bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spot scanning proton therapy minimizes neutron dose in the setting of radiation therapy administered during pregnancy
Authors: Wang Xin , Poenisch Falk , Sahoo Narayan , Zhu Ronald X. , Lii MingFwu , Gillin Michael T. , Li Jing , Grosshans David 
Published: February 2017

This is a real case study to minimize the neutron dose equivalent (H) to a fetus using spot scanning proton beams with favorable beam energies and angles. Minimum neutron dose exposure to the fetus was achieved with iterative planning under the guidance of neutron H measurement. Two highly conformal treatment plans, each with three spot scanning beams, were planned to treat a 25‐year‐old pregnant female with aggressive recurrent chordoma of the base of skull who elected not to proceed with termination. Each plan was scheduled for delivery every other day for robust target coverage. Neutron H to the fetus was measured using a REM500 neutron survey meter placed at the fetus position of a patient simulating phantom. 4.1 and 44.1 were measured for the two initial plans. A vertex beam with higher energy and the fetal position closer to its central axis was the cause for the plan that produced an order higher neutron H. Replacing the vertex beam with a lateral beam reduced neutron H to be comparable with the other plan. For a prescription of 70 Gy in 35 fractions, the total neutron H to the fetus was estimated to be 0.35 mSv based on final measurement in single fraction. In comparison, the passive scattering proton plan and photon plan had an estimation of 26 and 70 mSv, respectively, for this case. While radiation therapy in pregnant patients should be avoided if at all possible, our work demonstrated spot scanning beam limited the total neutron H to the fetus an order lower than the suggested 5 mSv regulation threshold. It is far superior than passive scattering beam and careful beam selection with lower energy and keeping fetus further away from beam axis are essential in minimizing the fetus neutron exposure.PACS number(s): 87.53.Bn, 87.55.D‐, 87.55.N‐
Dosimetric and volumetric changes in the rectum and bladder in patients receiving CBCT‐guided prostate IMRT: analysis based on daily CBCT dose calculation
Authors: Pearson David , Gill Sukhdeep K. , Campbell Nina , Reddy Krishna 
Published: February 2017

Delivered dose can be calculated by transferring the planned treatment beams onto the daily CBCT. Bladder and rectum volumetric doses were calculated and correlated to the daily bladder and rectum fullness. Patients for this study underwent hypofractionated prostate IMRT to 70 Gy in 28 fractions. Daily CBCT was utilized for image guidance. A clinically acceptable plan was created using a CTV‐to‐PTV uniform margin of 5 mm. Image fusion was performed to transfer the bladder and rectum contours onto each CBCT. Contours were then edited to match the anatomy of each CBCT. Using the daily treatment isocenter, the planned beams were transferred onto the CBCT and daily and cumulative DVHs calculated. For the results a total of 168 daily CBCTs were evaluated. The bladder was found to be smaller for 74.7% of the 168 daily CBCTs accessed in this study. This reduction in volume correlated to an increase in the cumulative bladder V70 Gy from 9.47% on the planning CT to 10.99% during treatment. V70Gy for the rectum was 7.27% on the planning CT, when all six patients were averaged, and increased to 11.56% on the average of all daily treatment CBCTs. Increases in volumetric rectum dose correlated with increases in rectal volume. For one patient, the rectum and bladder absolute V70 Gy, averaged over the course of treatment, increased by 295% and 61%, respectively. Larger variations in the daily bladder and rectal volume were observed and these correlated to large deviations from the volumetric dose received by these structures. In summary, bladder and rectum volume changes during treatment have an effect on the cumulative dose received by these organs. It was observed that the volumetric dose received by the bladder decreases as the volume of the bladder increases. The inverse was true for the rectum.PACS number(s): 87.55.dk‐, 87.57.Q‐
Dosimetric assessment of brass mesh bolus for postmastectomy photon radiotherapy
Authors: Manger Ryan , Paxton Adam , Cerviño Laura 
Published: February 2017

