International Journal of Radiation Research
Volume:15 Issue: 4, Oct 2017

About 10% of apparently normal individuals are sensitive to clastogenic effects of physico-chemical agents. More than 45% of breast cancer patients’ exhibit elevated radiosensitivity. Although the nature of inherent radiosensitivity is not fully understood, but insufficiency and impaired DNA repair mechanism might be prime cause of radiosensitivity. This is evident from genetically affected individuals such as ataxia telangiectasia, severe combined immunodeficiency, Xeroderma pigmentasum, Fanconi anemia who show sensitivity to ionizing radiation, ultraviolet light and alkylating agents. All these genetic diseases are caused due to impaired DNA damage repair mechanism. Radiation therapy (RT) is a common and effective way of treatment in several types of malignant tumors. Some cancer patients suffer from side effects of RT such as radiation induced early or late adverse responses in normal tissues within weeks, months, or even years post irradiation, due to intrinsic radiosensitivity. The RT efficiency limitation raises from ionizing radiation toxicity reactions in normal tissues. An appropriate protocol to prevent or treat these side effects, has not been developed yet. Molecular pathways involved in adverse responses to cancer treatment agents have not been well defined. Identification of molecular mechanisms may be promising to enhance the output of treatment technologies and overall survival of cancer patients. Several techniques such as microarray technology has been used to clarify molecular mechanisms involved in radiosensitivity by finding genes related to RT normal tissue responses. DNA repair, apoptosis, cell cycle, and growth factor associated genes are the most important candidates in this field.

The dose-related effects of patient setup errors on bio-physical indices were evaluated for the conventional wedge (CW) and field-in-field (FIF) whole breast irradiation techniques (WBI). The treatment plans of 10 patients receiving left WBI were retrospectively selected for evaluation. The bio-physical effects of dose variations were evaluated by shifting the isocenters and gantry-angles of the treatment plans. Dose-volume histograms of the planning target volume (PTV), heart, and lungs were generated, and the conformity index (CI), homogeneity index (HI), tumor control probability (TCP), and normal tissue complication probability (NTCP) were determined. The D95 of the PTV for an “isocenter shift plan” with a posterior direction decreased by approximately 15%, and the TCP of the PTV decreased by approximately 50% for the FIF technique and by 40% for the CW; however, the NTCPs of the lungs and heart increased for both techniques. Increasing the gantry-angle decreased the TCPs of the PTV by 24.4% (CW) and by 34% (FIF). The NTCPs of the lungs and heart for the two techniques differed by only 3%. The CIs and HIs for the CW case were higher than the corresponding values obtained for the FIF case. Significant differences were observed between the two techniques (p Our results revealed that the biophysical properties of the FIF case were more sensitive to setup errors than those in the CW case. The radiobiological-based analysis could be detected significant dosimetric errors and provided a practical patient quality assurance method for guiding the bio-physical effects.

The aim of this study was to compare the differences of the dosimetric parameters between three-dimensional conformal radiotherapy (3D-CRT) and simultaneous-integrated boost intensity-modulated radiotherapy (SIB-IMRT) techniques in the prone and supine positions for breast irradiation.
Ten patients underwent a computed tomography simulation in both the prone and supine positions. For each set-up position, the treatment plans were created with 3D-CRT and SIB-IMRT. The dosimetric parameters were obtained from dose-volume histograms.
High-dose regions in the whole breast were decreased in IMRT with a simultaneous integrated boost technique. The lung doses were significantly reduced for all patients, and the heart doses were lower in left-sided breast cancer patients in the prone position. The heart doses except mean dose were not significantly lower with SIB-IMRT in the prone position.
SIB-IMRT allowed a more conformal dose distribution regardless of position. The prone position is superior to the supine treatment regarding doses in the ipsilateral, contralateral lung, and heart. The contralateral breast doses were increased in the prone position. Prone IMRT can be chosen for simultaneous integrated boost treatment in women with pendulous breasts.

