bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐F‐I‐66: The Effects of Nicotinic Agonists On Rat Hippocampal Glutamatergic Fluctuation by Using Proton Magnetic Resonance Spectroscopy at 9.4T
Authors: Lim S‐I , Song K‐H , Yoo C‐H , Woo D‐C , Choe B‐Y 
Published: July 2016

Purpose:Nicotine exerts its effects through the activation of nicotinic acetylcholine receptors (nAChRs). Varenicline, a smoking cessation aid, is a partial agonist acting at the α4β2 nAChRs. Although nicotine and varenicline contribute to the reward system at the same time, the influence of the substances on hippocampal neurochemical changes has not been investigated yet. We therefore studied the effects of repeated nicotine exposure and varenicline administration on hippocampus of rats by using in vivo proton magnetic resonance spectroscopy (1H MRS) at 9.4T.Methods:Male Wistar rats (n = 11; mean body weight, 304.9 ± 9.9 g) were divided into 3 groups: control rats (control, n = 3); nicotine‐induced rats (nicotine, n = 4); and nicotine‐ and varenicline‐induced rats (varenicline, n = 4). Acquisition of in vivo MRS was conducted by using 9.4 T Agilent Scanner. The linear combination of model spectra (LCModel, version 6.3, Stephen W. Provencher) fitting software was used to quantify the metabolites in the frequency domain, using the basis metabolites.Results:In this study, the results show the tendency of increased Glu level in nicotine group than in the control and varenicline groups. Moreover, GSH and NAA levels tended to decrease in the nicotine group in comparison with those in the control and varenicline groups.Conclusion:These findings indicate that the hippocampus is integrally linked to the brain reward sensitization involved in addiction and glutamate release through mobilization of intracellular calcium stores. Further, oxidative stress and toxicity of nicotine on brain would cause the decline of GSH and NAA. In conclusion, we found that varenicline effectively inhibits the reward cycle.
SU‐F‐I‐67: Neurometabolic Effect Induced by Repeated Exposure to Dizocilpine On Prefrontal Cortex of Schizophrenic Animal Model Using In Vivo Proton Magnetic Resonance Spectroscopy at 9.4 T
Authors: Yoo C‐H , Song K‐H , Lim S‐I , Woo D‐C , Choe B‐Y 
Published: July 2016

Purpose:Repeated exposure of dizocilpine (MK‐801) can provide a pathophysiological model for progressive development of schizophrenia. In vivo proton magnetic resonance spectroscopy (1H MRS) was widely used for non‐invasive measurement of neurometabolites, and assessment of disease‐induced neurometabolic alterations. The purpose of this study was to investigate neurometabolic alteration in prefrontal cortex (PFC) with respect to progression (from first‐episode to chronic stage) of schizophrenia by using in vivo 1H MRS.Methods:We used high‐field 1H MRS to investigate the neurometabolic alteration in the PFC region of the rats (N = 13) by comparing before and after 6 day of MK‐801 (0.5 mg/kg) treatment. A point‐resolved spectroscopy (PRESS) sequence was used to obtain spectra in a 22.5 µL of volume of interest carefully located in PFC region with parameters like follow; repetition time, 5000ms; echo time (TE), 13.4 ms; averages = 256. Another experiment group (N = 11) were conducted behavior test by recording the behavior for 20 min.Results:All the rats showed hyperlocomotion, stereotyped behaviors before initiation of MRS. Significantly increased level (N = 7, p < 0.05) of N‐acetylasrparate (NAA), glutamate (Glu), taurine and decreased level (N = 6, p < 0.05) of NAA, Glu and phosphocreatine were observed between baseline and day 6. Both metabolic alterations are consistent with results of first‐episode and chronic schizophrenia respectively.Conclusion:From our findings, the repeated MK‐801 model could be a pathophysiological model which can provide an insight into the transition from first‐episode to chronic stage. This is first time to investigate effects of repeated MK‐801 using high‐field in vivo 1H MRS. We expect our findings can contribute to combining previous diverging results into one pathophysiological interpretation, which can postulate the origin of diverging results to the progression of schizophrenia.
SU‐F‐I‐70: Investigation of Gafchromic EBT3 Film Energy Dependence Using Proton, Photon, and Electron Beams
Authors: Ferreira C , Schnell E , Ahmad S , De La Fuente Herman T 
Published: July 2016

