International Journal of Radiation Research
Year:2018 | Volume:16 | Issue:1|Papers Count:16

At the close of the 20th century, fundamental discoveries changed broadly the worlds of physics, biology and medicine. The rapid advancements achieved during recent years, mainly due to revolutionary methodological improvements, have led to an unparalleled explosion of information; often appear to overshadow the earlier works. However as more basic discoveries are made these separate scientific eras merged to contribute to the conquest of disease, especially cancer. The exponential growth of data has been so impressive that the conceptual evaluation of the material has seemed almost an insignificant part of the scientific process. All these achievements have allowed researchers to ask new questions or to rephrase old ones. The result is a virtual avalanche of new formed knowledge.

Background: To determine the basic physical and dosimetric properties of a new synthetic single-crystal diamond detector and its application for relative small field dosimetry. Materials and Methods: The pre-irradiation dose required to stabilize detector response, dose rate dependence, photon and electron energy dependence, temperature dependence and angular dependence of MicroDiamond detector response were evaluated. Output factors on Leksell Gamma Knife Perfexion and on CyberKnife were measured to assess detector feasibility in small radiation field dosimetry. For all measurements, the detector was connected to Unidos electrometer set to 0 voltage. Results: Relative output factors measured on Leksell Gamma Knife Perfexion for 4 mm and 8 mm collimators were in agreement with Monte Carlo reference values from the manufacturer, with deviations of 0. 3% and 2. 1%, respectively. For CyberKnife and fixed circular collimators, the difference in output factor values did not exceed 2% from vendor-supplied values, even for the smallest radiation field with a diameter of 5 mm. Conclusion: Our results indicate that the MicroDiamond detector is a promising tool for relative small field dosimetry. For output factor measurements on Leksell Gamma Knife Perfexion and CyberKnife, the detector can be used with minimal response corrections applied (correction factors not larger than 2%).

Background: In this study, we retrospectively reviewed the treatment outcome of 63 patients with T1 early glottic cancer treated with RT alone to determine the treatment outcome and the prognostic factors affecting local control. Materials and Methods: All patients were treated by 6 MV photons with conventional bilateral fields up to a median dose of 66 Gy in 33 fractions. Results: The 5-year local control rate and overall survival were 77. 7% and 93. 1%, respectively. The total radiation dose with a cut-off value of 66 Gy was a significant prognostic factor for local control. The 5-year local control rate was 54. 5% in patients treated with less than 66 Gy compared to 85. 7% in patients treated with 66 Gy or higher dose (p = 0. 014). In subgroup analysis, in patients who received 66 Gy or higher doses, all recurrences developed in whose overall treatment time was 49 days or longer, although the statistical significance was marginal (p = 0. 066). Conclusion: This study showed that a total dose of 66 Gy or higher is required for the treatment of T1 glottic cancer, and delivering the total dose within 49 days seems important for local control.

Background: Field-in-field (FIF) technique for treatment of breast cancer has become a widely performed method over the recent years. However, there was no study in the applica on of FIF technique in pa ents with breast cancer undergoing mastectomy and lumpectomy. This study is an a#empt to compare dosimetric outcomes a$er applying the FIF technique in these pa ents. Materials and Methods: Twenty-four pa ents with right and le$ breast cancer par cipated in this study. The FIF planning technique was carried out for pa ents undergoing mastectomy and lumpectomy using the TiGRT treatment planning system (TPS). For the comparison purpose, we used two main indices, i. e. dose homogeneity index (HI) and conformity index (CI), the number of subfields, as well as mean, maximum, and minimum doses, doses received by 2% (D2) and 98% (D98) of the target volume, volumes received greater than 107% (V>107%) and less than 95% (V<95%) of the prescribed dose, doses to organs at risk (OARs), and total monitor units (MUs). Results: The results indicated that CI and HI are be#er in pa ents with right and le$ breast lumpectomy surgery (p<0. 038 and p<0. 047) rela ve to mastectomy pa ents (p<0. 037 and p<0. 029), respec vely. Other parameters men oned in Materials and Methods did not show any significant difference between the two groups of pa ents (p>0. 05). Conclusion: The use of alterna ve subfields resulted in be#er dose distribu on in target volume with the increase in breast volume. Moreover, to disappear the hot spot areas in isodose curves, it is essen al to elevate the number of subfields.

