International Journal of Radiation Research
Volume:19 Issue: 3, Jul 2021

The purpose of this article was to present a brief review of pertinent information regarding the effects of microwave radiation on biological systems. Researchers have been intrigued by the interaction of electromagnetic fields (EMFs) and various life processes since the 18th century. Microwaves refer to the oscillation of an EMF with a wavelength of 1 mm to 1 m, which penetrates matter to varying degrees. With the widespread and ever-increasing use of microwaves, such as cellular telephones and other wireless technologies, great attention and research has been paid to the potential adverse biological effects. It is well recognized that microwaves affect the biological functions of living organisms at both the cellular and molecular levels, and can lead to the appearance of toxicity, genotoxicity and transformation. However, until now no satisfactory mechanism has been proposed to explain the biological effects of these fields. Therefore, increasing attention should be focused on the biological effects of microwaves in the future, especially since microwaves have extensive applications in various fields.

Cancer cells develop multidrug resistance after receiving fractionated ionizing radiation. However, the mechanisms underlying this phenomenon remain unknown. This study aimed to investigate the role of platelet/endothelial cell adhesion molecule 1 (PECAM-1), which was induced by ionizing radiation, in overcoming cisplatin resistance of nasopharyngeal carcinoma (NPC) cells.

Human NPC cell line CNE1 was subjected to fractionated ionizing radiation to obtain a subline with the phenotype of multidrug resistance (designated as CNE1/R). PECAM-1 gene expression in CNE1/R cells was knocked down by stable transfection of pSilencer plasmid carrying specific small hairpin RNA. The transcripts of PECAM-1 and multidrug resistance gene 1 (MDR1) were analyzed by reverse transcription–polymerase chain reaction, and their encoding proteins were detected by Western blot analysis. The in-vitro viability of tumor cells was examined with MTT assay and flow cytometry analysis. The tumor growth in xenograft mice was determined by measuring tumor weights.

The transcript and protein levels of PECAM-1 and MDR1 were concomitantly upregulated in CNE1 cells subjected to ionizing radiation. The inhibition of PECAM-1 expression with small hairpin RNA reduced the levels of MDR1 transcript and its encoding protein, P- glycoprotein. Furthermore, targeting PECAM-1 not only enhanced the sensitivity of irradiated CNE1 cells to cisplatin-mediated cell cytotoxicity in-vitro but also resulted in tumor regression in-vivo.

An increased PECAM-1 level in CNE1 cancer cells subjected to ionizing radiation contributed to cisplatin resistance via the upregulation of MDR1 expression. Thus, targeting PECAM-1 might help overcome drug resistance induced by ionizing radiation in CNE1 NPC cells.

Since different grades of gliomas have different treatment programs, prognosis, and survival rates, it’s important to differentiate them effectively. Intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced (DCE) with the two-compartment exchange model (2CXM) have showed great potential for identifying the brain tumors.

Thirty-nine patients with glioma underwent IVIM and DCE imaging at 3.0T. Quantitative parameters (mean, median, 10th, 25th, 75th and 90th percentiles) from IVIM (apparent diffusion coefficient (ADC), D, D*, f, and their product fD*) and DCE (vp, ve, PS, and Fp) were analyzed. The independent Student’s t-test and Mann-Whitney U-tests were used to assess whether these parameters could distinguish low- from high-grade glioma. Receiver-operating characteristic (ROC) curve analysis and Delong test were performed to determine and compare the diagnostic efficiency of IVIM and DCE parameters in differentiating low- and high-grade gliomas, respectively.

Various histogram statistics of IVIM and DCE parameters could differentiate different grades of glioma. ve and vp generally yielded higher area under the curve (AUC) values than IVIM parameters, and the differences in AUC values of ve_mean and IVIM parameters had a statistical significance. Although DCE had higher AUC values than IVIM, they didn’t reach statistical significance.

ve was the best parameter in differential diagnosis of gliomas. IVIM had the similar diagnosis performance with DCE, and both IVIM and DCE-MRI parameters can be used for preoperative grading of gliomas.

Our aim was to analyze the effects of set-up errors on dose distribution in radiotherapy treatment for lung cancer by using kilovoltage cone-beam CT (CBCT).

In this study, we used a Varian IX linear accelerator system to perform CBCT scans of 30 lung cancer patients before radiotherapy. Subsequently, the image was matched with the planned CT, and the left and right (LR), top and bottom (SI), and front and back (AP) directions were set incorrectly. And in the CMS planning system, the center of the plan has been moved to the center of the actual scan. Finally, the dose distribution before the bed-moving is simulated. We want to explore the impact of the planned target volume setting error (PTV), the total tumor volume (GTV), and radiation of normal tissues.

The set-up errors of the LR, SI and AP directions were (-0.20±2.84), (-1.09±5.40), and (-2.61±2.08) mm, respectively. The 5mm error accounted for 97.8%, 73% and 92.6% in the three directions. Statistically significant differences were found in the distribution of 95%PTV dose, the average dose of PTV, 95% GTV dose and the average dose of GTV without bed-moving, compared with the original plan.