Purpose:To investigate the energy dependence of Gafchromic EBT3 film over a range of clinically used proton, photon and electron energies.Methods:Proton beam energies of 117 and 204 MeV, corresponding respectively to ranges in water of 10 cm and 27 cm from a Mevion S250 double scatter system unit were used. Electron energies of 6 and 20 MeV and photon energies of 6 and 18 MV from a Varian Clinac 21EX Linac were used. Two pieces of film (5×5 cm2) were irradiated sequentially for doses of 100, 500, and 1000 cGy for all energies and modalities. Films were placed on the central beam axis for a 10×10 cm2 field size in the middle of spread out Bragg peak (SOBP) for proton and in respective dmax for photon and electron energies. Films were scanned on a flatbed Epson Expression 10000 XL scanner on the central region of the scanning window using 48‐bit, 300 dpi, and landscape orientation after 48 hours post‐irradiation of film to account for optical density (OD) stabilization. Film analysis of the red channel was performed using ImageJ 1.48v (National Institutes of Health).Results:The energy dependency of EBT3 among all energies and modalities for all doses studied was small within measurement uncertainties (1σ = ± 4.1%). The mean net OD in red channel for films receiving the same dose in the same energy modality had standard deviations within 0.9% for photons, 4.9% for electrons and 1.8% for protons. It was observed that film pieces were activated during proton irradiation, e.g., 7 mR/hr at surface after 30 minutes of irradiation, lasting for 2 hours post irradiation.Conclusion:EBT3 energy dependency was evaluated for clinically used proton, photon, and electron energies. The film self‐activation may have contributed to fog and negligible dose.
SU‐F‐I‐76: Fluoroscopic X‐Ray Beam Profiles for Spectra Incorporating Copper Filtration
Authors: Wunderle K , Godley A , Shen Z , Rakowski J , Dong F 
Published: July 2016

Purpose:The purpose of this investigation is to characterize and quantify X‐ray beam profiles for fluoroscopic x‐ray beam spectra incorporating spectral (copper) filtration.Methods:A PTW (Freiburg, Germany) type 60016 silicon diode detector and PTW MP3 water tank were used to measure X‐ray beam profiles for 60, 80, 100 and 120 kVp x‐ray beams at five different copper filtration thicknesses ranging from 0–0.9 mm at 22 and 42 cm fields of view and depths of 1, 5, and 10 cm in both the anode‐cathode axis (inplane) and cross‐plane directions. All measurements were acquired on a Siemens (Erlangen, Germany) Artis ZeeGo fluoroscope inverted from the typical orientation providing an x‐ray beam originating from above the water surface with the water level set at 60 cm from the focal spot.Results:X‐ray beam profiles for beam spectra without copper filtration compared well to previously published data by Fetterly et al. [Med Phys, 28, 205 (2001)]. Our data collection benefited from the geometric orientation of the fluoroscope, providing a beam perpendicular to the tank water surface, rather than through a thin side wall as did the previously mentioned study. Profiles for beams with copper filtration were obtained which have not been previously investigated and published. Beam profiles in the anode‐cathode axis near the surface and at lower x‐ray energy exhibited substantial heel effect, which became less pronounced at greater depth. At higher energy with copper filtration in the beam, the dose falloff out‐of‐field became less pronounced, as would be anticipated given higher scatter photon energy.Conclusion:The x‐ray beam profile data for the fluoroscopic x‐ray beams incorporating copper filtration are intended for use as reference data for estimating doses to organs or soft tissue, including fetal dose, involving similar beam qualities or for comparison with mathematical models.
SU‐F‐I‐80: Correction for Bias in a Channelized Hotelling Model Observer Caused by Temporally Variable Non‐Stationary Noise
Authors: Favazza C , Fetterly K 
Published: July 2016

