bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dosimetric characterization of the high‐dose‐rate brachytherapy source using the AAPM and ESTRO formalism
Authors: Thanh Minh‐Tri Ho , Munro John J. , Medich David C. 
Published: February 2017

The Source Production & Equipment Co. (SPEC) model is a new brachytherapy source model intended for use as a temporary high‐dose‐rate (HDR) brachytherapy source for the Nucletron microSelectron Classic afterloading system. The purpose of this study is to characterize this HDR source for clinical application by obtaining a complete set of Monte Carlo calculated dosimetric parameters for the M‐15, as recommended by AAPM and ESTRO, for isotopes with average energies greater than 50 keV. This was accomplished by using the MCNP6 Monte Carlo code to simulate the resulting source dosimetry at various points within a pseudoinfinite water phantom. These dosimetric values next were converted into the AAPM and ESTRO dosimetry parameters and the respective statistical uncertainty in each parameter also calculated and presented. The source was modeled in an MCNP6 Monte Carlo environment using the physical source specifications provided by the manufacturer. photons were uniformly generated inside the iridium core of the model with photon and secondary electron transport replicated using photoatomic cross‐sectional tables supplied with MCNP6. Simulations were performed for both water and air/vacuum computer models with a total of sources photon history for each simulation and the in‐air photon spectrum filtered to remove low‐energy photons below . Dosimetric data, including , and , and their statistical uncertainty were calculated from the output of an MCNP model consisting of an source placed at the center of a spherical water phantom of 100 cm diameter. The air kerma strength in free space, , and dose rate constant, Λ, also was computed from a MCNP model with source, was centered at the origin of an evacuated phantom in which a critical volume containing air at STP was added 100 cm from the source center. The reference dose rate, , is found to be . The air kerma strength, , is reported to be , and the dose rate constant, Λ, is calculated to be . The normalized dose rate, radial dose function, and anisotropy function with their uncertainties were computed and are represented in both tabular and graphical format in the report. A dosimetric study was performed of the new HDR brachytherapy source using the MCNP6 radiation transport code. Dosimetric parameters, including the dose‐rate constant, radial dose function, and anisotropy function, were calculated in accordance with the updated AAPM and ESTRO dosimetric parameters for brachytherapy sources of average energy greater than 50 keV. These data therefore may be applied toward the development of a treatment planning program and for clinical use of the source.PACS numbers: 87.56.bg, 87.53.Jw
Development of a novel remote‐controlled and self‐contained audiovisual‐aided interactive system for immobilizing claustrophobic patients
Authors: Ju Harang , Kim Siyong , Read Paul , Trifiletti Daniel , Harrell Andrew , Libby Bruce , Kim Taeho 
Published: February 2017

In radiotherapy, only a few immobilization systems, such as open‐face mask and head mold with a bite plate, are available for claustrophobic patients with a certain degree of discomfort. The purpose of this study was to develop a remote‐controlled and self‐contained audiovisual (AV)‐aided interactive system with the iPad mini with Retina display for intrafractional motion management in brain/H&N (head and neck) radiotherapy for claustrophobic patients. The self‐contained, AV‐aided interactive system utilized two tablet computers: one for AV‐aided interactive guidance for the subject and the other for remote control by an operator. The tablet for audiovisual guidance traced the motion of a colored marker using the built‐in front‐facing camera, and the remote control tablet at the control room used infrastructure Wi‐Fi networks for real‐time communication with the other tablet. In the evaluation, a programmed QUASAR motion phantom was used to test the temporal and positional accuracy and resolution. Position data were also obtained from ten healthy volunteers with and without guidance to evaluate the reduction of intrafractional head motion in simulations of a claustrophobic brain or H&N case. In the phantom study, the temporal and positional resolution was 24 Hz and 0.2 mm. In the volunteer study, the average superior–inferior and right–left displacement was reduced from 1.9 mm to 0.3 mm and from 2.2 mm to 0.2 mm with AV‐aided interactive guidance, respectively. The superior–inferior and right–left positional drift was reduced from 0.5 mm/min to 0.1 mm/min and from 0.4 mm/min to 0.04 mm/min with audiovisual‐aided interactive guidance. This study demonstrated a reduction in intrafractional head motion using a remote‐controlled and self‐contained AV‐aided interactive system of iPad minis with Retina display, easily obtainable and cost‐effective tablet computers. This approach can potentially streamline clinical flow for claustrophobic patients without a head mask and also allows patients to practice self‐motion management before radiation treatment delivery.PACS number: 87.55.Gh
Effect of radiation dose reduction on image quality in adult head CT with noise‐suppressing reconstruction system with a 256 slice MDCT
Authors: Baskan Ozdil , Erol Cengiz , Ozbek Hanefi , Paksoy Yahya 
Published: February 2017