In clinical lung cancer radiotherapy, the commonly used setting error is usually less than 5mm, most of which are along the AP direction. In this study, we found that the setting error is related to the patientchr('39')s inherent characteristics and can significantly change the radiation treatment dose in the target area.

To evaluate structural variation of the parotid gland in post-radiotherapy oral carcinoma patients.

52 patients (33 males, 19 females) with histologically confirmed cancer of head and neck region were enrolled. All the patients underwent intensity modulated radiotherapy (IMRT) with linear accelerator. A quantitative analysis was conducted with the help of contrast enhanced computed tomography (CECT) scan regarding the changes in the volume and density of the parotid glands (PGs) along with the assessment of their interrelationship in relation to the mean dose applied to the glands. The evaluations were done immediately after radiotherapy, and after 2 and 3 years.

Parotid size reduction was observed in 77.77 % of cases immediately after radiotherapy with a mean dose of 26.66 Gy applied to the parotid glands. Parotid shrinkage reduced to 61.5 % cases three years post radiotherapy. High density changes were revealed by 69.2 % cases immediately after radiotherapy with a mean dose of 34.53 Gy applied to these parotid glands. Low density changes were revealed by 48.1 % cases after 2 years follow up which further reduced to 25 % at three years follow up.

There was evidence of structural variation in the PGs during the course of IMRT which was significantly related with the mean dose applied to them. There were high density changes and low density changes immediately after radiotherapy and 2-3 years post-radiotherapy respectively. Further there was volumetric shrinkage post-radiotherapy which shows recovery 2 and 3 years post-radiotherapy.

In this study, clinical advantages and the dosimetric accuracy of volumetric modulated arc therapy (VMAT) technique for cranio-spinal irradiation (CSI) were investigated and compared with field in field (FinF) and intensity modulated radiotherapy (IMRT) techniques.

The organs at risk (OARs) and planning target volume (PTV) were generated on the RANDO phantom computerized tomography (CT) image series. The dose–volume parameters for PTVs and OARs were compared for three techniques. Furthermore, the dose distribution inside the RANDO phantom was measured with thermoluminescent dosimeter (TLD) for all three techniques. Comparisons were done between measured and calculated doses of field junctions, targets and OARs.

FinF failed to obtain an adequate dose distribution for the upper spine (US), while VMAT and IMRT provided good dose coverage for all parts of the PTV. The most homogeneous dose distribution at the field junctions was obtained with the VMAT. Although heart, thyroid, intestine, lung, liver and testicular maximum doses were lower for the VMAT, the mean doses were higher except for the heart and thyroid. The absolute volume receiving prescription dose was significantly lower for the VMAT. The median differences between the TLD measurements and TPS calculations were 0.27% (7.8, -9.7; p=0.394), -0.28% (8.1, -10.7; p=0.322) and -0.33% (8.4, -12; p=0.338) for the FinF, IMRT and VMAT, respectively.  These differences were not found statistically significant for the VMAT technique, as were the other two techniques.

We conclude that the VMAT technique is the optimal Linac based CSI treatment in regards to dose coverage, dose homogeneity in field junctions and OAR sparing for higher doses. In addition, the VMAT showed dose distribution accuracy as good as the two other techniques in measurements simulating real clinical situations.

Chronic long-term irradiation of mice with low dose-rate (20 mGy/day) gamma rays significantly shortened their life spans due to neoplasms and significant suppression of their ability to eliminate transplanted tumors.

Mice exposed to chronic 20 mGy/day gamma rays for 400 days and housed in an enriched environment (EE) were compared with those housed in a standard environment.

We demonstrate that an EE significantly ameliorates the suppression of transplanted tumors in mice exposed to chronic low dose-rate gamma rays. Peripheral blood analysis revealed that the proportions of some immune cells were increased by EE housing. Additionally, the number and activity of natural killer (NK) cells in the peripheral blood increased with EE housing, indicating that NK cells may be involved in enhancing the ability to reject transplanted tumors.

To our knowledge, this is the first study to report that the adverse effects, such as the suppression of tumor rejection activity of chronic low dose-rate irradiation exposure, may be alleviated by EE housing, which suggests the possibility that the adverse effects of irradiation may be mitigated by changes in lifestyle.

The purpose of this study is to analyze the cumulative dose profile tail beyond the scan lengths of 10-90 cm in CT examinations on central and peripheral axes of water phantoms (10-50 cm diameter). The analysis includes extension, trend, and dependency of the tails on the scan length and phantom diameter.

A validated Monte Carlo model of a GE LightSpeed 16-slice CT scanner was used to obtain a dose profile from narrow beam collimation (1µm). The cumulative dose profile tail was developed by applying the well-known "convolution method", i.e. convolving a dose profile with a RECT function. The tails were analyzed according to the phantom diameter and scan length statistically. 

For all phantoms, the statistical analysis shows no significant differences between tails of scan lengths of 10-90 cm for peripheral axis and those of scan lengths > 30 cm for the central axis. The tails have an exponential falloff from the scan edge modeled by D(z)=Ae-Bz. The A and B are related to the falloff speed and amplitude of the tails. By increasing the phantom diameter, the amplitude and falloff speed decrease 82% and 59% on the central axis and 65% and 31% on the peripheral axis respectively.