Purpose:Application of a channelized Hotelling model observer (CHO) over a wide range of x‐ray angiography detector target dose (DTD) levels demonstrated substantial bias for conditions yielding low detectability indices (d’), including low DTD and small test objects. The purpose of this work was to develop theory and methods to correct this bias.Methods:A hypothesis was developed wherein the measured detectability index (d'b) for a known test object is positively biased by temporally variable non‐stationary noise in the images. Hotelling's T2 test statistic provided the foundation for a mathematical theory which accounts for independent contributions to the measured d'b value from both the test object (d'o) and non‐stationary noise (d'ns). Experimental methods were developed to directly estimate d'o by determining d'ns and subtracting it from d'b, in accordance with the theory. Specifically, d'ns was determined from two sets of images from which the traditional test object was withheld. This method was applied to angiography images with DTD levels in the range 0 to 240 nGy and for disk‐shaped iodine‐based contrast targets with diameters 0.5 to 4.0 mm.Results:Bias in d’ was evidenced by d'b values which exceeded values expected from a quantum limited imaging system and decreasing object size and DTD. d'ns increased with decreasing DTD, reaching a maximum of 2.6 for DTD = 0. Bias‐corrected d'o estimates demonstrated sub‐quantum limited performance of the x‐ray angiography for low DTD. Findings demonstrated that the source of non‐stationary noise was detector electronic readout noise.Conclusion:Theory and methods to estimate and correct bias in CHO measurements from temporally variable non‐stationary noise were presented. The temporal non‐stationary noise was shown to be due to electronic readout noise. This method facilitates accurate estimates of d’ values over a large range of object size and detector target dose.
SU‐F‐J‐01: Measurement of Blood Flow During PDT Using Diffuse Correlation Spectroscopy
Authors: Ong Y , Penjweini R , Yodh A , Zhu T 
Published: July 2016

Purpose:To investigate the variation in blood flow during PDT and to determine the oxygen supplying rate, g, to refine the empirical macroscopic model.Methods:RIF tumors were propagated in female C3H mice by injecting cell suspension at a concentration of 1×106 cells/ml on the shoulder region. Photosensitizer(e.g., HPPH) was injected into the mice through tail vein at a concentration of 0.25 mg/kg when the tumors grew to ∼6 mm in diameter and depth. Temporal changes of tissue oxygen concentration were recorded prior, during and post PDT treatment using OxyLite single‐channel tissue pO2 monitor(OXFORD OPTRONIX). [3O2] was approximated by multiplying the measured pO2 with 3O2 solubility in tissue(1.295 µM/mmHg). The experimental [3O2] profile were compared with those simulated with the macroscopic model with and without considering the blood flow changes. The dynamical change of blood flow during PDT was simulated by making parameter g to be time dependent, in which the g function was obtained from Photofrin‐mediated PDT in RIF tumors. The relative blood flow changes in the tumors prior, during and post PDT treatment were measured using diffuse correlation spectroscopy (DCS) in a non‐contact configuration.Results:Both macroscopic models, with and without blood flow changes, show reasonably good agreement with the experimental [3O2] measurements. However, a rapid increase in the measured [3O2] between 700–1200s during PDT treatment could not be simulated with our empirical models. As blood flow is the direct measure of tissue oxygen supply and different photosensitizers might impact the blood flow differently, detailed studies are essential to investigate the variation in blood flow changes and the impact on the [3O2] consumption using different photosensitizers.Conclusion:DCS can be used to monitor relative blood flow noninvasively. The continuous input of oxygen supply rate is essential to refine our empirical macroscopic model to better predict PDT treatment outcome.
SU‐F‐J‐05: The Effect of Air Pockets in the Urinary Bladder During Bladder Hyperthermia Treatment
Authors: Schooneveldt G. , Kok H.P. , Bakker A. , Geijsen E.D. , de Reijke T.M. , Crezee J. 
Published: July 2016

