International Journal of Radiation Research
Year:2016 | Volume:14 | Issue:2|Papers Count:13

Background: Aim of this study is to evaluate the accuracy of the gated volumetric modulated arc therapy (VMAT/RapidArc) using 2D planar dosimetry, DynaLog files and COMPASS 3D dosimetry system.Materials and Methods: Pre-treatment quality assurance of 10 gated VMAT plans was verified using 2D array and COMPASS 3D dosimetry system. Advantage of COMPASS over 2D planar is that it provides the clinical consequence of error in treatment delivery. Measurements were performed for non-gated and different phase ga.ng window level (80%, 50%, 30% & 20%) to know the impact of ga.ng in VMAT dose delivery.Results: In 2D planar dosimetry, gamma agreement index (GAI) for all measurements were more than 95%.DynaLog file analysis shows the average devia.ons between actual and expected posi.ons of monitor units, gantry and mul.-leaf collimator. The STDVs MU and gantry posi.on were less than 0.10 MU and 0.33o respec.vely.Root mean square (RMS) of the devia.ons of all leaves were less than 0.58 mm. The results from COMPASS show that 3D dose volume parameters for ten pa.ents measured for different phase ga.ng window level were within the tolerance level of ±5%. Average 3D gamma of PTV and OAR’s for different window level was less than 0.6.Conclusion: The results from this study show that gated VMAT delivery provided dose distribu.ons equivalent to non-gated delivery to within clinically acceptable limits and COMPASS along with MatrixEvolution can be effec.vely used for pretreatment verifica.on of gated VMAT plans.

Background: Local ablave treatments play an important role for paents who cannot be treated surgically. Radiofrequency ablaon is a well-established alternave to surgical treatment of thyroid nodules, however it also has disadvantages. Microwave ablaon (MWA) is a new minimally invasive treatment promising several improvements. The aim of this retrospecve study was to evaluate the effects of microwave ablaon on thyroid nodules by99mTc-pertechnetate and 99mTc-MIBI scingraphy.Materials and Methods: 30 paents with overall 40 nodules were treated.For the ablaon of thyroid nodules, a microwave generator working with frequencies from 902 to 928 MHz was used. The ablaon me ranged between 120 and 300 seconds per ablaon zone. The target temperatures ranged between 60-80oC. Pre- and post- intervenonal, the radionuclide uptake was determined using a thyroid specific scinllaon camera. For 27 cold nodules99mTc-MIBI was used for evaluaon; 13 indifferent nodules were measured with99mTc-pertechnetate.Results: The relave change of uptake was detected as a quoent of pre- and post- therapeuc uptake. The stascal analysis of scingraphy data proved the efficacy of microwave ablaon.99mTc-pertechnetate scingraphy showed an uptake reducon of 39% (range 9 to 85%).99mTc-MIBI imaging showed a median reducon of 40% (p<0.01) (range 7 to 100%).Conclusion: The determined results show the effecveness of MWA as a treatment opon for benign thyroid nodules. With funconal scingraphy a significant acvity decrease could be detected in the ablaon zone; hence a verificaon of affecvity was possible a=er a short period of me.

Background: Radiaon absorbed dose to the red bone marrow, a crical organ in the therapy of thyroid carcinoma, is generally kept below 2 Gy for non-myeloablave therapies. The aim of this study was to calculate bone marrow radiaon dose by using MIRDOSE3 package program and to opmize the safe limit of acvity to be administered to the thyroid cancer paents.Materials and Methods: In this study, 83 thyroid cancer paents were divided into 3 groups based on the amount of acvity administered into the body. In the groups, 3700 MBq, 5550 MBq and 7400 MBq acvies were used respecvely. The curves of me-acvity were drawn from blood samples counts and effecve half-life and residence me were calculated. Correlaons of bone marrow radiaon dose and radioiodine effecve half-life were determined as a funcon of administered acvity via ANOVA test. Tg levels and tumour diameters were compared using Spearman’s correlaon.Results: The effecve half-lives of131I for three groups of whole-body, receiving 3700 MBq, 5550 MBq and 7400 MBq were calculated as 20.57±5.4, 17.8±5.8 and 18.7±3.9 hours, respecvely. The average bone marrow doses for 3 groups of paents were 0.32±0.08 Gy, 0.42±0.14 Gy and 0.60±0.24 Gy, respecvely.Conclusion: It was concluded that, the bone marrow dose to the paents sll remains within the recommended level even a9er administering an acvity of 7400 MBq of131I to the paents.

