International Journal of Radiation Research
Year:2015 | Volume:13 | Issue:1|Papers Count:14

Background: The rationale was to develop an ablation approach to destroy regions of tumor resistant to radiation and thus reduce the time required for whole tumor ablation, while improving overall tumor control after radiotherapy. Materials and Methods: The system is composed of a micro positron emission tomography (mPET), 7T magnetic resonance imaging (MRI), and a customized MRI‐compatible focused ultrasound applicator. 18Ffluoromisonidazole (18F‐miso) radioactive tracer delineated hypoxic regions based on a threshold tumor/muscle activity ratio.18F‐miso PET/MRI fused images were used for targeting tumor hypoxic regions for focused ultrasound ablation. With MRI real‐time temperature imaging guidance, PET‐detected hypoxic regions of tumor could be selectively ablated to temperatures (T>55 oC). In vivo validation experiments were performed in SCK and 4T1 murine mammary carcinomas. In two tumor response assays, sequence dependence of combined radiotherapy and ablation was studied in the SCK tumor model. Tumor ablation was performed using a conductive probe or focused ultrasound and ionizing radiation administered in single doses of 15‐20 Gy.Results: Tumor growth was abolished when ablation was applied immediately AFTER radiation while interestingly; when ablation was administered immediately BEFORE radiation, there was no difference in observed growth delay compared to ablation or radiation alone.Conclusion: PET and MRI guided focused ultrasound surgery (MRgFUS) of tumor hypoxic regions is feasible and will be potentially useful for preclinical studies using ultrasound, radiation or chemotherapy. This study suggests that radiation precedes ablative therapy to avoid unwanted stress response or additional hypoxia induced by the ablation, potentially confounding the improved response potential for combined therapy.

Background: A Boron Neutron Capture Therapy (BNCT) facility, based on a DT neutron generator, with the final goal to find out a potential, alternative, solution to existing BNCT treatment facilities which are based on nuclear reactors is examined. Materials and Methods: With the aim of the MCNP4B Monte Carlo code different beam‐shaping assembly (BSA) configurations were considered. Lead was selected as reflector material while CF2, D2O, Fluental, PbF4, PbF2, BiF3, BiF5, MgF2, Al2O3, AlF3, TiF3, BeD2, CaF2 and 7LiF were examined as spectrum shitiers. In order to improve the quality of the beam titanium, nickel‐60, iron and titanium alloy (Ti6Al14V) were simulated as fast neutrons filters while lead and bismuth were considered as gamma filters.Results: An extensive set of calculations performed with MCNP4B Monte Carlo code have shown that the combination of 7LiF which accommodates a conic part made of D2O, then followed by a TiF3 layer is the optimum moderator design. The use of three different materials for further reduction of fast neutrons, thermal neutrons and gamma rays is necessary.60Ni, Cd and Bi were chosen respectively for these purposes. The epithermal neutron flux obtained at the beam exit window turned out to be 3.94×109 n cm‐2 s‐1 while fulfilling all the recommended IAEA in‐air Figure Of Merit (FOM) criteria. The assessment of the dose profiles in head phantom and the in‐phantom FOM are also presented.Conclusion: The proposed assembly configuration may provide an atiractive option for centers wishing to install a BNCT facility.

Background: The exposure of cell lines to low‐dose irradiation leads to changes at molecular level, which may induce adaptive response. We examined radio‐adaptive doses effect on human colorectal adenocarcinoma cell line (HT29) and human fetal fibroblasts (MRC5) cell line followed by hyper and hypo fractionation regimes, with main purpose to decrease cell viability in HT29, and at the same time to spare MRC5 cells.Material and Methods: The cell lines were pre‐irradiated with 0.03Gy, 0.05Gy and 0.07Gy. Two hours later, control and pre‐irradiated cells were irradiated in hyper and hypo fractionation regimes. Cell viability and the total cell number were measured.Results: Comparing the response between two cell lines in the same regime, it was found that pre‐irradiation dose of 0.05Gy increased cell viability in MRC5 cell line, accompanied with decrease of cell viability in HT29 cell line, which gave a major contribution to the main goal of the present research, i.e.to determine the dose that might spare the normal tissue.Conclusion: To our best knowledge, fractionation in several consecutive days in two designed regimes is described for the first time. These are the first reported results using low‐doses pre‐irradiation followed by hyper and hypo fractionation regimes, with approximately same biological effective dose.

