International Journal of Radiation Research
Volume:10 Issue: 2, Apr 2012

Tea is one of the most popular beverages all over the world which is prepared from the leaves of a shrub camellia sinensis. Eastern Black Sea Region of Turkey which account for around 100% of all tea production in Turkey was among the areas contaminated by Chernobyl accident. A comprehensive study was planned and carried out to determine the level of gross α and β radioactivity and annual effective dose equivalent in different Turkish market tea using LSC. The average measurements for digestion and infusion are 5.0 mBql-1 and 1.8 mBql-1 for gross α, 80.7 mBql-1 and 9.0 mBql-1 for gross β in tea samples. Contributions of the infusion tea samples to total annual effective dose equivalent from 238U, 234U, 230Th, 226Ra, 210Po, 232Th, 238Th, 210Pb and 228Ra are 0.103, 0.112, 0.480, 0.640, 2.742, 0.525, 0.164, 7.740 and 7.740 μSvy-1 for adults. The obtained results showed that natural activity concentrations of α- and β-emitting radionuclides and annual effective dose equivalent in tea samples did not exceed WHO recommended levels.

The aim of this work was to study the feasibility of constructing a fast thorax model suitable for simulating lung motion due to respiration using only one CT dataset. For each of six patients with different thorax sizes, two sets of CT images were obtained in single-breath-hold inhale and exhale stages in the supine position. The CT images were then analyzed by measurements of the displacements due to respiration in the thorax region. Lung and thorax were 3D reconstructed and then transferred to the ABAQUS software for biomechanical fast finite element (FFE) modeling. The FFE model parameters were tuned based on three of the patients, and then was tested in a predictive mode for the remaining patients to predict lung and thorax motion and deformation following respiration. Starting from end-exhale stage, the model, tuned for a patient created lung wall motion at end-inhale stage that matched the measurements for that patient within 1 mm (its limit of accuracy). In the predictive mode, the mean discrepancy between the imaged landmarks and those predicted by the model (formed from averaged data of two patients) was 4.2 mm. The average computation time in the fast predictive mode was 89 sec. Fast prediction of approximate, lung and thorax shapes in the respiratory cycle has been feasible due to the linear elastic material approximation, used in the FFE model.

Radon is an odourless, colourless and tasteless gas and it is the first cause of lung cancer among non- smokers. The assessment of the level of radium in building materials helps in understanding the radiological implications. It has been observed that everyone has some levels of exposure to them. Therefore measurement of radium and radon in the soil samples are important from public health point of view. In the present work, radon exhalation rate and radium from soil samples have been measured through “Sealed Can technique” using LR-115 type II plastic track detector. Twenty two samples were collected from industrial area of Bulandshahr, Hapur and Meerut districts of Uttar Pradesh (India). The radium concentration ranges from 9.2 to 18.7 Bqkg-1 with an average value of 14.1 Bqkg-1. The area exhalation rate for radon ranges from 394.1 to 798.3 mBqm-2 h- 1 with an average value of 600.7 mBqm-2 h-1 and mass exhalation rate ranges from 15.1 to 30.7 mBqkg-1h-1 with an average value of 23.1 mBqkg-1h-1. A strong correlation coefficient has been observed between radium concentration and radon exhalation rate. The values of radium concentration in all the soil samples were found to be lower than the limit 370 Bqkg-1 as recommended by OECD, 1979. Hence, there is no matter of concern to the population living in this region.

X-ray computed tomography (CT) examinations deliver a significant amount of radiation doses to patients comparing to conventional radiography examinations. The objective of the current study was to analyze and investigate the average patient received dose from axial and spiral CT exams in a medical imaging center. In this study, the patient imaging technique, weight and height were recorded. The patients’ doses provided by CT unit in terms of CTDIw were also recorded. Then, other dosimetric quantities including dose-length product (DLP) and effective dose were calculated for each patient using the recorded data. The average values were obtained for all the studied dosimetric quantities. Also, their distribution in terms of examined regions and imaging mode; ie, axial and spiral CT were analyzed by SPSS software. For all patients, the mean effective dose of 4.4 mGy with the standard deviation of 9.2 was found. The CTDIw for axial group was two times higher than spiral ones. Conversely, the effective dose of axial group was less than spiral group. Additionally, the effective doses of 2.3 and 5.2 mSv were found for axial and spiral, receptively. For both quantities of CTDIw and effective dose, the observed difference between axial and spiral modes were significant (P<0.001). Our results showed that although the patient doses in the current study was comparable with the reported values by similar studies in other countries, it was higher than the reported values of a similar study in Iran. Exposure technique’s optimaization and further review in routine CT examinations were recommended.

