International Journal of Radiation Research
Year:2017 | Volume:15 | Issue:3|Papers Count:13

Background: Querce n has been reported to modulate cell prolifera on and apoptosis. The present study aimed at iden fying whether treatment of ionizing radia on (IR) combined with querce n induces apoptosis in HepG2 cells. Materials and Methods: HepG2 cells were plated at an appropriate density according to each experimental scale and irradiated with 1, 5 and 10 Gy gamma-rays from a 60Co source at room temperature. Cell viability, SOD and CAT were assessed by using commercial assay kits. Western blot analyses were done on apoptosis related proteins. The cells were treated with various concentra ons of querce n alone or in combina on with IR. Results: The cell viability was decreased in a concentra on-dependent manner 24 h a3er treatment of querce n. It was significantly lowered a3er the combined treatment of querce n with IR than that of the cells treated with querce n alone. Moreover, querce n increased the expression of p53 levels in a dosedependent manner. Combined treatment of querce n with IR significantly increased the levels of pro-apopto c proteins, cleaved caspase-3 and caspase-7, and Bax. Cell cycle analyses indicated a dras c increase in the Sub G1 popula on a3er querce n treatment combined with IR. The ac vity of caspase-3 increased coincidently with apoptosis. The combined treatment of querce n with IR decreased catalase and superoxide dismutase ac vi es, as well. Conclusion: Querce n made the radio-resistant HepG2 cells undergo apoptosis by ac va ng p53. These results suggest that the combined treatment of querce n with IR may provide an effec ve therapeu c strategy to improve the radiotherapy efficacy.

Background: This study aims to calculate the air-kerma strength (SK), the dose rate constant (∧ ) and the dose rate profiles of a Gammamed 12i Ir-192 source by using the Monte Carlo technique and to compare the dose rate values with those calculated by the Abacus HDR treatment planning system (TPS). Materials and Methods: Air-kerma strength (in units of U; 1 U= μ Gy m2 h-1) and the dose rate constant (∧ ) of a Gammamed 12i Ir-192 source were computed with the Monte Carlo-based code MCNP. For a single dwell posi4on, profiles of dose rate per air kerma rate strength (in unit of U) along the x axis were obtained with MCNP and compared with data from the Abacus TPS at y=0, 1, and 2 cm. Results: The air-kerma strength and the dose rate constant of the source were calculated to 9. 98×10-8 U and 1. 106 cGy h-1 U-1, respec4vely. The maximum dose differences between MCNP and TPS along the x axis were found to be 1. 3, 3. 7 and 5. 4% at distances more than 1 cm away from the source center for y= 0, 1 and 2 cm planes, respec4vely. Conclusion: The dose rate profiles calculated with MCNP and by the TPS show good agreement except for points located beyond the 4p of the source.

Background: To evaluate computed tomography (CT) and magne c resonance imaging (MRI) fusion images for delinea ng gross tumor volume (GTV) in three-dimensional conformal radiotherapy (3D-CRT) of nasophanrygeal carcinoma (NPC), and compare treatment outcomes between CT-and CT+MRI-based targets. Materials and Methods: A total of 120 NPC pa ents treated with 3D-CRT were included, in which, 60 each were treated with CT-based and 60 with CT+MRI fusion targets. We explored the clinical applica on of CT+MRI fusion targets and compared the 1-, 3-, and 5-year survival and relapse rates between both targets. Results: The clinical characteris cs and treatment factors were well balanced. The differences in public volume using CT alone in the CT+MRI (Group A) and the CT arm (Group B) were not significant (33. 6± 2. 18 vs. 34. 3± 2. 98, P > 0. 05). The public volumes of GTV in the two arms were 49. 48± 2. 46 cm3 and 33. 6± 2. 18 cm3 respec vely (P < 0. 05). CT+MR fusion images did not influence the one-, three-, and 5-year survival rates (100% vs. 98. 3%, 85. 0% vs. 81. 2%, and 73. 3% vs. 68. 3%, respec vely). The three-and 5-year out-of-field progression was reduced in the CT+MRI arm. However, only the difference in 3-year out-of-field relapse rate was significant (3. 3% vs. 13. 3%; P < 0. 05). The incidence of acute toxici es was similar between groups. Conclusion: The variability in GTV delinea on in NPC was ascribed to intermodality and not interobserver variability. CT+MR fusion images likely reduced the 3-year out-of-field relapse rate.

