bluuebunny/crossref_metadata_2025 huggingface dataset:
AAPM/SNMMI Joint Task Force: report on the current state of nuclear medicine physics training
Authors: Harkness Beth A. , Allison Jerry D. , Clements Jessica B. , Coffey Charles W. , Fahey Frederic H. , Gress Dustin A. , Kinahan Paul E. , Nickoloff Edward L. , Mawlawi Osama R. , MacDougall Robert D. , Pizzuitello Robert J.
Published: February 2017

The American Association of Physicists in Medicine (AAPM) and the Society of Nuclear Medicine and Molecular Imaging (SNMMI) recognized the need for a review of the current state of nuclear medicine physics training and the need to explore pathways for improving nuclear medicine physics training opportunities. For these reasons, the two organizations formed a joint AAPM/SNMMI Ad Hoc Task Force on Nuclear Medicine Physics Training. The mission of this task force was to assemble a representative group of stakeholders to:

Estimate the demand for board‐certified nuclear medicine physicists in the next 5–10 years,

Identify the critical issues related to supplying an adequate number of physicists who have received the appropriate level of training in nuclear medicine physics, and

Identify approaches that may be considered to facilitate the training of nuclear medicine physicists.

As a result, a task force was appointed and chaired by an active member of both organizations that included representation from the AAPM, SNMMI, the American Board of Radiology (ABR), the American Board of Science in Nuclear Medicine (ABSNM), and the Commission for the Accreditation of Medical Physics Educational Programs (CAMPEP). The Task Force first met at the AAPM Annual Meeting in Charlotte in July 2012 and has met regularly face‐to‐face, online, and by conference calls. This manuscript reports the findings of the Task Force, as well as recommendations to achieve the stated mission.

PACS number: 01.40.G‐
Impact of temporal probability in 4D dose calculation for lung tumors
Authors: Rouabhi Ouided , Ma Mingyu , Bayouth John , Xia Junyi
Published: February 2017

The purpose of this study was to evaluate the dosimetric uncertainty in 4D dose calculation using three temporal probability distributions: uniform distribution, sinusoidal distribution, and patient‐specific distribution derived from the patient respiratory trace. Temporal probability, defined as the fraction of time a patient spends in each respiratory amplitude, was evaluated in nine lung cancer patients. Four‐dimensional computed tomography (4D CT), along with deformable image registration, was used to compute 4D dose incorporating the patient's respiratory motion. First, the dose of each of 10 phase CTs was computed using the same planning parameters as those used in 3D treatment planning based on the breath‐hold CT. Next, deformable image registration was used to deform the dose of each phase CT to the breath‐hold CT using the deformation map between the phase CT and the breath‐hold CT. Finally, the 4D dose was computed by summing the deformed phase doses using their corresponding temporal probabilities. In this study, 4D dose calculated from the patient‐specific temporal probability distribution was used as the ground truth. The dosimetric evaluation matrix included: 1) 3D gamma analysis, 2) mean tumor dose (MTD), 3) mean lung dose (MLD), and 4) lung V20. For seven out of nine patients, both uniform and sinusoidal temporal probability dose distributions were found to have an average gamma passing rate for both the lung and PTV regions. Compared with 4D dose calculated using the patient respiratory trace, doses using uniform and sinusoidal distribution showed a percentage difference on average of and in MTD, and in MLD, and in lung V20, and in lung V10, and in lung V5, respectively. We concluded that four‐dimensional dose computed using either a uniform or sinusoidal temporal probability distribution can approximate four‐dimensional dose computed using the patient‐specific respiratory trace.

PACS number: 87.55.D‐
Treatment optimization with concurrent SBRT and intracavitary brachytherapy for locally advanced cervical cancer
Authors: Wan Bin , Lang Jinyi , Wang Pei , Ma C‐M
Published: February 2017

This work is aimed at investigating treatment planning strategies to optimally combine stereotactic body radiation therapy (SBRT) with intracavitary brachytherapy (ICBT) for the treatment of locally advanced cervical cancer. Forty patients (stage IIB – IIIB) previously treated with combined SBRT and ICBT were randomly selected for this retrospective study. All patients were CT‐ and MR‐scanned with a ring applicator in situ. HR‐CTV and OARs were contoured according to fused CT and MR images. Several ICBT plans were generated for each patient based on different dose prescription points, and then a matching SBRT plan was generated for each ICBT plan. The dose distribution of each composite plan was analyzed with a focus on the doses received by 90% and 100% of the target volume ( and ), the target volume receiving 100% of the prescription dose (), and the doses received by 2 cc and 40% of the OARs ( and ). As the distance, d, between the prescription point and the tandem varied within 1.0 and 1.9 cm, the and for the target, as well as and for the bladder and rectum approached their optimal values for d value between 1.0 and 1.4 cm. When designing a combined plan, one should measure the size of the cervix and set the prescription isodose line 1.0 to 1.4 cm away from the tandem for the ICBT plan first and then optimize the SBRT plan based on the ICBT dose distribution to achieve the best target coverage and critical structures sparing.

