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Cerebral hemorrhages require rapid diagnosis and intensive treatment. This study aimed to detect cerebral hemorrhages and their locations in images using a deep learning model applying explainable deep learning. Normal brain images with no hemorrhages and images with subarachnoid, intraventricular, subdural, epidural, and intraparenchymal hemorrhages according to computed tomography (CT) (n = 200) were analyzed. A ResNet deep learning model, including image processing, was utilized. The visual explanation from a heatmap was made at the hemorrhage location using a gradient-class activation map (Grad-CAM). To evaluate the performance of the deep learning system, the accuracy, sensitivity, and specificity were determined. A hemorrhage prediction system for images of normal brains and brains with subarachnoid, intraventricular, subdural, epidural, and intraparenchymal hemorrhages was built. The Grad-CAM representation indicated the location of the hemorrhages in these images. In the prediction results, accurate predictions of the hemorrhage areas were made and visualizations of the corresponding locations overlapped in the images within (− 4, 1) pixel difference. The evaluation of the system performance showed an accuracy of 0.81 with a sensitivity of 0.67 and specificity of 0.86. These results constitue a proof of concept for the use of explainable artificial intelligence (XAI) to detect cerebral hemorrhages and visualize their locations in medical images, which will allow rapid diagnosis and treatment.

In vivo measurement of radiotherapeutic doses is an important procedure for ensuring the accuracy of radiation treatments. The glass rod dosimeter is a known dosimeter for in vivo dosimetry, which has high reproducibility and low dependencies with respect to major radiotherapeutic conditions. A hemispherical buildup cap made of brass was fabricated to avoid a large measurement error owing to the partial lack of buildup effect during the measurement on the patient's skin. The correction factors (CFs) were experimentally obtained and verified using a Monte Carlo simulation. A clinical trial was performed with 117 patients. As a result, the measured CF was consistent with the simulation by a 2.3% error, and the mean errors of each site were within 2%. The total mean error was 1.84%, with a standard deviation of 1.39%. To conclude, this methodology can provide high accuracy and convenience in radiotherapeutic in vivo measurements.

The aim of this study is to evaluate the feasibility of a deep learning tumor segmentation network trained by merged tumor dataset. PET-CT datasets for head-and-neck (H&N) and limb tumors were used to train three different networks: H&N, Limb, and merged (H&N + Limb). Dice similarity coefficient (DSC) of the merged network (0.89) in limb tumors was the same as that of the Limb network. In H&N tumor, DSC of the merged network (0.72) was higher than that of the H&N network (0.69). We found that the merged network could be applied simultaneously in H&N and limb tumor segmentation.

In high energy electron beam therapy, a bolus can be used for the conformal dose to target and achieve the appropriate treatment quality. To evaluate the use of a customized silicone bolus, we analyzed the dosimetric properties of the electron beam according to the silicone bolus thickness. Eight silicone slits were fabricated using an acrylic mold. The size of each slit was 150 × 150 × 5 m3 (width × length × height). Degassing was performed to eliminate bubbles in the slits during the silicone casting process. Depth dose measurements were performed for a 6 MeV and 9 MeV electron beams with 10 × 10 cm2, 6 × 6 cm2 and 5 cm diameter circular fields with various silicone thickness and with the conventional bolus. For the depth dose measurement, the film was placed between two 6 cm solid water phantoms, and the electron beam was delivered parallel to the film. The Rando phantom dose with customized bolus were evaluated with the 10 × 10 cm2 6 MeV electron beam. As the slab thickness increased, the depth dose in the solid water phantom decreased after reaching the maximum dose depth (dmax). Depending on the silicone thickness, the surface dose of the phantom was increased until reaching the electron beam dmax and was decreased after dmax. The coefficient to convert the thickness of the silicone to water were 1.06 in 6 MeV and 1.07 in 9 MeV, respectively. We measured the electron beam dose properties for making patient-specific silicone boluses with optimal thickness. The results of this study can be used to predict the silicone bolus thickness required in order to deliver the appropriate dose to the target.

