectively) and combined photon-electron (up to 55%, 75%, 50%, and 20%, respectively) methods. CONCLUSION: Tangential beam is suggested for treating mastectomy patients, due to sufficient value of TCP, and also lower NTCP compared to the other techniques such as electron therapy and combined photon-electron.

Estimation of the Thyroid Secondary Cancer Risk on the Patient of Standard Breast External Beam Radiotherapy.

BACKGROUND: The purpose of this study was to estimate the secondary cancer risk of thyroid in standard radiotherapy methods which are commonly used for breast cancer patients. METHODS: A total of 64 breast cancer patients (their age range was around 50 years old) who referred to Seyed-Al-Shohada hospital (Isfahan, Iran) were included in this study. The radiotherapy of the mentioned patients was performed using 6-MV photon beams. Dose measurements were also done using thermoluminescent dosimeters. Calculation of the risk of developing secondary cancer in thyroid was done using the Biological Effects of Ionizing Radiation Committee VII and recommended quantity of the International Radiation Protection Commission, excess relative risk. RESULTS: The mean radiation dose to thyroid for the tangential beams, tangential field with supraclavicular (SC) field, and also a tangential field with SC field in modified radical mastectomy (MRM) were 0.883 ± 0.472, 1.512 ± 0.365, and 1.587 ± 0.37, respectively. The risk of developing secondary thyroid cancer over a period of 5 years after breast cancer therapy in the tangential, tangential with a SC field, and also tangential beam with SC field in MRM were 9.974 ± 4.318, 17.891 ± 0.365, and 18.783 ± 4.384, respectively. The mean of the measured thyroid doses in patients treated with tangent fields was significantly lower than the patients under the irradiation of the tangent fields with SC field (P < 0.001). CONCLUSIONS: Using radiation protection equipment is suggested for breast cancer patients who treated with the studied radiotherapy methods.

Circular Mitochondrial DNA: A Geant4-DNA User Application for Evaluating Radiation-induced Damage in Circular Mitochondrial DNA.

BACKGROUND: The aim of this study was to develop a nucleotide geometrical model of the circular mitochondrial DNA (mt-DNA) structure using Geant4-DNA toolkit to predict the radiation-induced damages such as single-strand breaks (SSB), double-strand breaks (DSB), and some other physical parameters. METHODS: Our model covers the organization of a circular human mt genetic system. The current model includes all 16,659 base pairs of human mt-DNA. This new mt-DNA model has been preliminarily tested in this work by determining SSB and DSB DNA damage yields and site-hit probabilities due to the impact of proton particles. The accuracy of the geometry was determined by three-dimensional visualization in various ring element numbers. The hit locations were determined with respect to a reference coordinate system, and the corresponding base pairs were stored in the ROOT output file. RESULTS: The coordinate determination according to the algorithm was consistent with the expected results. The output results contain the information about the energy transfers in the backbone region of the DNA double helix. The output file was analyzed by root analyzing tools. Estimation of SSBs and DSBs yielded similar results with the increment of incident particle linear energy transfer. In addition, these values seem to be consistent with the corresponding experimental determinations. CONCLUSIONS: This model can be used in numerical simulations of mt-DNA radiation interactions to perform realistic evaluations of DNA-free radical reactions. This work will be extended to supercoiled conformation in the near future.

Comparison of Accuracy in Calculation of Absorbed Dose to Patients Following Bone Scan with (99m)Tc-Marked Diphosphonates by Two Different Background Correction Methods.