A simple equation was suggested for dose calculation at any point beyond the scan range on the central and peripheral axes of water phantoms. The equation is independent of scan length and is useful for evaluating the dose of organs located at the edge or outside of the scan region.

The assessment of radiation dose is of great importance in the optimization process. It is crucial to develop strategies for dose estimation in developing countries in lack of dosimeters.

The Entrance Skin Dose (ESD) of 731 patients was calculated using the Davies model. Eight radiological procedures: Chest PA and LAT, lumbar spine AP and LAT, pelvis AP and LAT, skull PA and LAT and three-phase X-ray machines were considered. Based on the mathematical estimation of the radiation output of X-ray machines, a modified Davies model was proposed. The model was compared to others (Edmonds, Tung and Tsai) using their Mean Relative Errors (MRE) with respect to the reference Davies model and the Student’s test of comparison of means. The 3rd quartile values were also compared to those found in Cameroon, Nigeria, Iran, France and UK.

  The MRE of the proposed model in this work (1.9%) was significantly less than the MRE of the Tung and Tsai model (7.1%), which was in turn significantly less than the MRE of the Edmonds model (55.0%). Results also show that, the 3rd quartile values were mostly higher than reference level in UK. High values of doses are attributable to short Focus to Skin Distance (FSD) and high values of charges.

The model proposed in this study is a better alternative to the Davies model in the case of absence of dosimeter. An adjustment of technical parameters (FSD and charge) could help reduce high doses.

This study aimed to compare high-grade gliomas radiation therapy methods (high energy three-dimensional conformal radiation therapy [3D-CRT] vs. low energy intensity-modulated radiation therapy [IMRT]). 

Out-of-field photons resulting from 15- and 18-MV 3D-CRT and 6-MV IMRT techniques were measured with thermo-luminescent dosimeters in a head and neck homogeneous phantom. Moreover, the dose to the left and right eye lenses, parotid glands, the thyroid gland, and the tongue was determined for each of the treatment techniques. Additionally, the risk of secondary thyroid cancer was estimated according to the biological effects of ionizing radiation BEIR VII model.

Errors in the treatment planning system (TPS) increased with increasing distance from the field edge and varied in different treatment techniques. The 6-MV IMRT technique increased the photon dose to all of the organs. Further, the excess relative risk for thyroid cancer was obtained higher in the 6-MV IMRT technique than in the 15- and 18-MV 3D-CRT techniques, as the photon dose to the thyroid gland was higher.

Although 6-MV IMRT better improves local control and dose distribution than 3D-CRT, it increases the total dose equivalent in out-of-field organs independently of beam energy and exacerbates the risk of secondary thyroid cancer more significantly.

The computed tomography (CT) scan delivers a relatively high radiation dose to the patient. One of the critical factors that affects the absorbed dose is the intensity of tube current. The aim of this study is to measure and compare the radiation dose of three radiation-sensitive organs in constant current mode and tube current modulation (TCM) modes.

CT-scans from the chest and abdomen-pelvis regions of adults in three different current modes were obtained. The absorbed doses of thyroid, lungs, and ovaries were measured using the thermoluminescent dosimeter (TLD) chips embedded in the RANDO phantom. Furthermore, the confirmation of the organ doses was simulated using the Monte Carlo (MC) simulation. The measured doses were evaluated and confirmed by comparison with the simulated doses.

The relative differences between the measured and simulated doses for thyroid, lung, and ovary were -4.7%, -1.3%, and -11.7% for constant current mode, -2.2%, -11.2%, and -6.3% for longitudinal modulation mode, and 0.0%, -14.6%, and -9.9% for angular modulation mode, respectively. With longitudinal modulation mode, thyroid, lung, and ovary doses were reduced by 34.0%, 19.0%, and 19.0% for the measured doses and 32.0%, 26.0%, and 13.0% for the simulated doses, respectively. The longitudinal modulation mode resulted in a greater dose reduction compared to the angular modulation for both measured and simulated doses.

Using TCM resulted in reducing does received by the organs in both measured and simulated doses. The TCM reduces organ dose, which is more evident in the longitudinal modulation.

There are data suggesting that low dose radiation induced inflammatory reactions and changes of the immune system could be responsible for late circulatory and other chronic diseases. Chronic low dose radiation of occupationally exposed persons requires careful examination of their immune status. The purpose of this survey was to study some immunological parameters and serum proteins as suitable markers for screening cardiovascular diseases and chronic inflammatory state in NPP personnel.

Lymphocyte populations were determined using four parameters by flow cytometer. Plasma levels of interleukin IL6, CRP and INFγ were determined by ELISA.

The main T lymphocyte populations did not show any differences to controls but there were trends of increasing activated CD3 HLA, CD4+25+ and CD8+38+ T lymphocytes and  CRP and IL6 markers. Higher, but not significant averages were recorded for regulatory T lymphocytes probably due to their role in preventing of atherosclerosis. No dependence was established of the studied parameters to cardiovascular or other chronic diseases, a weak correlation was only recorded for IL6 with autoimmune ones (p=0.042). The results show that the age, obesity, and other lifestyle factors, particularly cigarette smoking could be considered as cofounder for circulatory diseases.

