A mammographic phantom to measure mean glandular dose by thermoluminescent dosimetry

We have designed a phantom to evaluate mean glandular dose (MGD) as part of the regulatory dosimetry control for mammographic equipment. The phantom is constituted by TLD-100 thermoluminescent dosemeters (TLDs) inserted within semicircular plates of acrylic. Different groups of TLDs are used to determine entrance surface air kerma and half-value layer (HVL). Calibration of both tasks has been performed using a Senographe 2000D system and an ionization chamber. The phantom has been tested in five clinical systems. The HVL and MGD obtained by this method agree, on average, within 3%, with those from standard procedures based on the use of ionization chambers. The phantom MGD measurements have a combined uncertainty better than 10% (k = 1).     

MCNP Dose Calculations in a CT Phantom for Therapeutic External Photon Beam

In this paper, we have addressed the problem of the radiation transport with the Monte Carlo N particle(MCNP) code. This is a general purpose Monte Carlo tool designed to transport neutron, photon and electron in three dimensional geometries. To examine the performance of MCNP5 code in the field of external radiotherapy, we performed the modeling of an Electron Density phantom (EDP) irradiated by photons from 60Co source. The model was used to calculate the Percent Depth Dose (PDD) at different depths in an EDP. One field size for PDD has been examined. A 60Co photons source placed at 80 cm source to surface distance (SSD). The results of calculations were compared to TPS data obtained at National Institute of Oncology of Rabat.     

Gauging universe expansion via scalar fields

In this study, we investigate the expansion of the FRLW universe in the open, closed, and flat geometries. The universe is dominated by a scalar field (spatially homogeneous) as a source of dark energy. We consider the three different classes of scalar fields – quintessence, tachyonic, and phantom field – for our analysis. A mathematical analysis is carried out by considering these three scalar fields with exponential and power-law potentials. Both potentials give exponential expansion in the open, closed, and flat FRLW universes. It is found that quintessence, tachyonic, and phantom scalar fields are indistinguishable under the slow roll approximation.     

Fluctuation with dust of de Sitter ground state of scalar-tensor gravity

An exact de Sitter solution of scalar-tensor gravity is found in our recent work, in which the non-minimal coupling scalar is rolling along a non-constant potential. Based on this solution, a dust-filled FRW universe is explored in frame of scalar-tensor gravity in this article. The effective dark energy induced by the sole non-minimal scalar can be quintessence-like, phantom-like, and more significantly, can cross the phantom divide. The rich and varied properties of scalar-tensor gravity even with only one scalar is shown.     

Effects of the tensor force on low-energy heavy-ion fusion reactions: a mini review

In recent several years, the tensor force, one of the most important components of the nucleon–nucleon force, has been implemented in time-dependent density functional theories and it has been found to influence many aspects of low-energy heavy-ion reactions, such as dissipation dynamics, sub-barrier fusions, and low-lying vibration states of colliding partners. Especially, the effects of tensor force on fusion reactions have been investigated from the internuclear potential to fusion crosssections systematically. In this work, we present a mini review on the recent progress on this topic. Considering the recent progress of low-energy reaction theories, we will also mention more possible effects of the tensor force on reaction dynamics.     

Effects of the Various Cooling Conditions on 1,064-nm nd:Yag Laser Treatment for Selective Photothermolysis

The purpose of this study was to find optimum treatment conditions for selective photothermolysis by evaluating internal–external heat distributions according to different cooling methods. The 1,064-nm Nd:YAG laser was transmitted into a skin-mimicking phantom with different cooling conditions, and its minimum temperatures and sub-zero times were measured. The cooling methods were classified into a total of eight conditions composed of five cryogen spray cooling conditions and three air cooling conditions. Based on the experimental results, condition 2 was selected as the optimum cooling condition for selective photothermolysis obtained from the cryogen spray cooling method.     

ILEEMS: Methodology and Applications to Iron Oxides

ILEEMS is the acronym for Integral Low-energy Electron Mössbauer Spectroscopy. In this variant of Mössbauer spectroscopy the low-energy electrons, E < ～15 eV, emitted by the probe nuclei in the absorber are counted as a function of source velocity. As a consequence of their low energy, the detected electrons' origin lies within a very thin surface layer with thickness of a few nanometers and consequently, ILEEMS is a useful technique to examine surfaces of Fe-containing substances. In a first part of this paper the authors briefly describe the design of a home-made ILEEMS equipment allowing the temperature of the investigated sample to be varied between 77 K and room temperature. The second part of this contribution deals with a selection of results obtained from ILEEMS spectra for various Fe oxides. In particular, the following items are covered: (1) surface versus bulk Morin transition in small-particle and near-bulk hematite, α-Fe₂O₃; (2) bulk and thin-film magnetite, Fe₃O₄; (3) ferrihydrite, 5Fe₂O₃·9H₂0, goethite, α-FeOOH, and lepidocrocite, γ-FeOOH, all to some extent in relation to their morphology. Interesting and intriguing findings concerning the surface properties of these oxides were obtained and it is argued that the results encourage more systematic research in this and related fields using the surface-sensitive ILEEMS technique.     

650nm光在Intralipid-10%中分布的测量和分析

本文提出一种用光纤测定光在生物组织模型Iitralipid内部光分布的方法并测定了650nm激光在Iitralipid 10%中的分布,该方法与各向同性球形光纤探头探测组织内光分布是一种互补的方法。实验结果揭示了在生物组织模型中不同方向散射光的分布规律,表明了不同的组织光学参数和不同直径的入射光束与光分布之间的关系;采用外推边界条件的漫射方程解拟合前向散射光的测量数据确定了组织模型的散射系数和吸收系数并得到较好的结果,所测量的光学参数与公开发表的结果比较其差别在2 35%以内。