To improve the accuracy of the activity quantification and the image quality in scintigraphy, scatter correction is a vital procedure. The aim of this study is to compare the accuracy in calculation of absorbed dose to patients following bone scan with (99m)Tc-marked diphosphonates ((99m)Tc-MDP) by two different methods of background correction in conjugate view method. This study involved 22 patients referring to the Nuclear Medicine Center of Shahid Chamran Hospital, Isfahan, Iran. After the injection of (99m)Tc-MDP, whole-body images from patients were acquired at 10, 60, 90, and 180 min. Organ activities were calculated using the conjugate view method by Buijs and conventional background correction. Finally, the absorbed dose was calculated using the Medical Internal Radiation Dosimetry (MIRD) technique. The results of this study showed that the absorbed dose per unit of injected activity (rad/mCi) ± standard deviation for pelvis bone, bladder, and kidneys by Buijs method was 0.19 ± 0.05, 0.08 ± 0.01, and 0.03 ± 0.01 and by conventional method was 0.13 ± 0.04, 0.08 ± 0.01, and 0.024 ± 0.01, respectively. This showed that Buijs background correction method had a high accuracy compared to conventional method for the estimated absorbed dose of bone and kidneys whereas, for the bladder, its accuracy was low.

Annexin V FITC conjugated as a radiation toxicity indicator in lymphocytes following radiation overexposure in radiotherapy programs.

BACKGROUND: Following human radiation exposure in hospital or accidents, dose assessments are of prime importance in radiation accidents. These issues are of continuing importance with respect to socioeconomic policy relating to the industrial and medical uses of ionizing radiation, and also for risk assessment among people who are occupationally exposed to low and/or high linear energy transfer (LET) radiation, such as astronauts, pilots, stewardesses, nuclear power plant workers, and victims of radiation accidents. MATERIALS AND METHODS: In this study, an assay for assessing radiation dose based on the induction of apoptosis in human T-lymphocytes was done to examine T-lymphocyte cells isolated from the fresh blood of 16volunteers, cultured and exposed to gamma rays. Radiation-induced apoptosis (RIA) was assessed by flow cytometric identification of cells displaying apoptosis-associated DNA condensation. RESULTS: Dose-response experiments showed that at 2Gy dose level of radiotherapy programs, the RIA frequency was significantly above control. Apoptotic levels significantly depend on the dose of radiation rather than the donor. CONCLUSION: The results demonstrate the potential use of this assay as a biological indicator of radiation toxicity, optimizing patient dose in radiotherapy and biological dosimetry process.

Comparison of electromagnetic and hadronic models generated using Geant 4 with antiproton dose measured in CERN.

After proposing the idea of antiproton cancer treatment in 1984 many experiments were launched to investigate different aspects of physical and radiobiological properties of antiproton, which came from its annihilation reactions. One of these experiments has been done at the European Organization for Nuclear Research known as CERN using the antiproton decelerator. The ultimate goal of this experiment was to assess the dosimetric and radiobiological properties of beams of antiprotons in order to estimate the suitability of antiprotons for radiotherapy. One difficulty on this way was the unavailability of antiproton beam in CERN for a long time, so the verification of Monte Carlo codes to simulate antiproton depth dose could be useful. Among available simulation codes, Geant4 provides acceptable flexibility and extensibility, which progressively lead to the development of novel Geant4 applications in research domains, especially modeling the biological effects of ionizing radiation at the sub-cellular scale. In this study, the depth dose corresponding to CERN antiproton beam energy by Geant4 recruiting all the standard physics lists currently available and benchmarked for other use cases were calculated. Overall, none of the standard physics lists was able to draw the antiproton percentage depth dose. Although, with some models our results were promising, the Bragg peak level remained as the point of concern for our study. It is concluded that the Bertini model with high precision neutron tracking (QGSP_BERT_HP) is the best to match the experimental data though it is also the slowest model to simulate events among the physics lists.

Evaluation on Geant4 Hadronic Models for Pion Minus, Pion Plus and Neutron Particles as Major Antiproton Annihilation Products.

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 reliable physic model to predict the final states of annihilation products like pions. Considering the fact that most of the antiproton deposited dose is resulted from high-LET nuclear fragments following pion interaction in surrounding nucleons, we reproduced 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 cm(3) 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.

Comparative study of the density of L2, L3, and L4 vertebrae in menopausal women aged over 50 years with osteoporosis.

