International Journal of Radiation Research
Year:2018 | Volume:16 | Issue:4|Papers Count:14

Background: Several high-precision stereotactic radiation therapy modalities are currently used in clinical settings. We aimed to evaluate whether the CyberKnife (CK) or TrueBeam (TB) radiation treatment systems were more appropriate for treating targets of various morphologies according to the physical properties of each device. Materials and Methods: Spheres (diameter = 5– 50 mm), as well as triangular prisms and cubes (length of a side = 10– 50 mm), were used as virtual targets for each treatment delivery system. A phantom with dosimetry film was irradiated to evaluate the flatness and gradient of the radiation treatment from each modality. Results: The homogeneity index (HI) for the spherical targets was significantly higher (dose distribution was more homogeneous) using the TB than when using the CK (1. 9 vs. 1. 4; p = 0. 002). There were no significant differences between treatment modalities in the HI for more complex shapes. The HI increased monotonically as the virtual target diameter increased for the CK (p = 0. 048). The flatness parameter was lower for the TB than for the CK (1. 4 vs. 1. 1; p < 0. 001). Conclusion: The CK is particularly robust for delivering therapeutic radiation to small targets, while the TB is more suitable for targets with a simple shape or when the HI is a critical treatment factor.

Background: This study was conducted to evaluate the recurrence patterns of GBM in regard to its contact with LVs, the relation between radiation doses to subventrivular zone (SVZ). Materials and Methods: Between 2012 and 2014, 80 adult patients with GBM were included this trial. Median follow-up period was 15 months. Median tumor size was 4. 5 cm (1. 3-8 cm), where 58% of the patients had a tumor larger than 4 cm. All of the lesions were located supratentorial part of brain. Tumors were classified based on whether the mass involved the SVZ and/or LVs. Reccurrence patterns and treatment outcomes were compared. Results: Tumor progression occurred in 60 (75%) of the patients. Of those 31 (51. 6%) were in-field. Median progression-free survival (PFS) and median overall survival (OS) times were 11 and 15 months, respectively. On multivariate analysis, the negative prognostic factors were maximal surgical resection (p=0. 027), LV-invading tumor (p=0. 001) and p53 positivity (p=0. 034) for PFS. It was found that the patients receiving >50 Gy to iSVZ dose (p=0. 024) or >40 Gy to cSVZ dose (p=0. 002) or >40 Gy to bSVZ dose (p=0. 028) or >50 Gy to bSVZ dose (p=0. 008) tended to have more recurrences. Both in-field and out-field recurrences were not affected by higher radiation doses. Conclusion: LVs invading and/or location close to the SVZs can be considered as an important prognostic factor in terms of decreased PFS and OS rates. Additionally both SVZs sparing and dose escalation to SVZs approaches are required to be evaluated in further researches.

Background: The dynamic phantom is one of the best tools to study the impact of motion on tumor target delineation and absorbed dose verification during dose delivery. Materials and Methods: this study, a 6-DOF (degrees of freedom) phantom was designed following the stacked serial kinematics and assembled by six commercial motion stages to generate 6-DOF motion, which were RotX (pitch, around X), RotY (roll, around Y), TransZ (anterior– posterior), RotZ (yaw, around Z), TransY (superior– inferior) and TransX (left– right). Tumor targets were designed by six plastic spheres for the delineation test. Also, an ionization chamber array detector and RW3 solid water were combined to measure the absorbed dose for dose verification tests. Results: The maximum translation speeds for LineX and LineY were 50mm/s and 35mm/s for LineZ, while the maximum rotation speeds for RotX, RotY, RotZ were 5. 33° per second, 6° per second and 15° per second respectively. Spiral-CT and 4D-CT images acquired in the static and dynamic states successfully showed the influences of tumor motion on target delineation. In the absorbed dose verification, all cases did not pass the gamma test; the pass rate for the 6-DOF motion case was only 34. 2% and the pass rates of all other cases were less than 90%. Conclusion: The phantom designed in this study is able to simulate complex tumor motion and can be used to study the influence of tumor motion in radiotherapy.