It could be assume that radiation induced aging of T cells and activation of inflammatory response are partly involved in the development of inflammatory chronic diseases as the more pronounced deviations in the parameters are observed with increasing age and cumulative dose.

The knowledge of distribution of radionuclides and background radiation levels in the environment is important for assessing the effects of radiation exposure due to both terrestrial and extra-terrestrial sources.

In-situ gamma dose survey and gamma spectrometry was employed to investigate background radiation levels in Ijebu-Ife.

In-situ gamma dose rates vary from 0.02 to 0.10 µSv/hr with mean value of 0.05 µSv/hr which is less than 0.133 μSv/hr, recommended by the ICRP. The resulting annual effective dose was below 1 mSv/yr maximum permissible limit for the general public set by the UNSCEAR, 2000. The activity concentrations of the three naturally occurring radionuclides in soils ranged from Below Detection Level (BDL) to 320.11 ± 28.53, 9.11 ± 1.65 and 8.55 ± 0.95 Bq/kg with mean values of 119.05 ± 11.24 Bq/kg, 4.44 ± 1.01 Bq/kg and 4.55 ± 0.62 Bq/kg respectively which are lower than the average values of 400, 35, and 30 Bq/kg recommended by the UNSCEAR, 2000 for 40K, 226Ra, and 232Th respectively. The mean computed values for absorbed dose rate, annual effective dose and radium equivalent are 10.03 nGy/hr, 0.03 mSv/yr, 20.11 Bq/kg respectively, which fall within UNSCEAR, 2000 threshold.

A significant positive relationship exists between the in-situ and evaluated effective dose equivalents (r = 0.89, p < 0.05). Radiation dose results indicate insignificant radiological risk, making the study area safe for living and agriculture purposes.

Radioactive material through scrap metal dealers, is often sold to steel processing facilities, which contaminate products with associated waste ends up in the environment. This study was to conduct radiological assessment of 137Cs contaminated at metal processing facility and surrounding environment at Southern Nigeria as a function of time.

Samples were randomly collected within the facility and at surrounding environment, and analyzed using HpGe detector.

The 137Cs concentration ranged (1.61±0.25- 2619.35±133.80) Bq/g, with mean of 417.17±23 Bq/g. The 137Cs concentration at 500 meters from the facility ranged (0.21±0.02- 3.63±0.25) Bq/g with the mean of 1.30±0.16 Bq/g. The 137Cs concentration in the facility was above admissible limit of 100 Bq/g except that recorded at 500 meters away. The radiological hazards within the first year were estimations, which showed Dose through Inhalation Pathways was 6.89x10-3 mSv/yr. Dose through Soil Ingestion Pathways was 0.91 mSv/yr, and Sum External Dose from all the Pathways to be 1.44 x103 mSv/yr. The sum of evaluated radiological risk was found to be higher than the 0.25 mSv/yr or 1 mSv/yr admissible limits. An evaluated Excess Life Cancer Risk was found to be 2.5 quite above admissible limit of (029x10-3).

It is inferred from the assessment that, there is a likelihood of radiological health risk due 137Cs contaminated to workers, public and other biota. Therefore, immediate remediation is recommended and as well as restrictions of the public using materials from the area for soil stabilization and farming purpose.

Since the radionuclides concentration in teeth is a good indicator of the human body’s radioactive contamination, the purpose of this study was to measure the track density of alpha particles emitted from the human teeth and to assess the resulting cancer risk.

In this cross-section study, 93 permanent and unfilled tooth samples were collected from the patients residing in Khorramabad, Iran, and visiting dental clinics in this city. The alpha track density for the tooth samples was measured using CR-39 nuclear track detector. Annual effective dose (AED) and excess lifetime cancer risk (ELCR) were estimated based on the recommendations made by ICRP and UNSCEAR.

The mean alpha track density from 222Rn in patients’ teeth was410.15 tracks cm-2, whereas the mean for women and men equaled 441.42 and 378.20, respectively. This difference was not statistically significant (P=0.22), but there was a statistically significant difference between the track densities in different age groups (P˂0.001).In this study, the average radon activity concentration was 40.62 Bq m-3. Also, the mean annual effective dose and the mean ELCR were calculated as 1.02 mSvy-1 and 3.59 ×10-3, respectively.

The AED value was higher than the permissible dose limit and also the mean ELCR was higher than the global average. Based on the results, it is necessary to perform periodical monitoring to detect pollution sources.

This study aimed to investigate the radiation hazard indices from sand samples of  Ma’rib Governorate in Yemen, where the majority of oil and gas facilities are installed.

Methods and Materials:

 Thirty five samples of desert sand from Ma’rib Governorate in Yemen were collected and tested their radiation hazard indices by using High Purity Germanium (HPGe) detector.