The aim of this work was to study the output factors for Linac using different ionization chambers and build up caps. Output factors were measured for open square fields (3 × 3 cm to 40 × 40 cm) defined by collimator jaws for 6 and 15 MV photon beams from a Varian Clinac 2100C accelerator were measured. The measurements in air were performed using Compact Cylindrical and Farmer type ionization chamber fitted with acrylic and brass build up caps. All measurements were taken with the detector set with its central axis perpendicular to the beam central axis and isocentrically positioned at the reference depth in empty water phantom. It was observed that out put factors increased with field size for both 6 and 15 MV photon beams. The increase in output factor is less prominent for brass build-up caps than acrylic build up caps. Up to 1.53% and 0.97 % difference were observed between 6 and 15 MV energies for acrylic and brass build up caps respectively. For acrylic build up cap, no significant difference was found for both ionization chambers. However, measurements for brass and acrylic build up caps with same ion chamber differ by up to 4.4 % for 15 MV energy. The measurement of output factors Shwith cylindrical build-up cap made of high Z material distorts Shand should be avoided. The use of buildup caps with Zeff close to that of water such as acrylic is a good choice. Ionization chamber is the best choice for Sh measurements for large field sizes.

In addition to determining the exact tumor location and its geometric features, an increase of the effective tumor atomic number will enhances the chance in treating the tumoral cells under suitable radiation. In the present study, we assessed metrezoate-labeled gallium transmission in Burkett lymphatic cells. Human Burkitt lymphatic cells were grown in culture media. Metrezoate-76% labeled with gallium-67 and the developed complex was used with a volumetric amount of 125%. The complex was added to the culture media, and then the absorbed volume was determined. Through the SPECT imaging system, the culture media containing the lymphatic cell colonies were scanned 1, 2, 4, 8, 24, 48, and 72-hr postaddition of metrezoate-gallium complex. The transmitted activities in the colonies area were measured after imaging. Gallium-metrezoate complex is significantly accumulated in malignant lymphatic cells. The study of the results throughout 72-hr revealed that most absorption, count quantity and transmitted activity had all occurred 4-hr after adding gallium-metrezoate complex solution. It can be concluded that gallium-metrezoate complex can be significantly accumulated in the Burkett lymphatic cells and uptake is non-linear with exposures time. This method of enhancing effective atomic number in malignant lymphatic cells therefore appears promising.

One of the key techniques for the preparation of 125I seeds is adsorption of 125I onto silver bits coated by palladium (pd). Carriers played an important role in the adsorption of 125I on palladium. KI is used as a carrier for fixing of 125I onto silver wire bits coated with palladium. Three procedures KI, KOH, NH4OH were investigated for adsorption of 125I activity by different carriers. Adsorptions percentage of 125I on treated silver beads showed about 85% by using KI as a carrier, the KOH showed 74% and 65% for NH4OH. The results indicated that, the use of KI as a carrier was suitable for adsorption of 125I on treated silver seeds with Pd than KOH and NH4OH.

Despite the relative success of surgical resection followed by proton, proton/photon, or conventional radiotherapy in terms of recurrence-free survival, chordomas are still associated with a high rate of recurrence. To our knowledge there are only very few reported cases of this rare tumor detected by F-18 FDG-PET. In this case we show the significance of F-18 FDG-PET/CT in detection of recurrent Chordoma in a 38 year old man with a history of the disease and a newly detected cervical lymphatic mass. The fused PET/CT images manifested the presence of two abnormal foci of tracer uptake corresponding to a retroclavicular and an infrajugular Lymph node proved to be metastases of the previous chordoma in histopathology. Further employment of F-18 FDG-PET/CT in this rare tumour type might eventually define and establish its value in staging of chordoma.