The purpose of our study was to investigate the effect of iterative reconstruction (IR) as a dose reduction system on the image quality (IQ) of the adult head computed tomography (CT) at various low‐dose levels, and to identify ways of setting the amount of dose reduction. We performed two noncontrast low‐dose (LD) adult head CT protocols modified by lowering the tube current with IR which were decided in the light of a group of phantom studies. Two groups of patients, each 100 underwent noncontrast head CT with LD‐I and LD‐II, respectively. These groups were compared with 100 consecutive standard dose (STD) adult head CT protocol in terms of quantitative and qualitative IQ. The signal‐to‐noise ratio (SNR) of the white matter (WM) and gray matter (GM) and contrast‐to‐noise ratio (CNR) values in the LD groups were higher than the STD group. The differences were statistically significant. When the STD and the LD groups were compared qualitatively, no significant differences were found in overall quality. By selecting the appropriate level of IR 34%, radiation dose reduction in adult head CT can be achieved without compromising IQ.PACS number: 87.57.‐s
VMAT linear accelerator commissioning and quality assurance: dose control and gantry speed tests
Authors: Barnes Michael P. , Rowshanfarzad Pejman , Greer Peter B. 
Published: February 2017

In VMAT treatment delivery the ability of the linear accelerator (linac) to accurately control dose versus gantry angle is critical to delivering the plan correctly. A new VMAT test delivery was developed to specifically test the dose versus gantry angle with the full range of allowed gantry speeds and dose rates. The gantry‐mounted IBA MatriXX with attached inclinometer was used in movie mode to measure the instantaneous relative dose versus gantry angle during the plan every 0.54 s. The results were compared to the expected relative dose at each gantry angle calculated from the plan. The same dataset was also used to compare the instantaneous gantry speeds throughout the delivery compared to the expected gantry speeds from the plan. Measurements performed across four linacs generally show agreement between measurement and plan to within 1.5% in the constant dose rate regions and dose rate modulation within 0.1 s of the plan. Instantaneous gantry speed was measured to be within of the plan (1 SD). An error in one linac was detected in that the nominal gantry speed was incorrectly calibrated. This test provides a practical method to quality‐assure critical aspects of VMAT delivery including dose versus gantry angle and gantry speed control. The method can be performed with any detector that can acquire time‐resolved dosimetric information that can be synchronized with a measurement of gantry angle. The test fulfils several of the aims of the recent Netherlands Commission on Radiation Dosimetry (NCS) Report 24, which provides recommendations for comprehensive VMAT quality assurance.PACS number(s): 87.55.Qr
Effect of contrast‐enhanced CT scans on heterogeneity corrected dose computations in the lung
Authors: Burridge Nichola A. , Rowbottom Carl G. , Burt Paul A. 
Published: February 2017