PACS number: 87.53.jw; 87.55.D‐
Moving stereotactic fiducial system to obtain a respiratory signal: proof of principle
Authors: Pinelo Roberto Caballero , Alfonso Rodolfo , Pérez Yelina González , García Albin Ariel , Rubio Arnaldo
Published: February 2017

The purpose of this study was to obtain a respiratory signal with the use of an add‐on device to a specific stereotactic body frame and evaluate precision and accuracy of the method, with the use of a dynamic phantom. The authors designed and constructed a simple add‐on device which, attached to a stereotactic body frame, provides information of the patient's respiratory signal in every CT axial image acquired. To assess the approach, 12 CT studies were acquired, on a phantom that simulates respiratory motion, which was placed inside the frame with the add‐on device. Images of the phantom with sinusoidal and shark‐fin motion patterns were acquired, with different amplitude in the movement of the external surrogate and the target. Cycle time was 6 s. Images were retrospectively processed to obtain a respiratory signal from the vertical movement of the “abdomen.” The obtained signal was adjusted to a sinusoidal function; the resultant amplitude and cycle time were compared with the preset function in the phantom. The cycle amplitude and time obtained with the method agreed with the preset values within 0.4 mm and 0.29 s, respectively. In the cases of sinusoidal movements the maximal discrepancy was less than 1 mm. A respiratory signal was obtained in all cine CT sequence studies with this method that consistently coincides with the preset motion of the phantom. The authors proposed a tool to obtain a respiratory signal based on information contained into the CT axial images.

PACS number: 87.57qp
Clinical implementation of multisequence MRI‐based adaptive intracavitary brachytherapy for cervix cancer
Authors: Zoberi Jacqueline E. , Garcia‐Ramirez Jose , Hu Yanle , Sun Baozhou , Bertelsman Carol G. , Dyk Pawel , Schwarz Julie K. , Grigsby Perry W.
Published: February 2017

The purpose of this study was to describe the clinical implementation of a magnetic resonance image (MRI)‐based approach for adaptive intracavitary brachytherapy (ICBT) of cervix cancer patients. Patients were implanted with titanium tandem and colpostats. MR imaging was performed on a 1.5‐T Philips scanner using T2‐weighted (T2W), proton‐density weighted (PDW), and diffusion‐weighted (DW) imaging sequences. Apparent diffusion coefficient (ADC) maps were generated from the DW images. All images were fused. T2W images were used for the definition of organs at risk (OARs) and dose points. ADC maps in conjunction with T2W images were used for target delineation. PDW images were used for applicator definition. Forward treatment planning was performed using standard source distribution rules normalized to Point A. Point doses and dose‐volume parameters for the tumor and OARs were exported to an automated dose‐tracking application. Brachytherapy doses were adapted for tumor shrinkage and OAR variations during the course of therapy. The MRI‐based ICBT approach described here has been clinically implemented and is carried out for each brachytherapy fraction. Total procedure time from patient preparation to delivery of treatment is typically 2 hrs. Implementation of our technique for structure delineation, applicator definition, dose tracking, and adaptation is demonstrated using treated patient examples. Based on published recommendations and our clinical experience in the radiation treatment of cervix cancer patients, we have refined our standard approach to ICBT by 1) incorporating a multisequence MRI technique for improved visualization of the target, OARs, and applicator, and by 2) implementing dose adaptation by use of automated dose tracking tools.

PACS numbers: 87.61.‐c, 87.53.Jw, 87.19.xj
Implementation of an in‐house visual feedback system for motion management during radiation therapy
Authors: Nguyen Vi Nhan V. , Ellerbusch David C. , Cetnar Ashley J. , James Joshua A. , Wang Brian
Published: February 2017

In this Technical Note, we describe an in‐house video goggles feedback system assembled using several commercially available products. This goggle video feedback system is currently being used at University of Louisville and Mayo Clinic for both CT simulation and linac treatment delivery. The setup details, including specific recommendations, are provided, along with an alternative option for using the video goggles system.

PACS number: 07.07Hj
An algorithm for automated ROI definition in water or epoxy‐filled NEMA NU‐2 image quality phantoms
Authors: Pierce Larry A. , Byrd Darrin W. , Elston Brian F. , Karp Joel S. , Sunderland John J. , Kinahan Paul E.
Published: February 2017

Drawing regions of interest (ROIs) in positron emission tomography/computed tomography (PET/CT) scans of the National Electrical Manufacturers Association (NEMA) NU‐2 Image Quality (IQ) phantom is a time‐consuming process that allows for interuser variability in the measurements. In order to reduce operator effort and allow batch processing of IQ phantom images, we propose a fast, robust, automated algorithm for performing IQ phantom sphere localization and analysis. The algorithm is easily altered to accommodate different configurations of the IQ phantom. The proposed algorithm uses information from both the PET and CT image volumes in order to overcome the challenges of detecting the smallest spheres in the PET volume. This algorithm has been released as an open‐source plug‐in to the Osirix medical image viewing software package. We test the algorithm under various noise conditions, positions within the scanner, air bubbles in the phantom spheres, and scanner misalignment conditions. The proposed algorithm shows runtimes between 3 and 4 min and has proven to be robust under all tested conditions, with expected sphere localization deviations of less than 0.2 mm and variations of PET ROI mean and maximum values on the order of 0.5% and 2%, respectively, over multiple PET acquisitions. We conclude that the proposed algorithm is stable when challenged with a variety of physical and imaging anomalies, and that the algorithm can be a valuable tool for those who use the NEMA NU‐2 IQ phantom for PET/CT scanner acceptance testing and QA/QC.