Brass mesh bolus has been shown to be an acceptable substitute for tissue‐equivalent bolus to increase superficial dose for chest wall tangent photon radiotherapy. This work investigated the increase in surface dose, the change in the dose at depth, and the safety implications of higher energy photon beams when using brass mesh bolus for postmastectomy chest wall radiotherapy. A photon tangent plan was delivered to a thorax phantom, and the superficial dose ranged from 40%–72% of prescription dose with no bolus. The surface dose increased to 75%–110% of prescription dose with brass mesh bolus and 85%–109% of prescription dose with tissue‐equivalent bolus. It was also found that the dose at depth when using brass mesh bolus is comparable to that measured with no bolus for en face and oblique incidence. Monte Carlo calculations were used to assess the photoneutron production from brass mesh bolus used with 15 MV and 24 MV photon beams. The effective dose from photoneutrons was approximated and found to be relatively small, yet not negligible. Activation products generated by these photoneutrons, the surface dose rate due to the activation products, and the half‐life of the activation products were also considered in this work. The authors conclude that brass mesh bolus is a reasonable alternative to tissue‐equivalent bolus, and it may be used with high‐energy beam; but one should be aware of the potential increased effective dose to staff and patients due to the activation products produced by photoneutrons.PACS number(s): 87.53.Kn, 87.55.K
Comparison of the low‐contrast detectability of two ultrasound systems using a grayscale phantom
Authors: Lorentsson Robert , Hosseini Nasser , Johansson Jan‐Olof , Rosenberg Wiebke , Stenborg Benny , Månsson Lars Gunnar , Båth Magnus 
Published: February 2017

The purpose of the present study was to use a commercially available grayscale phantom to compare two ultrasound systems regarding their ability to reproduce clinically relevant low‐contrast objects at different sizes and depths, taking into account human observer variability and other methodological issues related to observer performance studies. One high‐end and one general ultrasound scanner from the same manufacturer using the same probe were included. The study was intended to simulate the clinical situation where small low‐contrast objects are embedded in relatively homogeneous organs. Images containing 4 and 6.4 mm objects of four different contrasts were acquired from the grayscale phantom at different depths. Six observers participated in a 4‐alternative forced‐choice study based on 960 images. Case sample and human observer variabilities were taken into account using bootstrapping. At four of sixteen depth/size/contrast combinations, the visual performance of the high‐end scanner was significantly higher. Thus, it was possible to use a grayscale phantom to discriminate between the two evaluated ultrasound systems in terms of their ability to reproduce clinically relevant low‐contrast objects. However, the number of images and number of observers were larger than those usually used for constancy control.PACS number(s): 87.57.C‐, 87.63.dh
Investigation of dosimetric differences between the TMR 10 and convolution algorithm for Gamma Knife stereotactic radiosurgery
Authors: Rojas‐Villabona Alvaro , Kitchen Neil , Paddick Ian 
Published: February 2017

Since its inception, doses applied using Gamma Knife Radiosurgery (GKR) have been calculated using a simple TMR algorithm, which assumes the patient's head is of even density, the same as water. This results in a significant approximation of the dose delivered by the Gamma Knife. We investigated how GKR dose calculations varied when using a new convolution algorithm clinically available for GKR planning that takes into account density variations in the head compared with the established calculation algorithm. Fifty‐five patients undergoing GKR and harboring 85 lesions were voluntarily and prospectively enrolled into the study. Their clinical treatment plans were created and delivered using TMR 10, but were then recalculated using the density correction algorithm. Dosimetric differences between the planning algorithms were noted. Beam on time (BOT), which is directly proportional to dose, was the main value investigated. Changes of mean and maximum dose to organs at risk (OAR) were also assessed. Phantom studies were performed to investigate the effect of frame and pin materials on dose calculation using the convolution algorithm. Convolution yielded a mean increase in BOT of 7.4% (3.6%–11.6%). However, approximately 1.5% of this amount was due to the head contour being derived from the CT scans, as opposed to measurements using the Skull Scaling Instrument with TMR. Dose to the cochlea calculated with the convolution algorithm was approximately 7% lower than with the TMR 10 algorithm. No significant difference in relative dose distribution was noted and CT artifact typically caused by the stereotactic frame, glue embolization material or different fixation pin materials did not systematically affect convolution isodoses. Nonetheless, substantial error was introduced to the convolution calculation in one target located exactly in the area of major CT artifact caused by a fixation pin. Inhomogeneity correction using the convolution algorithm results in a considerable, but consistent, dose shift compared to the TMR 10 algorithm traditionally used for GKR. A reduction of the prescription dose may be necessary to obtain the same clinical effect with the convolution algorithm. Head shape definition using CT outlining can reduce treatment uncertainty from head shape approximations.PACS number(s): 87.53.‐j; 87.55.D; 87.55.kd
A dosimetric evaluation of knowledge‐based VMAT planning with simultaneous integrated boosting for rectal cancer patients
Authors: Wu Hao , Jiang Fan , Yue Haizhen , Li Sha , Zhang Yibao 
Published: February 2017