Background: The varia on of the radon progeny concentra on in outdoor environment and meteorological parameters at fine resolu on were studied for one year at a con nental loca on, Na onal Atmospheric Research Laboratory, Gadanki, India.Materials and Methods: The concentra ons were measured using Alpha Progeny Meter by collec ng air samples at a height of 1 m above the Earth’s surface at a known flow rate.Results: Radon progeny concentra on shows temporal varia ons on diurnal and monthly scales, and is due to mixing in the atmosphere. Peak in the early morning hours and low values during a*ernoon compared to nigh+me are due to differen al heat contrast between earth’s surface and its atmosphere. However, the ac vity during February shows maximum compared to June/July months. The diurnal varia on of radon progeny shows posi ve correla on with the rela ve humidity and nega ve correla on with ambient temperature. The monthly mean ac vity of radon progeny for the year 2012 was found to be 4.76 ± 0.73 mWL.Conclusion: The mean concentra on of radon progeny in the study region is rela vely high compared to the other loca ons in India and may be due to the rocky terrains and trapping of air-masses near the observa on site due to its topography.

Background: Hydrogen has been demonstrated can selecvely reduce the hydroxyl, which is the main cause of ionizing radiaon-induced damage.Amifosne (AM) is the only radioprotecve drug approved by the U.S. Food and Drug Administraon for use in radiotherapy. The purpose of the present study was to invesgate the combined radio-protecve effect of hydrogen rich water (HRW) and AM.Materials and Methods: Male ICR mice were treated intragastrically with HRW or/and intraperitoneally with AM 30 minutes prior to 9.0 Gy whole body irradiaon from a60Co source (dose rate 0.96Gy/min). Then the survival rate for 30 days, the hematological parameters, the Clinical chemistry parameters and the bone marrow nucleated cells were examined.Results: We found that the mice treated with HRW and AM before irradiaon could increase the 30-day survival rate and improve the body weight be2er than the HRW or AM treatment alone group and irradiaon alone group. Hematological test and Clinical chemistry assays also showed the same results that HRW combined AM could be2er improve the recovery of hemopoiec system and alleviate the detrimental effects of radiaon.Conclusion: The results indicate that the combined applicaon of HRW and AM may be a be2er method for radiaon therapy.

Background: New treatment modalies are developed with the aim of escalang tumor absorbed dose and simultaneously sparing the normal structures. The use of nanotechnology in cancer treatment offers some possibilies including destroying cancer tumors with minimal damage to healthy ssues. Zinc Oxide nanoparcles (ZnO NPs) are wide band gap semiconductors and seem to have a good effect on increasing the absorbed dose of target volume especially when doped with a high Z element. The aim of this study was to evaluate the effect of ZnO NPs doped with Gadolinium (Gd) on dose enhancement factor by 6MV photon beam irradiaon.Materials and Methods: Various concentraons of ZnO NPs doped with 5% Gd were incorporated into PRESAGE composion, the 3D chemical dosimeter. Then by using a UV-Vis spectrophotometer opcal density changes and also dose enhancement factor (DEF) were determined.Results: The results of this study showed that by incorporang 500, 1000, 3000 and 4000 mg/ml ZnO NPs doped with Gd into PRESAGE structure the dose enhancement factor of about 1.57, 1.69, 1.78 and 1.82 in a 15 ×15 cm2 field size could be found, respecvely.Conclusion: The results of this study showed that ZnO NPs doped with Gd could be considered as new compound for increasing the absorbed dose.

