Protective Effects of IMOD and Cimetidine against Radiation-induced Cellular Damage.

Radiation damage is to a large extent caused by overproduction of reactive oxygen species (ROS). Radioprotectors are agents or substances that reduce the effects of radiation in healthy normal tissues while maintaining the sensitivity to radiation damage in tumor cells. Radioprotectors are agents or substances that reduce the effects of radiation in healthy normal tissues while maintaining the sensitivity to radiation damage in tumor cells Cimetidine was found more effective when used in vivo; this effect might be due to the augmentation of the presence of Sulphur atom in the compound which is ýimportant for their scavenging activity. Recently, a new herbal-based medicine with immunomodulatory capacities, Setarud (IMOD), was introduced as an additional therapy in various inflammatory diseases and HIV infection. IMOD is a mixture of herbal extracts enriched with selenium. Selenium confers protection by inducing or activating cellular free-radical scavenging systems and by enhancing peroxide breakdown. This article suggests that nontoxic amount of IMOD and cimetidine have radioprotective properties and could reduce cytotoxic effects of radiation.

Calculation of Thyroid Dose with Planner System and Evaluation of Thyroid Function after Radiotherapy for Patients with Breast Cancer.

BACKGROUND: Much research has widely been conducted into thyroid hormones levels following radiotherapy for breast cancer. Consequently, in this study, we evaluated to relate the rate of thyroid hormones levels with the dose distribution among breast cancer patients. MATERIAL AND METHODS: Thirty patients were treated with 4-field breast cancer radiotherapy. The dose volume histograms, the volume percentage of the thyroid absorbing respectively 20, 30, 40 and 50 Gy were then estimated (V20, V30, V40 and V50) together with the individual average thyroid dose over the whole gland derived from their computed tomography-based treatment plans. Then, in serum samples triiodothyronine [T3], thyroxine [T4], thyroid-stimulating hormone [TSH] of the patients were measured before and after radiotherapy. RESULTS: There were no significant differences in thyroid hormones levels before and after radiotherapy for patients with breast cancer (P value >.05). CONCLUSION: On the balance, we understood that thyroid stimulating hormones levels did not change before and after cancer breast radiotherapy.

Calculation of Thyroid Dose with Planner System and Evaluation of Thyroid Function after Radiotherapy for Patients with Breast Cancer.

BACKGROUND: Much research has widely been conducted into thyroid hormones levels following radiotherapy for breast cancer. Consequently, in this study, we evaluated to relate the rate of thyroid hormones levels with the dose distribution among breast cancer patients. MATERIAL AND METHODS: Thirty patients were treated with 4-field breast cancer radiotherapy. The dose volume histograms, the volume percentage of the thyroid absorbing respectively 20, 30, 40 and 50 Gy were then estimated (V20, V30, V40 and V50) together with the individual average thyroid dose over the whole gland derived from their computed tomography-based treatment plans. Then, in serum samples triiodothyronine [T3], thyroxine [T4], thyroid-stimulating hormone [TSH] of the patients were measured before and after radiotherapy. RESULTS: There were no significant differences in thyroid hormones levels before and after radiotherapy for patients with breast cancer (P value >.05). CONCLUSION: On the balance, we understood that thyroid stimulating hormones levels did not change before and after cancer breast radiotherapy.

Application of neural network method to detect type of uranium contamination by estimation of activity ratio in environmental alpha spectra.

The discrimination of the composition of environmental and non-environmental materials by the estimation of the (234)U/(238)U activity ratio in alpha-particle spectrometry is important in many applications. If the interfering elements are not completely separated from the uranium, they can interfere with the determination of (234)U. Thickness as a result of the existence of iron in the source preparation phase and their alpha lines can broaden the alpha line of (234)U in alpha spectra. Therefore, the asymmetric broadening of the alpha line of (234)U and overlapping of peaks make the analysis of the alpha particle spectra and the interpretation of the results difficult. Applying Artificial Neural Network (ANN) to a spectrometry system is a good idea because it eliminates limitations of classical approaches by extracting the desired information from the input data. In this work, the average of a partial uranium raw spectrum, were considered. Each point that its slope was of the order of 0-1% per 10 channels, was used as input to the multi-layer feed forward error-back propagation network. The network was trained by an alpha spectrum library which has been developed in the present work. The training data in this study was actual spectral data with any reasonable thickness and interfering elements. According to the results, the method applied to estimate the activity ratio in this work, can examine the alpha spectrum for peaks which would not be expected for a source of given element and provide the clues about composition of uranium contamination in the environmental samples in a fast screening and classifying procedures.