Background: The purpose of this study was to evaluate the characteris cs of TomoDirect (TD) plans compared to conven onal TomoHelical (TH) plans in chest wall irradia on in pa ents with breast cancer. Materials and Methods: TD and TH plans for only chest wall were retrospec vely created for 30 pa ents previously treated with TH technique in our clinic. The beam angles were arranged to cover PTV chest wall and to minimize doses to OARs, ipsilateral lung and contralateral breast in TD plan. The prescribed dose was 50 Gy in 25 frac ons. Results: The mean treatment  mes were similar in TH and TD (310. 8 and 309 s, respec vely, p> 0. 05). There was no difference between the values of CI and HI of both plans (p>0. 05). The values of Dmean, V5 and V20 of the ipsilateral lung in TD plan was significantly lower than that in TH plan for all 30 pa ents (p<0. 001, p<0. 001 and p=0. 001, respec vely). V25 and V30 values of the heart were significantly lower in TH than those in TD plan in le5-sided chest wall irradia on (p=0. 006 and p<0. 001, respec vely). However, V5 values in TH was significantly higher than those in TD (p<0. 001). In the right-sided, there was no difference between two plans for V25 and V30 values of heart (p>0. 05). Conclusion: Both of TH and TD plans produce acceptable target dose coverage in chest wall RT. Considering the risk of low-dose radia on to the cri cal organs; TD mode improve dose distribu on.

Background: The purpose of this study was to assess the dose distribu on and coverage of level I-II axillary lymph nodes during whole breast tangen al field radiotherapy (RT) a er breast-conserving surgery in pa ents with breast cancer. Materials and Methods: The level I-II axillary lymph node volumes were retrospec vely contoured by a single radia on oncologist based on computed tomography simula on data from 44 pa ents who underwent breast-conserving surgery without axillary dissec on and who received postopera ve whole breast RT between January and December 2014. The dose distribu ons of the whole breast tangen al RT fields were reassessed in rela on to the axillary level I and II lymph node volumes. Results: : The average doses delivered to level I and I axillary lymph nodes were 49. 4% (range, 14. 2– 94. 6) and 30. 8% (range, 2. 6– 71. 5) of the prescribed radia on dose, respec vely. The volumes receiving at least 95% of the prescribed radia on dose were 12. 7% (range, 0– 67. 4%) for level I and 1. 4% (range, 0– 7. 7%) for level II nodes. Compared to thin pa ents, the average doses delivered to axillary lymph node levels I and II were significantly higher in overweight pa ents. Conclusion: The radia on dose coverage of axillary lymph nodes by whole breast tangen al RT varies greatly among pa ents. To safely omit axillary lymph node dissec on from the treatment of clinically axillary lymph node nega ve T1-2 breast cancer pa ents with 1– 2 posi ve sen nel lymph nodes, standardiza on and individualiza on of whole breast RT are necessary.

Background: The lack of lateral electronic disequilibrium (LED) becomes a main problem in small field. This factor affects the dose in target volume cannot predict correctly. In addi"on, u"liza"on of high-energy linear accelerator (10 MV) can emit some unwanted par"cles (electron contamina"on). Therefore, the aim of this study was to characterize head linear accelerator (linac) Varian Clinac iX 10 MV photon beam for square small field size (1×1, 2×2, 3×3, 4×4 and 5×5 cm2) using Monte Carlo (MC) simula"on. Materials and Methods: The commissioning process for this linac, has been conducted for field size 6×6, 10×10 and 20×20 cm2 by comparing the measurement and MC simula"on data. Head linac simula"on was performed with BEAMnrc and dose calcula"on with DOSXYZnrc. The phase space (phsp) data from BEAMnrc was analyzed using BEAMDP to get the par"cles informa"on in scoring plane. Results and Discussion: The sca6er angle of par"cles depends on the field size. This factor affects the penumbra width in water phantom. On the other hand, PDD data show that the depth of maximum dose and penumbra width in small field shi: ed correspond with the number of sca6er par"cle. The difference of rela"ve output factor between measurement and MC results were found less than 2%. However, the 2% difference was s"ll acceptable in photon beam dosimetry. Conclusion: From this simula"on, the electron contamina"on give contribu"on in surface dose of water phantom about 13. 0581% and less than 1% for field size 10×10 cm2 and small field size, respec"vely.

