bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐D‐207‐07: Implementation of Full/half Bowtie Filter Model in a Commercial Treatment Planning System for Kilovoltage X‐Ray Imaging Dose Estimation
Authors: Kim S , Alaei P 
Published: June 2015

Purpose:To implement full/half bowtie filter models in a commercial treatment planning system (TPS) to calculate kilovoltage (kV) x‐ray imaging dose of Varian On‐Board Imager (OBI) cone beam CT (CBCT) system.Methods:Full/half bowtie filters of Varian OBI were created as compensator models in Pinnacle TPS (version 9.6) using Matlab software (version 2011a). The profiles of both bowtie filters were acquired from the manufacturer, imported into the Matlab system and hard coded in binary file format. A Pinnacle script was written to import each bowtie filter data into a Pinnacle treatment plan as a compensator. A kV x‐ray beam model without including the compensator model was commissioned per each bowtie filter setting based on percent depth dose and lateral profile data acquired from Monte Carlo simulations. To validate the bowtie filter models, a rectangular water phantom was generated in the planning system and an anterior/posterior beam with each bowtie filter was created. Using the Pinnacle script, each bowtie filter compensator was added to the treatment plan. Lateral profile at the depth of 3cm and percent depth dose were measured using an ion chamber and compared with the data extracted from the treatment plans.Results:The kV x‐ray beams for both full and half bowtie filter have been modeled in a commercial TPS. The difference of lateral and depth dose profiles between dose calculations and ion chamber measurements were within 6%.Conclusion:Both full/half bowtie filter models provide reasonable results in kV x‐ray dose calculations in the water phantom. This study demonstrates the possibility of using a model‐based treatment planning system to calculate the kV imaging dose for both full and half bowtie filter modes. Further study is to be performed to evaluate the models in clinical situations.
SU‐D‐201‐02: Prediction of Delivered Dose Based On a Joint Histogram of CT and FDG PET Images
Authors: Park M , Choi Y , Cho A , Hwang S , Cha J , Lee N , Yun M 
Published: June 2015

Purpose:To investigate whether pre‐treatment images can be used in predicting microsphere distribution in tumors. When intra‐arterial radioembolization using Y90 microspheres was performed, the microspheres were often delivered non‐uniformly within the tumor, which could lead to an inefficient therapy. Therefore, it is important to estimate the distribution of microspheres.Methods:Early arterial phase CT and FDG PET images were acquired for patients with primary liver cancer prior to radioembolization (RE) using Y90 microspheres. Tumor volume was delineated on CT images and fused with FDG PET images. From each voxel (3.9×3.9×3.3 mm3) in the tumor, the Hounsfield unit (HU) from the CT and SUV values from the FDG PET were harvested. We binned both HU and SUV into 11 bins and then calculated a normalized joint‐histogram in an 11×11 array.Patients also underwent a post‐treatment Y90 PET imaging. Radiation dose for the tumor was estimated using convolution of the Y90 distribution with a dose‐point kernel. We also calculated a fraction of the tumor volume that received a radiation dose great than 100Gy.Results:Averaged over 40 patients, 55% of tumor volume received a dose greater than 100Gy (range : 1.1 – 100%). The width of the joint histogram was narrower for patients with a high dose. For patients with a low dose, the width was wider and a larger fraction of tumor volume had low HU.Conclusion:We have shown the pattern of joint histogram of the HU and SUV depends on delivered dose. The patterns can predict the efficacy of uniform intra‐arterial delivery of Y90 microspheres.
SU‐D‐210‐02: A New Phantom Design for Routine Doppler Ultrasound Testing
Authors: Grice J , Pickens D , Price R 
Published: June 2015