The aim of this study was to investigate and, if possible, compensate for the effect of intravenous contrast‐enhanced CT scans on the treatment planning dose distributions for lung patients. The contrast and noncontrast CT scans of 3 patients were registered, and the effect of contrast on the Hounsfield units (HU) was assessed. The effect of contrast was then simulated in the CT scans of 18 patients receiving radiotherapy of the lung by modification of the CT numbers for relevant sections of noncontrast‐enhanced CT scans. All treatment planning was performed on the Pinnacle3 planning system. The dose distributions computed from simulated contrast CT scans were compared to the original dose distributions by comparison of the monitor units (MUs) for each beam in the treatment plan required to deliver the prescribed dose to the isocenter as well as a comparison of the total MUs for each patient, a percentage change in required MUs being equivalent to a percentage change in the dose. A correction strategy to enable the use of contrast‐enhanced CT scans in treatment planning was developed, and the feasibility of applying the strategy was investigated by calculating dose distributions for both the original and simulated contrast CT scans. A mean increase in the overall patient MUs of was found, with a maximum increase of 3.3% when contrast was simulated on the original CT scans. The simulated contrast scans confirmed that the use of contrast‐enhanced CT scans for routine treatment planning would result in a systematic change in the dose delivered to the isocenter. The devised correction strategy had no clinically relevant effect on the dose distribution for the original CT scans. The application of the correction strategy to the simulated contrast CT scans led to a reduction of the mean difference in the overall MUs to compared to the original scan, demonstrating that the effect of contrast was eliminated with the correction strategy. This work has highlighted the problems associated with using contrast‐enhanced CT scans in heterogeneity corrected dose computation. Contrast visible in the CT scan is transient and should not be accounted for in the treatment plan. A correction strategy has been developed that minimizes the effect of intravenous contrast while having no clinical effect on noncontrast CT scans. The correction strategy allows the use of contrast without detriment to the treatment plan.PACS number: 87.53.Tf
Simplifying intensity‐modulated radiotherapy plans with fewer beam angles for the treatment of oropharyngeal carcinoma
Authors: Takamiya Robert , Missett Brian , Weinberg Vivian , Akazawa Clayton , Akazawa Pam , Zytkovicz Andrea , Bucci Mary Kara , Lee Nancy , Quivey Jeanne , Xia Ping 
Published: February 2017

The first aim of the present study was to investigate the feasibility of using fewer beam angles to improve delivery efficiency for the treatment of oropharyngeal cancer (OPC) with inverse‐planned intensity‐modulated radiation therapy (IP‐IMRT). A secondary aim was to evaluate whether the simplified IP‐IMRT plans could reduce the indirect radiation dose. The treatment plans for 5 consecutive OPC patients previously treated with a forward‐planned IMRT (FP‐IMRT) technique were selected as benchmarks for this study. The initial treatment goal for these patients was to deliver 70 Gy to of the planning gross tumor volume (PTV‐70) and 59.4 Gy to of the planning clinical tumor volume (PTV‐59.4) simultaneously. Each case was re‐planned using IP‐IMRT with multiple beam‐angle arrangements, including four complex IP‐IMRT plans using 7 or more beam angles, and one simple IMRT plan using 5 beam angles. The complex IP‐IMRT plans and simple IP‐IMRT plans were compared to each other and to the FP‐IMRT plans by analyzing the dose coverage of the target volumes, the plan homogeneity, the dose–volume histograms of critical structures, and the treatment delivery parameters including delivery time and the total number of monitor units (MUs). When comparing the plans, we found no significant difference between the complex IP‐IMRT, simple IP‐IMRT, and FP‐IMRT plans for tumor target coverage (PTV‐70: ; PTV‐59.4: ). The plan homogeneity, measured by the mean percentage isodose, did not significantly differ between the IP‐IMRT and FP‐IMRT plans , although we observed a trend toward greater inhomogeneity of dose in the simple IP‐IMRT plans. All IP‐IMRT plans either met or exceeded the quality of the FP‐IMRT plans in terms of dose to adjacent critical structures, including the parotids, spinal cord, and brainstem. As compared with the complex IP‐IMRT plans, the simple IP‐IMRT plans significantly reduced the mean treatment time (maximum probability for four pairwise comparisons: ). In conclusion, our study demonstrates that, as compared with complex IP‐IMRT, simple IP‐IMRT can significantly improve treatment delivery efficiency while maintaining similar target coverage and sparing of critical structures. However, the improved efficiency does not significantly reduce the total number of MUs nor the indirect radiation dose.PACS number: 87.53.tf
GafChromic XR‐QA film in testing panoramic dental radiography
Authors: Chu Robert Y.L. , Lam Tin , Liang Yongguang 
Published: February 2017