PACS number: 87.57.C‐
Evaluation of fluence‐based dose delivery incorporating the spatial variation of dosimetric leaf gap (DLG)
Authors: Kumaraswamy Lalith K. , Xu Zhengzheng , Bailey Daniel W. , Schmitt Jonathan D. , Podgorsak Matthew B.
Published: February 2017

The Eclipse treatment planning system uses a single dosimetric leaf gap (DLG) value to retract all multileaf collimator leaf positions during dose calculation to model the rounded leaf ends. This study evaluates the dosimetric impact of the 2D variation of DLG on clinical treatment plans based on their degree of fluence modulation. In‐house software was developed to retrospectively apply the 2D variation of DLG to 61 clinically treated VMAT plans, as well as to several test plans. The level of modulation of the VMAT cases were determined by calculating their modulation complexity score (MCS). Dose measurements were done using the MapCHECK device at a depth of 5.0 cm for plans with and without the 2D DLG correction. Measurements were compared against predicted dose planes from the TPS using absolute 3%/3 mm and 2%/2 mm gamma criteria for test plans and for VMAT cases, respectively. The gamma pass rate for the 2 mm, 4 mm, and 6 mm sweep test plans increased by 23.2%, 28.7%, and 26.0%, respectively, when the measurements were corrected with 2D variation of DLG. The clinical anal VMAT cases, which had very high MLC modulation, showed the most improvement. The majority of the improvement occurred for doses created by the 1.0 cm width leaves for both the test plans and the VMAT cases. The gamma pass rates for the highly modulated head and neck (H&N) cases, moderately modulated prostate and esophageal cases, and minimally modulated brain cases improved only slightly when corrected with 2D variation of DLG. This is because these cases did not employ the 1.0 cm width leaves for dose calculation and delivery. These data suggest that, at the very least, the TPS plans with highly modulated fluences created by the 1.0 cm fields require 2D DLG correction. Incorporating the 2D variation of DLG for the highly modulated clinical treatment plans improves their planar dose gamma pass rates, especially for fields employing the outer 1.0 cm width MLC leaves. This is because there are differences in DLG between the true DLG exhibited by the 1.0 cm width outer leaves and the constant DLG value modeled by the TPS for dose calculation.

PACS numbers: 87.55.D, 87.55.Qr, 87.56.Fc, 87.56.N, 87.56.nk
Application of dose kernel calculation using a simplified Monte Carlo method to treatment plan for scanned proton beams
Authors: Mizutani Shohei , Takada Yoshihisa , Kohno Ryosuke , Hotta Kenji , Tansho Ryohei , Akimoto Tetsuo
Published: February 2017

Full Monte Carlo (FMC) calculation of dose distribution has been recognized to have superior accuracy, compared with the pencil beam algorithm (PBA). However, since the FMC methods require long calculation time, it is difficult to apply them to routine treatment planning at present. In order to improve the situation, a simplified Monte Carlo (SMC) method has been introduced to the dose kernel calculation applicable to dose optimization procedure for the proton pencil beam scanning. We have evaluated accuracy of the SMC calculation by comparing a result of the dose kernel calculation using the SMC method with that using the FMC method in an inhomogeneous phantom. The dose distribution obtained by the SMC method was in good agreement with that obtained by the FMC method. To assess the usefulness of SMC calculation in clinical situations, we have compared results of the dose calculation using the SMC with those using the PBA method for three clinical cases of tumor treatment. The dose distributions calculated with the PBA dose kernels appear to be homogeneous in the planning target volumes (PTVs). In practice, the dose distributions calculated with the SMC dose kernels with the spot weights optimized with the PBA method show largely inhomogeneous dose distributions in the PTVs, while those with the spot weights optimized with the SMC method have moderately homogeneous distributions in the PTVs. Calculation using the SMC method is faster than that using the GEANT4 by three orders of magnitude. In addition, the graphic processing unit (GPU) boosts the calculation speed by 13 times for the treatment planning using the SMC method. Thence, the SMC method will be applicable to routine clinical treatment planning for reproduction of the complex dose distribution more accurately than the PBA method in a reasonably short time by use of the GPU‐based calculation engine.

PACS number(s): 87.55.Gh
Fricke gel dosimeter with improved sensitivity for low‐dose‐level measurements
Authors: Vaiente Mauro , Molina Wladimir , Silva Lila Carrizales , Figueroa Rodolfo , Malano Francisco , Pérez Pedro , Santibañez Mauricio , Vedelago José
Published: February 2017

Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue‐equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, independence of dose rate and incident direction, as well as linear dose response. This work presents the development and characterization of an improved Fricke gel system, based on modified chemical compositions, making possible its application in clinical radiology due to its improved sensitivity. Properties of standard Fricke gel dosimeter for high‐dose levels are used as a starting point, and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low‐dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose‐dependency, showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain an adequate dosimeter response for low‐dose levels. A suitable composition from among those studied is selected as a good candidate for low‐dose‐level radiation dosimetry consisting of a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, Xylenol orange, and tridistilled water. Dosimeter samples are prepared in standard vials for in‐phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated using typical X‐ray tubes for radiology and calibrated Farmer‐type ionization chamber is used as reference to measure dose rates inside phantoms at vial locations. Once sensitive material composition is optimized, dose‐response curves show significant improvement regarding overall sensitivity for low dose levels. The aim of this work consists of implementing the optimized gel dosimeter to perform direct measurements of absorbed dose in samples irradiated during microcomputed tomography scanning in order to preliminary assess dose levels for further scanning of small animals for further applications in veterinary and paleontology. As a first attempt, dose distributions were measured in water‐equivalent phantoms having dimensions comparable to small animals, 100 to 1000 cm3, approximately. According to the obtained results, it is found that the proposed method shows satisfactory reliability and adequate performance for a promising gel dosimetry system.