Ulexite-galena intermediate-weight concrete as a novel design for overcoming space and weight limitations in the construction of efficient shields against neutrons and photons.

Recently, due to space and weight limitations, scientists have tried to design and produce concrete shields with increased attenuation of radiation but not increased mass density. Over the past years, the authors' had focused on the production of heavy concrete for radiation shielding, but this is the first experience of producing intermediate-weight concrete. In this study, ulexite (hydrated sodium calcium borate hydroxide) and galena (lead ore) have been used for the production of a special intermediate-weight concrete. Shielding properties of this intermediate-weight concrete against photons have been investigated by exposing the samples to narrow and broad beams of gamma rays emitted from a 6°Co radiotherapy unit. Densities of the intermediate-weight concrete samples ranged 3.64-3.90 g cm⁻³, based on the proportion of the ulexite in the mix design. The narrow-beam half-value layer (HVL) of the ulexite-galena concrete samples for 1.25 MeV 6°Co gamma rays was 2.84 cm, much less than that of ordinary concrete (6.0 cm). The Monte Carlo (MC) code MCNP4C was also used to model the attenuation of 6°Co gamma-ray photons and Am-Be neutrons of the ulexite-galena concrete with different thicknesses. The 6°Co HVL calculated by MCNP simulation was 2.87 cm, indicating a good agreement between experimental measurements and MC simulation. Furthermore, MC-calculated results showed that thick ulexite-galena concrete shields (60-cm thickness) had a 7.22 times (722 %) greater neutron attenuation compared with ordinary concrete. The intermediate-weight ulexite-galena concrete manufactured in this study may have many important applications in the construction of radiation shields with weight limitations such as the swing or sliding doors that are currently used for radiotherapy treatment rooms.

Effectiveness Evaluation of Skin Covers against Intravascular Brachytherapy Sources Using VARSKIN3 Code.

BACKGROUND AND OBJECTIVE: The most common intravascular brachytherapy sources include (32)P, (188)Re, (106)Rh and (90)Sr/(90)Y. In this research, skin absorbed dose for different covering materials in dealing with these sources were evaluated and the best covering material for skin protection and reduction of absorbed dose by radiation staff was recognized and recommended. METHOD: Four materials including polyethylene, cotton and two different kinds of plastic were proposed as skin covers and skin absorbed dose at different depths for each kind of the materials was calculated separately using the VARSKIN3 code. RESULTS: The results suggested that for all sources, skin absorbed dose was minimized when using polyethylene. Considering this material as skin cover, maximum and minimum doses at skin surface were related to (90)Sr/(90)Y and (106)Rh, respectively. CONCLUSION: polyethylene was found the most effective cover in reducing skin dose and protecting the skin. Furthermore, proper agreement between the results of VARSKIN3 and other experimental measurements indicated that VRASKIN3 is a powerful tool for skin dose calculations when working with beta emitter sources. Therefore, it can be utilized in dealing with the issue of radiation protection.

Development and characterization of a novel PRESAGE formulation for radiotherapy applications.

A novel water equivalent formulation of PRESAGE dosimeter more suitable for radiotherapy applications has been introduced and its radiological water equivalency has been investigated. Furthermore, its radiological properties have been compared with an existing PRESAGE formulation over an energy range from 10 to 20 MeV. Monte Carlo simulation method has been implemented to determine and compare depth dose profiles in both of the PRESAGE formulations at two different photon energies (140 KV(P) and 6 MV). The results show that our proposed PRESAGE formulation is more water equivalent than its known formulation especially for low photon energy beams.

Is metal artefact reduction mandatory in cardiac PET/CT imaging in the presence of pacemaker and implantable cardioverter defibrillator leads?

