bluuebunny/crossref_metadata_2025_split huggingface dataset:
Addendum to brachytherapy dose‐volume histogram commissioning with multiple planning systems
Authors: Gossman Michael S. 
Published: February 2017

The process for validating dose‐volume histogram data in brachytherapy software is presented as a supplement to a previously published article. Included is the DVH accuracy evaluation of the Best NOMOS treatment planning system called “Best TPS VohvmePlan” As done previously in other software, a rectangular cuboid was contoured in the treatment planning system. A single radioactive 125I source was positioned coplanar and concentric with one end. Calculations were performed to estimate dose deposition in partial volumes of the cuboid structure, using the brachytherapy dosimetry formalism defined in AAPM Task Group 43. Hand‐calculated, dose‐volume results were compared to TPS‐generated, point‐source‐approximated dose‐volume histogram data to establish acceptance. The required QA for commissioning was satisfied for the DVH as conducted previously for other software, using the criterion that the DVH “actual variance” calculations should differ by no more than 5% at any specific radial distance with respect to , and the “average variance” DVH calculations should differ by no more than 2% over all radial distances with respect to . The average disagreement observed between hand calculations and treatment planning system DVH was less than 0.5% on average for this treatment planning system and less than 1.1% maximally for .PACS number(s): 87.10.+e, 87.55.‐x, 87.53.Jw, 07.05.Tp
Inverse treatment planning for spinal robotic radiosurgery: an international multi‐institutional benchmark trial
Authors: Blanck Oliver , Wang Lei , Baus Wolfgang , Grimm Jimm , Lacornerie Thomas , Nilsson Joakim , Luchkovskyi Sergii , Cano Isabel Palazon , Shou Zhenyu , Ayadi Myriam , Treuer Harald , Viard Romain , Siebert Frank‐Andre , Chan Mark K.H. , Hildebrandt Guido , Dunst Jürgen , Imhoff Detlef , Wurster Stefan , Wolff Robert , Romanelli Pantaleo , Lartigau Eric , Semrau Robert , Soltys Scott G. , Schweikard Achim 
Published: February 2017

Stereotactic radiosurgery (SRS) is the accurate, conformal delivery of high‐dose radiation to well‐defined targets while minimizing normal structure doses via steep dose gradients. While inverse treatment planning (ITP) with computerized optimization algorithms are routine, many aspects of the planning process remain user‐dependent. We performed an international, multi‐institutional benchmark trial to study planning variability and to analyze preferable ITP practice for spinal robotic radiosurgery. 10 SRS treatment plans were generated for a complex‐shaped spinal metastasis with 21 Gy in 3 fractions and tight constraints for spinal cord (, ) and target (coverage ). The resulting plans were rated on a scale from 1 to 4 (excellent‐poor) in five categories (constraint compliance, optimization goals, low‐dose regions, ITP complexity, and clinical acceptability) by a blinded review panel. Additionally, the plans were mathematically rated based on plan indices (critical structure and target doses, conformity, monitor units, normal tissue complication probability, and treatment time) and compared to the human rankings. The treatment plans and the reviewers' rankings varied substantially among the participating centers. The average mean overall rank was 2.4 (1.2‐4.0) and 8/10 plans were rated excellent in at least one category by at least one reviewer. The mathematical rankings agreed with the mean overall human rankings in 9/10 cases pointing toward the possibility for sole mathematical plan quality comparison. The final rankings revealed that a plan with a well‐balanced trade‐off among all planning objectives was preferred for treatment by most participants, reviewers, and the mathematical ranking system. Furthermore, this plan was generated with simple planning techniques. Our multi‐institutional planning study found wide variability in ITP approaches for spinal robotic radiosurgery. The participants', reviewers', and mathematical match on preferable treatment plans and ITP techniques indicate that agreement on treatment planning and plan quality can be reached for spinal robotic radiosurgery.PACS number(s): 87.55.de
On flattening filter‐free portal dosimetry
Authors: Pardo Eduardo , Novais Juan Castro , Molina López María Yolanda , Maqueda Sheila Ruiz 
Published: February 2017