Background: Boron neutron capture therapy (BNCT) is a binary radiotherapy combining biochemical targeting with neutron irradiation. However, monitoring the boron distribution is a fundamental problem in BNCT. Prompt gamma rays emitted by boron capture reaction can be used to address the issue. Materials and Methods: The general-purpose Monte Carlo toolkits Geant4 and MCNP were used for the simulations. A cubic phantom with soft tissue was used to study the prompt gamma emission during BNCT. The Chinese hybrid phantom with arbitrary tumors was constructed and used to acquire the 0. 478 MeV prompt gamma rays in BNCT. Tomographic images were reconstructed with the maximum likelihood expectation maximization (MLEM) algorithm. Results: Comparison between MCNP and Geant4 showed a similar gamma rays emission rate in soft tissue. Up to 30 gamma ray peaks were found in the simulation, and 0. 478 MeV prompt gamma ray from boron was clearly observed. The single brain tumor with variable diameter from 1 cm to 4 cm in the heterogeneous anthropomorphic phantom was each time found to be recognizable in the reconstructed image. Furthermore, in a patient with four tumors, the variable distance between the source and the tumors leads to a neutron attenuation thus resulting in an inhomogeneous number of prompt gammas. Conclusion: The SPECT system for a heterogeneous phantom in BNCT was simulated with Geant4. The results show that BNCT-SPECT is valid for the reconstruction of the boron capture interaction position for a heterogeneous patient.

Background: Due to abscopal effect, cell damage may occur outside of the radiation field and the quantification of this effect is one of the most challenging debates in radiation therapy. The aim of this study was to estimate the abscopal effect induced in non-irradiated tumors quantitatively by means of biological effective dose (BED). Materials and Methods: Breast tumors using 4T1 and MC4-L2 cells, were induced into the flank region of Balb/c mice. When palpable, the tumor on one side of the body was irradiated with dose of 28Gy in 14 fractions and 2 Gy per fraction, 5 fractions per week. The tumor on the other side of the body was shielded with a lead plate. BED was estimated based on tumor volume. H&E staining and TUNEL assay were performed to assess histological changes and apoptosis in irradiated and non-irradiated tumors. Results: The effect of radiation on non-irradiated tumors was more than that on irradiated ones. The BED was 4. 49 and 6. 74 in 4T1 and MC4-L2 tumors, respectively. The ratio of the tumor volume in the last fraction to that in the first fraction for irradiated 4T1 tumors was 2. 32 and in non-irradiated was 1. 50. This ratio in irradiated and non-irradiated MC4-L2 tumors was 2. 64 and 1. 98, respectively. The number of apoptotic cells was higher in non-irradiated tissues. Conclusion: Results indicate that the occurrence of abscopal effect is highly depends on the type of tumor. By means of the abscopal effect, more radiation dose can be delivered to the tumor and metastatic sites.

Background: Chamomile essential oil (CEO) hauls out from Matricaria chamomilla L., is a well-known anti-oxidant. Oxidative stress induces clastogenic and biochemical disorders after γ-irradiation of animals. Materials and Methods: Mice were divided into five groups. Control group received vehicle only. CEO-treated group received CEO. Irradiated group received vehicle and exposed to γ-rays. Pre-treated group received CEO ½ h before γ-rays exposure. Post-treated group received CEO ½ hour after γ-rays exposure. Peripheral-blood micronucleus (PMN), bone-marrow micronucleus (BMN), frequency of chromosomal aberrations (CAs), reduced glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (PGx) and myeloperoxidase (MPO), lactate dehydrogenase (LDH) and tumor necrosis factor-α (TNF-α ) parameters were assessed. Results: In irradiated mice group, PMN score, BMN occurrence and CAs were increased when compared with control mice group. In addition, significant increases in levels of liver lipid peroxidation (LP); expressed as MDA and TNF-α . In addition, activities of liver MPO and LDH were found. Besides, significant decreases in content of GSH, activities of SOD and PGx in liver tissues were recognized. CEO treatment (1. 0 g/kg body weight) before-and after-irradiation ameliorated all these biochemical indices, as well as cytogenetic alterations induced by γ-rays when compared with irradiated group, indicating that pre-or post-treatment with CEO significantly attenuates the acute hazards caused by γ-rays exposure. Conclusion: The data suggest that CEO possesses a radioprotective potential against γ-radiation induced cytogenetic and biochemical damages in mice.