The purpose of this study is to investigate the possibility of interchanging patients on beam-matched linear accelerators (linacs), by evaluating the dosimetric variation and the dose delivery accuracy of volumetric modulated arc therapy (VMAT). Two VitalBeam linacs installed recently in our center were included in this study. For dosimetric data comparison, beam data, such as percentage depth doses (PDDs), beam profiles, output factors, multi-leaf collimator (MLC) leaf transmission factors, and the dosimetric leaf gap (DLG), for 6-MV and 10-MV beams were measured on both linacs. Sixty patients (20 head and neck, 20 lung, and 20 prostate cancers) were selected to evaluate the dosimetric parameters and the delivery accuracy of the VMAT plans created for various treatment sites. All the VMAT plans were generated using the Eclipse treatment planning system (TPS) with the same optimizer algorithm. The dose differences between two beam-matched linacs for planning target volumes (PTVs) and organs at risk (OARs) were recorded and analyzed. Patient-specific dosimetric quality assurance (DQA) using the Electronic Portal Image Device (EPID) were performed, and the measured planar doses were compared with those calculated by using the TPS though absolute dose gamma evaluation using 2%/2 mm and 2%/3 mm criteria. The differences in all dosimetric beam data between the two beam-matched linacs were all within 1% for the 6-MV and the 10-MV beams. For all 60 cases of three treatment sites, no notable differences were observed in the dosimetric comparison and the DVH variation between the beam-matched linacs. The average differences in dosimetric parameters of PTV and OARs were all within 1%. Furthermore, all passing rates of measured doses on the beam-matched linacs were higher than 93% and 97% for the 2%/2 mm and the 2%/3 mm criteria, respectively. Our overall dosimetric variation in beam data and VMAT plans remains within the tolerance of clinical acceptability. Pretreatment verification results were also clinically acceptable, showing good agreement with the calculated doses. Therefore, this study demonstrated the possibility of swapping patients in a VMAT plan without any modification and re-planning between two beam-matched linacs.

A deep-inspiration breath-hold (DIBH) is a useful technique that can reduce the risk of radiation-related toxicity to major organs during radiation treatment (RT) of breast cancer. A laser sensor-based position monitoring system was developed to measure the absolute position of the object and to realize high accuracy and reproducibility during DIBH. A laser distance sensor (LDS) was manufactured to be mounted on a commercial breast board and to measure the absolute distance between the sensor and the patient's sternum. The absolute distance measured by using the LDS was evaluated for the movement generated by the motorized jack system. The respiration of five volunteers was measured by using the LDS and commercial real-time position management (RPM) to evaluate the correlation of the signals. The data measured by using the LDS for the input to the motorized jack had a relative error of 0.2%. At DIBH, the average correlation coefficient between the LDS and RPM was 0.98, and at FB, it was 0.84. The LDS and RPM showed almost similar timings for the rising and the falling portions, but the magnitudes of amplitudes were slightly different from each other. The LDS proposed in this study can easily reproduce patient setup and monitor DIBH without any disturbance from the treatment beam. The measuring accuracy of the LDS for the quantitative motion of a motorized jack system was successfully verified. The performance of the LDS compared to RPM in the FB and the DIBH of five volunteers was also clinically acceptable.

The dependency of the output factor on the field size in the passive scattering proton therapy at the National Cancer Center (NCC) in Korea was investigated through a comparison of the measured output factors. The output factor of the fields of the representative beam options was measured using a Pinpoint chamber with standard circular blocks of less than 5 cm in diameter. The measured output factors for different field sizes show that the dependency of the output factor on the field size is not negligible even in the field for the 5 cm in diameter for long-range proton beams. In addition, the conflicting dependency in shallow fields indicates that the potential contribution of scattered protons should be considered in predicting and modelling of the output factors in small fields.

Radiation pneumonitis (RP) is a major radiation-induced lung injury in patients with lung cancer. When an extremely high risk of severe RP is predicted, it is a critical issue that severely affects radiation dose and treatment planning. It is essential to assess which prognostic factor affects the occurrence of RP before initiating radiation treatment. In this study, we aimed to identify the variable importance (VI) of prognostic factors related to RP by using an artificial neural network (ANN) containing complex association between several prognostic factors. We reviewed 110 cases in patients with lung cancer who received radiation therapy (RT) from August 2000 to December 2018. The multi-layer perceptron algorithm, which is a back-propagation ANN algorithm, was implemented by SPSS Modeler (verl3.1, IBM SPSS Inc., Chicago, IL). The fifteen input variables were set, and the target variable was the occurrence of RP. The VI, which indicates the effect of each prognostic factor on the occurrence of RP, was analyzed by the variance-based method. To evaluate the VI of the ANN, we qualitatively compared the VI of the ANN with the odds ratios (OR) obtained from previously published literature. Patients who had an RP grade >2 comprised 13.6%. The accuracy of the ANN model was 76.92% and the and the area under the curve (AUC) was 0.774. From the results of the VI from the ANN, mean lung dose (MLD) had the highest VI among the prognostic factors at 15.96%. The OR of interstitial lung disease (ILD) was the highest at 25.70. While the VI of the ANN includes complex associations of the prognostic factors, ORs include independent associations between exposure and outcome. This preliminary study is meaningful as it proposes a method to quantify the VI of prognostic factors related to patient outcome using even simple ML algorithm. By further acquiring the more refined big data, optimizing the ML model, and performing clinical validation, the accurate VI can be adopted for personalized RT planning.

