سال:1397 | دوره: | شماره: |تعداد مقالات:14

Background: Using high energy X-rays (>10 MV) as a radiotherapy boost in trea ng oropharyngeal cancers (OPC) to reduce mandible radia on exposure may result in deteriora on of disease control rates due to re-build-up of X-rays at the tumor surface. Therefore, we retrospec vely compared the treatment outcomes and toxici es in OPC pa ents treated with radiotherapy using 15 MV and/or 4– 6 MV Xrays as a boost. Materials and Methods: Between 2008 and 2014, 63 OPC pa ents received defini ve 3-dimensional conformal radiotherapy. The median total dose was 70. 2 (range, 46. 8– 75. 6) Gy. The median follow-up period for surviving pa ents was 48 (range, 9– 88) months. Twenty-one pa ents (33. 3%) received a boost employing 15 MV X-ray in at least one beam during treatment, and 42 pa ents (66. 7%) received only 4– 6 MV X-rays. Local control (LC), locoregional control (LRC), disease-free survival (DFS), overall survival (OS) rates and the incidence of osteoradionecrosis (ORN) in the mandible for the two cohorts were es mated using the Kaplan-Meier method and compared using the log-rank test. Results: There were no sta s cally significant differences between the two cohorts in either treatment outcomes (3-year LC, 81% versus 75% [p=0. 742]; 3-year LRC, 71% versus 71% [p=0. 925]; 3-year DFS, 66% versus 66% [p=0. 934]; 3-year OS, 65% versus 78% [p=0. 321]) or incidence of grade >2 ORN in the mandible (9. 5% versus 11. 9% [p=0. 883]). Conclusion: Employing 15 MV X-rays in a boost may provide comparable treatment outcomes to 4– 6 MV X-rays. However, reduc on in the incidence of ORN in the mandible was not demonstrated.

Background: To compare the following techniques for hypofrac onated whole-breast irradia on (WBI) with simultaneous integrated boost (SIB) a er breast-conserving surgery (BCS): three-dimensional conformal radia on therapy plus electron boost (3DCRT-EB), intensity-modulated radia on therapy (IMRT) plus EB (IMRT-EB), field-in-field IMRT plus EB (FIF-IMRT-EB), FIF-IMRT plus IMRT boost (FIF-IMRT-IB), IMRT plus IMRT boost (IMRT-IB), and volumetric-modulated arc therapy (VMAT) plus VMAT boost (VMAT-VB). Materials and Methods: Twenty pa ents with le breast cancer were enrolled. The prescribed dose was 40. 05 Gy in 15 frac ons to the whole breast and an SIB to the tumor bed of 3. 2 Gy/frac on (total, 48 Gy). Target-volume coverage, dose-conformity index, homogeneity index (HI), doses to organs at risk (OAR), and costs were compared. Results: FIF-IMRT-EB performed the best, while FIF-IMRT-IB, IMRT-IB, and VMAT-VB performed the worst. The mean dose to the planning target volume for breast evalua on (PTV Eval-breast) was significantly lower for IMRT-EB and FIF-IMRT-EB than for the other plans. For both PTV Eval-breast and PTV Eval-boost, VMAT-VB had the lowest target-volume coverage for 95% of the prescrip on dose and the highest target-volume coverage for >105% of the prescrip on dose. Among the six plans, VMAT-VB had the best HI for PTV Eval-boost and the highest doses to all OAR, except the coronary artery. Plans with EBs had lower mean doses for the contralateral lung and contralateral breast than plans with IMRT boosts. FIF-IMRT-EB had a low cost; plans with IMRT boosts had the highest costs. Conclusion: FIF-IMRT-EB may be the most suitable irradia on technique for hypofrac onated WBI with SIB a er BCS.