Background: Protection of hematopoietic system has become a primary goal in the development of novel medical countermeasures against ionization radiation and radiotherapy. This study was to explore the role of rapamycin in normal tissues against radiation. Materials and Methods: Mice were pretreated with rapamycin by i. p. every other day for five times before 5 Gy or 8. 5 Gy γ-ray whole body irradiation. Blood cell counts, HE staining of bone marrow and liver, bone marrow transplantation, CFU of spleen were used to measure the damage of hematopoiesis and extramedullary hemopoietic organs. Regular karyotype analysis and expression of γ-H2AX (by flow cytometry and western blot) were used to measure DNA damage. Rad 50 and DNA Lig 4 expression by western blot were to see the DNA repair ability. Results: The decrease of red blood cells and platelet induced by radiation were alleviated by pretreatment with rapamycin (d 7, 15, p<0. 01), and the long-term restoration of white blood cells, lymphocytes and bone marrow were enhanced in rapamycin pretreatment group (d 30, 40, 70, p<0. 05). The transplantation experiment also indicates that the long-term reconstitution in lethally irradiated recipient mice was improved in rapamycin group (p<0. 05). The hepatocellular injury by radiation was also reduced and the colony formation numbers of spleen after irradiation was improved in rapamycin group (p<0. 05). Karyotype analysis indicates that rapamycin protected bone marrow cells from chromosome mutation. Furthermore, expression of DNA repair proteins Rad 50 and DNA Lig 4 was enhanced and DNA damage marker γ-H2AX was reduced in mice exposed to radiation by rapamycin pretreatment. Conclusion: Rapamycin pretreatment mitigates hematopoietic system from radiation injury in both bone marrow and extramedullary hematopoietic organs by improving genomic stability and increasing survival of hematopoietic stem and progenitor cells (HSPCs).

Background: Radiation‐ induced acute lung damages are refractory side effects in lung cancer radiotherapy (RT). Prospective study investigates the possible role of piperine (Pip) as anti-inflammatory agent against γ-rays-induced lung tissue lesions in an applicable rat model. Materials and Methods: Fifty-six Sprague-Dawley rats were divided into four groups: Control, rats were administered the vehicle by gastric tube for 6-weeks, Pip-treated, (each rat received 40mg Pip/kg body-weight; once daily, orally for 6weeks), irradiated, (animals subjected to a single dose of whole body γ-rays (12Gy), and Pip-treated & irradiated, (each rat received the Pip-dosages, then one hour later after the last treatment, rats were exposed to 12Gy γ-rays. Results: The administration of Pip to rats pre-irradiation was significantly abolish the radiation-induced alleviation in lungs catalase (CAT) and glutathione peroxidase (PGx) activities and reduced glutathione (GSH) content and significantly limited the elevation in serum tumor necrosis factor-α (TNF-α ), interleukin-1β (IL-1β ) and interleukin-6 (IL-6) levels compared to irradiated group. The histopathological findings in lung tissues of irradiated group, showed partial desquamation of bronchiolar epithelial with peri-bronchiolar round cell infiltration and serous exudates, in some cases lung presented sero-fibrinous pneumonia with emphysema and collapse of some alveoli with thickness of inter-alveolar septa, while in Pip-treated & irradiated group, lung tissues showed minimum injury with or without few degenerative changes. Conclusion: Pip acts as a potent scavenger of free radicals to prevent and/or ameliorates the harmful effects of γ-rays. To our knowledge, this is the preliminary report of Pip mediated γ-rays induced lung inflammation in-vitro.

Background: Genomic instability is one of primary causes for malignant cell transformation. In this study induced genomic instability expressed as micronuclei in breast cancer (BC) patients with different stages of the disease compared with their unaffected first degree relatives (FDR) and normal unrelated controls was investigated. Materials and Methods: The background and net micronucleus frequency as well as other cellular damages induced after in vitro treatment with 25 µ g/ml of bleomycin were evaluated using cytokinesis block micronucleus-cytome assay in peripheral blood lymphocytes of 120 Iranian individuals comprised of 40 BC patients, 40 FDRs and 40 normal control groups. Considering the protocol for each person total of 1, 000 binucleated cells with well-preserved cytoplasm were blind scored on coded slides. Results: The net frequency of micronuclei was dramatically higher in breast cancer patients compared with controls. Also the net micronucleus (MN) frequency was significantly higher in FDRs compared with normal unrelated control. Considering cancer stages and clinical parameters, our results showed that the higher net frequency of MN was observed in higher stages and distant metastasis. Conclusion: This higher MN frequency both background and bleomycin induced in FDR compared with control group, clearly demonstrates that MN frequencies are determined by genetic factors to a major part and MN frequencies represent an intermediate phenotype between molecular DNA repair mechanisms and the cancer phenotype and affirms the approaches that are made to utilize them as predictors’ cancer risk. Also the association between MN frequency and metastasis proposes it as a possible prognostic marker.