Radiation toxicity grades must be reviewed based on existing knowledge-based clinical evidence or be assessed by referencing the clinical research literature to minimize radiation toxicity associated with radiotherapy. The aim of this study was to develop a radiation toxicity prediction system using metarule-guided mining of the clinical research literature to predict radiation pneumonitis and esophagitis in lung cancer patients. A semantic pattern database was built using 100 clinical research articles. Semantic patterns of prognostic factors and toxicity grades were extracted by metarule-guided mining. Feature analysis and correlation investigation of prognostic factors and toxicity grades were performed by using dendrogram and heatmap. A web-based user interface for the prediction system was designed. Patient prognostic factors were used in this prediction system to predict toxicity grade results. Radiation toxicity grades for patients with radiation pneumonitis and esophagitis were calculated through our prediction system. Age and chemotherapy were prognostic factors as were toxicity grades 1–3 and 5 based on the metarule-guided mining system. The odds ratios had similar trends to those in the existing meta-analysis literature. The radiation toxicity prediction system that we developed can potentially be used as a clinical decision support system for patient-specific radiation treatment after weighting of prognostic factors, performing a correlation analysis, and performing a validity evaluation.

BaFe11CoO19 hexaferrites were prepared by using a co-precipitation method and heat treatment. By changing the ion molar ratio of (Fe + Co)/Ba = (x + 1)/1, we found a clear difference in the crystalline structural and magnetic properties. Particularly, the magnetic properties became optimal at x = 11 - 13 based on the saturation magnetization and coercivity values. The effects of heat treatment on the morphological, structural and magnetic properties were assessed. With the results of thermal gravimetric analyses, X-ray diffraction patterns, and magnetic-field-dependent magnetization, we found that M-type hexaferrite nanocrystals start being formed at a temperature of 650°C, which was much lower than temperatures reported previously.

The aim of this study was to derive a new plan-scoring index using normal tissue complication probabilities to verify different plans in the selection of personalized treatment. Plans for 12 patients treated with tomotherapy were used to compare scoring for ranking. Dosimetric and biological indexes were analyzed for the plans for a clearly distinguishable group (n = 7) and a similar group (n = 12), using treatment plan verification software that we developed. The quality factor (QF) of our support software for treatment decisions was consistent with the final treatment plan for the clearly distinguishable group (average QF = 1.202, 100% match rate, n = 7) and the similar group (average QF = 1.058, 33% match rate, n = 12). Therefore, we propose a normal tissue complication probability (NTCP) based on the plan scoring index for verification of different plans for personalized treatment-plan selection. Scoring using the new QF showed a 100% match rate (average NTCP QF = 1.0420). The NTCP-based new QF scoring method was adequate for obtaining biological verification quality and organ risk saving using the treatment-planning decision-support software we developed for prostate cancer.

In the present study, we developed a position-sensitive NaI(Tl) scintillation detector module for use in the development of a large-area Compton camera. The developed detector module employs a large (i.e., 27 × 27 × 2 cm3) monolithic NaI(Tl) scintillator coupled with a closely packed array of 6 × 6 square PMTs. A multiplexer-based signal processing circuit and a data acquisition system were developed to estimate the interaction position in the scintillator from the signals of the PMTs by using the maximum likelihood position estimation algorithm (MLPE). The performance of the developed detector was evaluated experimentally, showing that the energy and the time resolution of the detector are 7.88% (for 662-keV gamma ray) and 9.6 ns FWHM, respectively, which are comparable to those of a commercial three-inch cylindrical NaI(Tl) scintillation detector. In addition, the spatial resolutions were about 3-to-6-mm FWHM for a wide energy range (59.5 - 1173 keV) and various interaction positions on the detector (from center to edge), which are satisfactory results considering that a 3-mm-diameter collimated gamma-ray beam was used in the experiments.