Background: the increasing use of mobile phones in daily life causes many concerns about their effects on human health. Therefore, this work was designed to study the effects of exposure to 1800 MHz electromagnetic waves (EMW) on the liver and intestine of male albino rats and the protective role of ferulic acid (FA) against these harmful effects. Materials and Methods: twenty-four male albino rats were randomly divided into four groups as follows: 1) control group, 2) treated group given FA, 3) irradiated group exposed to 1800 MHz EMW and 4) treatedirradiated group given FA then exposed to EMW. Biochemical analysis and histopathological examination were performed. Results: a significant increase in serum activities of alanine transaminase and aspartate transaminase, and serum levels of interleukin (IL)-6 and tumor necrosis factor-α was shown in the irradiated group, while IL-10 was significantly decreased. There was a significant decrease in lactate dehydrogenase and total antioxidant capacity in the tissues of liver and intestine of this group as well as some histopathological changes. All these serum and tissues parameters and histopathological changes were improved in the group treated with FA before exposure to EMW. Conclusion: prolonged exposure to EMW emitted from mobile phones might produce harmful effects in the liver and intestinal tissues of albino rats. These effects can be prevented by FA administration which may be protective against tissue damage induced by EMW through the suppression of oxidative stress.

Background: With the development of technology, human beings are increasingly under the exposure of Radio Frequency Radiation (RFR) (due to wireless technologies, mobile phones, base stations etc). The aim was to investigate the possible effects of Radio Frequency Radiation (RFR) on blood, aorta and heart tissue in hypertensive and non-hypertensive rats with various parameters. Materials and Methods: Male Wistar Albino rats were divided into 4 groups: 1. Control (C), 2. Hypertension (H), 3. RFR, 4. RFR+Hypertension (RFR+H). 60 mg/kg L-Nitroarginine Methyl Ester (L-NAME) was administered for 1 month by oral gavage to induce hypertension. The rats were exposed to 2100 MHz RFR for 60 minutes/day, 5 days/ week for 8 weeks. Blood hematocrit, blood and plasma viscosity, malondialdehyde (MDA), total nitric oxide (NOX), and Total sulphydril groups (RSH) / glutathione (GSH) levels in plasma and heart tissue were determined. Histological examination of the aortic wall and left ventricular muscle was performed. Results: RFR exposure resulted in a marked increase in cardiac and plasma MDA and NOX levels and a decrease in RSH/GSH levels (p<0. 05). Blood viscosity increased in the hypertensive group with RFR exposure (p<0. 05). There was an increase in left ventricular weight and number of muscle cells in hypertensive groups (p<0. 05). Conclusion: According Our study suggests that exposure to RFR causes more negative effects on hypertension in terms of oxidative stress and antioxidants in the heart and plasma. Also, RFR exposure showed more prominent left ventricular fibrosis and aortic degenerative effects in hypertensive groups.

Background: The present work aims to determine the activity concentrations of 226Ra, 233Th and 40K in soil samples collected in Mounana in the Southeastern region of Gabon, to evaluate the contribution of the natural. Materials and Methods: An HPGe p-type detector coupled with a multichannel analyzer DSA-1000 was used to perform measurements and process data. Data acquisition and analysis were made possible using Genie 2000 software version 2. 1 and detector was calibrated using the IAEA certified soil reference standard material multigamma (No71863/3). Results: The activity concentrations of 226Ra, 232Th and 40K varied respectively from 12 ± 03 Bq kg-1 to 23022 ± 2572 Bq kg-1, 12 ± 04 Bq kg-1 to 265 ± Bq kg-1 and64 ± 13 Bq kg-1 to 811 ± 74 Bq kg-1with means values of 2811 ± 198Bq kg-1, 63 ± 14 Bq kg-1 and of 355 ± 93 Bq kg-1wet weight. In order to assess the radiological risks due to primordial radionuclides in Mounana, the absorbed dose rate, effective dose, radium equivalent and external hazard index were estimated. Conclusion: Absorbed dose rates which have been calculated for each site varied from 26. 12 nGy h-1 to 10817. 99nGy h-1 with a mean value of 1352. 76 nGy h-1. The mean value of annual effective dose was estimated to be 10. 96 mSv y-1 from the studied area. The areas investigated in this study showed a strong radioactive contamination of sites inhabited by populations.

Background: Inspection of the level of radioactivity from radionuclides in soil is important for the assessment of the exposure to natural radiation. Materials and Methods: Ten samples from soil were collected from different sites of Kirkuk-IRAQ and the level of natural radioactivity was measured using gamma-ray spectrometry based on a high purity germanium (HPGe) detector. Results: It was found that the specific activity ranged from 27. 4 to 57. 0 Bq kg− 1 for 226Ra, from 11. 0 to 25. 4 Bq kg− 1 for 232Th, and from 207. 4 to 516. 0 Bq kg− 1 for 40K. The results have been compared with the average values worldwide. The hazard indices have also been calculated. In general certain average values were found to be lower than the world average values; these included the average value of the radium equivalent activity (Raeq), the absorbed gamma dose rate (D), the external and internal hazard Hex and Hin, the gamma radiation representative level Index (Iγ ) and the outdoor and indoor annual effective dose rate (AEDE) Conclusion: In general there are no harmful radiations effects posed to the population who live in the study area; however there are some spots which have values higher than the internationally allowable values.