This study aims to investigate the metabolic characteristics of radiotherapy-induced temporal lobe injury in elderly patients with nasopharyngeal carcinoma using 1H-magnetic resonance spectroscopy (MRS).
Data were collected from 21 elderly patients and 33 young patients before and during therapy with different radiation dosages (20, 40, and 60 Gy). The Student’s t-test was used to compare the 1H-MRS-based N-acetyl aspartate /Creatine (NAA/Cr), Choline/Creatine (Cho/Cr), and NAA/Cho ratios in the temporal lobes.
Statistically significant differences in the NAA/Cr and NAA/Cho ratios was found between the two groups (P Under the same radiotherapy pattern and radiation dosage, the injury to the neurons in the temporal lobes was significantly greater in elderly patients than that in young patients. The intervention conducted in elderly patients at a dosage of 20 Gy might help minimize the injury to the neurons.

External beam radiotherapy and brachytherapy plays a vital role in the management of cancer cervix. High dose rate brachytherapy is being presently used worldwide for the brachytherapy applications. At present, 2-Dimensional linear array detectors are the most common QA tool used for pretreatment patient specific quality assurance in external beam radiotherapy alone and till date no dedicated brachytherapy tool is available. An attempt has been made to explore the feasibility of using 2 dimensional linear array, Imatrixx as a QA tool for brachytherapy.
Reference treatment plans are generated by Plato treatment planning system using the images of Imatrix acquired with Siemens CT simulator. The efficacy of Imatrixx as a QA tool for intracavitary treatment plan verification, dwell position and dwell time accuracy verification are studied.
The length and the widths along with the area of the reference isodose curves of the intracavitary treatment plans generated by Plato Planning system and measured with Imatrixx is compared. The difference in area of the reference isodose curve is found to vary from -0.59 cm2 to 4.59 cm2. The estimated user correction factor for Iridium-192 energy, 0.38 MeV is 1.090 with a standard deviation of ±0.0211. Machine related QA such as dwell position and dwell time were measured with Imatrixx with an accuracy of 0.5 mm and 0.02 s respectively.
Results shows that the 2-Dimensional linear array, Imatrixx can be used with accepted accuracy for both machine and patient specific quality assurance in brachytherapy treatments.

This study evaluates dosimetric and spatial variations in inter–fraction applicator positioning in high dose rate (HDR) brachytherapy.
This study includes 25 retrospective patients of carcinoma of the cervix. Each patient received 5 fractions of HDR intracavitary brachytherapy. High Risk-Clinical Target Volume (HR-CTV) were drawn on CT images. First implant was considered as a reference, and all subsequent CT data sets were rigidly registered on first implant’s CT data set. Another point A, called point Aabs, was defined on first plan and all subsequent plans. Registration properties were recorded for all 125 plans that include X, Y, Z DICOM offset, rotational, translational values and normalized D90 (ND90) doses were also recorded.
The mean angle of rotation on X, Y and Z axis are 0.63 ± 1.85 deg, -0.86 ± 1.30 deg, -1.14 ± 2.44 deg, respectively. While mean translational motion on X, Y and Z axes are –2.77 ± 10.32 mm, -6.12 ± 9.71 mm and 14.62 ± 23.83 mm, respectively. Mean ND90, and mean HR-CTV were found to be 1.18 ± 0.26 and 26.91 ± 17.70 cc, respectively.
Results of the study reveals that translational motion is higher than the rotational motions, and inter – fraction applicator variation does not produce any significant change in Point A doses. The change in volume coverage is observed only due to applicator motion. HR-CTV coverage decreases with increasing HR-CTV volume. Hence, dose prescription should be based on 3D HR-CTV volume.