We have measured the transmission spectra of the conventional Bardeen-Cooper-Schrieffer (BCS) superconductor niobium nitride (NbN) thin films (T c = 11 K) using terahertz time-domain spectroscopy (THz-TDS) over the spectral range of 10 - 110 cm −1 and the temperature range of 3.9 - 295 K. We extracted both the real part, σ1, and the imaginary part, σ2, of the optical conductivity, σ = σ1 + iσ2, independently and simultaneously, without a Kramers-Kronig analysis. The superconducting gap Δ(T) was observed in the real part of the conductivity, σ1, below T c = 11 K with a maximum value of 2Δ(0) = 30 cm −1 and the gap ratio 2Δ(0)/k B T c = 3.92.

The aim of this study is an integrated research for text-based data mining and toxicity prediction modeling system for clinical decision support system based on big data in radiation oncology as a preliminary research. The structured and unstructured data were prepared by treatment plans and the unstructured data were extracted by dose-volume data image pattern recognition of prostate cancer for research articles crawling through the internet. We modeled an artificial neural network to build a predictor model system for toxicity prediction of organs at risk. We used a text-based data mining approach to build the artificial neural network model for bladder and rectum complication predictions. The pattern recognition method was used to mine the unstructured toxicity data for dose-volume at the detection accuracy of 97.9%. The confusion matrix and training model of the neural network were achieved with 50 modeled plans (n = 50) for validation. The toxicity level was analyzed and the risk factors for 25% bladder, 50% bladder, 20% rectum, and 50% rectum were calculated by the artificial neural network algorithm. As a result, 32 plans could cause complication but 18 plans were designed as non-complication among 50 modeled plans. We integrated data mining and a toxicity modeling method for toxicity prediction using prostate cancer cases. It is shown that a preprocessing analysis using text-based data mining and prediction modeling can be expanded to personalized patient treatment decision support based on big data.

The purpose of this research is to demonstrate, based on a Monte Carlo simulation code, the procedure of radiation treatment planning for proton-boron fusion therapy (PBFT). A discrete proton beam (60 - 120 MeV) relevant to the Bragg peak was simulated using a Monte Carlo n-particle extended (MCNPX, Ver. 2.6.0, National Laboratory, Los Alamos NM, USA) simulation code. After computed tomography (CT) scanning of a virtual water phantom including air cavities, the acquired CT images were converted using the simulation source code. We set the boron uptake regions (BURs) in the simulated water phantom to achieve the proton-boron fusion reaction. Proton sources irradiated the BUR, in the phantom. The acquired dose maps were overlapped with the original CT image of the phantom to analyze the dose volume histogram (DVH). We successfully confirmed amplifications of the proton doses (average: 130%) at the target regions. From the DVH result for each simulation, we acquired a relatively accurate dose map for the treatment. A simulation was conducted to characterize the dose distribution and verify the feasibility of proton-boron fusion therapy (PBFT). We observed a variation in proton range and developed a tumor-targeting technique for treatment that was more accurate and powerful than both conventional proton therapy and boron-neutron capture therapy.

We used a spectrophotometer to compare the dosimetric properties of two non-scattering (radiochromic) gel dosimeters: a non-scattering gel dosimeter developed in-house and a PRESAGE™ gel dosimeter. We evaluated the dosimetric characteristics, including spectral absorption, dose linearity, reproducibility, and dose rate dependency of the two gel dosimeters. The non-scattering gel and the PRESAGE™ gel dosimeters showed peak sensitivity at wavelengths of 600 nm and 630 nm, respectively. Over a range of doses the best dose linearities of the non-scattering and the PRESAGE™ gel dosimeters resulted in R2 values of 0.99 at wavelengths of 600 nm and 630 nm, respectively. The reproducibility and dose-rate dependence of each of the two gel dosimeters were within the range of ±3 %. Our results revealed that the peak sensitivities of the two radiochromic gel dosimeters were significantly different; the in-house non-scattering gel dosimeter demonstrated peak sensitivity at a wavelength of 600 nm while the PRESAGE™ gel dosimeter had peak sensitivity at a wavelength of 630 nm. We confirmed that for 3D gel dosimetry, the in-house non-scattering gel dosimeter had a more stable dose response compared with a commercial non-scattering gel dosimeter.