Background: Dental hygiene departments in Korean institutions of higher education regularly use radiography systems for educating students. Despite reports indicating that exposure doses from these radiation-generating devices are small, and thus, present low risks for causing physical harm or chromosomal abnormalities, the large numbers of people who participate in oral examinations involving dental radiography raise questions about the optimal methods for managing radiation safety. Materials and Methods: Social cognitive theory incorporating major variables pertaining to radiation safety management derived from the Haddon Matrix was used. This model proposes and refines an approach for enhancing the radiation safety behaviors of both professors and students in Korea’ s collegiate dental hygiene departments. Results: The results of the study indicate that professors respond most favorably to stated expectations for accomplishing effective radiation safety management; thus model proposes that enhancing safety behaviors among professors depends upon cultivating organizational environments with clear expectations. Students, in contrast, engage in desirable radiation safety management behaviors when they can display self-efficacy; thus, the model proposes that personal education that enhances their practical knowledge for engaging in desired behaviors is most desirable. Conclusion: To enhance the current radiation safety management behaviors of the collegiate dental hygiene departments in Korea, it will be helpful to establish a strategy arising from the model developed here.

Background: Computed tomography angiography (CTA) scan is a suitable imaging technique to evaluate the blood vessels. However, one major disadvantage is the potential risk of cancer related to ionizing radiation exposure during the procedures. The aim of this investigation was to estimate the risk of exposure induced cancer death (REID) values for some common computed tomography angiography (CTA) scans. Materials and Methods: The scan parameters and patient gender and age were collected for a total of 251 patients undergoing CTA scans of the head (51), carotid (50), abdomen (50), thoracic (50) and the lower extremities (50). The effective diameter, scan length, effective tube current and the dose-length product (DLP) values were obtained for each patient. The organ doses and the effective dose were calculated by the ImpactDose program. The REID values were estimated for the different CTA scans by the calculated organ doses and corresponding age-and sex-specific risk factors. Results: The REID values for the CTA scans of head were 17± 4 and 20± 3 per million, carotid were 35± 9 and 67± 14 per million, the lower extremities were 60± 26 and 64± 24 per million, thoracic were 97± 28 and 204± 72 per million, and for abdomen were 101± 25 and 194± 72 per million, for males and females, respectively. Conclusion: The results of this investigation showed that CTA scans are associated with non-negligible risk of exposure induced cancer. A variation in radiation cancer risk as a function of age and gender of the patients was demonstrated and found that the younger female patients were at the highest risk.

Background: This study aimed to investigate dose area product (DAP), effective dose, and radiation risk in newborn infants hospitalized in neonatal intensive care units in Isfahan and Kashan. Materials and Methods: During a period of six months, DAP for chest X-ray examinations for newborn infants hospitalized in NICUs of five special hospitals including Beheshti (in Kashan), Al-Zahra, Imam Hossein, Amin and Goldis (in Isfahan) were measured using DAP meter. Then, using the dose area product (DAP) and conversion coefficients, the effective dose was calculated. Radiation risk per single exposure was estimated by applying 2. 8 × 10-2 and 13 × 10-2 factors per Sievert. Also, to estimate the radiation risk in the exposed population, the collective effective dose and the mentioned factors were used. Results: The mean DAP, the effective dose, the radiation risk per single exposure, and the radiation risk in the exposed population were found to be 15. 37 ± (1. 19), 45. 52 ± (3. 28), [1. 27-5. 91] × 10-6, and [0. 0045-0. 021], respectively. Conclusion: Findings indicate that the effective dose and therefore radiation risk in NICUs for newborn infants is higher than that of other studied cities in Iran. Consequently, it is necessary to attempt to reduce radiation dose while maintaining the image quality. In addition, theoretical and practical training programs are needed to increase the knowledge and skills of radiologic technologists on the concept of As Low As Reasonably Achievable (ALARA) and possible radiation cancer risks.