In CT systems, the machine utilizes a bowtie filter to shape the X-ray beam and remove lower energy photons. The shape of this bowtie filter is complicated and its geometry is often not available in detail. These renders the CT dose index (CTDI) to have different values in measurement versus Monte Carlo simulation studies and other analytical calculations especially in dosimetry of internal organs. In existing literature, the bowtie filter shape is extracted by using expensive sensors
In the present work, the shape of the bowtie filter of the Biograph 6 PET/CT was derived by using Thermolumenecence dosimeters (TLDs). Subsequently, to evaluate the accuracy of the body bowtie filter shape as generated by TLDs, Monte Carlo simulation of CT was performed. 16 X-ray sources in various angles were used within the Monte Carlo code (MCNP-4C) to simulate the CT section of the PET-CT Biograph 6 system and to calculate dose.
The relative difference between simulated and measured CTDI value for the PET/CT Siemens Biograph 6 at 80, 110 and 130 kVp were 4.2, 2.9 and 2.3%, respectively.
In this study, we demonstrate that it is possible to calculate the bowtie filter shape by using an inexpensive TLD method. The results showed that it is possible to determine the shape of the bowtie filter in PET/CT using TLDs with acceptable accuracy.

Natural radionuclides in rock samples, primarily 238U (uranium), 232Th (thorium) and 40K (potassium), are the main source of radiation exposure to workers and general public and their measurement is of paramount importance from radiation protection point of view.
Gamma spectrometry using HPGe detector was used to measure the radioactivity and assess the radiological hazards and annual effective dose. The data is statistically significant.
In the studied rock samples, the mean activity of 238U, 232Th, 40K is 12.15 ± 1.68 Bq/kg, 45.17 ± 6.92 Bq/kg and 639.24 ± 115.86 Bq/kg, respectively. The mean values of radium equivalent activity, radiological hazards external hazard index (Hex), Internal hazard index (Hin), Gamma index (Iγ) and Alpha index (Iα) are 125.96 ± 14.94 Bq/kg, 0.34 ± 0.04, 0.37 ± 0.04, 0.48 ± 0.06 and 0.06 ± 0.00 respectively. The mean values of absorbed dose rate, indoor and outdoor annual effective dose of gamma radiation are 59.55 ± 7.16 nGy/h, 0.29 ± 0.04 mSv and 0.07 ± 0.00 respectively. A strong positive correlation was observed between the radium equivalent activity and the absorbed dose (correlation coefficient R2 = 0.99).
The present investigations showed that the inborn radioactivity is within the world and Indian average value. And the findings indicate that the studied samples do not pose any significant radiation hazard to the public in large and the workers in particular and when used as construction material also.

The natural radioactivity levels in soil samples of Karadağ Mountain in central Anatolia region have been determined.
Analyses on the collected samples were performed to determine gross alpha and beta radioactivity concentrations by using a gas-flow proportional counter and the concentrations of 238U, 232Th and 40K by using a NaI(Tl) scintillation detector.
The estimated activities of gross alpha and beta ranged between 305.155±46.830 and 1305.437±77.23 Bq.kg-1, 479.743±22.658 and 1177.373±30.908 Bq.kg-1, respectively. The mean activity values of U, Th and K radionuclides were found to be 71.6, 83.9 and 451.1 Bq.kg-1, respectively. Also, known radiation health hazard indices were calculated using radioactivity concentrations of soil samples.
The present results have been compared with the obtained values from other regions in Turkey and the internationally reported values as well as the reference values. The soil samples in the studied area are safe and can be used as a construction material without posing any significant radiological threat to public. This investigation reveals a baseline of levels of natural radioactivity in Karadağ Mountain, Turkey.