Background: It has recently been shown that the parcle size of materials used for radiaon shielding can affect the magnitude of radiaon aenuaon.Over the past years, applicaon of nano-structured materials in radiaon shieldinghas aracted aen on world-wide. The purpose of this study was to invesgate the shielding properes of the lead-free shields containing micro and nano-sized WO3 against low energy x-rays.Materials and Methods: The radiaon shields were constructed using nano and micro WO3 parcles incorporated into an EPVC polymer matrix. The aenuaon coefficients of the designed shields were evaluated for low energy x-rays (diagnosc radiology energy range).Results: The results indicate that nano-structured WO3/PVC shields have higher photon aenuaon properes compared to those of the micro-sized samples.Conclusion: Our experiment clearly shows that the smaller size of nano-structured WO3 parcles can guarantee a beer radiaon shielding property. However, it is too early to draw any conclusion on the possible mechanisms of enhanced aenuaon of nano-sized WO3 parcles.

Background: Radiology staff needs to jusfy the radiaon exposures in order to protect themselves and others from radiaon risks. The aims of this study were to examine the awareness level of radiaon dose and protecon amongst radiographers and to compare their performance between major Jordanian hospitals.Materials and Methods: A cross-seconal survey was conducted in 4 major Jordanian hospitals. A total of 85 radiographers agreed to parcipate in the study. The quesonnaire included demographic informaon, general radiaon protecon, radiaon dose esmaon and radiaon induced cancer risk secons.Results: The average total score of radiographers in all hospitals was less than 50%. The lowest score was for radiaon induced cancer quesons secon (34%). There was no significant difference in the level of awareness between radiographers from different hospitals except for the radiaon dose awareness secon (p=0.001).Experience and training courses did not correlate significantly with the total score or with the score of individual secons.Conclusion: The level of radiaon dose and protecon awareness amongst radiographers in the sampled Jordanian hospitals is inadequate. At this stage, establishing an annual assessment of the radiographer’s awareness through the Jordanian naonal radiaon agency is highly encouraged.

Background: The aim of the study was to esmate the radiaon dose during emergency exposure to paents treated with iodine-131 during the isolaon period.Materials and Methods: The dose rate from a sample of 192 paents administrated by three different radioacvity of 131I (3.7, 5.55 and 7.4 GBq) was measured, at 1 meter a+er 1, 24 and 48 hours post dose administraon, at three different levels from the paent body (thyroid glands, abdomen and knee). The average of decay curve of the measured radiaon dose rate was plo.ed and their values were fi.ed. The medical emergency exposure was esmated in the form of an equaon to take into account the duraon and the posion of the intervenon.Results: The esmated radiaon doses received during 10 minutes of intervenon emergency at a distance of 20, 40 and 60 cm from paent a+er different mes post dose administraon were in the range of 72.2 to 1207.5, 18.1 to 301.9 and 8.0 to 134.2 mSv, respecvely.Conclusion: During the first ten hours following paent dose administraon, the esmated emergency dose could be considered as high occupaonal dose value compared to the dose limit recommended by ICRP.