Purpose:Hyperthermia combined with Mitomycin C is used for the treatment of non‐muscle invasive bladder cancer (NMIBC), using a phased array system of microwave antennas for bladder heating. Often some air is present in the bladder, which effectively blocks the microwave radiation, potentially preventing proper treatment of that part of the bladder. Air can be a relevant fraction of the bladder content and large air pockets are expected to have a noticeable influence on achieved temperatures.Methods:We analysed 14 NMIBC patients treated at our institute with our AMC‐4 hyperthermia device with four 70MHz antennas around the pelvis. A CT scan was made after treatment and a physician delineated the bladder on the CT scan. On the same scan, the amount of air present in the bladder was delineated. Using our in‐house developed hyperthermia treatment planning system, we simulated the treatment using the clinically applied device settings. We did this once with the air pocket delineated on the CT scan, and once with the same volume filled with bladder tissue.Results:The patients had on average 4.2ml (range 0.8–10.1ml) air in the bladder. The bladder volume was delineated by the physician, that is including air pocket and bladder wall, was on average 253ml (range 93–452ml). The average volume in which changes exceeded 0.25°C was 22ml (range 0–108 ml), with the bladder being up to 2°C cooler when an air pocket was present. Except for extreme cases, there was no evident relation between the quantity of air and the difference in temperature.Conclusion:The effect of an air pocket in the bladder during bladder hyperthermia treatment varies strongly between patients. Generally, this leads to lower temperatures in the bladder, potentially affecting treatment quality, and suggesting that care need be taken to minimise the size of air pockets during hyperthermia treatments.The KWF Dutch Cancer Society financially supported this work, grant UVA 2012‐5539.
SU‐F‐J‐08: Quantitative SPECT Imaging of Ra‐223 in a Phantom
Authors: Yue J , Hobbs R , Sgouros G , Frey E 
Published: July 2016

Purpose:Ra‐223 therapy of prostate cancer bone metastases is being used to treat patients routinely. However, the absorbed dose distribution at the macroscopic and microscopic scales remains elusive, due to the inability to image the small activities injected. Accurate activity quantification through imaging is essential to calculate the absorbed dose in organs and sub‐units in radiopharmaceutical therapy, enabling personalized absorbed dose‐based treatment planning methodologies and more effective and optimal treatments.Methods:A 22 cm diameter by 20 cm long cylindrical phantom, containing a 3.52 cm diameter sphere, was used. A total of 2.01 MBq of Ra‐223 was placed in the phantom with 177.6 kBq in the sphere. Images were acquired on a dual‐head Siemens Symbia T16 gamma camera using three 20% full‐width energy windows and centered at 84, 154, and 269 keV (120 projections, 360° rotation, 45 s per view). We have implemented reconstruction of Ra‐223 SPECT projections using OS‐EM (up to 20 iterations of 10 subsets) with compensation for attenuation using CT‐based attenuation maps, collimator‐detector response (CDR) (including septal penetration, scatter and Pb x‐ray modeling), and scatter in the patient using the effective source scatter estimation (ESSE) method. The CDR functions and scatter kernels required for ESSE were computed using the SIMIND MC simulation code. All Ra‐223 photon emissions as well as gamma rays from the daughters Rn‐219 and Bi‐211 were modeled.Results:The sensitivity of the camera in the three combined windows was 107.3 cps/MBq. The visual quality of the SPECT images was reasonably good and the activity in the sphere was 27% smaller than the true activity. This underestimation is likely due to partial volume effect.Conclusion:Absolute quantitative Ra‐223 SPECT imaging is achievable with careful attention to compensate for image degrading factors and system calibration.
SU‐F‐J‐16: Planar KV Imaging Dose Reduction Study
Authors: Gershkevitsh E , Zolotuhhin D 
Published: July 2016

Purpose:IGRT has become an indispensable tool in modern radiotherapy with kV imaging used in many departments due to superior image quality and lower dose when compared to MV imaging. Many departments use manufacturer supplied protocols for imaging which are not always optimised between image quality and radiation dose (ALARA).Methods:Whole body phantom PBU‐50 (Kyoto Kagaku ltd., Japan) for imaging in radiology has been imaged on Varian iX accelerator (Varian Medical Systems, USA) with OBI 1.5 system. Manufacturer's default protocols were adapted by modifying kV and mAs values when imaging different anatomical regions of the phantom (head, thorax, abdomen, pelvis, extremities). Images with different settings were independently reviewed by two persons and their suitability for IGRT set‐up correction protocols were evaluated. The suitable images with the lowest mAs were then selected. The entrance surface dose (ESD) for manufacturer's default protocols and modified protocols were measured with RTI Black Piranha (RTI Group, Sweden) and compared. Image quality was also measured with kVQC phantom (Standard Imaging, USA) for different protocols. The modified protocols have been applied for clinical work.Results:For most cases optimized protocols reduced the ESD on average by a factor of 3(range 0.9–8.5). Further reduction in ESD has been observed by applying bow‐tie filter designed for CBCT. The largest reduction in dose (12.2 times) was observed for Thorax lateral protocol. The dose was slightly increased (by 10%) for large pelvis AP protocol.Conclusion:Manufacturer's default IGRT protocols could be optimised to reduce the ESD to the patient without losing the necessary image quality for patient set‐up correction. For patient set‐up with planar kV imaging the bony anatomy is mostly used and optimization should focus on this aspect. Therefore, the current approach with anthropomorphic phantom is more advantageous in optimization over standard kV quality control phantoms and SNR metrics.
SU‐F‐J‐22: Lung VolumeVariability Assessed by Bh‐CBCT in 3D Surface Image Guided Deep InspirationBreath Hold (DIBH) Radiotherapy for Left‐Sided Breast Cancer
Authors: Gutierrez A , Stanley D , Papanikolaou N , Crownover R 
Published: July 2016