BACKGROUND: The Index used for osteoporosis detection was BMD measured in L2, L3, and L4 vertebrae. We compared the density of the vertebrae to select the one with maximum change in the density for decreasing the cost and the time. METHODS AND MATERIALS: Ninety seven osteoporotic post-menopausal women with a mean age of 61.78 ± 8.48 (50 - 86) years and a mean body mass index (BMI) of 24.75 ± 2.66 (kg/m(2)) (18 - 30) without any known diseases and on any medication affecting bone mineral density (BMD) were examined at osteoporosis section of a teaching hospital. The vertebral bodies (L2 - L4) of participants were measured by using a dual energy X-ray absorptiometry system (DEXA). To investigate if the BMD measurement of a single vertebra could replace the total L2 - L4 measurement, the mean BMDs and the correlations of the L2 - L4 were compared. RESULTS: Among the 97 studied women, the mean BMI was 24.75 ± 2.66. The mean BMD of L2, L3, and L4 vertebrae were 0.7199, 0.7258, and 0.7402, respectively. There was no significant difference between the mean BMD of L2 and L3 vertebrae (P > 0.05), suggesting a strong relationship between L2 and L3. The mean BMD in the L4 vertebra was significantly higher than the other two vertebrae (P < 0.05), Statistical analysis showed that the BMD in all three L2, L3, and L4 vertebrae were associated with BMI (r > 0 and P < 0.05), but there was no significant relationship between BMD and age in the three L2, L3, and L4 vertebrae (r ≅ 0 and P > 0.05). CONCLUSION: Since the mean BMDs of L2 and L3 were not significantly different, and due to a very high correlation between L2 and L3, we recommend the measurement of L2 rather than L2 - L4 in order to save patient scanning time, cost, and the patient X-ray exposure.

Non Invasive XRF Analysis of Human Hair for Health State Determination of Breast Tissue.

BACKGROUND: Using hair samples to analyze the trace element concentrations is of interest among many researchers. X-ray fluorescence (XRF) and X-ray diffraction (XRD) are the most common methods in studying the structure and concentration of elements of tissues and also crystalline materials, using low energy X-ray. OBJECTIVES: In the present study, the detection ability of Wave Length X-ray Fluorescence (WLXRF) of breast cancer at early stages was evaluated and the results were compared with other routine modalities such as mammography. MATERIALS AND METHODS: Hair samples of 54 women (including 27 healthy and 27 patients) with average age of 52.03 ± 11.44 years were analyzed. All the sample donors were Iranian women. For the measurements Wave Length X-ray Fluorescence (WLXRF) method was used. RESULTS: Trace elements in healthy individuals were higher than those in cancer patients. In addition, sensitivity of the used method (WLXRF) was 96% compared to mammography (77%) as a gold standard for breast cancer detection. CONCLUSIONS: Trace elements in healthy individuals were higher than cancer patients and it seems that WLXRF may be used as a safe, low cost and reliable method with sensitivity higher than those of the other two relevant methods, XRD and mammography.

Monte Carlo Simulation of Siemens ONCOR Linear Accelerator with BEAMnrc and DOSXYZnrc Code.

The Monte Carlo method is the most accurate method for simulation of radiation therapy equipment. The linear accelerators (linac) are currently the most widely used machines in radiation therapy centers. In this work, a Monte Carlo modeling of the Siemens ONCOR linear accelerator in 6 MV and 18 MV beams was performed. The results of simulation were validated by measurements in water by ionization chamber and extended dose range (EDR2) film in solid water. The linac's X-ray particular are so sensitive to the properties of primary electron beam. Square field size of 10 cm × 10 cm produced by the jaws was compared with ionization chamber and film measurements. Head simulation was performed with BEAMnrc and dose calculation with DOSXYZnrc for film measurements and 3ddose file produced by DOSXYZnrc analyzed used homemade MATLAB program. At 6 MV, the agreement between dose calculated by Monte Carlo modeling and direct measurement was obtained to the least restrictive of 1%, even in the build-up region. At 18 MV, the agreement was obtained 1%, except for in the build-up region. In the build-up region, the difference was 1% at 6 MV and 2% at 18 MV. The mean difference between measurements and Monte Carlo simulation is very small in both of ONCOR X-ray energy. The results are highly accurate and can be used for many applications such as patient dose calculation in treatment planning and in studies that model this linac with small field size like intensity-modulated radiation therapy technique.