Purpose:The objective of this project is to develop a simple, inexpensive, and highly portable Doppler ultrasound quality assurance phantom for routine testing. A prototype phantom has been designed and fabricated. It is powered by gravity alone, requires no external equipment for operation, and produces a stable fluid velocity useful for quality assurance. In contrast, currently available Doppler testing systems are large, expensive, and require external power. The new phantom aims to remedy these problems while still offering satisfactory capability of routine quality testing.Methods:The current system measures 15.9cmx10.8cmx12.7cm, is sealed, and contains about 55 ml of Doppler test fluid. Two reservoirs for the Doppler fluid to flow between were designed and then printed on a 3D printer. The printed components were connected with latex tubing and then seated in a tissue‐mimicking gel. Data to confirm reproducibility was acquired on an Acuson Sequoia 512 ultrasound system (Siemens Medical Solutions).Results:The current system maintains stable flow from one reservoir to the other for approximately 7 seconds. Color Doppler imaging has shown to be qualitatively consistent with laminar flow. Using Pulsed Doppler, average velocities from the current system have been measured at 0.178 m/s with a standard deviation of 0.021 m/s across 102 measurements.Conclusion:Due largely to unavailability of an appropriate phantom, Doppler ultrasound often lacks frequent quality testing. This system attempts to address several obstacles facing Doppler testing, which may make weekly, and even daily Doppler testing feasible in clinical settings. The future goals of this project will be to further refine the system and measurement techniques to achieve more stable measurements and longer periods of flow. There are still several degrees of freedom in the system (transducer location, fluid temperature, tube radius, etc.) that have yet to be optimized and should increase the reproducibility of the system.
SU‐D‐210‐03: Limited‐View Multi‐Source Quantitative Photoacoustic Tomography
Authors: Feng J , Gao H 
Published: June 2015

Purpose:This work is to investigate a novel limited‐view multi‐source acquisition scheme for the direct and simultaneous reconstruction of optical coefficients in quantitative photoacoustic tomography (QPAT), which has potentially improved signal‐to‐noise ratio and reduced data acquisition time.Methods:Conventional QPAT is often considered in two steps: first to reconstruct the initial acoustic pressure from the full‐view ultrasonic data after each optical illumination, and then to quantitatively reconstruct optical coefficients (e.g., absorption and scattering coefficients) from the initial acoustic pressure, using multi‐source or multi‐wavelength scheme.Based on a novel limited‐view multi‐source scheme here, We have to consider the direct reconstruction of optical coefficients from the ultrasonic data, since the initial acoustic pressure can no longer be reconstructed as an intermediate variable due to the incomplete acoustic data in the proposed limited‐view scheme. In this work, based on a coupled photo‐acoustic forward model combining diffusion approximation and wave equation, we develop a limited‐memory Quasi‐Newton method (LBFGS) for image reconstruction that utilizes the adjoint forward problem for fast computation of gradients. Furthermore, the tensor framelet sparsity is utilized to improve the image reconstruction which is solved by Alternative Direction Method of Multipliers (ADMM).Results:The simulation was performed on a modified Shepp‐Logan phantom to validate the feasibility of the proposed limited‐view scheme and its corresponding image reconstruction algorithms.Conclusion:A limited‐view multi‐source QPAT scheme is proposed, i.e., the partial‐view acoustic data acquisition accompanying each optical illumination, and then the simultaneous rotations of both optical sources and ultrasonic detectors for next optical illumination. Moreover, LBFGS and ADMM algorithms are developed for the direct reconstruction of optical coefficients from the acoustic data.Jing Feng and Hao Gao were partially supported by the NSFC (#11405105), the 973 Program (#2015CB856000) and the Shanghai Pujiang Talent Program (#14PJ1404500).
SU‐D‐210‐07: The Dependence On Acoustic Velocity of Medium On the Needle Template and Electronic Grid Alignment in Ultrasound QA for Prostate Brachytherapy
Authors: Kapoor P , Kapoor R , Curran B 
Published: June 2015