Background: This study evaluated whether IMRT using fewer beams and segments could reduce delivery  me without compromising plan quality in gastric cancer adjuvant radiotherapy. Materials and Methods: Fi een pa ents with advanced gastric cancer who underwent D2, R0 surgery were included in this study. IMRT plans for each pa ent were designed as 7 equal beams with 40 segments, 5 beams with 25 segments and 4 beams with 20 segments. The dosimetric parameters were compared for the planned target volume (PTV). The dose of normal organs at risk (OARs) was also assessed. The monitor units and treatment  mes of the different IMRT plans were calculated. Results: The 20-segment IMRT plan significantly reduced the PTV maximum dose compared to the 40-segment IMRT plan. The 20-segment IMRT plan improved le kidney and liver dose sparing in V20 and V30 as well as the 40-segment IMRT plan did and provided be4er protec on for the V20 (13. 86± 7. 78) of the right kidney, the V30 (9. 25± 4. 04) of the le kidney, the D mean (19. 68± 2. 47) of liver and D max (38. 79± 3. 57) of the spinal cord. Irradia on  mes in the 20-segment and 25-segment plans decreased by 2. 5 and 1. 9 min, respec vely, compared to the 40-segment IMRT plan. Conclusion: IMRT using fewer beams and segments reduced delivery  me without compromising plan quality in gastric cancer adjuvant radiotherapy. Fewer segments IMRT plans lowered the monitor units and the treatment  me.

Background: The aim of this study was to develop and implement a Monte Carlo framework for evalua on of pa ent specific out-of-field organ equivalent dose (OED). Materials and Methods: Dose calcula ons were performed using a Monte Carlo-based model of Oncor linac and tomographic phantoms. Monte Carlo simula ons were performed using EGSnrc user codes. Dose measurements were performed using radiochromic films. Furthermore, the applicability of this framework was examined for a 3D conformal radiotherapy of breast. Results: Commissioning of the beam model was done by comparing the measured and calculated out-of-field dose values of several points in the physical and tomographic phantoms, respec vely. The maximum percentage difference was 17%, which was smaller than 30% acceptance criteria for Monte Carlo modeling. The maximum sta s cal uncertainty in out-of-field dose calcula on was 23%. Organ equivalent doses for out of field organs in 3D conformal radiotherapy of le1 breast varied from 2. 4 cGy for right kidney to 134. 6 cGy for the le1 humeral head. Conclusion: The framework developed in this research is a valuable tool for calcula ng peripheral dose and out-of field pa ent specific OEDs, the quan  es needed for calcula ng risk of secondary cancer induc on as a result of radiotherapy. This code can be used as a pa ent specific treatment plan op miza on tool in order to select a treatment plan with the lowest risk of secondary cancer induc on.

Background: The radia on dose received by contralateral breast (CLB) is one of the concerns of breast radiotherapy, because it may lead to the induc on of secondary breast cancer. The aim of this study was to evaluate the CLB surface dose in the breast treatment in Yazd radiotherapy center. Materials and Methods: The surface dose of CLB was measured using TLD dosimetry in 50 cancer breast pa ents. The TLD chips were placed at four points on the each of CLBs. The pa ents were treated by 6MV photon beams of Oncor (physical wedge) and Compact (motorized wedge) LINAC. The TLD chips were placed on the surfaces of CLB during the medial and lateral tangent radia on fields in one of radiotherapy frac ons. Results: The mean percent of prescrip on dose of the CLB surface doses on the point 1 in the two Linac (Oncor & Compact) were significantly different. The mean of CLB surface doses of point 1 in the physical and the motorized wedge techniques were 5. 78 and 7. 84 percent of prescrip on dose of breast cancer, respec vely. The medial and lateral fields' contribu on from 7. 4% surface dose of CLB were 5. 8% and 1. 6%, respec vely. Conclusion: In Shahid Ramezanzadeh radiotherapy center, the CLB surface dose due to breast cancer radiotherapy by the Compact machine (7. 84 %) was significantly more than the allowable value (6% prescrip on dose). The CLB does due to the medial field beam was more than the lateral field.