Background: People occasionally undergo medical diagnostic X-ray examinations and expose their red blood cells to radiation. Radiation that is generated from medical diagnostic X-ray machines is widely used in medical diagnoses. One of the important parameters is kilo-voltage (kV) that is applied across the X-ray tube in medical diagnostic X-ray machines. Kilo-voltage influences the radiation dosage. The aim of this study is to determine the hemolysis, osmotic fragility, and fluorescence anisotropy value on irradiated red blood cells as a function of kV during medical diagnostic X-ray examinations. Materials and Methods: The kV, kilo-voltage that is applied across an X-ray tube, of a medical diagnostic X-ray machine was operated at 50, 70 and 100 kV. We determined the hemolysis, osmotic fragility, and fluorescence anisotropy value in red blood cells at 0. 5 and 4 hours post-irradiation. In order to determine hemolysis and osmotic fragility, the release of hemoglobin was measured by spectrophotometry technique. 1, 6-diphenyl-1, 3, 5-hexatriene (DPH) was used as a molecular probe for determining fluorescence anisotropy value by fluorescence anisotropy technique. Non-irradiated red blood cells served as the control. Results: For the 50, 70, and 100 kV of medical diagnostic X-rays, the hemolysis, osmotic fragility, and fluorescence anisotropy values of irradiated red blood cells at 0. 5 and 4 hours post-irradiation did not significantly change when compared to the control. Conclusion: Our results suggested that 50, 70, and 100 kV of medical diagnostic X-ray did not influence hemolysis, osmotic fragility, and fluorescence anisotropy values of irradiated red blood cells.

Background: Exposure to ionizing radiation is known to have various effects on hematological parameters of biological sample. This study was aimed at evaluating the effect of ionizing radiation on some hematological parameters in guinea pigs. Materials and Methods: Thirty-six (36) apparently healthy adult guinea pigs of both sexes weighing between 700g – 1200g were used in the present study. The guinea pigs were categorized into three groups, 12 per group; group A (control), group B, and C were exposed to X-rays within the diagnostic range, using 70 kV and 12. 5mAs; using X-ray machine MS-185, serial no. 0904 GE at a source to skin distance (SSD) of 90cm. Blood samples were collected from all the guinea pigs at intervals of 1 hour, 24 hours 72 hours, 168 hours and 336 hours post-irradiation, and subjected to standard hematological analysis. Results: A continuous decline in the mean total white blood cell count and mean lymphocyte, monocyte, neutrophil and eosinophil count after 1hour in both groups was observed, and more pronounced after 24 hours post-irradiation. However, stability was observed 72 hours post-irradiation in both groups. Conclusion: This study found a depleting effect of low dose ionizing radiation on white blood cell count, with appreciable recovery occurring after 72 hours onward.

Background: The aim of this study was to calculate the radiation amount exposed during percutaneous nephrolithototomy (PCNL) and to make the urologists and other staff sensitive about the radiation risk they were exposed to. Materials and Methods: We measured the radiation exposure during 114 cases of PCNL performed. Thermoluminescent dosimeters (TLD) were placed between the operation table and the patient at the location of kidney and gonads of patients to measure the radiation exposure of patients. TLD were placed at the head, neck, finger and the legs of the operating surgeon to measure the occupational exposure of the urologist. And also two dosimeters were placed to the inner wall of the operating room and two dosimeters were placed to the hall. Results: The mean fluoroscopy screening time was 2. 18 minutes (0. 15-6. 12) and the mean operation time was 49 minutes (10-150). The mean radiation exposure for patients was 1. 307 milisievert (mSv) at kidney location and 0. 562 mSv at gonad location per procedure. Surgeon exposure was 0. 021 and 0. 003 mSv per procedure for hand and leg, respectively. Radiation amounts exposed inside the room and by the surgeon were statistically significantly lower than measured radiation results compared to patient kidney. Conclusion: According to our findings radiation exposure of the patient and the surgeon is below the annual occupational dose limit recommendations. However, for protecting from stochastic effects of radiation, fluoroscopy should be used as low as possible and lead aprons and thyroid shields must be worn to minimize the radiation exposure.