318 research outputs found
Internal dose escalation is associated with increased local control for non-small cell lung cancer (NSCLC) brain metastases treated with stereotactic radiosurgery (SRS)
Perilesional edema in radiation necrosis reflects axonal degeneration
BACKGROUND: Recently, we characterized a Gamma Knife® radiation necrosis mouse model with various magnetic resonance imaging (MRI) protocols to identify biomarkers useful in differentiation from tumors. Though the irradiation was focal to one hemisphere, a contralateral injury was observed that appeared to be localized in the white matter only. Interestingly, this injury was identifiable in T2-weighted images, apparent diffusion coefficient (ADC), and magnetization transfer ratio (MTR) maps, but not on post-contrast T1-weighted images. This observation of edema independent of vascular changes is akin to the perilesional edema seen in clinical radiation necrosis. FINDINGS: The pathology underlying the observed white-matter MRI changes was explored by performing immunohistochemistry for healthy axons and myelin. The presence of both healthy axons and myelin was reduced in the contralateral white-matter lesion. CONCLUSIONS: Based on our immunohistochemical findings, the contralateral white-matter injury is most likely due to axonal degeneration
A Measurement of Parity-Violating Neutron Transmission in Xenon
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Distant intracranial failure in melanoma brain metastases treated with stereotactic radiosurgery in the era of immunotherapy and targeted agents
Characterization and validation of an intra-fraction motion management system for masked-based radiosurgery
Distinguishing tumor admixed in a radiation necrosis (RN) background: 1H and 2H MR with a novel mouse brain-tumor/RN model
PURPOSE: Distinguishing radiation necrosis (RN) from recurrent tumor remains a vexing clinical problem with important health-care consequences for neuro-oncology patients. Here, mouse models of pure tumor, pure RN, and admixed RN/tumor are employed to evaluate hydrogen (
MATERIALS AND METHODS: A pipeline of common quantitative
RESULTS: Differences in quantitative
CONCLUSIONS: These findings, employing a pipeline of quantitativ
A feasibility study to evaluate early treatment response of brain metastases one week after stereotactic radiosurgery using perfusion weighted imaging
BACKGROUND: To explore if early perfusion-weighted magnetic resonance imaging (PWI) may be a promising imaging biomarker to predict local recurrence (LR) of brain metastases after stereotactic radiosurgery (SRS).
METHODS: This is a prospective pilot study of adult brain metastasis patients who were treated with SRS and imaged with PWI before and 1 week later. Relative cerebral blood volume (rCBV) parameter maps were calculated by normalizing to the mean value of the contralateral white matter on PWI. Cox regression was conducted to explore factors associated with time to LR, with Bonferroni adjusted p\u3c0.0006 for multiple testing correction. LR rates were estimated with the Kaplan-Meier method and compared using the log-rank test.
RESULTS: Twenty-three patients were enrolled from 2013 through 2016, with 22 evaluable lesions from 16 patients. After a median follow-up of 13.1 months (range: 3.0-53.7), 5 lesions (21%) developed LR after a median of 3.4 months (range: 2.3-5.7). On univariable analysis, larger tumor volume (HR 1.48, 95% CI 1.02-2.15, p = 0.04), lower SRS dose (HR 0.45, 95% CI 0.21-0.97, p = 0.04), and higher rCBV at week 1 (HR 1.07, 95% CI 1.003-1.14, p = 0.04) had borderline association with shorter time to LR. Tumors \u3e2.0cm3 had significantly higher LR than if ≤2.0cm3: 54% vs 0% at 1 year, respectively, p = 0.008. A future study to confirm the association of early PWI and LR of the high-risk cohort of lesions \u3e2.0cm3 is estimated to require 258 patients.
CONCLUSIONS: PWI at week 1 after SRS may have borderline association with LR. Tumors \u3c2.0cm3 have low risk of LR after SRS and may be low-yield for predictive biomarker studies. Information regarding sample size and potential challenges for future imaging biomarker studies may be gleaned from this pilot study
Neutron cross sections for He-3 at epithermal energies
High accuracy, absolute measurements of the neutron total cross section for He-3 are reported for incident neutron energies 0.1-400 eV. The measurements were performed at the LANSCE short-pulse neutron spallation source. Using the previously determined cross section for neutron elastic scattering, 3.367+/-0.019 b, we extract a new value for the energy dependence of the He-3(n,p)He-3 reaction cross section, sigma(np)=(849.77+/-0.14+/-1.02)E-1/2-(1.253+/-0.00+/-(+0.008)(-0.049))b, where the neutron energy is expressed in eV. The first uncertainty is statistical, the second systematic
Observation of a large parity nonconserving analyzing power in Xe
A large parity nonconserving longitudinal analyzing power was discovered in polarized-neutron transmission through Xe. An analyzing power of 4.3±0.2% was observed in a p-wave resonance at En=3.2 eV. The measurement was performed with a liquid Xe target of natural isotopic abundance that was placed in the polarized epithermal neutron beam, flight path 2, at the Manuel Lujan Neutron Science Center. This apparatus was constructed by the TRIPLE Collaboration, and has been used for studies of parity symmetry in compound nuclear resonances. Part of the motivation of the experiment was to discover a nucleus appropriate for a sensitive test of time-reversal invariance in polarized-neutron transmission. The large analyzing power of the observed resonance may make it possible to design a test of time reversal invariance using a polarized-Xe target
An international survey of speciality training in oral and maxillofacial pathology
BACKGROUND: Speciality training in oral and maxillofacial
pathology (OMFP) across the world would be aided
by guidance on a generic curriculum and training
programme that all countries could use as a template.
In order to facilitate this, we require an understanding of
the various forms which OMFP training takes across the
world.
METHODS: We sent a questionnaire to OMF pathologists
in the 42 countries represented in the IAOP
membership, via their Regional Councillor. The questionnaire
included detailed demographics, entry requirements,
specialty training program and facilities/
resources.
RESULTS: Replies were received from 22/42 countries
(52%). OMFP is a dental/dental and medical speciality in
72%, and in 92% of those, this is recognised by a licensing
board. Training was undertaken in an academic environment
in 85% (with many offering a further academic
qualification) and the median length of training was
4 years. General/anatomical pathology training is mandated
in 85% of programs and a common core of general
sub-specialities was identified. An end of training assessment
was conducted in 80% of programs with most
including written, practical and oral elements. Training
program directors and educational supervisors were in
place in 12/16 programs and, in most, Quality Assurance
of training was externally monitored. In only one country
was the number of trainees linked to workforce planning.
CONCLUSIONS: Training in OMFP varies across the
world. However, we feel there is sufficient commonality
for the development of an agreed indicative framework
on education and training in Oral and Maxillofacial
Pathology, perhaps under the auspices of the IAOP.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1600-0714hb201
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