The electronic structures of multiferroic oxides of Ba(1-x)Bi(x)Ti(0.9)Fe(0.1)O(3) (0 < x < 0.12) have been investigated by employing photoemission spectroscopy and soft x-ray absorption spectroscopy (XAS). The measured Fe and Ti 2p XAS spectra show that Ti ions are in the Ti4+ states for all x and that Fe ions are Fe2+-Fe3+ mixed-valent for x > 0. The valence states of Fe ions are found to be nearly trivalent for x=0, and decreases with increasing x from being nearly trivalent (v(Fe)~ 3) for x=0 to v(Fe)~ 2.6 for x=0.12. The valence states of both Ti and Ba ions do not change for all x < 0.12. Based on the obtained valence states of Fe ions, the electronic and magnetic properties of Ba(1-x)Bi(x)Ti(0.9)Fe(0.1)O(3) are explored., 9 pages, 3 figures

To evaluate the self-heating effects of FeCo magnetic nanoparticles, we synthesized surfaceoxidized FeCo nanoparticles by using the co-precipitation method with the reduction reaction without any post treatments. As-synthesized FeCo nanoparticles exhibited a mean diameter of about 39 nm with an oxidized shell thickness of about 4 − 5 nm. The saturation magnetization and coercivity were found to be 172 emu/g and 268 Oe at 300 K, respectively. The heat elevation of the FeCo magnetic colloid was measured under alternating magnetic fields of 76, 102, and 127 Oe with selectable frequencies of 190, 250 and 355 kHz. The heat temperature increased up to about 45 ◦C from an initial temperature of 24 ◦C under a 127 Oe field with a frequency of 355 kHz, at which the specific absorption was about 35.7 W/g.

We investigated high-frequency behavior of FeN thin films prepared by reactive sputtering through ferromagnetic resonance (FMR) and its relationship with the static magnetic properties. The FMR was observed in the frequency range from 2 to 18 GHz in the FeN films fabricated at proper nitrogen flow rate (NFR). In those FeN thin films, a decrease of the saturation magnetization and the corresponding decrease of the FMR frequency were observed as NFR was increased during the deposition. The external field dependences of the FMR frequencies were well fit to the Kittel formula and the Land\'e g-factors determined from the fit were found to be very close to the free electron value. The high-field damping parameters were almost insensitive to the growth condition of NFR. However, the low-field damping parameters exhibited high sensitivity to NFR very similar to the dependence of the hard-axis coercivity on NFR, suggesting that extrinsic material properties such as impurities and defect structures could be important in deciding the low-field damping behavior., Comment: 18 pages, 6 figures, ICAMD 2015 conference

In this study, the geometric and dosimetric accuracy of an in-house-developed couch-based tracking system (CBTS) was investigated using both film and in-house-developed polymer gel dosimeters. We evaluated the 1D and the 2D motion accuracies of our couch system by using Gafchromic EBT film. For the 1D test, the couch system was moved 5, 10, and 20 mm in the X, Y, and Z directions, respectively. Meanwhile, for the 2D test, it was moved along the XY, YZ, and ZX directions. We compared the profiles, full widths at half maximum (FWHMs), and penumbras between the static and the tracking fields. For the 3D test, we quantitatively compared the dose distribution between the static and the tracking fields by using the polymer gel dosimeter when it was simultaneously moved in the XYZ directions. We confirmed that the film was moved according to motion amplitudes of 5, 10, and 20 mm in the X, Y, and Z directions, respectively, in the 1D and 2D motion tests. The value of the FWHM of the static field and the three tracking fields were 51.88, 53.28, 57.67, and 64.43 mm, respectively. Two types of penumbras became wider with increasing amplitudes compared to the static field. For the 3D test, the dose distribution of the XYZ tracking field was qualitatively larger than that of the static field. We conclude that this CBTS has the potential for pre-clinical applications in adaptive radiation therapy.

