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J Conway

Publications and source records attributed to J Conway.

At least 19 recordsLinked to original sources
PubMed2006

Optimizing localization accuracy in head and neck, and brain radiotherapy.

The purpose of this study was to investigate the impact on localization of utilizing contrast-enhanced CT scans and the formal input of a radiologist in the planning process. 25 head and neck/brain patients had pre- and post-contrast CT scans in the treatment position. Radiotherapy treatment was planned on the unenhanced CT images as per standard practice. Retrospectively, their scans (unenhanced and enhanced) were re-contoured by two oncologists and a radiologist. These new contours were compared with the original unenhanced treatment contours and differences in contour volume, geographical isocentre position and tolerance coverage of the associated planning target volumes (PTVs) were evaluated using the original plans. The use of contrast enhanced CT data during localization by the oncologist shows little change in gross tumour volumes (GTVs) or PTVs, geographical position or tolerance coverage for the targets in the brain studied here. Larger changes in mean volume are seen for the head and neck cases alone. Changes are greater and statistically significant (p < 0.05, Wilcoxon signed rank test) for localization by the radiologist. Furthermore, when comparing the original PTV marked by the oncologist with a new PTV re-contoured by the oncologist, but based on a GTV marked-up by the radiologist, again statistically significant (p < 0.01) changes in percentage volume are noted. Intraoperator precision is good, percentage volume differences being of the order 3-6%. PTVs also show improved standard deviations compared with GTVs. Geographic shifts are generally within our departmental tolerance levels for daily patient setup. Comparing precision of unenhanced data with enhanced, mean percentage volume changes are smaller, but not statistically significant. The use of enhanced scan data for localization has little effect on size, geographical position or tolerance coverage of PTVs marked up by the oncologists in this study. However, more important is the input from a radiologist. Statistically significant differences due to mark-up on enhanced scans by the radiologist are shown. Furthermore, significant differences are also seen between PTVs based on oncologist-generated GTVs, and those based on radiologist-generated GTVs.

Brain Neoplasms↗
PubMed2006

Inhaled heparin in cystic fibrosis.

Cystic fibrosis (CF) is characterised by inspissated airway secretions and chronic endobronchial infection associated with exuberant neutrophilic inflammation. Unfractionated heparin may be mucolytic and has demonstrated a number of anti-inflammatory properties; however, further safety data are needed in these subjects who are at risk of airway bleeding. The current study aimed to assess the medium-term safety and tolerability of moderately high-dose inhaled heparin in CF adults and to explore possible in vivo mucolytic and anti-inflammatory outcomes. A randomised, double-blind, placebo-controlled crossover study of twice daily inhalation of 50,000 IU of heparin for 2 weeks was undertaken in CF adults, with a 1-week washout period. Eighteen subjects were randomised and 14 (mean+/-sd age 23+/-7.8 yrs and percentage-predicted forced expiratory volume in one second 52.1+/-15.56%) completed the study protocol. Heparin neither affected blood coagulation parameters nor resulted in any increase in adverse events. Heparin inhalation had no significant effect upon forced expiratory volume in one second, symptoms of sputum clearance or sputum inflammatory markers. The current pilot study demonstrated no evidence of improved sputum clearance with 50,000 IU of inhaled heparin given twice daily to adult cystic fibrosis subjects. However, inhaled heparin was safe and the future evaluation of larger doses over a longer period may be warranted.

Administration, Inhalation↗
PubMed2005

Search for Higgs bosons decaying into bb and produced in association with a vector boson in pp collisions at square root of s = 1.8 TeV.

We present a new search for H0V production, where H0 is a scalar Higgs boson decaying into bb with branching ratio beta, and V is a Z0 boson decaying into e+e-, mu+mu-, or nunu. This search is then combined with previous searches for H0V where V is a W+/- boson or a hadronically decaying Z0. The data sample consists of 106 +/- 4 pb(-1) of pp collisions at square root of s = 1.8 TeV accumulated by the Collider Detector at Fermilab. Observing no evidence of a signal, we set 95% Bayesian credibility level upper limits on sigma(pp --> H0V) x beta. For H0 masses of 90, 110, and 130 GeV/c2, the limits are 7.8, 7.2, and 6.6 pb, respectively.