Based on the measurement of the concentrations of 226Ra, 232Th, and 40K, the radium equivalent activity (Raeq), the activity concentration index (Iγ), the external hazard index (Hex) and the internal hazard index (Hin) were all calculated.  Also, the absorbed dose rate in Air (ADR) and the annual effective dose (AED) are calculated.

Comparing the practically attained results with internationally permissible values, it was found that most of the radiological parameters, including the radiation hazard indices of the studied samples, fall within the worldchr('39')s permissible limits and donchr('39')t expose risks to the human beings and environments.

The present study aims to compare the impacts of dose rate in intensity-modulated radiation therapy (IMRT) plan delivery by using the gamma agreement between the calculated and measured doses by pretreatment quality assurance (QA).

Ten nasopharynx cancer patients who underwent IMRT treatment were included in this study. The treatment plans were performed using Varian DHX eclipse treatment planning system (TPS) version 15.1. and the QA plans were generated for the dose rates of 300, 400, 500 and 600 MU/min. All measurements were performed by aS1000 Electronic Portal Imaging Device (Epid) integrated into Varian DHX linear accelerator and 2D array detector. The dose distribution was evaluated with gamma area histograms (GAHs) generated using different γ criteria (2%/2 mm and 3%/3 mm) for dose agreement and distance to agreement parameters. Statistical analyses were evaluated by using Mann-Whitney Test and a p-value of p <0.05 was considered to be significant.

There was a significant decrease in the percentage gamma pass rate when the dose rate was increased from 300 MU/min to 600 MU/min (p<0.05). There was a significant difference between Epid and Epiqa for all dose rates (p<0.05). The total number of MU was correlated to the dose rate. When comparing MU from 300 MU/min to 600 MU/min dose rate, it was observed that the MU of IMRT plans increaed as the dose rate was increased.

In this study, we have demonstrated that IMRT delivery using sliding window method is affected by the dose rate.

In this work, a low-dose rate (100mGy/min of whole body gamma irradiation fractionated (0.5, 1, and 2Gy) was used to study the effects of cumulative doses on the expression of target genes implicated in the intestinal inflammatory process in high fat diet (HFD) wistar rats.

Total RNA was extracted and the expression of target genes was measured in the four intestinal segments (duodenum, jejunum, ileum and colon) of HFD Wistar rats.

Our in-vivo results in the four intestinal segments (duodenum, jejunum, ileum, and colon) demonstrated that gamma irradiation exposure in HFD rats amplified the low-grade inflammatory state already induced by HFD. This phenomenon occurs through the induction of pro-inflammatory cytokines mainly the tumor necrosis factor-alpha (TNFα) and interleukin 6 (IL-6) or via overexpression/increasing of anti-inflammatory response involved interleukin 10 (IL-10) and the growth factor β (TGFβ) overall the bowel segments. Results suggested that whole body gamma irradiation might have dual roles, first, engraving the inflammatory state already initiated by HFD, and second, an over expressed anti-inflammatory response via anti-inflammatory cytokines mainly IL-10 and TGFβ.

The current study clearly demonstrated the important role of the gut in HFD rats during fractionated whole body irradiation (FWBGI) and indicated that TGFβ and IL-10 may be the target in whole body radiotherapy as a mechanism to recompense for the ‎imbalance between pro-inflammatory and anti-inflammatory cytokines.

Accumulating reports suggest that radiation may change gene expression in cancer cells and promote cell migration and invasion, as well as inducing cancer stem cell (CSC). However, the correlation between these processes and radiation dose has not been shown yet. Therefore, the present study aimed to evaluate the effect of low, medium, and high doses of X-ray on expressing three genes involved in CSC induction in colon cancer cell line (HT-29).

The cells cultured in flasks were irradiated with X- rays in different doses including 0.1, 2.5, 5, and 10 Gy. Then, the expression of Oct4, CD44, and ALDH1 genes was measured using real-time PCR. PCR efficiency was evaluated for each gene using Linreg PCR software, and relative changes for mRNA were calculated based on the ∆∆Ct method.

CD44 gene expression increased equally at all doses. Oct4 and ALDH1 gene expression were not affected by 10 Gy, but low and moderate doses increased them equally.

The effects of low and moderate doses on increasing the expression of stem-related genes are equal. In addition, the effect of the high dose on increasing CD44 gene expression was equal to the low and moderate doses.

The existence of air in hollow organs in the thoracic cavity constitutes a life-threatening situation most of the times. However, sometimes in thoracic Computed Tomography (CT) there are artifacts from different sources that could mimic air densities, disorientating the diagnosis.

100 patients (46 females and 54 males, mean age: 60 years, range: 20-90 years), who had been routinely scanned in the area of thorax using three different imaging protocols (follow up, aorta, pulmonary vessels) were retrospectively studied. In 67 cases, contrast agent was used during the examination. Every case was studied by two specialists.

Artifacts in pulmonary veins were observed in 38 of the cases. Of these artifacts 27 stemmed from contrast agent, calcifications in the vessels, metallic implants, movement of the patient, malfunction of a detector due to the size of field of view (FOV) or due to the existence of contrast agent on the examination table of the CT scanner. In 11 cases, small amounts of air had been inserted into blood circulation during contrast injection.