Background: Increasing the complexity in modern radiotherapy techniques have increased the delivery time lowering consequently the treatment efficacy. Through simulating the delivery time delay encountered in such techniques, its’ effect on two cancer cell lines and the compensating doses given to prevent such effect was investigated.Materials and Methods: F10B16 and 4T1 cancer cell lines were exposed to simulated clinical fractionated radiotherapy procedures commonly used in complex techniques. The survival rate of the cells exposed to 2, 4, and 6 Gy of ionizing radiation with two equal subfractions given at various time intervals between the fractions (0.25‐4 hours) were determined using the MTT assay. Then, relevant compensating doses were calculated and their efficacy in counterbalancing the time delay was assessed.Results: The cells’ survival was increased with prolonged treatment times in the fractionated groups being more significant at the lower time intervals (up to 2 hours) and for the higher radiosensitive cells (4T1). Giving the compensated doses decreased the survival of the cells.Conclusion: Delivering appropriate compensating doses to the prolonged fractionated groups can counterbalance the effect of time delays encountered in complex radiotherapy techniques.

Background: 3DCRT (three‐dimensional conformal radiotherapy) and IMRT (intensity‐modulated radiotherapy) has provided us with tools to delineate the radiation dose distribution of tumor targets. However, the precision of radiation can be compromised by respiratory motion, which usually limits the geometric and dosimetric accuracy of radiotherapy. The purpose of this study is to evaluate the impact of respiratory motion on dose distributions of 3DCRT and dynamic IMRT by simulating the respiratory motion, and provide suggestions to optimize treatment planning. Materials and Methods: American Sun Nuclear Mapcheck 2D‐ARRAY was placed on a moving platform to simulate the respiratory motion. The dose distributions were measured with a Sun Nuclear Mapcheck 2D‐ARRAY on the moving platform. The motion cycle was 3.5s, the amplitude was ±3mm, ±5mm, ±10mm, ±15mm. Dosimetric distribution between 3DCRT and IMRT plans were contrasted byg‐passing rate analysis. SPSS 13.0 software was used for data processing and analysis.Results: The respiratory motion could blur the target dose distribution of 3DCRT and IMRT. The pass rate (3% 3mm) in 3DCRT was larger than that in IMRT.The Mapcheck software reflected that, the respiratory motion largely affected the marginal dose distribution of 3D‐CRT, while affected the whole target volumes of IMRT. Conclusions: Respiratory motion has a greater impact on the dose distribution of IMRT than on 3D‐CRT. As for tumors with large motion amplitude, it is advisable to use 3DCRT rather than IMRT techniques.

Background: The increasing use of nuclear radiation for human welfare necessitates the search for new, safe, cost effective radio protectors not only for the personnel’s charged with the responsibility of working or testing with radiations in laboratories, but also for general public. With this view the present study has been undertaken to determine the deleterious effects of sub lethal gamma radiation on testes and its modulation by Prunus domestica extract (PDE).Material and Methods: For this purpose Swiss albino mice were divided into five groups: (1) Control (2) PDE treated (400 mg kg-1 day-1 for 15 days) (3) Irradiated (5 Gy) (4) PDE+Irradiated and (5) Irradiated+PDE treated. Antioxidant and biochemical assays as well as histopathological analysis were performed to verify PDE radioprotective potential.Results: Radiation induced histological lesions in testicular architecture were observed more severe in all experimental groups. PDE administration before irradiation significantly ameliorated radiation induced elevation in lipid peroxidation and deficit in glutathione, protein, superoxide dismutase, catalase concentration in testes. PDE was found to have strong radical scavenging activity in 2, 2‐ diphenyl‐1‐picrylhydrazyl (DPPH*) and also showed in vitro radioprotective activity.Conclusion: The results indicate the radioprotective potential of Prunus domestica fruit extract in testicular constituents against gamma irradiation in mice.

Background: Astronauts will be exposed to both chronic space radiation and acute high doses of energetic radiation of solar particle events in long‐term deep space missions. The application of radioprotectors in space missions has basic limitations such as their very short time window as well as their acute toxicity and considerable side effects. The aim of the present study was to investigate the potential radiation mitigation effect of vitamin C that is known as an effective antioxidant and free radical scavenger. Materials and Methods: One hundred twenty male Wistar albino rats weighing 250‐300 g were randomized into the following study groups: I, control; II, Only exposure to gamma‐radiation (LD50/30); treated with a single dose of vitamin C, III, 1h before irradiation, IV, V and VI, 1h, 12h and 24 h after irradiation.Measurement of cell viability and proliferation was also performed by using MTT cell proliferation assay.Results: The survival rate in animals received vitamin C 1h, 12h and 24h after irradiation were 55%, 60%, and 80%, respectively. The viability of cells in animals received vitamin C 1h, 12h and 24h after irradiation were 94.9%, 99.0%, and 100%, respectively. The viability of the cells in animals only exposed to gamma rays was 50.1%.Conclusion: These findings reveal that a single dose of vitamin C can potentially be used up to 24 hours after exposure to reduce the detrimental effects of high levels of ionizing radiation in cases such as the occurrence of currently unpredictable solar particle events.