PURPOSE: Cardiac PET/CT imaging is often performed in patients with pacemakers and implantable cardioverter defibrillator (ICD) leads. However, metallic implants usually produce artefacts on CT images which might propagate to CT-based attenuation-corrected (CTAC) PET images. The impact of metal artefact reduction (MAR) for CTAC of cardiac PET/CT images in the presence of pacemaker, ICD and ECG leads was investigated using both qualitative and quantitative analysis in phantom and clinical studies. METHODS: The study included 14 patients with various leads undergoing perfusion and viability examinations using dedicated cardiac PET/CT protocols. The PET data were corrected for attenuation using both artefactual CT images and CT images corrected using the MAR algorithm. The severity and magnitude of metallic artefacts arising from these leads were assessed on both linear attenuation coefficient maps (µ-maps) and attenuation-corrected PET images. CT and PET emission data were obtained using an anthropomorphic thorax phantom and a dedicated heart phantom made in-house incorporating pacemaker and ICD leads attached at the right ventricle of the heart. Volume of interest-based analysis and regression plots were performed for regions related to the lead locations. Bull's eye view analysis was also performed on PET images corrected for attenuation with and without the MAR algorithm. RESULTS: In clinical studies, the visual assessment of PET images by experienced physicians and quantitative analysis did not reveal erroneous interpretation of the tracer distribution or significant differences when PET images were corrected for attenuation with and without MAR. In phantom studies, the mean differences between tracer uptake obtained without and with MAR were 10.16±2.1% and 6.86±2.1% in the segments of the heart in the vicinity of metallic ICD or pacemaker leads, and were 4.43±0.5% and 2.98±0.5% in segments far from the leads. CONCLUSION: Although the MAR algorithm was able to effectively improve the quality of µ-maps, its clinical impact on the interpretation of PET images was not significant. Therefore cardiac PET images corrected for attenuation using CTAC in the presence of metallic leads can be interpreted without correction for metal artefacts. It should however be emphasized that in some special cases with multiple ICD leads attached to the myocardium wall, MAR might be useful for accurate attenuation correction.

A basic dosimetric study of PRESAGE: the effect of different amounts of fabricating components on the sensitivity and stability of the dosimeter.

Over the past few years there has been much interest in the development of three-dimensional dosimeters to determine the complex absorbed dose distribution in modern radiotherapy techniques such as IMRT and IGRT. In routine methods used for three-dimensional dosimetry, polymer gels are commonly used. Recently, a novel transparent polymer dosimeter, known as PRESAGE, has been introduced in which a radiochromic color change is observed upon radiation. PRESAGE has some advantages over usual polymer gel dosimeters. It has been noted that the sensitivity of PRESAGE can be changed when different amounts of the components are used for its fabrication. This study has focused on the assessment of dosimetric characteristics of PRESAGE for various amounts of components in its formulation. To achieve this, PRESAGE dosimeters were fabricated using various amounts of their constituting components. Then the dosimeters were irradiated to (60)Co gamma photons for a range of radiation doses from 0 to 50 Gy. Consequently, the light absorption changes of the dosimeters were measured by a spectrophotometer at different post-irradiation time periods. It was generally observed that as the concentration of the radical initiator is increased, the PRESAGE dosimeter sensitivity is increased while its stability is decreased. Furthermore, it was noted that with the high concentration of the radical initiator and leuco dye, the sensitivity of PRESAGE is decreased.

Radionuclide concentrations in the diet of residents in a high level natural radiation area in Iran.

Concentrations of 137Cs and 226Ra in the diet (foodstuffs and drinking water) of adult inhabitants in the high-level natural radiation area (HLNRA) of Ramsar, Iran have been determined. The annual intake of foodstuffs was estimated on the basis of their average annual consumption. Food samples collected from local markets were analyzed by means of a gamma spectrometer. The estimated annual dietary intakes of 137Cs and 226Ra were 130Bq and 245Bq, respectively. The concentrations of natural radionuclides in food and drinking water of the residents are higher than the world average, and are correlated with the high concentration of these radionuclides in soil and water. Calculations were also made to determine the potential dose to an individual consuming such diets.