Background: The purpose of this study was to evaluate the feasibility of a mul-purpose quality assurance (QA) phantom for pretreatment verifica on of volumetric modulated arc therapy (VMAT). Materials and Methods: The QA phantom was constructed with polymethyl methacrylate (PMMA) to perform rela ve dosimetry using EBT3 film and MapCHECK, as well as absolute dosimetry using an ioniza on chamber. The QA phantom was constructed to perform rela ve dosimetry using EBT3 film and MapCHECK, as well as the absolute dosimetry using ioniza on chamber. In order to verify the pretreatment plans, 25 pa ents treated with VMAT were selected. The pretreatment plans were calculated in the Eclipse treatment planning system using the Acuros XB dose calcula on algorithm and CT images for the QA phantom, with the same beam setup and monitor units (MUs) as those for pa ent treatment. All plans were delivered to the Varian TrueBeam accelerator equipped with a high-defini on mul-leaf collimator. Results: The mul-purpose QA phantom is developed for convenient VMAT dose verifica on. By using the QA phantom, all 25 cases passed ± 3% acceptability criteria in absolute dosimetry with an ioniza on chamber for pretreatment verifica on. The rela ve dosimetry using EBT3 film and MapCHECK system also showed high agreement of more than 90% for 2%/2-mm and 3%/3-mm criteria. Conclusion: The results of this study demonstrated the good mul-purpose capabili es of the phantom for the absolute and rela ve dosimetry. Therefore, the developed mul-purpose QA phantom was applied in our ins tu on for rou ne VMRT dose verifica on.

Background: In the tube current modula on (TCM) technique, tube current is changed dynamically during the scanning process. To quan fy the effect of a dynamic tube current, a dis nct calculator is needed to es mate the CT output radia on dose in terms of volume CT dose index (CTDIvol) and individual pa ent dose in terms of size-specific dose es mate (SSDE). This study developed a specific calculator for CT scanning using the TCM technique. Materials and Methods: The tube current was extracted from the DICOM header for every slice, and averaged over the scan length. The water equivalent diameter (Dw) and SSDE values were calculated for each tube rota on. The so*ware was retrospec vely applied to 57 pa ents who had undergone abdominal and thoracic CT examina ons using a mul-detector CT, the Somatom Emo on 6. Results: The differences between the calculated CTDIvol and the CTDIvol reported by the CT scanner were 4. 4 ± 1. 2% and 6. 0 ± 2. 0% for abdominal and thoracic examina ons, respec vely. The average tube current was found to be linearly correlated with Dw with R2 values of 0. 707 and 0. 696 for abdominal and thoracic examina ons, respec vely. The average tube current was also linearly and strongly correlated with the SSDE with R2 values of 0. 941 and 0. 887 for abdominal and thoracic examina ons, respec vely. Conclusion: Calculator for es ma ng CTDIvol and SSDE specifically for TCM in CT scanning has been successfully developed. The difference between calculated CTDIvol values using this calculator and reported CTDIvol values were less than 10%.

Background: To study a enua on and increased skin dose for the iBEAM Standard couchtop, and a enua on of the BreastSTEP board, for an Elekta Compact 6 MV accelerator. Materials and Methods: Couchtop a enua on were measured for the range of gantry angles 125°-180° and field sizes 5×5-20×8 cm2. H&N extension and the BreastSTEP a enua ons measured in an 8×8 cm2 field. The couchtop effect on percentage depth-dose (PDD) measured by an EFD diode for field sizes 5×5-20×20 cm2 and compared with that produced by a Co-60 beam passing through a ‘ tennis-racket’ couch insert. A Monte Carlo (MC) model of the couchtop produced to provide more superficial PDDs. (PDDs that are more superficial) Results: Maximum couchtop a enua on (7. 6%) measured for the 135° gantry and 5×5 cm2 field. Couch extension a enua on was 1. 5% lower. Adding BreastSTEP increased a enua on by 2. 4%. MC a enua on results agreed with measurements to within 0. 2%. The couchtop removed the dose buildup effect almost completely and increased the PDD at 0. 4 mm depth by 60. 6%-74. 6%. MC-calculated PDDs at the depth range of skin basal cell layer (0. 1-0. 4 mm) increased by 55. 3%-63. 2%. The couch insert in the Co-60 beam increased the dose at 0. 4 mm depth by 18. 1%. For the same dose prescrip on at 10 cm depth, the insert in the Co-60 beam produced a skin dose 49. 7% lower than the couchtop at 6 MV. Conclusion: These results provide useful prac cal data on a enua on and skin dose increase applicable to many centres. The acceleratorcouchtop combina on creates a greater skin dose increase than a tennis-racket insert on a Co-60 unit.