This study characterized and classified many artifacts related to thorax CT in order to separate them from other serious thoracic pathologies (e.g. aortic dissection, ulcer of veins or arteries). The knowledge and identification of the different types of artifacts is very important in order to avoid the risk of misdiagnosis.

There is no data concerning water equivalent ratio (WER) values for helium ion beams in an extensive range of energies as well as relevant dosimetric materials.

In this work, quantities related to depth-dose profiles and WER values were evaluated in water, Polyethylene (PE), Polymethyl Methacrylate (PMMA), Polystyrene (PS), Lead (Pb), Tungsten (W) and Aluminum (Al) for helium ion energies ranging from 25-250 MeV/u using MCNPX 2.4.0 Monte Carlo code.

For all the studied energy range, the mean values of WER for PMMA, PE, PS, Pb, W and Al were 1.161, 0.995, 1.049, 5.421, 9.512 and 2.091, respectively. Among the studied materials, PE and W showed the least and most difference to water, respectively. Also the WER values of some of the studied materials for helium ion beams were compared with the same materials for proton beam.

The evaluated WER values were in acceptable accordance with the data reported in the literature by less than 2.6 % difference. Also, WER values of the mentioned materials for helium ions and protons have been compared and it was concluded that dose characteristics of PE are the most similar to water in the field of both helium ions and proton beams.

Aim of this study was to evaluate the extent of the error that the gating system incorporates into an intensity-modulated radiation therapy (IMRT) delivery for the different duty cycles of beam gated treatments (beam-interruption) by comparing the gamma between the dose planes.

Respiratory motion patterns was recorded in the real-time position management (RPM) software, which controls the triggering of the linear accelerator for the beam ON/OFF based on the predefined gating window. 10 IMRT plans consisting of 60 IMRT fields were delivered for three different duty cycles (20%DC, 30%DC and 40%DC) of gated and non-gated delivery. Planar dose measurements of IMRT delivery were performed with the commercially available two-dimensional ion chamber array and portal dosimetry. Gamma evaluation was carried out for the three different duty cycles of gated delivery with that of the reference of non-gated delivery, and the measured dose planes of gated and non-gated delivery were gamma analyzed with the treatment planning system (TPS) dose planes. Multileaf collimator (MLC) dynalog files were acquired and analyzed for the different duty cycles of gated and non-gated IMRT deliveries.

Gamma between the gated and non-gated dose planes were found within the 3% deviation.  Area gamma for the gated and non-gated delivery to the reference of TPS dose planes were found within the deviation of 6%.

Gamma comparison of the gated delivery with the reference of non-gated delivery results demonstrated that increasing the duty cycle reduced the deviation between the gated and non-gated delivery.

The present study aimed to investigate the dependence of the response of the genipin gel dosimeter on readout temperatures.

To this aim, after the gel preparation, they were exposed by a Varian Medical Linac accelerator with a dose range of 0-10 Gy. Then the irradiated samples were readout by a spectrophotometer device at 5°C, 10°C, 15°C and 20 °C temperatures.

Results revealed that the response of the genipin gel dosimeter is extremely temperature-dependent. For the mentioned readout temperatures, the maximum dose sensitivity was related to 10°C and its value was 35×10-3cm-1Gy-1. Investigation of the AUS (area under spectra) depicted that the maximum dose sensitivity was also related to 10°C. Furthermore, investigation of the dose resolution of this gel dosimeter showed that the minimum detectable dose was related to 10°C, and its amount was 0.24 Gy.

The results confirmed a noticeable change in the response of the genipin gel dosimeter due to variations of the readout temperature. It can be concluded that the response sensitivity of this radiochromic gel dosimeter increased by readout temperature decreasing.

The objective in this study was to create AAPM TG 119 test plans for Intensity-modulated radiation therapy (IMRT), burst mode and volumetric modulated arc therapy (VMAT) in convolution study in order to investigate accuracy of the United Imaging Healthcarechr('39')s URT treatment planning system (URT-TPS).

The plans were delivered to the phantom using the United Imaging Healthcarechr('39')s URT-Linac 506C. For there treatment mode as IMRT, Burst Mode and VMAT, with two kind of beams as flattening filter (FF) photon beam and flattening filter free (FFF) photon beam, calculated by uRT-TPS Monte Carlo algorithm, the overall accuracy was measured, and analyzed with five test geometries provided in TG 119. The point measurements were measured by a Farmer type ion chamber and fluence measurements were done with film respectively.

For the FF photon beams, the difference between measured point doses and planned doses of static multi-leaf collimator (MLC), dynamic MLC, Burst Mode and VMAT were within±3.92%,±3.26%, ±4.11%and±3.31% respectively. Gamma passing rates of Static IMRT, Dynamic IMRT Burst Mode and VMAT were >93.08%, 90.93%, 90.40% and> 92.00% respectively. For the FFF photon beams, the deviation between measured point doses and planed dose of static MLC, dynamic MLC, Burst Mode and VMAT were within 1.84%, 3.36%, 2.65%and 3.11% respectively. Gamma passing rates of Static IMRT, Dynamic IMRT Burst Mode and VMAT were>92.60%, 94.07%, 93.54% and 94.39% respectively and all confidence limits of the TG 119 report were matched.