Background: The purpose of this study was to find the accurate absorbed dose in the femur bone marrow during the X‐ray radiography for constant mAs and AEC techniques.Materials and Methods: The DOSXYZnrc was used to simulate radiation doses in two human femurs during diagnostic radiography. EGSnrc phantoms produced from actual CT images of human femurs were modified by adding seven micrometre layers of marrow tissues. The X‐ray machine was simulated using BEAMnrc using 30 billions particles for different combinations of energies and filters. The resultant data was used to in DOSXYSnrc simulations to evaluate the absorbed dose in the human femur.Results: In the head of the femur, for 2.5 mm aluminium filtered 85 kVp X‐ray set at 50 mAs, the absorbed dose in the marrow was found to be 1.360 mGy, ~ 36% of the absorbed dose in the cortical bone. It was also found that for the constant mAs technique, the radiation dose in the marrow over the studied energies and filter combination, ranges from 0.356 mGy to 2.403 mGy, with higher dose recorded for higher kVp settings. However, for the AEC technique, the dose is lower for higher kVp settings. For a typical setting, viz.85 kVp, 6 mAs at 48 inches SID, the bone marrow absorbed dose was found to be 0.186 mGy for the constant mAs technique and 0.0308 mGy for the AEC technique.Conclusion: It was confirmed that the radiation dose is lower when the AEC exposure technique is used as opposed to using constant mAs technique. For the AEC technique, typical dose to the bone marrow was found to be ~ 0.05 mGy, decreasing with both kVp settings and beam filtration. For constant mAs technique, the typical dose to bone marrow is found to be higher, ~ 0.2 mGy, decreasing with the amount of filtration used but increasing with the kVp setting.

Background: Radioactive iodine is widely used for the treatment of various thyroid disorders. Safety issues are often a source of worry and anxiety for the patients, their families and comforters. The patients are advised to restrict their social and work related activities. The work presented in this study describes the results of a structured survey conducted on patients visiting our hospital. Materials and Methods: The total number of patients inducted was 419. The patients were asked about their housing conditions, family set up, number of children, travelling modes and travelling time back to home. The hospital leaving exposure rates from the patients were measured and radiation doses to others were estimated.Results: Patients residing in joint family system were 93%. The measured dose rate at one meter were 5.7, 11.0, 15.7, 18.7, 23.0 and 28.0 mSvh‐1 for the administered 131I activity of 185, 370, 555, 740, 925 and 1100 MBq respectively. The corresponding radiation doses to others from the patient were estimated as 0.76, 1.53, 2.29, 3.06, 3.82 and 4.58 mSv. The patients using public transport were 78.04% whereas 21.96% used private transport. There were 11.93% of the patients with no children and 88.07% of the patients had children residing with them. It was observed that 1.67% of the patients had no toilets at home and 98.33% had multiple toilets available.Conclusion: The radiation protection advice and regulatory requirements need to be formulated keeping in view the individual patient life styles and other living conditions.

Multiple primary tumors in a single patient are relatively rare when four or more distinct lesions are considered. Herein, we report a case of woman with four different primary tumors: meningioma, renal angiomyolipoma, spinal ependymoma and high‐grade soft tissue sarcoma. There was no family history and hereditary syndrome. The genetic analysis was completely normal. To best of our knowledge, the present patient is the first case in the literature, who presented with these four types of tumors.

Background: For radiotherapy of total skin including sub‐cutaneous tissue up to a depth of 3 cm on the entire left leg of an adult (Angiosarcoma skin), a complex treatment with multiple stationary electron fields was planned at our clinic. The details of dosimetry, clinical dose measurements are presented. Materials and Methods: The treatment planned with 6 overlapping 9 MeV electron fields in Clinac 2300CD linac. With 25×25 cm cone, a cut‐out insert provided 56×30 cm field at FSD 213 cm, while patient lying on the floor. Dose distributions were checked using Kodak V densitometric film in cylindrical plastic can phantom. The calibration was carried out using solid water phantom, water equivalent IMRT phantom and water can leg phantom. A dose of 45 Gy in 23 fractions at 5 fractions/week was prescribed. 6 field overlapping field factor was measured by the method described for total body electron irradiation (AAPM). Skin doses were estimated at random selected points using TLD chips and semiconductor diodes.Results: Measured absorbed doses by three methods were 0.174 cGy/MU, 0.166 cGy/MU and 0.162 cGy/MU agreed well with the calculated value 0.163 cGy/MU.6 field overlap factor was 2.315. Clinical dose estimates of mean skin dose was 246.0±14 cGy (n=18), delivering higher dose by 23%.The gonad dose estimate under shield was<5%. The excess dose to skin delivered in first 14 fractions was adjusted in following 9 fractions.Conclusion: It appears that the excess dose in real situation may be due to either floor backscatier or non uniform overlap of dose from adjacent fields.