Background: Positron Emission Tomography-Computed Tomography (PET-CT) is a useful hybrid imaging modality in the diagnosis of various malignancies. This modality imposes almost 20 mSv radiation dose to the patient. The purpose of the present study was to evaluate the uncertainties in calculated CT effective dose in TUBE CURRENT MODULATION-activated scans by Impact-Dose software. Materials and Methods: Sixty total body DICOM (30 male and 30 female) whole body PET-CT images were selected. Volume CT Dose Index (CTDIvol) was recorded for each of the procedures. The image was divided into 5 regions of head & neck, chest, abdomen, pelvis and lower limbs according to special anatomical markers. Effective doses for total body and separate organs were calculated by means of Impact-Dose software once with global CTDIvol and once with a summation of doses calculated by 5 Regional CTDIvol and related scan ranges. Results: The difference among effective doses for some organs and total body were considerable. The mean and standard deviation (SD) of the coefficient of variations (CV%) for total body, breast, gonads, liver, lung, red bone marrow (RBM), thyroid, kidneys, and uterus were 12. 56, 11. 61, 9. 44, 8. 1, 11. 31, 5. 93, 8. 61, 6. 03 and 12. 49, respectively. Uncertainties were higher for smaller patients by 19 noise indexes while these changes were higher for bigger patients and 22 noise indexes. Conclusion: The tube current variation depends on the acquisition and patient parameters. For measuring and reporting the total body and organs’ effective doses in order to estimate the risks of CT’ s radiation for total body PET-CT procedures, the tube current variations must be considered.

Background: In this study, human absorbed dose of a newly introduced bone imaging agent, 68Ga-(4-{[(bis(phosphonomethyl))carbamoyl]methyl}-7, 10-bis (carboxymethyl)-1, 4, 7, 10-tetraazacyclododec-1-yl) acetic acid (68Ga-BPAMD), was estimated based on the rats data. Materials and Methods: 68Ga was obtained from the 68Ge/68Ga generator and it's radionuclidic and radiochemical purities were investigated. 68Ga-BPAMD complex was prepared at optimal conditions and the radiochemical purity was studied using instant thin layer chromatography (ITLC) method. The final preparation was injected to the normal rats and the biodistribution of the complex was followed up to 120 min post injection. The accumulated activity for animal organs was calculated. Finally, the human absorbed dose of the complexes was estimated by RADAR method. Results: 68Ga-BPAMD complex was prepared in high radiochemical purity (>99%, ITLC) at optimal conditions. The biodistribution of the complex demonstrated that the main remained radioactivity would considerably accumulate into the bones. The results showed the highest amounts of absorbed dose on the bone surface (0. 253 mGy/MBq) and in the bone marrow (0. 250 mGy/MBq), while the other organs would receive an insignificant absorbed dose after injection of the 68Ga-BPAMD complex. Conclusion: The comparison of dosimetric results for 68Ga-BPAMD with other complexes shows this complex is a safer agent for bone scanning. This property as well as other characteristics such as the high resolution images of the positron emission tomography (PET) scanning and the availability of 68Ga in the form of 68Ge/68Ga generator, make this complex as a suitable agent for PET bone imaging.

Background: Post-operative fibrosis related pains and functional anomalies can be serious problems for patients. Radiotherapy (RT) could inhibit fibrosis which may occurs post-operation especially following laminectomy. Therefore, this study was designed to investigate the effect of peri-operative RT on the prevention of post-operative fibrosis and scar formation on rats. Materials and Methods: Twenty three male Wistar albino rats, were divided into three experimental groups. Laminectomy was performed to L3 and L4 lomber vertebral regions of group L and L+R rats. The rats in L+R group in addition to this procedure also received peri-operative RT on the laminectomy area. A total dose of 700 cGy of RT was applied as a single fraction using electrons. Control rats received no treatment. A rotarod test was performed at 20, 30 and 40 rpm/min speed rates to determine the physical performances of the rats. Results: The results have indicated statistically significant (P<0. 05) differences for the 30 rpm/min rotarod test between the L and L+R groups. Histopatologically, significant differences were observed in epidural fibrosis, fibroblast cell density and arachnoid adhesion between the L and L+R groups. Conclusion: It was concluded that peri-operative RT may provide a significant advantage for prevention post-laminectomic of scar tissue formation.