Varian introduced (in 2010) the option of removing the flattening filter (FF) in their C‐Arm linacs for intensity‐modulated treatments. This mode, called flattening filter‐free (FFF), offers the advantage of a greater dose rate. Varian's “Portal Dosimetry” is an electronic portal imager device (EPID)‐based tool for IMRT verification. This tool lacks the capability of verifying flattening filter‐free (FFF) modes due to saturation and lack of an image prediction algorithm. (Note: the latest versions of this software and EPID correct these issues.) The objective of the present study is to research the feasibility of said verifications (with the older versions of the software and EPID). By placing the EPID at a greater distance, the images can be acquired without saturation, yielding a linearity similar to the flattened mode. For the image prediction, a method was optimized based on the clinically used algorithm (analytical anisotropic algorithm (AAA)) over a homogeneous phantom. The depth inside the phantom and its electronic density were tailored. An application was developed to allow the conversion of a dose plane (in DICOM format) to Varian's custom format for Portal Dosimetry. The proposed method was used for the verification of test and clinical fields for the three qualities used in our institution for IMRT: 6X, 6FFF and 10FFF. The method developed yielded a positive verification (more than 95% of the points pass a gamma) for both the clinical and test fields. This method was also capable of “predicting” static and wedged fields. A workflow for the verification of FFF fields was developed. This method relies on the clinical algorithm used for dose calculation and is able to verify the FFF modes, as well as being useful for machine quality assurance. The procedure described does not require new hardware. This method could be used as a verification of Varian's Portal Dose Image Prediction.PACS number(s): 87.53.Kn, 87.55.T‐, 87.56.bd, 87.59.‐e
Automated Calculation of Water‐equivalent Diameter (DW) Based on AAPM Task Group 220
Authors: Anam Choirul , Haryanto Freddy , Widita Rena , Arif Idam , Dougherty Geoff 
Published: February 2017

The purpose of this study is to accurately and effectively automate the calculation of the water‐equivalent diameter () from 3D CT images for estimating the size‐specific dose. is the metric that characterizes the patient size and attenuation. In this study, was calculated for standard CTDI phantoms and patient images. Two types of phantom were used, one representing the head with a diameter of 16 cm and the other representing the body with a diameter of 32 cm. Images of 63 patients were also taken, 32 who had undergone a CT head examination and 31 who had undergone a CT thorax examination. There are three main parts to our algorithm for automated calculation. The first part is to read 3D images and convert the CT data into Hounsfield units (HU). The second part is to find the contour of the phantoms or patients automatically. And the third part is to automate the calculation of based on the automated contouring for every slice (). The results of this study show that the automated calculation of and the manual calculation are in good agreement for phantoms and patients. The differences between the automated calculation of and the manual calculation are less than 0.5%. The results of this study also show that the estimating of using (central slice along longitudinal axis) produces percentage differences of and , and estimating using produces percentage differences of and , for thorax and head examinations, respectively. From this study, the percentage differences between normalized size‐specific dose estimate for every slice () and are and for thorax and head examinations, respectively; between and are and for thorax and head examinations, respectively.PACS number(s): 87.57.Q‐, 87.57.uq‐
Evaluation of target and cardiac position during visually monitored deep inspiration breath‐hold for breast radiotherapy
Authors: Conroy Leigh , Yeung Rosanna , Watt Elizabeth , Quirk Sarah , Long Karen , Hudson Alana , Phan Tien , Smith Wendy L. 
Published: February 2017

A low‐resource visually monitored deep inspiration breath‐hold (VM‐DIBH) technique was successfully implemented in our clinic to reduce cardiac dose in left‐sided breast radiotherapy. In this study, we retrospectively characterized the chest wall and heart positioning accuracy of VM‐DIBH using cine portal images from 42 patients. Central chest wall position from field edge and in‐field maximum heart distance (MHD) were manually measured on cine images and compared to the planned positions based on the digitally reconstructed radiographs (DRRs). An in‐house program was designed to measure left anterior descending artery (LAD) and chest wall separation on the planning DIBH CT scan with respect to breath‐hold level (BHL) during simulation to determine a minimum BHL for VM‐DIBH eligibility. Systematic and random setup uncertainties of 3.0 mm and 2.6 mm, respectively, were found for VM‐DIBH treatment from the chest wall measurements. Intrabeam breath‐hold stability was found to be good, with over 96% of delivered fields within 3 mm. Average treatment MHD was significantly larger for those patients where some of the heart was planned in the field compared to patients whose heart was completely shielded in the plan (p < 0.001). No evidence for a minimum BHL was found, suggesting that all patients who can tolerate DIBH may yield a benefit from it.PACS number(s): 87.53.Jw, 87.53.Kn, 87.55.D‐
Rounded leaf end modeling in Pinnacle VMAT treatment planning for fixed jaw linacs
Authors: Young Lori A. , Yang Fei , Cao Ning , Meyer Juergen 
Published: February 2017