Background: To evaluate the risk involved, there is need to know the quantum of personnel exposures in whole service. Dose reports from an Oncology Centre over 7 block periods, 5 years each from 1979 till 2013 are analyzed.Materials and Methods: Personnel monitoring (PM) reports till 1990s with film badges and later thermoluminescent (TL) badges (CaSo4.Dy) were evaluated.35 years total service was taken to represent total professional service of staff superannua$ng at age 60 years.Results: Mean personnel equivalent dose for 5 year block period is 3.30±0.43 mSv (n=7 blocks). Maximum dose in any block period was 30-60 mSv. Equivalent doses 22% were zero, 64.3% within 5 mSv.2.1% were above 30 mSv in 5 year periods. Doses were decreasing order 11.8 mSv (radiopharmaceutical preparation), 4.3 mSv (nuclear medicine), 4.1 mSv (medical physics), 2.2 mSv (brachytherapy); 1.2 mSv (radiodiagnosis), 1.1 mSv (external beam radiotherapy) and 0.73 mSv (radia$on sterilization plant).Conclusion: The whole body personnel dose in are much lower than recommended annual dose equivalent limits of 100 mSv/ 5 years. The magnitude of recorded doses to staff show that the risk is negligible and the principle of ALARA is being prac$ced in the work areas.

Background: Radiochromic film is used for radiaon dose measurement, XRRV3 is used in fluoroscopy and EBT2 film in radiaon therapy. The aim was to determine if the dosimetric properes of these two films are comparable in megavolt photon beams.Materials and Methods: Comparison measurements included: calibraon curves, heterogeneous phantom dose profiles, and nasopharynxdose distribuon measurement.Results: Both film types required 24 hours to stabilize. Their heterogeneous phantom dose profiles were similar, and their dose distribuons for a nasopharynx treatment were within 3%/3mm.Conclusion: Dose distribuons between both films showed good correlaon and XR-RV3 film can be used in radiotherapy for quality control checks.

Background: An early diagnosis of breast cancer relates directly to an accurate treatment plan and strategy. Early detecon of breast cancer before its development would be a significant reducon of morbidity and mortality rates. The aim of this preliminary study is to invesgate the sensivity of Wide Angle X-ray diffracon (WAXRD) method on women hair samples of healthy and breast cancer paents in comparison with other modalies such as synchrotron based XRD beam and mammography.Materials and Methods: Hair samples were taken from occipital region of skull from healthy and breast cancer paents (43 women) were analyzed using X-ray diffracon and the results wereanalyzed and compared with mammography and pathology reports.Results: The results of analyzed samples showed the sensivity for purposed WAXRD method was 86% in comparison with synchrotron based XRD beam (64%) andalso with mammography (70%).Conclusion: This non-invasive method is less harmful and is more sensive than the two other methods and help the physicians for choosing accurate treatment plan.

Background: This study set out to evaluate the ulity of cerebrovascular virtual non-contrast (VNC) scans.Materials and Methods: Convenonal non-contrast (CNC) and dual-energy computed tomography angiography (DE-CTA) head scans were conducted on 100 subjects, of which 46 were normal, 15 had parenchymal hematomas of the brain, 13 had ischemic infarcon, 22 had tumors, and 4 had calcified lesions. VNC images were extracted from the DE-CTA head scans by post-processing. The true (or convenonal) and VNC images were compared in terms of the mean CT a.enuaon value and signal-to-noise rao (SNR) of the cerebral parenchyma, the image quality, the lesion detecon sensivity, and the radiaon exposure level.Results: The image qualies of the CNC and VNC scans were (4.95 ± 0.22) points and (3.94 ± 0.24) points (t=31.18, P<0.05), the mean CT values for the CNC and VNC images were (34.6 ± 2.44) and (28.6 ± 5.40) HU (t =10.126, P<0.05), the SNRs were (9.45 ± 1.26) and (6.87 ± 1.77), and the HU for white ma.er was (t=11.859, P<0.05), respecvely. The effecve radiaon doses from the DE-CTA head scans and the convenonal non-contrast scans were (8.55 ± 0.57) mSv and (9.41 ± 1.00) mSv, respecvely. No significant difference in the lesion detecon sensivies was observed between the CNC and VNC scans, except for ny calcified lesions, which could not be idenfied by a VNC scan.Conclusion: VNC and contrast-enhanced images could be obtained from DE-CTA head scans and could aid in the diagnosis of cerebral lesions. The radiaon dose from the VNC scan was less than that from the CNC scan.