RapidPlan, a commercial knowledge‐based optimizer, has been tested on head and neck, lung, esophageal, breast, liver, and prostate cancer patients. To appraise its performance on VMAT planning with simultaneous integrated boosting (SIB) for rectal cancer, this study configured a DVH (dose‐volume histogram) estimation model consisting 80 best‐effort manual cases of this type. Using the model‐ generated objectives, the MLC (multileaf collimator) sequences of other 70 clinically approved plans were reoptimized, while the remaining parameters, such as field geometry and photon energy, were maintained. Dosimetric outcomes were assessed by comparing homogeneity index (HI), conformal index (CI), hot spots (volumes receiving over 107% of the prescribed dose, ), mean dose and dose to the 50% volume of femoral head ( and ), and urinary bladder ( and ), and the mean DVH plotting. Paired samples t‐test or Wilcoxon signed‐rank test suggested that comparable CI were achieved by RapidPlan ( for , and for PTV) and original plans ( for and for PTV), respectively . Slightly improved HI of planning target volume and PTV were observed in the RapidPlan cases ( for , and for PTV) than the original plans ( for and for PTV), . More cases with positive were found in the original (18 plans) than the RapidPlan group (none). RapidPlan significantly reduced the (by from to ), (by from to G), (by from to ), and (by from to ), respectively. The more concentrated distribution of RapidPlan data points indicated an enhanced consistency of plan quality.PACS number(s): 87.55.de; 87.55.dk
Validation of an improved helical diode array and dose reconstruction software using TG‐244 datasets and stringent dose comparison criteria
Authors: Ahmed Saeed , Nelms Benjamin , Kozelka Jakub , Zhang Geoffrey , Moros Eduardo , Feygelman Vladimir 
Published: February 2017

The original helical ArcCHECK (AC) diode array and associated software for 3D measurement‐guided dose reconstruction were characterized and validated; however, recent design changes to the AC required that the subject be revisited. The most important AC change starting in 2014 was a significant reduction in the overresponse of diodes to scattered radiation outside of the direct beam, accomplished by reducing the amount of high‐Z materials adjacent to the diodes. This change improved the diode measurement accuracy, but in the process invalidated the dose reconstruction models that were assembled based on measured data acquired with the older version of the AC. A correction mechanism was introduced in the reconstruction software (3DVH) to accommodate this and potential future design changes without requiring updating model parameters. For each permutation of AC serial number and beam model, the user can define in 3DVH a single correction factor which will be used to compensate for the difference in the out‐of‐field response between the new and original AC designs. The exact value can be determined by minimizing the dose‐difference with an ionization chamber or another independent dosimeter. A single value of 1.17, corresponding to the maximum measured out‐of‐field response difference between the new and old AC, provided satisfactory results for all studied energies (6X, 15X, and flattening filter‐free 10XFFF). A library of standard cases recommended by the AAPM TG‐244 Report was used for reconstructed dose verification. The overall difference between reconstructed dose and an ion chamber in a water‐equivalent phantom in the targets was (1 SD). The reconstructed dose on a homogeneous phantom was also compared to a biplanar diode dosimeter () using gamma analysis with cutoff criteria. The mean agreement rate was . For the plans common with the previous comparison, the mean agreement rate was , essentially unchanged. We conclude that the proposed software modification adequately addresses the change in the dosimeter response.PACS number(s): 87.55Qr
Dosimetric comparison of intensity‐modulated radiotherapy and volumetric‐modulated arc radiotherapy in patients with prostate cancer: a meta‐analysis
Authors: Ren Wenting , Sun Chao , Lu Ningning , Xu Yingjie , Han Fei , Ping Liu Yue , Dai Jianrong 
Published: February 2017