During volume‐modulated arc therapies (VMAT), dosimetric errors are introduced by multiple open dynamic leaf gaps that are present in fixed diaphragm linear accelerators. The purpose of this work was to develop a methodology for adjusting the rounded leaf end modeling parameters to improve out‐of‐field dose agreement in SmartArc VMAT treatment plans delivered by fixed jaw linacs where leaf gap dose is not negligible. Leaf gap doses were measured for an Elekta beam modulator linac with 0.4 cm micro‐multileaf collimators (MLC) using an A16 micro‐ionization chamber, a MatriXX ion chamber detector array, and Kodak EDR2 film dosimetry in a solid water phantom. The MLC offset and rounded end tip radius were adjusted in the Pinnacle treatment planning system (TPS) to iteratively arrive at the optimal configuration for 6 MV and 10 MV photon energies. Improvements in gamma index with a acceptance criteria and an inclusion threshold of 5% of maximum dose were measured, analyzed, and validated using an ArcCHECK diode detector array for field sizes ranging from 1.6 to 14 cm square field arcs and Task Group (TG) 119 VMAT test cases. The best results were achieved for a rounded leaf tip radius of 13 cm with a 0.1 cm MLC offset. With the optimized MLC model, measured gamma indices ranged between 99.9% and 91.7% for square field arcs with sizes between 3.6 cm and 1.6 cm, with a maximum improvement of 42.7% for the 1.6 cm square field size. Gamma indices improved up to 2.8% in TG‐119 VMAT treatment plans. Imaging and Radiation Oncology Core (IROC) credentialing of a VMAT plan with the head and neck phantom passed with a gamma index of 100%. Fine‐tune adjustments to MLC rounded leaf ends may improve patient‐specific QA pass rates and provide more accurate predictions of dose deposition to avoidance structures.PACS number(s): 87.55.D‐, 87.55.kd, 87.55.kh
Development of a universal medical X‐ray imaging phantom prototype
Authors: Groenewald Annemari , Groenewald Willem A. 
Published: February 2017

Diagnostic X‐ray imaging depends on the maintenance of image quality that allows for proper diagnosis of medical conditions. Maintenance of image quality requires quality assurance programs on the various X‐ray modalities, which consist of projection radiography (including mobile X‐ray units), fluoroscopy, mammography, and computed tomography (CT) scanning. Currently a variety of modality‐specific phantoms are used to perform quality assurance (QA) tests. These phantoms are not only expensive, but suitably trained personnel are needed to successfully use them and interpret the results. The question arose as to whether a single universal phantom could be designed and applied to all of the X‐ray imaging modalities. A universal phantom would reduce initial procurement cost, possibly reduce the time spent on QA procedures and simplify training of staff on the single device. The aim of the study was to design and manufacture a prototype of a universal phantom, suitable for image quality assurance in general X‐rays, fluoroscopy, mammography, and CT scanning. The universal phantom should be easy to use and would enable automatic data analysis, pass/fail reporting, and corrective action recommendation. In addition, a universal phantom would especially be of value in low‐income countries where finances and human resources are limited. The design process included a thorough investigation of commercially available phantoms. Image quality parameters necessary for image quality assurance in the different X‐ray imaging modalities were determined. Based on information obtained from the above‐mentioned investigations, a prototype of a universal phantom was developed, keeping ease of use and reduced cost in mind. A variety of possible phantom housing and insert materials were investigated, considering physical properties, machinability, and cost. A three‐dimensional computer model of the first phantom prototype was used to manufacture the prototype housing and inserts. Some of the inserts were 3D‐printed, others were machined from different materials. The different components were assembled to form the first prototype of the universal X‐ray imaging phantom. The resulting prototype of the universal phantom conformed to the aims of a single phantom for multiple imaging modalities, which would be easy to use and manufacture at a reduced cost. A PCT International Patent Application No. PCT/IB2016/051165 has been filed for this technology.PACS number(s): 87.57.C, 87.59.‐e
Production and quality control 177Lu (NCA)—DOTMP as a potential agent for bone pain palliation
Authors: Salek Nafise , Shamsaei Mojtaba , Maragheh Mohammad Ghannadi , Arani Simindokht Shirvani , Samani Ali Bahrami 
Published: February 2017