Many studies have reported that a patient can move even when an immobilization device is used. Researchers have developed an immobilization-device quality-assurance (QA) system that evaluates the validity of immobilization devices. The QA system consists of force-sensing-resistor (FSR) sensor units, an electric circuit, a signal conditioning device, and a control personal computer (PC) with in-house software. The QA system is designed to measure the force between an immobilization device and a patient’s skin by using the FSR sensor unit. This preliminary study aimed to evaluate the feasibility of using the QA system in radiation-exposure situations. When the FSR sensor unit was irradiated with a computed tomography (CT) beam and a treatment beam from a linear accelerator (LINAC), the stability of the output signal, the image artifact on the CT image, and changing the variation on the patient’s dose were tested. The results of this study demonstrate that this system is promising in that it performed within the error range (signal variation on CT beam < 0.30 kPa, root-mean-square error (RMSE) of the two CT images according to presence or absence of the FSR sensor unit < 15 HU, signal variation on the treatment beam < 0.15 kPa, and dose difference between the presence and the absence of the FSR sensor unit < 0.02%). Based on the obtained results, we will volunteer tests to investigate the clinical feasibility of the QA system.

We study the crystal structure and the magnetic properties of Ba1−x Bi x Ti0.9Fe0.1O3 (0 ≤ x ≤ 0.12) ceramics prepared by using a conventional solid-state reaction. X-ray diffraction and Raman scattering spectroscopy measurements show that Bi3+ substitution suppresses the formation of the hexagonal BaTiO3 phase and stabilizes the tetragonal BaTiO3 phase. The samples with x ≥ 0.08 demonstrate a single tetragonal BaTiO3 phase. Samples with x ≤ 0.1 show obvious magnetic orders at room temperature. The saturated magnetization, paramagnetic contribution and magnetic transition temperature are found to depend on the Bi doping concentration. Samples with 0.08 ≤ x ≤ 0.1 show a single tetragonal phase structure with a ferromagnetic order. These results indicate that the crystal structure and the ferromagnetic properties of Ba1−x Bi x Ti0.9Fe0.1O3 (0 ≤ x ≤ 0.12) ceramics are intrinsic.

A nanoscale investigation of the local electrical properties of individual vanadium-pentoxide (V2O5) nanowires (NWs) deposited on a SiO2/p+ Si substrate was carried out by using electrostatic force microscopy (EFM) in ambient conditions. We found that the EFM phase shift as an electrostatic response of V2O5 NWs to the biased-tip decreases with the lift height due to the electrostatic force gradient. We also observed that the EFM phase shift of V2O5 NWs shows the quadratic voltage dependence for a biased-tip with a fixed lift height. Furthermore, it is observed that the crossed junctions or bundles of the NWs compared to the single NWs showed higher electrostatic response, resulting in a large phase shift in the EFM measurements. These results suggest that the local electrical properties of V2O5 NW surface can be characterized in the nanoscale range by using EFM.

An ideal alignment method based on the external anatomical surface of the patient should consider the entire region of interest. However, optical-camera-based systems cannot blindly monitor such areas as the patient’s back, for example. Furthermore, collecting enough information to correct the associated deformation error is impossible. The study aim is to propose a new patient alignment method using tactile array sensors that can measure the distributed pressure profiles along the contact surface. The TactArray system includes one sensor, a signal-conditioning device (USB drive/interface electronics, power supply, and cables), and a PC. The tactile array sensor was placed between the patient’s back and the treatment couch, and the deformations at different location on the patient’s back were evaluated. Three healthy male volunteers were enrolled in this study, and pressure profile distributions (PPDs) were obtained with and without immobilization. After the initial pretreatment setup using the laser alignment system, the PPD of the patient’s back was acquired. The results were obtained at four different times and included a reference PPD dataset. The contact area and the center-of-pressure value were also acquired based on the PPD data for a more elaborate quantitative data analysis. To evaluate the clinical feasibility of using the proposed alignment method for reducing the deformation error, we implemented a real-time self-correction procedure. Despite the initial alignment, we confirmed that PPD variations existed in both cases of the volunteer studies (with and without the use of the immobilization tool). Additionally, we confirmed that the contact area and the center of pressure varied in both cases, and those variations were observed in all three volunteers. With the proposed alignment method and the real-time selfcorrection procedure, the deformation error was significantly reduced. The proposed alignment method can be used to account for the limitation of the camera-based system and to improve the accuracy of the external surface-based patient setup.