Based on this analysis which were performed in accordance with the TG 119 recommendations, it is evident that the URT treatment planning system and URT-Linac 506C have commissioned IMRT and VMAT techniques with adequate accuracy.

The intensity-modulated radiotherapy (IMRT) enables personalized treatment; the complexity of this technique increased the need for patient-specific quality assurance (QA).

Comparing three dosimeters that common for patient-specific QA of IMRT.

cases were planned at Eclipse treatment planning system (TPS) to receive radiotherapy at Unique VARIAN linear accelerator LINAC; Patient-specific QA was performed with three independent dosimeters: Gafchromic films EPT2, Electronic Portal Image Device (EPID), and PTW 2D array. The absolute dose was measured and analysis of 2D gamma index was performed, then compared with the plan calculated in TPS.

Analysis of absolute dose measured have highest difference from dose in Gafchromic film (89.1±4) % while EPID had a lower range (96.6 ± 1.2) and 2Darray showed an agreement up to (99±1.2) for patient specific QA both EBT2 and EPID enable to compare the measured map with TPS calculations, for plan conformity the gafchromic film enable measurement with lower accuracy even with localized brain tumor, the heterogeneity in lung case slightly affect the EPID measurement, this found also with irregular surface of head and neck and increased depth within pelvic case examine. Measurement with 2D array found to be the optimum dosimeter within different conditions.

different parameters might affect the accuracy of gafchromic film including film scanning, storing, and calibration curve. EPID has an average deviation appears in beam fluence and 2D array as a 2D ion chamber found to have the most accurate dosimeter, but still time consuming when compared to EPID.

Inherent radiosensitivity associated with elevated chromosomal aberrations (CA) was shown in breast cancer (BC) patients at cellular level. Different agents were used to protect cells against adverse effects of ionizing radiation (IR), mainly antioxidants such as vitamins. The aim of this study was to evaluate the modulating effect of saffron extract on radiation induced CA in lymphocytes of normal individuals and BC patients.

G2 assay was applied on whole peripheral blood lymphocytes received from 5 normal controls and 10 BC patients with luminal A subtype. Blood culture was initiated in complete culture medium, 4h prior to harvesting cells were irradiated with 1 and 2 Gy X-rays. Pretreatment of samples with saffron was done 2 h before irradiation. After metaphase preparation and slide making, slides were stained in Giemsa. Hundred well spread metaphases were scored for presence of chromatid type aberrations with a microscope at a magnification of 1000×.

Results indicated a high and significant frequency of CA both in lymphocytes of normal and BC patient after irradiation. Pretreatment of samples with saffron led to a significant increase in the frequency of breaks in lymphocytes of both normal individuals and BC patients.

Results indicate that despite its antioxidant property, pretreatment of lymphocytes of normal individuals and BC patients with saffron before X-irradiation led to radiosentisizing effect. The way saffron sensitize lymphocytes to X-rays is not known, but it might be possible to inhibit repair of radiation induced DNA strand breaks.

The presence of radon and radioactive nuclei emitted from uranium could result in a radiological hazard. Humans are exposed to natural radiation, which arises from cosmic radiation, radon gas, and radiation from radioactive nuclei of each thorium, uranium, and thorium.

This research cares to study the concentration of the natural radioactivity (238-U, 232-Th and 40-K) and radon for fourteen samples of soil from different fourteen location in Wadi Hodein region in Egypt (Southern Eastern Desert). The radon gas was measured using CR-39 detector, while the activity concentration for natural radioactivity measured by HPGD system.

The results of the gamma ray spectroscopy show that main activity concentration of 238-U, 232-Th and 40-K are 13.04±1.15, 12.33±1.54 and 445.33±23.54 Bq/Kg respectively. The 43% form concentration value for K-40 are higher than the exemption level 412 Bq/Kg proposed by the UNSCEAR 2008. Moreover, the 15% of values for absorbed dose Dab were higher than public average 57 nGy/h. But annul effective dose values AED were less than recommended limits for the radiation which reported by UNSCEAR 2000 and 2008. The mean value concentration of radon was 265.96± 25.45 Bq/m3. The results of samples show that 28.27% of the radon gas concentrations and annul effective dose from radon (AEDR) in soil is higher than allowed limit recommended from International Commission on Radiological Protection agency (ICRP 2007).

Radium, shows good relationship with radon exhalation rate in soil. Good correlation observed between lung cancer per year per million people and radon concentrations for all soil samples.

To measure the knowledge levels of dentists and dental students about radiation doses of dental imaging techniques.

A structured questionnaire containing 13 questions was conducted to 251 participants (168 dentists and 83 dental students). The first 6 questions were related to their personal and professional information, and the remaining 7 questions were about the participants’ radiation education and knowledge about radiation doses. Chi-square test was used to determine the relationship between categorical variables, and P < 0.05 was considered statistically significant.