Skeletal uptake of radiolabeled‐1, 4, 7, 10‐tetraazacyclododecane‐1, 4, 7, 10‐tetramethylene phosphoric acid (e.g., 177Lu‐DOTMP) complex, is used for bone pain palliation. The moderate energy of β‐emitting has been considered as a potential radionuclide for development of the bone‐seeking radiopharmaceutical. Since the specific activity of the radiolabeled carrier molecules should be high, the “no‐carrier‐added radionuclides” have significant roles in nuclear medicine. Many researchers illustrated no‐carrier‐added 177Lu production; among these separation techniques such as ion exchange chromatography, reversed phase ion‐pair, and electrochemical method, extraction chromatography has been considered more capable than other methods. In order to optimize the conditions, some effective factors on separation of Lu/Yb were investigated by EXC. The NCA 177Lu, produced by this method, was mixed with of DOTMP solution (20 mg in 1 mL of 0.5 M NaHCO3, ) and incubated under stirring at room temperature for 45 min. Radiochemical purity of the 177Lu‐DOTMP complex was determined using radio‐thin‐layer chromatography (RTLC) method. The complex was injected to wild‐type rats and biodistribution was then studied for seven days. The NCA 177Lu was produced with specific activity of 48 Ci/mg and with a radinuclidic purity of 99.99% through irradiation of enriched 176Yb target (1 mg) in a thermal neutron flux of for 14 days. 177Lu‐DOTMP was obtained with high radiochemical purities () under optimized reaction conditions. The radiolabeled complex exhibited excellent stability at room temperature. Biodistribution of the radiolabeled complex studies in rats showed favorable selective skeletal uptake with rapid clearance from blood along with insignificant accumulation within the other nontargeted organs.PACS number(s): 87.57.un, 87.57.uq
A comparison of methods for monitoring photon beam energy constancy
Authors: Gao Song , Balter Peter A. , Rose Mark , Simon William E. 
Published: February 2017

In extension of a previous study, we compared several photon beam energy metrics to determine which was the most sensitive to energy change; in addition to those, we accounted for both the sensitivity of each metric and the uncertainty in determining that metric for both traditional flattening filter (FF) beams (4, 6, 8, and 10 MV) and for flattening filter‐free (FFF) beams (6 and 10 MV) on a Varian TrueBeam. We examined changes in these energy metrics when photon energies were changed to and from their nominal energies: 1) an attenuation‐based metric (the percent depth dose at 10 cm depth, PDD(10)) and, 2) profile‐based metrics, including flatness (Flat) and off‐axis ratios (OARs) measured on the orthogonal axes or on the diagonals (diagonal normalized flatness, ). Profile‐based metrics were measured near and also near 10 cm depth in water (using a 3D scanner) and with ionization chamber array (ICA). PDD(10) was measured only in water. Changes in PDD, OAR, and were nearly linear to the changes in the bend magnet current (BMI) over the range from to +10% for both FF and FFF beams: a change in energy resulted in a change in PDD(10) for both FF and FFF beams, and changes in OAR and were for FF beams and for FFF beams. The uncertainty in determining PDD(10) was estimated to be 0.15% and that for OAR and about 0.07%. This resulted in minimally detectable changes in energy of 2.5% for PDD(10) and 0.5% for OAR and . We found that the OAR‐ or FDN‐ based metrics were the best for detecting energy changes for both FF and FFF beams. The ability of the OAR‐based metrics determined with a water scanner to detect energy changes was equivalent to that using an ionization chamber array. We recommend that OAR be measured either on the orthogonal axes or the diagonals, using an ionization chamber array near the depth of maximum dose, as a sensitive and efficient way to confirm stability of photon beam energy.PACS number(s): 87.55.Qr, 87.56.Fc
Establishment of an AUC
0–24
Threshold for Nephrotoxicity Is a Step towards Individualized Vancomycin Dosing for Methicillin-Resistant Staphylococcus aureus Bacteremia
Authors: Chavada R. , Ghosh N. , Sandaradura I. , Maley M. , Van Hal S. J. 
Published: February 2017