Purpose:To analyze the impact on acoustic velocity (AV) of two different media (water and milk) using the needle template/electronic grid alignment test. Water, easily available, makes a good material to test the alignment of the template and grid although water's AV (1498 m/s at 25°C) is significantly different from tissue (1540 m/s). Milk, with an AV much closer (1548 m/s) to prostate tissue, may be a good substitute for water in ultrasound quality assurance testing.Methods:Tests were performed using a Hitachi ultrasound unit with a mechanical arrangement designed to position needles parallel to the transducer. In this work, two materials – distilled water and homogenized whole milk (AVs of 1498 and 1548 m/s at 25°C) were used in a phantom to test ultrasound needle/grid alignment. The images were obtained with both materials and analyzed for their placement accuracy.Results:The needle template/electronic grid alignment tests showed displacement errors between measured and calculated values. The measurements showed displacements of 2.3mm (water) and 0.4mm (milk), and 1.6mm (water) and 0.3mm (milk) at depths of 7cm and 5cm respectively from true needle positions. The calculated results showed a displacement of 2.36 mm (water); 0.435mm (milk), and 1.66mm (water) and 0.31mm (milk) at a depth of 7cm and 5cm respectively. The displacements in the X and Y directions were also calculated. At depths of 7cm and 5cm, the (ΔX,ΔY) displacements in water were (0.829mm, 2.21mm) and (0.273mm, 1.634mm) and for milk were (0.15mm, 0.44mm) and (0.05mm, 0.302mm) respectively.Conclusion:The measured and calculated values were in good agreement for all tests. They show that milk provides superior results when performing needle template and electronic grid alignment tests for ultrasound units used in prostate brachytherapy.
SU‐E‐E‐12: Validation of the Implementation of Different CT Scanners in Proton Treatment Planning
Authors: Fuentes C Llina , Geismer D , Christiaens M , Vermeren X , Ding X 
Published: June 2015

Purpose:To quantify the impact of the relationship of CT number and Relative Stopping Power (RSP) among different CT‐scanners in the evaluation of dose distribution, for different tumor sites and proton therapy modalities like Pencil Beam and Uniform Scanning.Methods:The same tissue characterization phantom was used to analyze the difference in the X‐rays energy spectra of 2 CT scanners of the same vendor. One CT is for planning and the other for treatment verification. The Hounsfield unit (HU) variations and associated dosimetric uncertainty were investigated in uniform scanning and pencil beam treatment plans of different sites. At the same time comparisons of the CT calibration curve were done using the same acquisition protocols. The phantom was imaged on a 16 multi‐row CT scanner, with energies of 120 and 140 kVp,currents of 263 and 245 mA and slice thickness of 2 and 3mm respectively. The dosimetric uncertainty of the plans was evaluated in a homogeneus phantom comparing DVHs, gamma index criteria 3% 3mm, and range between them.Results:The variation of HU was within the standard deviation of the average for each tissue substitute. The curves fitted with a bilinear interpolation show a maximum deviation in high density materials like cortical bone and solid water, where the HU values deviated more than 0,6% for the 120kVp protocol. For the others curves the deviation was more than 2% for low densities materials. The gamma index uncertainty criteria passed in all the cases.Conclusion:The HU variations for the different scanners were ≤3%. Lower than the 3,5% uncertainties considered in our treatment planning system. The dosimetric analysis shows that the X‐ray spectrum has a small effect on the HU‐RSP curve, allowing the use of a single tissue characterization curve in our proton treatment planning system for plans verifications.
SU‐E‐P‐08: Establishment of Local Diagnostic Reference Levels of Routine Abdomen Exam in Computed Tomography According to Body Weight
Authors: Wang H , Wang Y , Weng H 
Published: June 2015

Purpose:The national diagnostic reference levels (NDRLs) is an efficient, concise and powerful standard for optimizing radiation protection of a patient. However, for each hospital the dose‐reducing potential of focusing on establishment of local DRLs (LDRLs). A lot of study reported that Computed tomography exam contributed majority radiation dose in different medical modalities, therefore, routine abdomen CT exam was choose in initial pilot study in our study. Besides the mAs of routine abdomen CT exam was decided automatic exposure control by linear attenuation is relate to body shape of patient. In this study we would like to establish the local diagnostic reference levels of routine abdomen exam in computed tomography according to body weight of patient.Methods and Materials:There are two clinical CT scanners (a Toshiba Aquilion and a Siemens Sensation) were performed in this study. For CT examinations the basic recommended dosimetric quantity is the Computed Tomography Dose Index (CTDI). The patient sample involved 82 adult patients of both sexes and divided into three groups by their body weight (50–60 kg, 60–70 kg, 70–80 kg).Carried out the routine abdomen examinations, and all exposure parameters have been collected and the corresponding CTDIv and DLP values have been determined. The average values were compared with the European DRLs.Results:The majority of patients (75%) were between 50–70 Kg of body weight, the numbers of patient in each group of weight were 40–50:7; 50–60:29; 60–70:33; 70–80:13. The LDRLs in each group were 10.81mGy, 14.46mGy, 20.27mGy and 21.04mGy, respectively. The DLP were 477mGy, 630mGy, 887mGy and 959mGy, respectively. No matter which group the LDRLs were lower than European DRLs.Conclusions:We would like to state that this was a pioneer work in local hospital in Chiayi. We hope that this may lead the way to further developments in Taiwan
SU‐E‐P‐10: Establishment of Local Diagnostic Reference Levels of Routine Exam in Computed Tomography
Authors: Yeh M , Wang Y , Weng H 
Published: June 2015