PACS number(s): 87.53.Bn, 87.57.uq, 87.59.‐e
Initial clinical experience with ArcCHECK for IMRT/VMAT QA
Authors: Aristophanous Michalis , Suh Yelin , Chi Pai C. , Whittlesey Luke J. , LaNeave Scott , Martel Mary K.
Published: February 2017

Many devices designed for the purpose of performing patient‐specific IMRT/VMAT QA are commercially available. In this work we report our experience and initial clinical results with the ArcCHECK. The ArcCHECK consists of a cylindrical array of diode detectors measuring entry and exit doses. The measured result is a cumulative dose displayed as a 2D matrix. The detector array requires both an absolute dose calibration, and a calibration of the detector response, relative to each other. In addition to the calibrations suggested by the manufacturer, various tests were performed in order to assess its stability and performance prior to clinical introduction. Tests of uniformity, linearity, and repetition rate dependence of the detector response were conducted and described in this work. Following initial testing, the ArcCHECK device was introduced in the clinic for routine patient‐specific IMRT QA. The clinical results from one year of use were collected and analyzed. The gamma pass rates at the criterion were reported for 3,116 cases that included both IMRT and VMAT treatment plans delivered on 18 linear accelerators. The gamma pass rates were categorized based on the treatment site, treatment technique, type of MLCs, operator, ArcCHECK device, and LINAC model. We recorded the percent of failures at the clinically acceptable threshold of 90%. In addition, we calculated the threshold that encompasses two standard deviations (2 SD) (95%) of QAs (T95) for each category investigated. The commissioning measurements demonstrated that the device performed as expected. The uniformity of the detector response to a constant field arc delivery showed a 1% standard deviation from the mean. The variation in dose with changing repetition rate was within 1 cGy of the mean, while the measured dose showed a linear relation with delivered MUs. Our initial patient QA results showed that, at the clinically selected passing criterion, 4.5% of cases failed. On average T95 was 91%, ranging from 73% for gynecological sites to 96.5% for central nervous system sites. There are statistically significant differences in passing rates between IMRT and VMAT, high‐definition (HD) and non‐HD MLCs, and different LINAC models (p‐values ). An additional investigation into the failing QAs and a comparison with ion‐chamber measurements reveals that the differences observed in the passing rates between the different studied factors can be largely explained by the field size dependence of the device. Based on our initial experience with the ArcCHECK, our passing rates are, on average, consistent with values reported in the AAPM TG‐119. However, the significant variations between QAs that were observed based on the size of the treatment fields may need to be corrected to improve the specificity and sensitivity of the device.

PACS number(s): 87.55.Qr, 87.56.Fc
Comprehensive dosimetric planning comparison for early‐stage, non‐small cell lung cancer with SABR: fixed‐beam IMRT versus VMAT versus TomoTherapy
Authors: Xhaferllari Ilma , El‐Sherif Omar , Gaede Stewart
Published: February 2017

Volumetric‐modulated arc therapy (VMAT) is emerging as a leading technology in treating early‐stage, non‐small cell lung cancer (NSCLC) with stereotactic ablative radiotherapy (SABR). However, two other modalities capable of delivering intensity‐modulated radiation therapy (IMRT) include fixed‐beam and helical TomoTherapy (HT). This study aims to provide an extensive dosimetric comparison among these various IMRT techniques for treating early‐stage NSCLC with SABR. Ten early‐stage NSCLC patients were retrospectively optimized using three fixed‐beam techniques via nine to eleven beams (high and low modulation step‐and‐shoot (SS), and sliding window (SW)), two VMAT techniques via two partial arcs (SmartArc (SA) and RapidArc (RA)), and three HT techniques via three different fan beam widths (1 cm, 2.5 cm, and 5 cm) for 80 plans total. Fixed‐beam and VMAT plans were generated using flattening filter‐free beams. SS and SA, HT treatment plans, and SW and RA were optimized using Pinnacle v9.1, Tomoplan v.3.1.1, and Eclipse (Acuros XB v11.3 algorithm), respectively. Dose‐volume histogram statistics, dose conformality, and treatment delivery efficiency were analyzed. VMAT treatment plans achieved significantly lower values for contralateral lung compared to the HT plans, and significantly lower mean lung dose () compared to HT 5 cm treatment plans. In the comparison between the VMAT techniques, a significant reduction in the total monitor units () was found in the SA plans, while a significant decrease was observed in the dose falloff parameter, , (), for the RA treatments. The maximum cord dose was significantly reduced () in grouped RA&SA plans compared to SS. Estimated treatment time was significantly higher for HT and fixed‐beam plans compared to RA&SA (). Although, a significant difference was not observed in the RA vs. SA (). RA&SA outperformed HT in all parameters measured. Despite an increase in dose to the heart and bronchus, this study demonstrates that VMAT is dosimetrically advantageous in treating early‐stage NSCLC with SABR compared to fixed‐beam, while providing significantly shorter treatment times.