ABSTRACT

Unlike vancomycin trough concentrations, data on the utility of vancomycin pharmacokinetic (PK) parameters, namely, the area under the concentration-time curve from 0 to 24 h (AUC
0–24
), in predicting acute kidney injury (AKI) are limited. Our aim was to investigate this relationship in patients receiving vancomycin therapy for methicillin-resistant
Staphylococcus aureus
bacteremia (MRSA-B). A single-center retrospective observational cohort study involving 127 consecutive MRSA-B patients was conducted to examine the incidence of AKI (defined as serum creatinine of ≥0.5 mg/liter and a 50% increase from baseline) and vancomycin exposure parameters associated with nephrotoxicity. Bayesian estimation was used to predict individual vancomycin AUC
0–24
. All patients received vancomycin monotherapy for a minimum of 14 days following the diagnosis of MRSA-B. AKI was observed in 15.7% of patients (20/127). Clinical characteristics were similar between patients with and without AKI. At steady state, higher vancomycin trough concentrations were associated with AKI (17.2 mg/liter versus 13.1 mg/liter;
P
= 0.003). A vancomycin AUC
0–24
threshold for AKI of >563 mg · h/liter was detected by classification and regression tree (CART) analysis; patients with exposures above this threshold were significantly more likely to experience AKI than patients with lower vancomycin exposures (40% [8/20] versus 11.2% [12/107];
P
= 0.002). This parameter remained an independent predictor of AKI on multivariate logistic regression (odds ratio [OR], 5.07; 95% confidence interval [CI], 1.57 to 16.29;
P
= 0.006) and was a better predictor of nephrotoxicity than vancomycin trough concentrations. Overall, AKI is associated with higher vancomycin exposure as measured by AUC
0–24
. These results suggest that individualized patient dosing may be possible with dose modifications directed toward established pharmacodynamic targets while balancing AKI risks.
Adjuvant Antibiotic Activity of Acidic Sophorolipids with Potential for Facilitating Wound Healing
Authors: Lydon Helen L. , Baccile Niki , Callaghan Breedge , Marchant Roger , Mitchell Christopher A. , Banat Ibrahim M. 
Published: February 2017

ABSTRACT

The sophorolipid class of biosurfactants is finding increasing use in personal care as well as pharmaceutical products and has the potential to disrupt biofilm formation and inhibit the growth of a variety of clinically relevant organisms. In order to investigate potential biomedical applications of sophorolipids derived from nonpathogenic organisms, we fractionated and purified glycolipid biosurfactant sophorolipids produced by the yeast
Starmerella bombicola
, which yielded nonacetylated acidic C
18:1
congeners that were essentially free from other contaminants (>95% purity). These acidic sophorolipids have antimicrobial activities against the nosocomial infective agents
Enterococcus faecalis
and
Pseudomonas aeruginosa
, with significant reductions in CFU at concentrations of as low as 5 mg ml
−1
. In addition, the sophorolipid showed similar effects against the same two bacterial strains when combined with kanamycin or cefotaxime. As a potential use of these sophorolipids is as a component of topically applied creams for the treatment of wound infections, it is clear that they must have no demonstrable adverse effect on wound healing. To assess this, we evaluated mammalian cell toxicity
in vitro
using viability tests, which revealed no adverse effect on either endothelial or keratinocyte-derived cell lines with sophorolipid concentrations of < 0.5 mg ml
−1
. In addition,
in vivo
experiments using a mouse skin wounding assay revealed that the time course of healing wounds was unaffected by the application of sophorolipid-containing creams, and histological examination of regenerated skin tissue confirmed that the healing process was similar to that observed for control animals, with no evidence of inflammation. These results are consistent with the suggestion that acidic sophorolipids can be used as a component of antimicrobial creams to reduce the risk of wound infection during healing.