Background: Modern radia on therapy such as intensity modulated radia on therapy (IMRT) and volumetric modulated arc therapy (VMAT) has resulted in using small therapeu c photon beams. The scope of this work is to inves gate the varia on in efficiency of different ioniza on chambers and semiconductor diodes in small mul-leaf collimator (MLC) defined fields of ARTISTE linear accelerator. Materials and Methods: Dose distribu ons measurements was done in field sizes ranging from 0. 5×0. 5 to 10×10 cm2 combining with Monte Carlo (MC) simula on. The treatment head of linac and the detectors were simulated by means of BEAMnrc/DOSXYZnrc of EGSnrc MC. The parameters such as output ra o (OR), penumbral width, dosimetric field size and the percentage surface dose in small radia on fields was evaluated using ioniza on chambers and semiconductor dosimeters. Results: ORs and beam profiles resul ng from various measurements showed significant difference between ioniza on chambers and diodes in small fields. Deriva on of less than 2% was observed between EDGE and Diode P. ORs vary by more than 30% for 1×1 cm2 field size but, in larger field sizes differences was less than 1%. Penumbra underes ma on was seen in Semiflex rela ve to pinpoint ioniza on chamber. No difference was seen in the pa? ern of surface dose among the applied detectors. Conclusion: Dosimetric characteris cs of different detectors showed significant differences in small photon beams. Profiles and ORs analysis with different dosimeters showed that not only water equivalency of detectors, but also dosimeter ac ve volume is important factors for determina on of dosimetric behavior in small photon beams.

Background: Calcium sennosides are the main ac ve metabolites of sennas, which have a powerful interest to phytochemical and pharmacological research, due to their brilliant medicinal values. It is well known in folk medicine for their laxa ve and purga ve uses. Materials and Methods: This experiment aimed to assess cytogene c (micronucleus assay and chromosomal aberra on study) and biochemical effects of calcium sennosides at a working dose (24 or 48 mg/ ml) on suppressing radia on hazards in human blood cultures. Biochemical inves ga ons include superoxide dismutase (SOD), catalase (CAT), tumor necrosis factor-α (TNF-α ), interleukin-8 (IL-8), cyclooxygenase-2 (COX-2) and lactate dehydrogenase (LDH) levels. The treatment periods were 48 and 72 hrs post-irradia on at a dose of 3 Gy. Triple blood cultures for each blood sample were set up. Results: Ionizing radia on exposure induced significant increase in micronuclei (MN) frequencies in both mono-and bi-nucleated cells, and all types of chromosome aberra ons, beside significant decrease in SOD and CAT ac vi es. While TNF-α , IL-8, COX-2 and LDH levels were significantly increased a: er irradia on. Treatment with calcium sennosides exhibited decreased of micronuclei and chromosome aberra on numbers and enhancement in the level of SOD and CAT ac vi es. In addi on, a significant ameliora on in IL-8, TNF-α , COX-2 levels and LDH ac vity were scored. Conclusion: Present results revealed the an mutagenic and the an-inflammatory effects of sennosides against oxida ve stress induced by γ-irradia on.

Background: Radioiodine I131 therapy (RAI) is an efficient method to decrease the func oning of very ac ve thyroid  ssues and to ablate the remnant thyroidal  ssue a er surgery and its metastases in differen ated thyroid carcinomas. Several cytoprotec ve, an-oxidant or radioprotec ve mediators have been used in trials for RAI-induced damage in other organ systems. The hypothesis of this study was that zinc would ameliorate RAI-induced histopathological parameters in the rat gastrointes nal system. Materials and Methods: A total of 30 female Wistar albino rats were separated into 3 groups of 10. First group received only 0. 003 mCi/ g of I131, second group received 0. 003 mCi/g of I131 and 0. 01 mg/g of zinc and the control group (Sham Group) were given neither I131 nor zinc. Zinc was started via gastric gavage two days before I131 administra on and con nued for five days a er RAI. At 24 hours a er the last dosage of zinc, all the animals were sacrificed and the gastrointes nal  ssues, including stomach, duodenum, ileum and colon were removed for histopathological examina on. Results: All the histopathological parameters were diminished in the I131-zinc group compared to the I131 group. The histopathological differences were sta s cally significant in respect of inflamma on and fibrosis between the I131-zinc group and the I131 group in all the evaluated gastrointes nal organs (p< 0. 05). Conclusion: The co-administra on of zinc was observed to significantly prevent RAI-induced histopathological altera ons in rats.