PACS number(s): 87.55.D, 87.55.dk, 87.55.kd
An EPID‐based system for gantry‐resolved MLC quality assurance for VMAT
Authors: Zwan Benjamin J. , Barnes Michael P. , Fuangrod Todsaporn , Stanton Cameron J. , O'Connor Daryl J. , Keall Paul J. , Greer Peter B.
Published: February 2017

Multileaf collimator (MLC) positions should be precisely and independently measured as a function of gantry angle as part of a comprehensive quality assurance (QA) program for volumetric‐modulated arc therapy (VMAT). It is also ideal that such a QA program has the ability to relate MLC positional accuracy to patient‐specific dosimetry in order to determine the clinical significance of any detected MLC errors. In this work we propose a method to verify individual MLC trajectories during VMAT deliveries for use as a routine linear accelerator QA tool. We also extend this method to reconstruct the 3D patient dose in the treatment planning system based on the measured MLC trajectories and the original DICOM plan file. The method relies on extracting MLC positions from EPID images acquired at 8.41 fps during clinical VMAT deliveries. A gantry angle is automatically tagged to each image in order to obtain the MLC trajectories as a function of gantry angle. This analysis was performed for six clinical VMAT plans acquired at monthly intervals for three months. The measured trajectories for each delivery were compared to the MLC positions from the DICOM plan file. The maximum mean error detected was 0.07 mm and a maximum root‐mean‐square error was 0.8 mm for any leaf of any delivery. The sensitivity of this system was characterized by introducing random and systematic MLC errors into the test plans. It was demonstrated that the system is capable of detecting random and systematic errors on the range of 1–2 mm and single leaf calibration errors of 0.5 mm. The methodology developed in the work has potential to be used for efficient routine linear accelerator MLC QA and pretreatment patient‐specific QA and has the ability to relate measured MLC positional errors to 3D dosimetric errors within a patient volume.

PACS number(s): 87.55.Qr
Evaluation of dose‐area product of common radiographic examinations towards establishing a preliminary diagnostic reference levels (PDRLs) in Southwestern Nigeria
Authors: Jibiri Nnamdi N. , Olowookere Christopher J.
Published: February 2017

In Nigeria, a large number of radiographic examinations are conducted yearly for various diagnostic purposes. However, most examinations carried out do not have records of doses received by the patients, and the employed exposure parameters used are not documented; therefore, adequate radiation dose management is hindered. The aim of the present study was to estimate the dose‐area product (DAP) of patients examined in Nigeria, and to propose regional reference dose levels for nine common examinations (chest PA, abdomen AP, pelvis AP, lumbar AP, skull AP, leg AP, knee AP, hand AP, and thigh AP) undertaken in Nigeria. Measurement of entrance surface dose (ESD) was carried out using thermoluminescent dosimeter (TLD). Measured ESDS were converted into DAP using the beam area of patients in 12 purposely selected hospitals. Results of the study show that the maximum/minimum ratio ranged from 3 for thigh AP to 57 in abdomen AP. The range of determined mean and 75th percentile DAPs were 0.18–17.16, and 0.25–28.59 Gy cm2, respectively. Data available for comparison show that 75th percentile DAPs in this study (in chest PA, abdomen AP, pelvis AP, lumbar AP) are higher than NRPB‐HPE reference values. The DAP in this study is higher by factor of 31.4 (chest PA), 9.9 (abdomen AP), 2.2 (pelvis AP), and 2.1 (lumbar AP) than NRPB‐HPE values. The relative higher dose found in this study shows nonoptimization of practice in Nigeria. It is expected that regular dose auditing and dose optimization implementation in Nigeria would lead to lower DAP value, especially in abdomen AP. The 75th percentile DAP distribution reported in this study could be taken as regional diagnostic reference level in the Southwestern Nigeria; however, a more extensive nationwide dose survey is required to establish national reference dose.

PACS number(s): 87.53.Bn, 87.59.B
Clinically relevant investigation of flattening filter‐free skin dose
Authors: Guy Christopher L. , Karki Kishor , Sharma Manju , Kim Siyong
Published: February 2017

As flattening filter‐free (FFF) photon beams become readily available for treatment delivery in techniques such as SBRT, thorough investigation of skin dose from FFF photon beams is necessary under clinically relevant conditions. Using a parallel‐plate PTW Markus chamber placed in a custom water‐equivalent phantom, surface‐dose measurements were taken at , and field sizes, at 80, 90, and 100 cm source‐to‐surface distances (SSDs), and with fields defined by jaws and multileaf collimator (MLC) using multiple beam energies (6X, 6XFFF, 10X, and 10XFFF). The same set of measurements was repeated with the chamber at a reference depth of 10 cm. Each surface measurement was normalized by its corresponding reference depth measurement for analysis. The FFF surface doses at 100 cm SSD were higher than flattened surface doses by 45% at to 13% at for 6 MV energy. These surface dose differences varied to a greater degree as energy increased, ranging from at to at for 10 MV. At small field sizes, higher energy increased FFF surface dose relative to flattened surface dose; while at larger field sizes, relative FFF surface dose was higher for lower energies. At both energies investigated, decreasing SSD caused a decrease in the ratios of FFF‐to‐flattened surface dose. Variability with SSD of FFF‐to‐flattened surface dose differences increased with field size and ranged from 0% to 6%. The field size at which FFF and flattened beams gave the same skin dose increased with decreasing beam energy. Surface dose was higher with MLC fields compared to jaw fields under most conditions, with the difference reaching its maximum at a field size between and for a given energy and SSD. This study conveyed the magnitude of surface dose in a clinically meaningful manner by reporting results normalized to 10 cm depth dose instead of depth of dose maximum.