The purpose of this study was to use various dosimetrical indices to determine the best intensitymodulated radiation therapy (IMRT) modality - for treating patients with prostate cancer. Ten patients with prostate cancer were included in this study. IMRT plans were designed to include different modalities, including the linac step and shoot, tomotherapy, RapidArc, and proton systems. Various dosimetrical indices, like the prescription isodose to target volume (PITV) ratio, conformity index (CI), homogeneity index (HI), target coverage index (TCI), modified dose homogeneity index (MHI), conformation number (CN), critical organ scoring index (COSI), and quality factor (QF), were determined to compare the different treatment plans. Biological indices, such as the generalized equivalent uniform dose (gEUD) based the tumor control probability (TCP), and the normal tissue complication probability (NTCP), were also calculated and used to compare the treatment plans. The RapidArc plan attained better PTV coverage, as evidenced by its superior PITV, CI, TCI, MHI, and CN values. Regarding organ at risks (OARs), proton therapy exhibited superior dose sparing for the rectum and the bowel in low dose volumes, whereas the tomotherapy and RapidArc plans achieved better dose sparing in high dose volumes. The QF scores showed no significant difference among these plans (p = 0.701). The average TCPs for prostate tumors in the RapidArc, linac and proton plans were higher than the average TCP for Tomotherapy (98.79%, 98.76%, and 98.75% vs. 98.70%, respectively). Regarding the rectum NTCP, RapidArc showed the most favorable result (0.09%) whereas linac resulted in the best bladder NTCP (0.08%).

We compare the dosimetrical differences between plans generated for helical tomotherapy by using the 2D or 3D the margining technique for the treatment of prostate cancer. Ten prostate cancer patients were included in this study. For 2D plans, the planning target volume (PTV) was created by adding 5 mm (lateral/anterior-posterior) to the clinical target volume (CTV). For 3D plans, a 5-mm margin was added not only lateral/anterior-posterior, but also superior-inferior, to the CTV. Various dosimetrical indices, including the prescription isodose to target volume (PITV) ratio, conformity index (CI), homogeneity index (HI), target coverage index (TCI), modified dose homogeneity index (MHI), conformation number (CN), critical organ scoring index (COSI), and quality factor (QF) were determined to compare the different treatment plans. Differences between the 2D and the 3D PTV indices were not significant except for the CI (p = 0.023). 3D margin plans (11195 MUs) resulted in higher (13.0%) monitor units than 2D margin plans (9728 MUs). There were no significant differences in any organs at risk (OARs) between the 2D and the 3D plans. Overall, the average dose for the 2D plan was slightly lower than that for the 3D plan dose. Compared to the 2D plan, the 3D plan increased the average treatment time by 1.5 minutes; however, this difference was not statistically significant (p = 0.082). We confirmed that the 2D and the 3D margin plans were not significantly different with regard to various dosimetric indices such as the PITV, CI, and HI for PTV and the OARs with tomotherapy.

We measured the conductance of a series of amine-terminated oligophenyl molecular junction formed with carbon electrodes by using a scanning tunneling microscope based break-junction technique. The tight-binding model that includes the molecular backbone states accurately captured the experimentally measured the molecular conductance and the exponential decay trend of the conductance with the molecular backbone length. Furthermore, we found that this model tracked successfully the shift of the highest occupied molecular orbital toward the Fermi energy as increasing the molecular length. Finally, we found that the tight-binding model explaining more week coupling strength with the graphite electrode than that with the Au electrode is in quantitative agreement with the density functional theory calculations.

A phase transformation from insulating brownmillerite SrCoO2.5 to conducting perovskite SrCoO3 through electrochemical oxidation has been demonstrated for thin films of SrCoOx on a SrTiO3 (001) substrate. The cobalt-oxide film strongly favors the brownmillerite phase of SrCoO2.5 instead of the perovskite phase of SrCoO3 on a SrTiO3 (001) substrate due to its low lattice mismatch. Therefore, the phase transformation has its own retention. The alkaline water electrolysis occurs between the copper cathode and the SrCoO2.5 film anode. The H+ ions are attracted to the cathode and generate H2 gas. The OH− ions are attracted to the film’s surface and generate a rich amount of oxygen to fill the oxygen vacancy channel of brownmillerite SrCoO2.5. The phase transformation was verified from the change in the out-of-plane lattice constant and the change in the resistivity of the electrolyzed film.

Representative traditional Korean pigments (oyster shell white [hobun], massicot [miltaseung], indigo [jjok], azurite [seokcheong], malachite [seokrok], and red lead [yeondan]) have been studied with terahertz time-domain spectroscopy (THz-TDS) and Fourier-transform infrared spectroscopy (FTIRS) over the spectral region of 0.1–7.5 THz. Both the refractive index n and the extinction coefficient k were simultaneously and independently determined in the terahertz region without a Kramers-Kronig analysis while the absoprtion coefficient spectra were acquired in the infrared region. All pigments studied in the present work exhibited a set of characteristic absorption peaks unique to the pigment species in addition to a background that increased with increasing frequency. Our study demonstrates that terahertz and infrared techniques can be useful identification and diagnostic tools for the traditional Korean pigments used in heritage buildings and artworks.