Background: : Due to the difficul es of locally obtaining ZnS(Ag), preliminary inves ga on of the radioluminescence characteriza on of Zinc oxide (ZnO) for alpha par cle detec on was performed. Materials and Methods: The scin lla on proper es of ZnO films were tested using alpha sources (Am-241). The correla ons between ZnO scin lla on responses and irradia on me and source ac vity were also verified and compared with the response of a ZnS(Ag) detector. Results: The obtained results showed that the response of ZnO was linear with the exposure me, and the uncertainty of the repeatability was less than 1%. In addi on, ZnO was found to have good radia on resistance over a wide range of doses. Conclusion: The preliminary results may be indica ve that the proposed ZnO detector could be considered as a promising detector for alpha par cles.

Background: In this study, the health risk associated with three types of drinking waters (fissure, underground treated and surrounding waters) from two mines in South Africa were assessed. Materials and Methods: The measurement of the radionuclides concentra on was carried out by liquid scin lla on counter and alpha spectrometer. The es mated radiological risk pose to the people consuming the water types were evaluated based on the calculated radionuclide concentra ons. Results: The value of the gross alpha was 1. 08 ± 0. 02 Bq/L and gross beta ac vity was 0. 65 ± 0. 04 Bq/L in the treated underground water. These values were several fold above the limit value of 1. 0 Bq/L for gross alpha and 0. 1 Bq/L for gross beta. For the fissure water, the gross alpha ac vity value was 0. 59 ± 0. 07 Bq/L which is less than the limit of 1. 0 Bq/L and the gross beta ac vity was high with a value of 0. 54 ± 0. 05 Bq/L compared to the limit value of 0. 1 Bq/L. The results around the Princess gold mine showed very high gross alpha and beta ac vity in the collected water samples studied. In general, the concentra ons of the natural radionuclides were high especially 238U, 226Ra, 230Th, 235U, 234U and 210Po in all the water samples. Conclusion: The calculated chemical toxicity, cancer mortality/morbidity and hazards quo ent with respect to 238U were very high. Hence, the waters within these vicini es are polluted with radionuclides and may posed serious health effect to the inhabitant.

Background: The Ural region is highlighted among other Russian regions for its unfavorable radia on situa on and complexity of the overall environmental situa on. The source of man-made radioac ve contamina on is the work of the "Mayak" Produc on Associa on. A significant radioac ve contamina on has happened as a result of several radia on incidents in the early period of the company ac vity and it has affected a territory total area of over 23, 000 km2 in the Chelyabinsk, Kurgan and Sverdlovsk regions. Our primary aim is to compare the characteris cs of Heart Rate Variability among residents of the Ural region, living in the territories with different levels of radioac ve contamina on. Materials and Methods: The segment of the popula on exposed to increased radia on exposure amounted to approximately 500 thousand people. We have dis nguished three territories in the Urals region to perform a compara ve study of environmental factors (the radioac ve contamina on) on human health. Two of these territories are case territories, which are exposed to environmental hazards, and one of them is the control. Data were collected from 1992 to 1995. Results: To assess the dependence of the state of adapta on abili es of the organism exposed to radia on contamina on of the territory, we used the stress index. We determined the sta s cally significant influence of man-made radioac ve contamina on of the environment on the func onal adapta on of the body. Conclusion: Our study showed the predominance of sympathe c regula on of heart rate, which indicates the tension of adapta on capabili es of the organism for the popula on living in radioac ve contaminated areas.

Background: The activity concentrations of natural radionuclides in soil around a coal-fired thermal power plant of northwest China were investigated for assessing the radioactivity level. Materials and Methods: Soil samples were collected around the coal-fired thermal power plant and their radioactivity levels were determined using gamma ray spectrometry. Radiation hazards were assessed by radium equivalent activity (Raeq), air absorbed dose rate (D) and annual effective dose equivalent (AEDE). ResultsThe activity concentrations of 226Ra, 232Th and 40K ranged from 24. 7 to 89. 8, 38. 4 to 122. 3 and 206. 7 to 573. 8 Bq kg-1 with an average of 49. 7, 63. 5 and 396. 3 Bq kg-1, respectively. The mean Raeq value was less than the recommended limit, while the mean values of D and AEDE were slightly higher than the corresponding world average. Conclusion: The coal-fired thermal power plant enhanced the natural radiation of surrounding soil environment.