PACS number(s): 87.53.Bn, 87.53.Ly, 87.55.‐x, 87.55.N‐, 87.56.N‐
Evaluation of kidney motion and target localization in abdominal SBRT patients
Authors: Sonier Marcus , Chu William , Lalani Nafisha , Erler Darby , Cheung Patrick , Korol Renee
Published: February 2017

The purpose of this study was to evaluate bilateral kidney and target translational/rotational intrafraction motion during stereotactic body radiation therapy treatment delivery of primary renal cell carcinoma and oligometastatic adrenal lesions for patients immobilized in the Elekta BodyFIX system. Bilateral kidney motion was assessed at midplane for 30 patients immobilized in a full‐body dual‐vacuum‐cushion system with two patients immobilized via abdominal compression. Intrafraction motion was assessed for 15 patients using kilovoltage cone‐beam computed tomography (kV‐CBCT) datasets () correlated to the planning CT. Patient positioning was corrected for translational and rotational misalignments using a robotic couch in six degrees of freedom if setup errors exceeded 1 mm and 1°. Absolute bilateral kidney motion between inhale and exhale 4D CT imaging phases for left–right (LR), superior–inferior (SI), and anterior–posterior (AP) directions was , and , respectively. Residual setup error determined across CBCT type (pretreatment, intrafraction, and post‐treatment) for x (LR), y (SI), and z (AP) translations was , and ; while for x (pitch), y (roll), and z (yaw) rotations was , and , respectively. Targets were localized to within 2.1 mm and 0.8° 95% of the time. The frequency of misalignments in the y direction was significant () when compared to the x and z directions with no significant difference in translations between IMRT and VMAT. This technique is robust using BodyFIX for patient immobilization and reproducible localization of kidney and adrenal targets and daily CBCT image guidance for correction of positional errors to maintain treatment accuracy.

PACS number(s): 87.55.‐x, 87.56.‐v, 87.56.Da
Real‐time in vivo dosimetry for SBRT prostate treatment using plastic scintillating dosimetry embedded in a rectal balloon: a case study
Authors: Cantley Justin L. , Cheng Chee‐Wai , Jesseph Fredrick B. , Podder Tarun K. , Colussi Valdir C. , Traughber Bryan J. , Ponsky Lee E. , Ellis Rodney J.
Published: February 2017

A novel FDA approved in vivo dosimetry device system using plastic scintillating detectors placed in an endorectal balloon to provide real‐time in vivo dosimetry for prostatic rectal interface was tested for use with stereotactic body radiotherapy (SBRT). The system was used for the first time ever to measure dose during linear accelerator based SBRT. A single patient was treated with a total dose of 36.25 Gy given in 5 fractions. Delivered dose was measured for each treatment with the detectors placed against the anterior rectal wall near the prostate rectal interface. Measured doses showed varying degrees of agreement with computed/ planned doses, with average combined dose found to be within 6% of the expected dose. The variance between measurements is most likely due to uncertainty of the detector location, as well as variation in the placement of a new balloon prior to each fraction. Distance to agreement for the detectors was generally found to be within a few millimeters, which also suggested that the differences in measured and calculated doses were due to positional uncertainty of the detectors during the SBRT, which had sharp dose falloff near the penumbra along the rectal wall. Overall, the use of a real time in vivo dosimeter provided a level of safety and improved confidence in treatment delivery. We are evaluating the device further in an IRB‐approved prospective partial prostate SBRT trial, and believe further clinical investigations are warranted.

PACS number(s): 87.53.Bn, 87.53.Ly, 87.55.km
Tn
6350
, a Novel Transposon Carrying Pyocin S8 Genes Encoding a Bacteriocin with Activity against Carbapenemase-Producing Pseudomonas aeruginosa
Authors: Turano Helena , Gomes Fernando , Barros-Carvalho Gesiele A. , Lopes Ralf , Cerdeira Louise , Netto Luis E. S. , Gales Ana C. , Lincopan Nilton
Published: February 2017

A novel transposon belonging to the Tn
3
-like family was identified on the chromosome of a commensal strain of
Pseudomonas aeruginosa
sequence type 2343 (ET02). Tn
6350
is 7,367 bp long and harbors eight open reading frames (ORFs), an ATPase (IS
481
family), a transposase (DDE catalytic type), a Tn
3
resolvase, three hypothetical proteins, and genes encoding the new pyocin S8 with its immunity protein. We show that pyocin S8 displays activity against carbapenemase-producing
P. aeruginosa
, including IMP-1, SPM-1, VIM-1, GES-5, and KPC-2 producers.
An Adaptive Semantic Descriptive Model for Multi-Document Representation to Enhance Generic Summarization
Authors: Dief Nada A. , Al-Desouky Ali E. , Eldin Amr Aly , El-Said Asmaa M.
Published: February 2017