Intensity‐modulated radiotherapy (IMRT) and volumetric‐modulated arc therapy (VMAT) are two main radiotherapy techniques. The aim of this study is to explore which is the preferred technique in prostate treatment through the related publications and meta‐analysis. Two authors independently identified all relevant articles available regarding eligibility criteria on PubMed, Embase, and Cochrane Library databases until December 2015. Publication bias was evaluated with funnel plot, and statistical analyses were performed with Stata software. was thought statistically significant. Ten studies comprised a total of 110 patients; in total 110 IMRT plans and 110 VMAT plans that were included in this study. V40, V60, and V70 of rectum were significantly decreased in VMAT than in IMRT. However, V50 of rectum and V40, V50, V60, V70 of bladder had no statistical differences between IMRI and VMAT plans. Compared with IMRT, the treatment time and MUs of VMAT were significantly lower. VMAT protects rectum better than IMRT and improves the delivery efficiency. VMAT may be the preferred modality for treating prostate cancer.PACS number(s): 87.55. D‐
In Vitro
Selection of Meropenem Resistance among Ceftazidime-Avibactam-Resistant, Meropenem-Susceptible Klebsiella pneumoniae Isolates with Variant KPC-3 Carbapenemases
Authors: Shields Ryan K. , Nguyen M. Hong , Press Ellen G. , Chen Liang , Kreiswirth Barry N. , Clancy Cornelius J. 
Published: February 2017

ABSTRACT

Ceftazidime-avibactam resistance is mediated by
bla
KPC-3
mutations, which restore carbapenem susceptibility. We subjected
Klebsiella pneumoniae
isolates with different
bla
KPC-3
mutations (
n
= 5) or wild-type
bla
KPC-3
(
n
= 2) to serial passages with meropenem. The meropenem MIC against each isolate increased. Mutations in the
ompK36
porin gene evolved in 5 isolates. Among isolates with D179Y substitutions in KPC-3,
bla
KPC-3
mutations reverted to wild type, were replaced by new mutations, or were retained. Carbapenem treatment of ceftazidime-avibactam-resistant
K. pneumoniae
infections may select for carbapenem resistance.
GMP and IMP Are Competitive Inhibitors of CMY-10, an Extended-Spectrum Class C β-Lactamase
Authors: Na Jung-Hyun , An Young Jun , Cha Sun-Shin 
Published: February 2017

ABSTRACT

Nucleotides were effective in inhibiting the class C β-lactamase CMY-10. IMP was the most potent competitive inhibitor, with a

K
i

value of 16.2 μM. The crystal structure of CMY-10 complexed with GMP or IMP revealed that nucleotides fit into the R2 subsite of the active site with a unique vertical binding mode where the phosphate group at one terminus is deeply bound in the subsite and the base at the other terminus faces the solvent.
Molecular Epidemiology of Colistin-Resistant, Carbapenemase-Producing Klebsiella pneumoniae in Serbia from 2013 to 2016
Authors: Novović Katarina , Trudić Anika , Brkić Snežana , Vasiljević Zorica , Kojić Milan , Medić Deana , Ćirković Ivana , Jovčić Branko 
Published: February 2017

ABSTRACT

Twenty-seven colistin-resistant, carbapenemase-producing
Klebsiella pneumoniae
isolates were identified from hospitals in Serbia. All isolates were
bla
CTX-M-15
positive; ST101, ST888, ST437, ST336, and ST307 were
bla
OXA-48
positive; and ST340 was
bla
NDM-1
positive. ST307 had an insertion, and ST336 had a premature stop codon in the
mgrB
gene. Amino acid substitutions were detected in PmrAB of isolates ST101, ST888, ST336, and ST307. The
mcr-1
and
mcr-2
were not detected. An increase in
phoP
,
phoQ
, and
pmrK
gene transcription was detected for all sequence types.
A Farnesylated Coxiella burnetii Effector Forms a Multimeric Complex at the Mitochondrial Outer Membrane during Infection
Authors: Fielden Laura F. , Moffatt Jennifer H. , Kang Yilin , Baker Michael J. , Khoo Chen Ai , Roy Craig R. , Stojanovski Diana , Newton Hayley J. 
Published: February 2017