Purpose:With the increasing use of DIBH techniques for left‐sided breast cancer, 3D surface‐image guided DIBH techniques have improved patient setup and facilitated DIBH radiation delivery. However, quantification of the daily separation between the heart and left breast still presents a challenge. One method of assuring separation is to ensure consistent left lung filling. With this in mind, the aim of this study is to retrospectively quantify left lung volume from weekly breath hold‐CBCTs (bh‐CBCT) of left‐sided breast patients treated using a 3D surface imaging system.Methods:Ten patients (n=10) previously treated to the left breast using the C‐Rad CatalystHD system (C‐RAD AG, Uppsala Sweden) were evaluated. Patients were positioned with CatalystHD and with bh‐CBCT. bh‐CBCTs were acquired at the validation date, first day of treatment and at subsequent weekly intervals. Total treatment courses spanned from 3 to 5 weeks. bh‐CBCT images were exported to VelocityAI and the left lung volume was segmented. Volumes were recorded and analyzed.Results:A total of 41 bh‐CBCTs were contoured in VelocityAI for the 10 patients. The mean left lung volume for all patients was 1657±295cc based on validation bh‐CBCT. With the subsequent lung volumes normalized to the validation lung volume, the mean relative ratios for all patients were 1.02±0.11, 0.97±0.14, 0.98±0.11, 1.02±0.01, and 0.96±0.02 for week 1, 2, 3, 4, and 5, respectively. Overall, the mean left lung volume change was ≤4.0% over a 5‐week course; however left lung volume variations of up to 28% were noted in a select patient.Conclusion:With the use of the C‐RAD CatalystHD system, the mean lung volume variability over a 5‐week course of DIBH treatments was ≤4.0%. By minimizing left lung volume variability, heart to left breast separation maybe more consistently maintained.AN Gutierrez has a research grant from C‐RAD AG.
SU‐F‐J‐28: Development of a New Imaging Filter to Remove the Shadows From the Carbon Fiber Grid Table Top
Authors: Maehana W , Nagao T 
Published: July 2016

Purpose:For the image guided radiation therapy (IGRT), the shadows caused by the construction of the treatment couch top adversely affect the visual evaluation. Therefore, we developed the new imaging filter in order to remove the shadows. The performance of the new filter was evaluated using the clinical images.Methods:The new filter was composed of the band‐pass filter (BPF) weighted by the k factor and the low‐pass filter (LPF). In the frequency region, the stop bandwidth were 8.3×103 mm−1 on u direction and 11.1×103 mm−1 on v direction for the BPF, and the pass bandwidth were 8.3×103 mm−1 on u direction and 11.1×103 mm−1 on v direction for the LPF. After adding the filter, the shadows from the carbon fiber grid table top (CFGTT, Varian) on the kV‐image was removed. To check the filter effect, we compared the clinical images, which are thorax and thoracoabdominal region, with to without the filter. The subjective evaluation tests was performed by adapting a three‐point scale (agree, neither agree nor disagree, disagree) about the 15 persons in the department of radiation oncology.Results:We succeeded in removing all shadows of CFGTT using the new filter. This filter is very useful shown by the results of the subjective evaluation having the 23/30 persons agreed to the filtered clinical images.Conclusion:We concluded that the proposed method was useful tool for the IGRT and the new filter leads to improvement of the accuracy of radiation therapy.