To compensate for the acceptor dopant Fe3+ in Fe-doped BaTiO3 ceramics, we introduced a donor dopant into these ceramics in order to investigate its effects on their phase structure and on the magnetic and ferroelectric properties. We prepared 5% Fe-doped BaTiO3 ceramic and used Bi3+ as the donor dopant. We found that the formation of the hexagonal phase in Fe-doped BaTiO3 was suppressed and that the magnetic and the ferroelectric properties of these ceramics were changed by the Bi3+ doping. These results indicate that the structural, magnetic and ferroelectric properties of BaTi0.95Fe0.05O3 ceramics can be controlled by Bi3+ doping and that a multiferroic property was observed in the Ba0.98Bi0.02Ti0.95Fe0.05O3 ceramic.

The pump-wavelength dependence of the emission properties for Er-Yb-Bi triply-doped borosilicate glasses with different concentrations of bismuth was investigated. The peak intensity of the 1538 nm emission of Er3+ ions in the glass with 2 mol% of Bi2O3 upon 980 nm excitation was found to increase 14.5 times compared to that after the 805 nm excitation. The lifetime of the 1538 nm emission slightly decreased with the addition of 0.5 mol% of Bi2O3, but increased with increasing bismuth concentration up to 2 mol% upon 980 nm excitation (774 → 913 µs). The efficiency of the energy transfer from Yb3+ to Er3+ ions increased with increasing bismuth concentration, and the highest efficiency was 10.4% when 2 mol% of Bi2O3 was added.

Investigating with a continuous-wave 488-nm argon-ion laser, we rstly report on the visible optical limiting properties of germano-silicate optical bers with gold nanoparticles incorporated. The ground-state conduction, the surface plasmon band and the free carrier band were considered as a three-level model to theoretically explain the obtained optical limiting behaviors. In the visible wavelength region around the surface plasmon resonance absorption peak of the gold nanoparticles, the e ective nonlinear absorption coe cient was estimated to be 22.4 cm/GW.

Non-Resonant Optical Nonlinearity of Germano-Silicate Optical Fiber Incorporated with Si Nanocrystals Hye Jin Cho, Aoxiang Lin, Songbae Moon and Won-Taek Han Department of Information and Communications, School of Photon Science and Technology, Gwangju Institute of Science and Technology, Gwangju 500-712 Bok Hyeon Kim Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 500-712 (Received 12 December 2007) The non-resonant optical nonlinearity of a germano-silicate glass optical ber with silicon (Si) nanocrystals incorporated, fabricated by using a modi ed chemical vapor deposition process, was investigated by the continuous-wave self-phase modulation method. The measured non-resonant nonlinear refractive index, n2 = 5:70 10 20 m2/W, of the ber was found to be 2 times larger than that of the ber without Si incorporation. PACS numbers: 42.70.-a, 42.65.wi, 78.67.Bf

Ferromagnetic Resonance Behaviors of Integrated CoPdAlO Magnetic Film on Coplanar Waveguide Ki Hyeon Kim Department of Physics, Yeungnam University, Gyeongsan 712-749 Masahiro Yamaguchi Department of Electrical and Communication Engineering, Tohoku University, Sendai 980-8579, Japan Jongryoul Kim Department of Metallurgy and Materials Science, Hanyang University, Ansan 425-791 (Received 30 August 2007) CoPdAlO magnetic lms, whose ferromagnetic resonance (FMR) frequency was 4.2 GHz, were deposited on a coplanar waveguide (CPW) by using a RF magnetron sputtering method and were then patterned with a size of 2000 m 50 m 2 m (l w t). In the case of the patterned magnetic lms on CPW, the calculated and the measured FMR frequencies were shifted to around 7 GHz, and the measured characteristic impedance of the CPW was also changed by around 7 GHz. In addition, the propagation wavelength shortening e ect was enhanced by about 17 % up to 7 GHz compared with that of the CPW without magnetic lm. These results show that patterned magnetic lms can be used as band-pass lters and broad-band EMI noise lters in the RF and the microwave regions. PACS numbers: 75.90.+w, 85.70.k, 07.55.-w