Introduction National diagnostic reference levels (NDRLs) can be used as a reference dose of radiological examination can provide radiation dose as the basis of patient dose optimization. Local diagnostic reference levels (LDRLs) by periodically view and check doses, more efficiency to improve the way of examination. Therefore, the important first step is establishing a diagnostic reference level. Computed Tomography in Taiwan had been built up the radiation dose limit value,in addition, many studies report shows that CT scan contributed most of the radiation dose in different medical. Therefore, this study was mainly to let everyone understand DRL's international status. For computed tomography in our hospital to establish diagnostic reference levels. Methods and Materials: There are two clinical CT scanners (a Toshiba Aquilion and a Siemens Sensation) were performed in this study. For CT examinations the basic recommended dosimetric quantity is the Computed Tomography Dose Index (CTDI). Each exam each different body part, we collect 10 patients at least. Carried out the routine examinations, and all exposure parameters have been collected and the corresponding CTDIv and DLP values have been determined.Results:The majority of patients (75%) were between 60–70 Kg of body weight. There are 25 examinations in this study. Table 1 shows the LDRL of each CT routine examination.Conclusions:Therefore, this study would like to let everyone know DRL's international status, but also establishment of computed tomography of the local reference levels for our hospital, and providing radiation reference, as a basis for optimizing patient dose.
SU‐E‐P‐12: Pinnacle‐Based Tool to Evaluate the Effect of Prostate Rotation as Determined by Calypso
Authors: Narayanan S , Velasco‐Schmitz R , Claeys K , Cho P 
Published: June 2015

Purpose:When the Calypso reports a large prostate rotation and one does not have the means to make corrections, it is helpful to quantify its dosimetric effects. We have devised a simple scheme to achieve this in Pinnacle TPS. If it is determined that the PTV margin is inadequate, an alternate larger‐margin plan may be adapted for the day.Methods:A three‐step process using the Pinnacle Image fusion module was formulated to analyze the clinical effect of prostate rotation. The process includes (1) translating the image set such that the rotational axis is about the isocenter, (2) performing 3D rotations of the structures of interest, and (3) restoring the coordinates associated with the plan. The rotated structures are imported and overlayed on the original plan for evaluation. The tool was applied to three prostate cancer patients with relatively large rotations (95 fractions total). Prostate rotations are primarily due to variations in bladder and rectal filling, which may also affect the seminal vesicles. It is difficult to estimate the perturbation of seminal vesicles for a given prostate rotation. Therefore, the Calypso‐derived rotation matrix was applied only to CTV and PTV (CTV+5mm).Results:The rotations were predominantly in the pitch direction with an absolute value ranging from 0–29 degrees (Median = 10°, Average = 14.5°). For various magnitudes of rotation, the CTV V100 decreased from the original 100% to 99.6%/99%/95% for 10°/15°/29° rotations, respectively. Likewise, the PTV V100 diminished from 95% to 92%/89%/82%.Conclusion:A tool, consisting only of features within a TPS, was used to evaluate the dosimetric effect of prostate rotation. Our study shows that under large uncorrected rotations, the tumor coverage is degraded and may require intervention in the form of plan adaptation. To this end, alternate plans with variable margins can be generated in advance for daily adaption.
SU‐E‐P‐14: Dosimetric Effects of Magnetic Field in MRI‐Guided Radiation Therapy Delivery for Breast Cancer
Authors: Chen G , Currey A , Li X 
Published: June 2015