The data from 144 (57.4%) women and 107 (42.6%) men were obtained. Gender was not effective on knowledge about radiation doses during dental imaging (p = 0.222). The knowledge of dentists working at the university was statistically higher than those working in the state hospital or private dental offices (p < 0.001). Of the participants, 43.4% (n = 109) stated that the craniofacial mode of cone beam computerized tomography radiates less radiation than the actual dose range, while 32.7% (n = 82) said they had no idea.

Most of the dentists and dental students underestimated the actual radiation doses of dental imaging techniques. The dental curriculum should be revised to emphasize radiation protection during imaging. In addition, compulsory vocational postgraduate courses should be organized.

To observe the efficacy of temozolomide in combination with radiotherapy against metastatic brain tumors.

This study was a prospective, observational, open-label study, conducted in clinical practice implanted for metastatic brain tumor patients. A total of 106 patients with metastatic brain tumors were enrolled in this study, and according to the sequence of admission, they were randomized into the experiment group (temozolomide + radiotherapy) and the control group (radiotherapy). During the 24 months of follow-up, we compared the clinical efficacy, recurrence time, survival time and quality, and the adverse reactions of the patients between two groups.

Short-term remission after treatment was higher in the experimental group compared to control (P<0.05). During the 24-month follow-up, we found that patients in the experiment group had longer recurrence time and survival time than their counterparts in the control group (P < 0.05). After treatment, the scores of the life quality of patients in the experiment group were better than those in the control group (P<0.05). Also, there was a lower rate of the incidence of the adverse reactions in the experiment group (P<0.05).

For metastatic brain tumors, temozolomide in combination with radiotherapy works better as a safe and reliable strategy in prolonging the survival time, increasing life quality while reducing the adverse reactions. The strength of this study was evaluating the quality of life as an important outcome of the chemotherapy+radiotherapy regimen.

Nnewi town has undergone a marked increase in industrialization over the years. Considering the continuous disposal of automotive and hospital wastes in dumpsites within the town there is a need to ascertain the background radiation level of some of its dumpsites.

 To evaluate the level of background radiation in some selected dumpsites in Nnewi and compare the background radiation dose levels with the worldwide recommended average natural dose of 2.4mSv/yr to humans.

The levels of background radiation in these dumpsites were estimated using a well-calibrated International Medicom CRM-100 Digital Radiation Monitor (survey meter). A cross-sectional survey was adopted for this study. Following the standard procedure, the radiation monitor was held at a distance of 1.0 meters above the ground and three readings are taken at each location and the mean recorded. The Annual Absorbed Dose Rate (ADR), Absorbed Dose Rate (AD) and the Annual Equivalent Dose Rate (AEDR) were calculated. Descriptive statistics were used to summarize the data using Statistical Package for Social Sciences SPSS version 20.

 The mean of the calculated Annual Absorbed Dose Rates recorded at 21 and 24 meters was marginally greater than the accepted exposure rate for the public with the values of 1.5 mSv/year respectively. At 12 and 27 meters, the values were 1.5 mSv/year for Bank Road dumpsite respectively. Other distances were below the limit of 1mSv/year for the public and also below the dose limit of 20mSv/year for radiation workers as recommended by the ICRP.

 The radiation levels emitted from the study area were within permissible limits for the general population. Therefore there is little risk of instantaneous radiation hazard with an estimated safety zone at 6 meters from the dumpsites.

A 48-year-old male patient with a history of uremia was diagnosed with pulmonary adenocarcinoma based on a computed tomography (CT) scan and biopsy. In addition, an epidermal growth factor receptor (EGFR) exon 19 deletion was identified by gene detection. Surgical treatment was not acceptable because of his poor physical condition, so he was treated with gefitinib. Kidney function deteriorated and the serum urea nitrogen and creatinine levels were increased. Two weeks after discontinuing treatment with gefitinib, kidney function gradually returned to normal and was treated with erlotinib. This is an unusual case involving a patient with EGFR-mutated pulmonary adenocarcinoma and a history of uremia who was successfully treated with erlotinib after gefitinib-induced kidney dysfunction.

Fibrous dysplasia is a rare benign bone disorder characterized by the fibrous tissue containing trabeculae of non-lamellar bone (woven bone) and occupying normal medullary spaces. The uptake of the radiotracer in the affected bone is variable, and specificity is too low to diagnose fibrous dysplasia in the bone scan.

We are presenting four cases with monostotic fibrous dysplasia which were detected incidentally on the routine planar bone scan while being investigated for a metastatic cancer work-up. During a cancer work-up at our institution, we find lesions of fibrous dysplasia showing significantly increased uptake on the bone scan which may mimic metastatic bone lesions.

The SPECT/CT increases diagnostic confidence and improves accuracy and specificity of a planar bone scan. These cases were all asymptomatic at the one-year follow-up The subsequent bone scan and radiography studies have revealed no progression of these bone lesions.

The SPECT/CT images increase the diagnostic accuracy of the bone scan, which may avoid unnecessary surgery or overtreatment of fibrous dysplasia as bone metastasis. Abbreviation: SPECT/CT = single photon emission computed tomography/computed tomography.