The location and field size of the incident X‐ray beam in panoramic dental radiography cannot be ascertained visually most of the time. However, these parameters are needed for quality control and dosimetry determination. To alleviate this problem, we tested GafChromic XR‐QA film on two panoramic systems. For each system, we used the length of a cross‐sectional image of the incident beam and the exposure measurement with a pencil ion chamber to compute the dose–area product. The result was confirmed by direct analysis of a dose distribution on a film. Placement of the ion chamber was determined by the latter images. The GafChromic XR‐QA version of radiochromic film has thus been demonstrated to usefully complement a pencil ion chamber in the testing of a panoramic radiography system.PACS numbers: 87.52.Df, 87.59Bh, 87.66.Cd, 87.66Jj
The Ice Water Paths of Small and Large Ice Species in Hurricanes Arthur (2014) and Irene (2011)
Authors: Kalina Evan A. , Matrosov Sergey Y. , Cione Joseph J. , Marks Frank D. , Vivekanandan Jothiram , Black Robert A. , Hubbert John C. , Bell Michael M. , Kingsmill David E. , White Allen B. 
Published: February 2017

AbstractDual-polarization scanning radar measurements, air temperature soundings, and a polarimetric radar-based particle identification scheme are used to generate maps and probability density functions (PDFs) of the ice water path (IWP) in Hurricanes Arthur (2014) and Irene (2011) at landfall. The IWP is separated into the contribution from small ice (i.e., ice crystals), termed small-particle IWP, and large ice (i.e., graupel and snow), termed large-particle IWP. Vertically profiling radar data from Hurricane Arthur suggest that the small ice particles detected by the scanning radar have fall velocities mostly greater than 0.25 m s−1 and that the particle identification scheme is capable of distinguishing between small and large ice particles in a mean sense. The IWP maps and PDFs reveal that the total and large-particle IWPs range up to 10 kg m−2, with the largest values confined to intense convective precipitation within the rainbands and eyewall. Small-particle IWP remains mostly <4 kg m−2, with the largest small-particle IWP values collocated with maxima in the total IWP. PDFs of the small-to-total IWP ratio have shapes that depend on the precipitation type (i.e., intense convective, stratiform, or weak-echo precipitation). The IWP ratio distribution is narrowest (broadest) in intense convective (weak echo) precipitation and peaks at a ratio of about 0.1 (0.3).
Evaluation of MRMS Snowfall Products over the Western United States
Authors: Wen Yixin , Kirstetter Pierre , Gourley J. J. , Hong Yang , Behrangi Ali , Flamig Zachary 
Published: February 2017

Abstract
Snow is important to water resources and is of critical importance to society. Ground-weather-radar-based snowfall observations have been highly desirable for large-scale weather monitoring and water resources applications. This study conducts an evaluation of the Multi-Radar Multi-Sensor (MRMS) quantitative estimates of snow rate using the Snowpack Telemetry (SNOTEL) daily snow water equivalent (SWE) datasets. A detectability evaluation shows that MRMS is limited in detecting very light snow (daily snow accumulation &lt;5 mm) because of the quality control module in MRMS filtering out weak signals (&lt;5 dBZ). For daily snow accumulation greater than 10 mm, MRMS has good detectability. The quantitative comparisons reveal a bias of −77.37% between MRMS and SNOTEL. A majority of the underestimation bias occurs in relatively warm conditions with surface temperatures ranging from −10° to 0°C. A constant reflectivity–SWE intensity relationship does not capture the snow mass flux increase associated with denser snow particles at these relatively warm temperatures. There is no clear dependence of the bias on radar beam height. The findings in this study indicate that further improvement in radar snowfall products might occur by deriving appropriate reflectivity–SWE relationships considering the degree of riming and snowflake size.
The things that make for peace: The purpose, promise, and peril of interfaith engagement
Authors: Sehested Ken 
Published: February 2017