Purpose:MRI‐guided radiation therapy (RT) delivery would be beneficial for breast irradiation. The electron return effect due to the presence of a transverse magnetic field (TMF) may cause dosimetric issues on dose on skin and at the lung‐tissue interface. The purpose of this study is to investigate these issues.Methods:IMRT plans with tangential beams and VMAT plans with 200 degree arcs to cover ipsilateral breast were generated for 10 randomly selected breast cancer cases using a research planning system (Monaco, Elekta) utilizing Monte Carlo dose calculation with or without a TMF of 1.5 T. Plans were optimized to deliver uniform dose to the whole breast with an exclusion of 5 mm tissue under the skin (PTV‐EVAL). All four plans for each patient were re‐scaled to have the same PTV‐EVAL volume to receive the same prescription dose. The skin is defined as the first 5 mm of ipsilateral‐breast tissue, plus extensions in the surrounding region.Results:The presence of 1.5 T TMF resulted in (1)increased skin dose, with the mean and maximum skin dose increase of 5% and 9%, respectively; (2) similar dose homogeneity within the PTV‐EVAL; (3) the slightly improved (3%) dose homogeneity in the whole breast; (4) Averages of 9 and 16% increases in V5 and V20, respectively, for ipsilateral lung; and (5) increased the mean heart dose by 34%. VMAT plans don't improve whole breast dose uniformity as compared that to the tangential plans.Conclusion:The presence of transverse magnetic field in MRI‐guided RT delivery for whole breast irradiation can Result in slightly improved dose homogeneity in the whole breast, increased dose to the ipsilateral lung, heart, and skin. Plan optimization with additional specific dose volume constraints may eliminate/reduce these dose increases.This work is partially supported by Elekta Inc.
SU‐E‐P‐22: AAPM Task Group 263 Tackling Standardization of Nomenclature for Radiation Therapy
Authors: Matuszak M , Moran J , Xiao Y , Mayo C , Bosch W , Popple R , Marks L , Wu Q , Molineu A , Miller R , Yock T , McNutt T , Brown N , Purdie T , Yorke E , Santanam L , Gabriel P , Michalski J , Moore J , Richardson S , Siochi R , Napalitano M , Ulin K , Fitzgerald T , Feng M , Verbakel W , Siddiqui S , Morgas T , Martel M , Archambault Y , Ladra M , Lansing B , Ruo R , Fogliata‐Cozzi A , Hurkmans C 
Published: June 2015

Purpose:There is growing recognition of need for increased clarity and consistency in the nomenclatures used for body and organ structures, DVH metrics, toxicity, dose and volume units, etc. Standardization has multiple benefits; e.g. facilitating data collection for clinical trials, enabling the pooling of data between institutions, making transfers (i.e. hand‐offs) between centers safer, and enabling vendors to define “default” settings. Towards this goal, the American Association of Physicists in Medicine (AAPM) formed a task group (TG263) in July of 2014, operating under the Work Group on Clinical Trials to develop consensus statements. Guiding principles derived from the investigation and example nomenclatures will be presented for public feedback.Methods:We formed a multi‐institutional and multi‐vendor collaborative group of 39 physicists, physicians and others involved in clinical use and electronic transfer of information. Members include individuals from IROC, NRG, IHE‐RO, DICOM WG‐7, ASTRO and EORTC groups with overlapping interests to maximize the quality of the consensus and increase the likelihood of adoption. Surveys of group and NRG members were used to define current nomenclatures and requirements. Technical requirements of vendor systems and the proposed DICOM standards were examined.Results:There is a marked degree of inter and intra institutional variation in current approaches, resulting from inter‐vendor differences in capabilities, clinic specific conceptualizations and inconsistencies. Using a consensus approach, the group defined optimal formats for the naming of targets and normal structures. A formal objective assessment of 13 existing clinically‐used software packages show that all had capabilities to accommodate these recommended nomenclatures.Conclusions:A multi‐stakeholder effort is making significant steps forward in developing a standard nomenclature that will work across platforms. Our current working list includes > 550 structures. Outreach efforts are ongoing to ensure broader participation in evaluating and testing the principles as they are developed by TG263.