Due to the increasing accessibility of online data and the availability of thousands of documents on the Internet, it becomes very difficult for a human to review and analyze each document manually. The sheer size of such documents and data presents a significant challenge for users. Providing automatic summaries of specific topics helps the users to overcome this problem. Most of the current extractive multi-document summarization systems can successfully extract summary sentences; however, many limitations exist which include the degree of redundancy, inaccurate extraction of important sentences, low coverage and poor coherence among the selected sentences. This paper introduces an adaptive extractive multi-document generic (EMDG) methodology for automatic text summarization. The framework of this methodology relies on a novel approach for sentence similarity measure, a discriminative sentence selection method for sentence scoring and a reordering technique for the extracted sentences after removing the redundant ones. Extensive experiments are done on the summarization benchmark datasets DUC2005, DUC2006 and DUC2007. This proves that the proposed EMDG methodology is more effective than the current extractive multi-document summarization systems. Rouge evaluation for automatic summarization is used to validate the proposed EMDG methodology, and the experimental results showed that it is more effective and outperforms the baseline techniques, where the generated summary is characterized by high coverage and cohesion.
XML Clustering by Structure-Constrained Phrases: A Fully-Automatic Approach Using Contextualized N-Grams
Authors: Costa Gianni , Ortale Riccardo
Published: February 2017

Using the bag-of-word model to represent the textual data of XML documents may not be beneficial in XML clustering by content and structure. Indeed, the occurrence of similar structure-constrained textual items across distinct XML documents may enforce relatedness, despite the possibly different meaning implied by the order of item occurrence in the respective contexts.

We propose XML clustering by structure-constrained phrases. It is a new method that better captures the meaning of the structure-constrained textual items of XML documents, by resorting to the more accurate bag-of-phrase model for improved clustering effectiveness. In order to conduct an in-depth and systematic study of the validity of the proposed method, we develop a parameter-free approach, that projects the XML documents into a space of XML features corresponding to sequences of textual items in the context of root-to-leaf paths. Automatic feature selection allows for choosing a subset of XML features, whose relevance is assessed through an innovative scoring scheme. The devised approach can operate with representations of the XML documents over both fixed- and mixed-length sequences of contextualized textual items. A novel criterion is presented to combine XML features with mixed lengths. A comparative experimentation on real-world benchmark XML corpora reveals the overcoming effectiveness of our approach. This highlights the potential of XML clustering by structure-constrained phrases and fosters further efforts. The scalability of the devised approach is also investigated.
Static and Dynamic Portfolio Methods for Optimal Planning: An Empirical Analysis
Authors: Rizzini Mattia , Fawcett Chris , Vallati Mauro , Gerevini Alfonso E. , Hoos Holger H.
Published: February 2017

Combining the complementary strengths of several algorithms through portfolio approaches has been demonstrated to be effective in solving a wide range of AI problems. Notably, portfolio techniques have been prominently applied to suboptimal (satisficing) AI planning.

Here, we consider the construction of sequential planner portfolios for domainindependent optimal planning. Specifically, we introduce four techniques (three of which are dynamic) for per-instance planner schedule generation using problem instance features, and investigate the usefulness of a range of static and dynamic techniques for combining planners. Our extensive empirical analysis demonstrates the benefits of using static and dynamic sequential portfolios for optimal planning, and provides insights on the most suitable conditions for their fruitful exploitation.
An Optical Fiber Measurement System for Blade Tip Clearance of Engine
Authors: Binghui Jia , Lei He
Published: February 2017

The benefits of reducing the tip clearance have been receiving many scholars’ attention all the time, which bring turbine efficiency increasing, emissions reduction, payloads increasing, and mission range abilities extension. In order to gain the blade tip clearance dynamically, a prototype optical fiber measurement system was built and tested based on the rotor test rig. The optical fiber tip clearance measurement system consists of the reflective intensity-modulated optical fiber bundle (sensor), main signal processing unit, high-speed data acquisition card, and a computer. The static performance and dynamic performance experiments were conducted to verify the performance of the system we designed. In addition, the results show that the accuracy of the system is 25 μm or better; the stability of the measurement system was evaluated in room temperature. The clearance measurement range is about 5 mm, and sensitivity of the sensor is 0.0733/mm. Furthermore, the typical tip clearance dynamic measurement experiment results show that the system has good dynamic response characteristics as well. The system will provide a new tool for engine health monitoring or fast active tip clearance control.
Vonoprazan-Based Regimen Is More Useful than PPI-Based One as a First-LineHelicobacter pyloriEradication: A Randomized Controlled Trial
Authors: Maruyama Masafumi , Tanaka Naoki , Kubota Daisuke , Miyajima Masayuki , Kimura Takefumi , Tokutake Koujiro , Imai Ryujiro , Fujisawa Toru , Mori Hiromitsu , Matsuda Yoshiaki , Wada Shuichi , Horiuchi Akira , Kiyosawa Kendo
Published: February 2017