Background: Exposure to electromagnetic radiation may impair memory. This study was conducted to evaluate the effect of radiofrequency wave (hereafter referred to as RFW) on passive avoidance learning and memory in healthy males and females. Materials and Methods: Ten adult male and ten female Sprague-Dawley rats (230± 20 gr) were randomly divided into four groups including two control groups (one for males and one for females), and two experimental groups (exposed to 900 MHz radio frequency wave) each representing one gender. The exposure was performed for 30 consecutive days (4h/day). Evaluation of learning and memory of the rats started on the last day of exposure by shuttle box. Learning and memory of animals was recorded by the period of time they remained within the light area; this time was called the light time. Results: Results of the study showed that exposure to RFW significantly decreased the duration of light time in the rats within the experimental groups as compared to the control groups (P<0. 05). Exposure to RFW significantly decreased the light time in females in comparison to males in the experimental group (P<0. 05). Histological study of brain section did not show significant changes between groups. Conclusion: With regard to these findings, it was concluded that exposure to RFW causes disorder in memory retention of passive avoidance learning in rats. The extent of damage to the learning and memory in rats exposed to RFW was more for females than males.

Background: Commissioning tests are recommended before implementing Intensity Modulated Radiation Therapy. This study evaluated five different plans of IMRT mocks for different modulation indices. Materials and Methods: IMRT tests were done in slab phantom for both 6MV and 15 MV photon energies using a 2D array ion chamber dosimeter. Results: The acceptance criteria were based on 3% /3mm. All tests passed the gamma criteria except for the prostate test with 15 MV photon beams and C shape test for both 6 MV and 15 MV energies. The Ratio passing points for Multi target test in 6 MV and 15 MV plans were 93. 1% and 91. 5%, respectively. The results of the prostate tests with 3%/3mm was 92. 3% for 6MV and 91. 2% for 15 MV in 4%/4 mm tolerance limit. For Head and Neck test with the same gamma criteria, the percentages of the points were 93. 2 and 94 for 6 MV and 15 MV plans, respectively. For C shape tests, the used gamma criteria were 4%/ 4 mm. The ratio passing points were 94. 9% and 94. 3% for 6MV and 15MV plans, respectively. However, C shape hard test could not pass the gamma criteria of 4%/ 4mm for 6MV. Conclusion: results showed that by increasing the complexity of the IMRT plan, the verification test must be done in a more strict-manner, because a small change in dose delivery can cause a large discrepancy between planned and real dosimetry and may produce hot spots in organs or a cold spot in the target volume.

Background: Skyshine describes the radiation scattered by the atmosphere above a LINAC facility to a point on the ground. The aim of this study was to measure the skyshine photon dose rates from two different (9 MV and 18 MV) medical linear accelerators. Materials and Methods: The photon beam was directed upward (180° gantry position), with a maximum photon field size (40 × 40 cm2) at the isocenter. Measurements were obtained around the external points selected outside the room facilities at a horizontal distance from the target by the calibrated RDS-110 survey meter at four points around the isocenter. Results: The measured values of the skyshine photon exposure rates at four points for 9 MV and 18 MV were 0. 6, 0. 5, 0. 5, and 0. 4 μ Sv/h, and 0. 6, 0. 4, 0. 4, and 0. 5 μ Sv/h, respectively. All the measured skyshine photon exposure rates were lower than the values recommended by NCRP 147. Conclusion: There is a poor agreement between the measured and the calculated values; therefore it seems that caution is needed while using the equations available in NCRP 147 or 151.

A 17-year-old boy with hyperparathyroidism exhibited a large cyst in the left hemi-thorax on his chest X-ray. The cyst was identified as a hydatid cyst. He was referred for biphasic methoxy isobutyl isonitrile (MIBI) parathyroid scan. A discrete ectopic parathyroid was detected in the left upper mediastinum in addition to accumulation of the MIBI tracer in the cyst wall. Using radio-guided occult lesion localization with an injection of 3 mCi 99m Tc-MIBI in the morning of the operation day, an ectopic adenoma was detected with a gamma probe within the thymus, resected with a consequent decline of serum high parathyroid hormone (PTH). This report is remarkable in two different aspects: the importance of radio-guided localization of ectopic adenoma, which in this case was within the thymus, and the accumulation of MIBI in hydatid cyst wall, as a unique report of this condition.