ABSTRACT

Coxiella burnetii
, the causative agent of Q fever, establishes a unique lysosome-derived intracellular niche termed the
Coxiella
-containing vacuole (CCV). The Dot/Icm-type IVB secretion system is essential for the biogenesis of the CCV and the intracellular replication of
Coxiella
. Effector proteins, translocated into the host cell through this apparatus, act to modulate host trafficking and signaling processes to facilitate CCV development. Here we investigated the role of CBU0077, a conserved
Coxiella
effector that had previously been observed to localize to lysosomal membranes. CBU0077 was dispensable for the intracellular replication of
Coxiella
in HeLa and THP-1 cells and did not appear to participate in CCV biogenesis. Intriguingly, native and epitope-tagged CBU0077 produced by
Coxiella
displayed specific punctate localization at host cell mitochondria. As such, we designated CBU0077 MceA (
m
itochondrial

C

oxiella
e
ffector protein
A
). Analysis of ectopically expressed MceA truncations revealed that the capacity to traffic to mitochondria is encoded within the first 84 amino acids of this protein. MceA is farnesylated by the host cell; however, this does not impact mitochondrial localization. Examination of mitochondria isolated from infected cells revealed that MceA is specifically integrated into the mitochondrial outer membrane and forms a complex of approximately 120 kDa. Engineering
Coxiella
to express either MceA tagged with 3×FLAG or MceA tagged with 2×hemagglutinin allowed us to perform immunoprecipitation experiments that showed that MceA forms a homo-oligomeric species at the mitochondrial outer membrane during infection. This research reveals that mitochondria are a bona fide target of
Coxiella
effectors and MceA is a complex-forming effector at the mitochondrial outer membrane during
Coxiella
infection.
Tail-Anchored Inner Membrane Protein ElaB Increases Resistance to Stress While Reducing Persistence in Escherichia coli
Authors: Guo Yunxue , Liu Xiaoxiao , Li Baiyuan , Yao Jianyun , Wood Thomas K. , Wang Xiaoxue 
Published: February 2017

ABSTRACT

Host-associated bacteria, such as
Escherichia coli
, often encounter various host-related stresses, such as nutritional deprivation, oxidative stress, and temperature shifts. There is growing interest in searching for small endogenous proteins that mediate stress responses. Here, we characterized the small C-tail-anchored inner membrane protein ElaB in
E. coli
. ElaB belongs to a class of tail-anchored inner membrane proteins with a C-terminal transmembrane domain but lacking an N-terminal signal sequence for membrane targeting. Proteins from this family have been shown to play vital roles, such as in membrane trafficking and apoptosis, in eukaryotes; however, their role in prokaryotes is largely unexplored. Here, we found that the transcription of
elaB
is induced in the stationary phase in
E. coli
and stationary-phase sigma factor RpoS regulates
elaB
transcription by binding to the promoter of
elaB
. Moreover, ElaB protects cells against oxidative stress and heat shock stress. However, unlike membrane peptide toxins TisB and GhoT, ElaB does not lead to cell death, and the deletion of
elaB
greatly increases persister cell formation. Therefore, we demonstrate that disruption of C-tail-anchored inner membrane proteins can reduce stress resistance; it can also lead to deleterious effects, such as increased persistence, in
E. coli
.

IMPORTANCE
Escherichia coli
synthesizes dozens of poorly understood small membrane proteins containing a predicted transmembrane domain. In this study, we characterized the function of the C-tail-anchored inner membrane protein ElaB in
E. coli
. ElaB increases resistance to oxidative stress and heat stress, while inactivation of ElaB leads to high persister cell formation. We also demonstrated that the transcription of
elaB
is under the direct regulation of stationary-phase sigma factor RpoS. Thus, our study reveals that small inner membrane proteins may have important cellular roles during the stress response.