Background. A new agent, potassium-competitive acid blocker vonoprazan (VPZ) has potent acid-inhibitory effects and may offer advantages over conventionalH. pylorieradication therapies. We aimed to compare the eradication rate between VPZ-based treatment and PPI-based one.Methods. This randomized controlled trial was designed to assign 141 patients withH. pylori-positive gastritis to VPZ group (VPZ 20 mg, amoxicillin 750 mg, and clarithromycin 200 or 400 mg twice daily for 7 days) or PPI group (rabeprazole 20 mg or lansoprazole 30 mg, amoxicillin 750 mg, and clarithromycin 200 or 400 mg twice daily for 7 days). Primary endpoints were eradication rates and adverse events.Results. Seventy of 72 patients in VPZ group and 63 of 69 patients in PPI group completed the treatment after 7 days. The eradication rate was significantly higher in VPZ group than PPI group by intention-to-treat analysis (95.8% versus 69.6%,P=0.00003, 95% confidence interval [CI] 88.3-99.1% versus 57.3-80.1%) and per-protocol analysis (95.7% versus 71.4%,P=0.0002, 95% CI 88.0-99.1% versus 58.7-82.1%). The incidence of adverse events was not different between the groups (26.3% in VPZ group versus 37.7% in PPI group,P=0.15).Conclusion. VPZ-based regimen is more useful than that PPI-based regimen as a first-lineH. pylorieradication therapy.
Deciphering the Roles of Thiazolidinediones and PPARγin Bladder Cancer
Authors: Chiu Melody , McBeth Lucien , Sindhwani Puneet , Hinds Terry D.
Published: February 2017

The use of thiazolidinedione (TZD) therapy in type II diabetic patients has proven useful in the lowering of blood glucose levels. However, recent investigations have shown that there may be potential health concerns associated, including the risk of developing bladder cancer as well as complications in the cardiovasculature. TZDs are ligands for the nuclear receptor PPARγ, and activation causes lipid uptake and insulin sensitization, both of which are critical processes for diabetic patients whose bodies are unable to utilize insulin effectively. Several studies have shown that PPARγ/TZDs decrease IGF-1 levels and, thus, reduce cancer growth in carcinomas such as the pancreas, colon, liver, and prostate. However, other studies have shed light on the potential of the receptor as a biomarker for uroepithelial carcinomas, particularly due to its stimulatory effect on migration of bladder cancer cells. Furthermore, PPARγmay provide the tumor-promoting microenvironment by de novo synthesis of nutrients that are needed for bladder cancer development. In this review, we closely examine the TZD class of drugs and their effects on PPARγin patient studies along with additional molecular factors that are positive modulators, such as protein phosphatase 5 (PP5), which may have considerable implications for bladder cancer therapy.
Energy Optimal Control Strategy of PHEV Based on PMP Algorithm
Authors: Wu Tiezhou , Ding Yi , Xu Yushan
Published: February 2017

Under the global voice of “energy saving” and the current boom in the development of energy storage technology at home and abroad, energy optimal control of the whole hybrid electric vehicle power system, as one of the core technologies of electric vehicles, is bound to become a hot target of “clean energy” vehicle development and research. This paper considers the constraints to the performance of energy storage system in Parallel Hybrid Electric Vehicle (PHEV), from which lithium-ion battery frequently charges/discharges, PHEV largely consumes energy of fuel, and their are difficulty in energy recovery and other issues in a single cycle; the research uses lithium-ion battery combined with super-capacitor (SC), which is hybrid energy storage system (Li-SC HESS), working together with internal combustion engine (ICE) to drive PHEV. Combined with PSO-PI controller and Li-SC HESS internal power limited management approach, the research proposes the PHEV energy optimal control strategy. It is based on revised Pontryagin’s minimum principle (PMP) algorithm, which establishes the PHEV vehicle simulation model through ADVISOR software and verifies the effectiveness and feasibility. Finally, the results show that the energy optimization control strategy can improve the instantaneity of tracking PHEV minimum fuel consumption track, implement energy saving, and prolong the life of lithium-ion batteries and thereby can improve hybrid energy storage system performance.
Genetic Background and Clinical Characters of Pediatric Chronic Pancreatitis: Data and Implications from the East
Authors: Liu Muyun , Xia Tian , Zhang Di , Hu Lianghao , Liao Zhuan , Sun Chang , Li Zhaoshen
Published: February 2017

Background.The clinical pattern and genetic background of juvenile idiopathic chronic pancreatitis (ICP) are yet unclear.Methods. A retrospective study of 73 Chinese juvenile ICP patients was performed, and genetic tests were carried out to detect relevant mutations using direct sequencing technique and high-resolution melting technique. Subjects without pancreatitis served as controls.Results.The SPINK1 c.194+2T>C variant was present in 56.16% and 42.00% of juvenile and adult ICP patients, respectively (p=0.020), but was not present in any of the control subjects. Thirty-four (46.58%) of the 73 juvenile ICP patients were male, and a significantly higher ratio of male patients in the adult group was identified (46.58% versus 64.00%,p=0.022). Although most of the juvenile patients presented with abdominal pain (70/73, 95.89%), the patterns of pain attack are significantly different in patients with or without SPINK1 c.194+2T>C mutation. Patients carrying the mutation are more likely to present with recurrent acute pancreatitis (70.70%).Conclusions.The main symptom of pediatric ICP was abdominal pain. SPINK1 c.194+2T>C mutation had a higher occurrence in juvenile ICP patients than in adult group and typically presented with recurrent acute pancreatitis. There may be unidentified factors that lead to a greater incidence rate of ICP in adult male population.
Some Differential Inequalities on Time Scales and Their Applications to Feedback Control Systems
Authors: Fan Yonghong , Yu Yangyang , Wang Linlin
Published: February 2017

This paper deals with feedback control systems on time scales. Firstly, we generalize the semicycle concept to time scales and then establish some differential inequalities on time scales. Secondly, as applications of these inequalities, we study the uniform ultimate boundedness of solutions of these systems. We give a new method to investigate the permanence of ecosystem on time scales. And some known results have been generalized. Finally, an example is given to support the result.