In the early weeks of 2011, during the Arab Spring uprising, Egyptian blogger Nevine Zaki posted a photograph from Cairo’s Tahrir Square. It showed a group of people bowing in the traditional style of Muslim prayer, surrounded by other people standing hand-in-hand, facing outward, as a wall of protection against hostile pro-government forces. Zaki affixed this caption: “A picture I took yesterday of Christians protecting Muslims during their prayers.” Similar scenes, some ancient, some as recent as yesterday’s newspaper, can be referenced in numerous ways with a variety of religious identities. No religious tradition can claim a monopoly on compassionate courage, yet such stories are rarely headlined. This article will review some of the progress made in interfaith collaboration on issues of justice, peace, and human rights, beginning with a review of organizational breakthrough statements, like “Dabru Emet,” a document from Jewish intellectuals and rabbis affirming that “Jews and Christians worship the same God,” and “A Common Word Between Us and You,” by leading Islamic scholars and clerics, followed by multiple responses from Christian bodies. With these as evidence of closer interfaith orbits on a large scale, we then examine the purpose, promise and pitfalls of interfaith collaboration on the ground in regions and communities, especially in the United States.
Changes in heparin dose response slope during cardiac surgery: possible result in inaccuracy in predicting heparin bolus dose requirement to achieve target ACT
Authors: Ichikawa Junko , Mori Tetsu , Kodaka Mitsuharu , Nishiyama Keiko , Ozaki Makoto , Komori Makiko 
Published: February 2017

Introduction: The substantial interpatient variability in heparin requirement has led to the use of a heparin dose response (HDR) technique. The accuracy of Hepcon-based heparin administration in achieving a target activated clotting time (ACT) using an HDR slope remains controversial. Methods: We prospectively studied 86 adult patients scheduled for cardiac surgery requiring cardiopulmonary bypass. The total dose of calculated heparin required for patient and pump priming was administered simultaneously to achieve a target ACT of 450 s for HDR on the Hepcon HMS system. Blood samples were obtained after the induction of anesthesia, at 3 min after heparin administration and after the initiation of CPB to measure kaolin ACT, HDR slope, whole-blood heparin concentration based on the HDR slope and anti-Xa heparin concentration, antithrombin and complete blood count. Results: The target ACT of 450 s was not achieved in 68.6% of patients. Compared with patients who achieved the target ACT, those who failed to achieve their target ACT had a significantly higher platelet count at baseline. Correlation between the HDR slope and heparin sensitivity was poor. Projected heparin concentration and anti-Xa heparin concentration are not interchangeable based on the Bland–Altman analysis. Conclusion: It can be hypothesized that the wide discrepancy in HDR slope versus heparin sensitivity may be explained by an inaccurate prediction of the plasma heparin level and/or the change in HDR of individual patients, depending on in vivo factors such as extravascular sequestration of heparin, decreased intrinsic antithrombin activity level and platelet count and/or activity.
The influence of diffusion gradient direction on diffusion-weighted imaging of breast mass-like lesions at 3.0T
Authors: Yao Feifei , Li Ying , Xiao Yunfei , Zheng Dandan , Zhang Yan , Cheng Jingliang 
Published: February 2017

Background It has been challenging to achieve ideal breast diffusion-weighted imaging (DWI). The optimization of diffusion gradient direction is of great importance. Purpose To evaluate the effect of diffusion gradient direction on the apparent diffusion coefficient (ADC) values of breast mass-like lesions and the visual grades of image quality, lesion visibility, and sharpness of breast contour at 3.0T. Material and Methods Sixty consecutive patients with mass-like lesions were enrolled in this study. In addition to typical breast magnetic resonance imaging (MRI) protocols, the breasts were scanned with conventional orthogonal DWI (c-DWI), tetrahedral DWI (t-DWI), and 3in1 DWI (3in1-DWI) sequences. The DW images were observed and visually graded by two radiologists independently. For ADC measurement, one radiographer manually selected the region of interest (ROI). Results For both readers, t-DWI had better image quality and sharpness of breast contour than c-DWI. Regarding lesion visibility, no significant differences were observed among three sequences. The mean ADC values were 1.462 × 10−3, 1.490 × 10−3, and 1.446 × 10−3 mm2 s−1 for c-DWI, t-DWI, and 3in1-DWI, respectively. The ADC values extracted from both t-DWI and 3in1-DWI were not statistically different compared with those from c-DWI. In all DWI sequences, the ADC of malignant lesions was significantly reduced compared with benign lesions. Conclusion DWI with tetrahedral or 3in1 diffusion gradients is a more useful technique in clinical breast MRI than c-DWI because the image quality and sharpness of breast contour are improved. ADC is comparable to c-DWI.