Radioactive contamination in soil arises due to various activities of human being, such as nuclear energy generation, use of radioisotopes in industrial applications, science, technology, medicine and release of radiation in nuclear weapon tests.
The two districts (Peshawar and Nowshera) of Khyber Pakhtunkhwa, Pakistan were selected for the study of anthropogenic Cs-137 assessment. A total of 102 soil samples were collected from different locations of these two districts of Khyber Pakhtunkhwa.
The activity concentration of Cs-137 was determined by gamma ray spectrometry using a high purity germanium detector coupled with a PC. The highest values for Peshawar and Nowshera found were 44.1 ± 4.6 Bq/kg and 27.9 ± 4.3 Bq/kg, respectively.
The presence of Cs-137 shows that the areas under study have gained some fallout, however, the activity concentrations of Cs-137 found in the surveyed area were nominal and do not pose any potential health hazard to human beings.

Environmental ionizing radiation has been associated with increased cancer risk by several studies. The Brazilian city of Poços de Caldas, MG, seats on a huge deposit of uranium, which was until recently mined. We performed a retrospective analysis of 310 cases of patients with breast cancer, who were exposed for at least ten years to different levels of ionizing radiation around their homes, to verify whether a correlation existed between disease incidence, prevalence, and exposure.
Gamma radiation was measured on the roads and the urban street grid. We retrieved the clinical files of 310 patients from the Population-Based Cancer Registry of Poços de Caldas city, MG, Brazil and compared the local prevalence and incidence of breast cancer per city district to the local effective doses.
Effective doses of radiation around patients’ homes varied from 0.72 and 1.30 mSv/year, with 70% of the homes exposed to doses > 1.0 mSv/year. When considered the number of cases in the study in relation to the adult female population of the city, the incidence of female breast cancer was 25.9% higher than the national average incidence for the same period, 2003-2011 (68.32/100,000 versus 50.61/100,000 respectively).
The higher incidence of breast cancer among the adult female population of Poços de Caldas may be associated with chronic exposure for ten or more years to effective doses equal or slightly above the international reference dose of 1.0 mSv/year. Other known risk factors for breast cancer in our patients were not different from those found nationwide.

Ultraviolet radiation is present in sunlight. If ultraviolet radiation exceeds the limit, it can cause detrimental effects on human health such as skin cancer and cataract.
In this descriptive cross-sectional study, the level of solar ultraviolet radiation type A (UVA) were measured using UV LOG HAND HELD in Kermanshah city. The intensity of ultraviolet radiation was measured three times a day including two hours before noon, noon and two oclock in the afternoon. The results were analyzed using ANOVA statistical tests with a confidence interval of 95%.
The lowest and highest average intensity levels of solar UVA in Kermanshah were in December (14.21± 0.94 w/m2) and August (32.87 ±2.3 w/m2), respectively. Also, winter and summer seasons (with average intensities of 16.37± 1.12 w/m2 and 30.12±1.7 w/m2) had the lowest and highest intensity of this radiation, respectively.
Regarding that UVA radiation exceeds the safe exposure level, even in the winter in Kermanshah, it is recommended for people to avoid from long-term staying in open spaces at noon and use proper protective wears especially in summer.

CdWO4 is a scintillator with some unique properties. For example, high density, thermal and chemical stability and so on. Different applications of this scintillator such as X-ray scintillator has been investigated thoroughly so far. However, there is limited number of studies reporting the characteristics of CdWO4 as an alpha counter.
The CdWO4 powder was synthesized by a simple co-precipitation method. Then, the CdWO4 films with different thicknesses were prepared by spin coating method on glass substrates. The CdWO4 powder and films were characterized by X-ray diffraction, photoluminescence, scanning electron microscopy, Fourier transformed-infrared spectroscopy, and ion beam induced luminescence. Finally, the response of samples with different thicknesses was measured using a 241Am alpha source with 1860 Bq activity.
The analyses revealed that the nanocrystalline CdWO4 with about 30 nm size was successfully synthesized without any impurity. Besides, the CdWO4 films had the same luminescence emission peak characteristics as CdWO4 powder had.
It was observed that the sample with 2.9 mg/cm2 thickness had the best counting efficiency (over 2π geometry) among the others.