Background: The presence of heavy metals and radon in water are considered as a poten al threat to public health. Modern day industrializa on has led to increase pollutants in ecosystem whilst the main source of public radia on exposure, especially exposure from radon, is caused by portable water. This study aimed to es mate the health risk related to radon concentra on and heavy metals in drinking and irrigated water. Materials and Methods: Water samples, from different sources, were collected from Kulim, Malaysia and analyzed for radon and heavy metals using RAD7 and Atomic Absorp on Spectrometry. Results: Results showed that the maximum average value of radon concentra on (16. 06± 1. 7) Bq/l was found in well water used for drinking and irriga on. Minimum average value of radon concentra on (2. 65± 0. 33) Bq/l was found in tap water used for drinking purpose. From the measured radon concentra ons, age dependent associated annual effec ve doses and contribu on of radon in drinking water to indoor air was calculated which were found below the lower limit of recommended ac on level. Metal concentra ons were found higher in stream and lake waters used for irriga on, compared to well and tap waters. The average daily intake of drinking water and health risk indices were found higher for infants and lower for children and adults. Conclusion: Radon concentra ons in well, stream and lake waters were found higher than EPA recommended level and lower than WHO ac on level while the annual effec ve doses and level of heavy metals in water reported in this study were found lower than recommended levels.

Background: Oil explora on is known to have great impact on the environment due the presence of natural radionuclides in crude oil and bitumen. Materials and Methods: In this study, high purity germanium (HpGe) detector was used to determine the ac vity concentra ons of 40K, 226Ra and 232Th in bituminous soil and viscous bitumen samples collected from 5 different loca ons within the tar-sand belt of southwest Nigeria. Soil samples were collected also from a non tar-sand area to serve as control. Results: The average concentra ons of 40K, 226Ra and 232Th in the bituminous-soil samples were 139. 32, 28. 21 and 27. 13 Bq kg-1, respec vely for Agbabu, 16. 09, 18. 71 and 17. 99 Bq kg-1, respec vely for Ilubirin, 33. 98, 38. 90 and 29. 82 Bq kg-1, respec vely for Iju Oke, 35. 01, 30. 06 and 21. 52 Bq kg-1, respec vely for Ode Aye, 7. 99, 4. 77 and 4. 08 Bq kg-1, respec vely for Ode Irele. Their respec ve values were 306. 82, 23. 52 and 23. 14 Bq kg-1 for the non bituminous-soil. The natural radioac vity levels of 40K, 226Ra and 232Th in the viscous bitumen samples ranged from below detec on level (BDL)-30. 74, 2. 02-36. 33 and 3. 38-33. 71 Bq kg-1, respec vely. The es mated gamma dose rate was higher in the non-bituminous soil than that of bituminous soil. Conclusion: All the radia on hazard indices es mated in this study are lower than the acceptable limits. It can therefore be concluded that the soil and bitumen samples are safe for use as materials for building and road construc ons.

Background: Indoor and outdoor gamma radia on exposure levels were measured in a total of 360 randomly selected dwellings categorized as local, semimodern and modern buildings across Ondo State, Nigeria to determine the annual effec ve doses. Materials and Methods: All radia on measurements were taken using a calibrated Kindenoo PG-15 Geiger Muller detector and a GPS for geographical coordinates of sample points. Equal number (360) sample point measurements were carried out for indoor and outdoor measurements. Measurements at each loca on point were performed holding the survey meter at 1 m above ground surface or floor to avoid unwanted effects of radia on from soil or building floor. The detector was also held at least six to seven meters away from buildings nearby in order to avoid unwanted effects of the building materials on outdoor measurements. Each measurement was repeated six mes and the average was taken to represent the value for a sample point. Results: The average outdoor and indoor dose rates were determined as 263 ± 32 μ Svh-1 and 213 ± 64 μ Svh-1 respec vely. The highest contribu on to the total indoor dose was from the local buildings followed by semi modern buildings and the modern buildings contributed the least dose. The average annual effec ve dose was calculated as 1. 56 ± 0. 33 mSv, which is higher than the world average value (0. 48 mSv). Conclusion: In view of the poten al radia on resul ng from building materials, comprehensive assessment of natural radia ons in such materials is required.