Background: In diagnostic radiology there are two reasons for measuring or estimating radiation doses to patients. Firstly measurements provide a means for setting and checking standards of good practice as an aid to the optimization of patient protection. Secondly estimates of the absorbed dose to tissue and organs in the patients.Materials and Methods: A total of 2382 patients were studied to calculate the Entrance Surface Air Kerma (ESAK) following seven radiographic examinations including: chest (PA, Lat), lumbar spines (AP, Lat), pelvis (AP), abdomen (AP), skull (PA, Lat), thoracic spine (AP, Lat) and cervical spines (AP, Lat). The ESAKs values were measured according to x‐ ray tube output, optimized exposure parameters and body thickness (tp) for each technique.Results: The parameters such as, 1st quartile, mean, median, 3rd quartile, minimum, maximum and standard deviation of each ESAK values are reported and compared to NRPB guide levels. The results showed that the ESAKs values in the lumbar spines and chest X‐ray examinations were 30% above the guide levels. However, for the pelvis (AP), skull (PA) and abdomen (AP) examinations, these values were below than those reported by the NRPB.Conclusion: Periodic quality control and monitoring the technical performance of radiographers might effectively improve the image quality and eventually reducing the dose received by patients.

Background: Seaweeds contain significant quantities of lipids, protein, vitamins and minerals. Aquavac Ergosan contains 1% alginic acid extracted from two brown seaweeds, Laminaria digitata and Ascophyllum nodosum. Both in vivo and in‐vitro researches have mainly been focused on the effect of Ergosan on fish growth, survival rate, reproductive performance and innate immunity in blood and epidermal mucus. Despite numerous studies on the effects of Ergosan on immune system of aquatic animals and evaluation of seaweeds in proximate analysis, there is no data available on proximate analysis of irradiated Ergosan extract (alginic acid). Therefore, the aim of this study was to assess the effect of on different groups of irradiated alginic acid (10, 20, 30, 40 and 50 KGy) for analyzing proximate composition. Materials and Methods: Alginic acid was prepared from the sonicated Ergosan extract. The Alginic acid extracted from Ergosan was irradiated with a gamma cell. The protein and lipid content and Moisture and ash were recorded.Results: Statistical analysis showed no significant differences among all of groups in terms of protein, lipid, ash and moisture.Conclusion: Radiation processing is a very convenient tool for imparting desirable effects in polymeric materials. The polysaccharide degradation by gamma or ultraviolet irradiation is free of initiators. High energy radiation technique can be effectively used to decrease the molecular weight of different polysaccharides such as alginate and Chitosan. Based on the results of this study, gamma irradiation of alginic acid as natural polysaccharide had no effect on crude protein, crude lipid, moisture and ash.

Background: Uranium poses both chemical and radiological hazard to the living system. Drinking water from river is one of the major sources of uranium intake. Dissolution of minerals, washout from rain water, rock‐water interaction, agricultural run off, and industrial disposals are some of the sources of uranium in river water system. Present study was aimed to determine the uranium in the water Alaknanda and Ganges rivers and its postmonsoon spatial distribution from Nandprayag to Haridwar.Materials and Methods: River water samples were collected during the post monsoon period in pre‐washed polypropylene botiles from the designated locations at both of the rivers. Samples were filtered and analyzed by fluorimetric technique.Results: The measurements showed the concentration of uranium in water of Alaknanda river varied from 3.05 mg/l to 2.53 mg/l along the downstream sampled locations with a mean value of 2.75 mg/l, whereas in water of Ganges river the concentration varied in the range 1.70 mg/l to 2.00 mg/l with a mean value of 1.86 mg/l.Conclusion: The average concentration of uranium was found significantly higher (2.75 mg/l) in water of Alaknanda river than in Ganges river the average values (1.86 mg/l) of. However, both the values were far lower than the permissible limits at the sampled locations. The values obtained in present studies were notably higher than that reported elsewhere which seems partly atiributable to post monsoon contributing factors.