Background: Total α-and β-as well as radium isotopes (226Ra, 228Ra) and uranium isotopes (234U, 238U) ac vity concentra ons were determined in six most popular Tunisian bo"led mineral waters samples. Materials and Methods: Total alpha/beta ac vity was measured by background gas-flow propor onal coun ng system, and the ac vity concentra ons of uranium were studied by radiochemical separa on procedures followed by alpha spectrometry and that of radium isotopes by gamma-ray spectrometry. Materials and Methods: The total-a ac vity ranged from 48 to 94 mBq L− 1 and the total-b ac vity between 45 and 430 mBq L− 1. The ac vity concentra ons of 238U, 234U, 226Ra and 228Ra in water samples varied in range 3. 3-22. 5 mBq. L− 1, 4. 0-34. 2 mBq L− 1, 2. 0-67. 0 mBq L− 1 and 2. 0-30. 2 mBq L− 1, respec vely. These values are comparable with those reported for many other countries in the world for different types of water. The 234U/238U ac vity ra o were found to be higher than 1 in all cases. Results: Based on the ac vity concentra on results obtained in this study, the es mated annual inges on dose rates for three different age groups (< 1 year, 7-12 years, and > 17 years) due to the inges on of radium and uranium isotopes through drinking water are lower than the limit of intake prescribed by WHO. The annual doses exceed the recommended value of 0. 1 mSv y-1 in one case for age group < 1 year. Conclusion: According Based on the ac vity concentra on results obtained in this study, the es mated annual inges on dose rates for three different age groups (< 1 year, 7-12 years, and > 17 years) due to the inges on of radium and uranium isotopes through drinking water are lower than the limit of intake prescribed by WHO. The annual doses exceed the recommended value of 0. 1 mSv y-1 in one case for age group < 1 year.

Background: The expression altera ons of specific miRNAs were analysed in response to gamma-irradia on in two breast cancer cell lines MCF-7 and MDA-MB-231 with low and high BCSCs content to design probable strategies for sensi zing breast cancer stem-like cells MDA-MB-231 to radia on. Materials and Methods: The expression levels of hsa-miR-34a, hsa-let-7i and hsa-miR-21 were assessed by QRT-PCR in MCF-7 and MDA-MB-231 breast cancer cells at three  me points a/er gamma irradia on using three different doses. Results: The results showed that the over-expression of hsa-miR-34a in MCF-7 cells was much more significant than MDA-MB-231 cells. Furthermore, there was a considerable overexpression of hsa-miR-21 in MDA-MB-231 cells following exposure to ionizing radia on (IR). The hsa-let-7i expression changes were different, depending on radia on dose,  me post irradia on and cell type. Conclusion: According to the results, we may be able to sensi ze stem-like MDA-MB-231 breast cancer cells to radia on by increasing miR-34a and decreasing miR-21 expression levels simultaneously.

Background: The aim of this study was to compare the radia on dose to ipsilateral lung and heart for different radiotherapy (RT) techniques including; two tangen al photon beams, electron therapy and combined photon-electron. Materials and Methods: Treatment planning of the men oned techniques on the CT images of a chest phantom was done using treatment planning system (TiGRT, Lina Tech, China). According to the plans, the phantom was irradiated with 6 MV photon and 10 MeV electron beams of Siemens Primus linac. Radia on dose was also measured using LiF Thermo Luminescence Dosimeter (TLD) which was placed inside 3 mm depth holes of ipsilateral lung and heart on the phantom. Results: The mean (± SD) radia on dose to the ipsilateral lung of the combined photon-electron was 66. 12 ± 5. 16% of prescribed dose. Whereas for the heart, it was 64. 05 ± 2. 62%. Mean (± SD) dose of ipsilateral lung and heart for electron irradia on was 54. 51 ± 3. 88 % and 34. 21 ± 3. 41%, respec vely. The mean (± SD) radia on dose to ipsilateral lung and heart of the tangen al was 50. 73 ± 3. 01 % and 31. 36 ± 3. 13%, respec vely. The mean (± SD) radia on dose to the chest wall-lung interface for electron therapy (72. 44 ± 2. 01 %) was significantly different in comparison with tangen al (65. 23± 4. 20%; p = 0. 045) and combined photon-electron (68. 14± 3. 53 %; p = 0. 032). Conclusion: Tangen al beams is more suitable for trea ng mastectomy pa ents compared to the other techniques such as electron therapy and combined photon-electron, due to lower radia on dose to pa ent's ipsilateral lung and heart.