Journal Article↗
PubMed2005

Measurement of charged-particle multiplicities in gluon and quark jets in pp collisions at square root of s = 1.8 TeV.

We report the first largely model independent measurement of charged particle multiplicities in quark and gluon jets, Nq and Ng, produced at the Fermilab Tevatron in pp collisions with a center-of-mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The measurements are made for jets with average energies of 41 and 53 GeV by counting charged particle tracks in cones with opening angles of theta(c) = 0.28, 0.36, and 0.47 rad around the jet axis. The corresponding jet hardness Q = Ejet theta c varies in the range from 12 to 25 GeV. At Q = 19.2 GeV, the ratio of multiplicities r = Ng/Nq is found to be 1.64+/-0.17, where statistical and systematic uncertainties are added in quadrature. The results are in agreement with resummed perturbative QCD calculations.

Journal Article↗
PubMed2005

Measurement of partial widths and search for direct CP violation in D0 meson decays to K-K+ and pi-pi+.

We present a measurement of relative partial widths and decay rate CP asymmetries in K-K+ and pi(-)pi(+) decays of D0 mesons produced in pp collisions at sqrt[s]=1.96 TeV. We use a sample of 2x10(5) D(*+)-->D0pi(+) (and charge conjugate) decays with the D0 decaying to K-pi(+), K-K+, and pi(-)pi(+), corresponding to 123 pb(-1) of data collected by the Collider Detector at Fermilab II experiment at the Fermilab Tevatron collider. No significant direct CP violation is observed. We measure Gamma(D0-->K-K+)/Gamma(D0-->K-pi(+))=0.0992+/-0.0011+/-0.0012, Gamma(D0-->pi(-)pi(+))/Gamma(D0-->K-pi(+))=0.035 94+/-0.000 54+/-0.000 40, A(CP)(K-K+)=(2.0+/-1.2+/-0.6)%, and A(CP)(pi(-)pi(+))=(1.0+/-1.3+/-0.6)%, where, in all cases, the first uncertainty is statistical and the second is systematic.

Journal Article↗
PubMed2005

First measurements of inclusive W and Z cross sections from run II of the fermilab tevatron collider.

We report the first measurements of inclusive W and Z cross sections times leptonic branching ratios for pp collisions at square root[s]=1.96 TeV, based on their decays to electrons and muons. The data correspond to an integrated luminosity of 72 pb(-1) recorded with the CDF detector at the Fermilab Tevatron. We test e-mu universality in W decays, and we measure the ratio of leptonic W and Z rates from which the leptonic branching fraction B(W-->lnu) can be extracted as well as an indirect value for the total width of the W and the Cabibbo-Kobayashi-Maskawa matrix element, |V(cs)|.

Journal Article↗
PubMed2005

The use of lung dose-volume histograms in predicting post-radiation pneumonitis after non-conventionally fractionated radiotherapy for thoracic carcinoma.

AIMS: To assess the use of lung dose-volume histogram (DVH) parameters (specifically V20Gy) in the prediction of radiation pneumonitis for non-conventional fraction sizes used in the treatment of lung cancer. MATERIALS AND METHODS: Patients requiring computed tomography planning for thoracic radiotherapy between January 1999 and January 2002 were identified. The patients receiving radical or high-dose palliative radiotherapy had DVH produced routinely during planning. These were retrospectively reviewed and the case notes accessed for additional pre-treatment parameters, demographics and evidence of radiation pneumonitis. The severity of the pneumonitis was then scored using Radiation Therapy Oncology Group criteria. Data were analysed using the SPSS computer program. RESULTS: One hundred and sixty consecutive patients were reviewed. Ninety patients received hypofractionated treatment (fraction size > 2.5 Gy) and 57 continuous hyperfractionated accelerated radiation therapy (CHART) (fraction size 1.5 Gy). Lung V20Gy values ranged from 3% to 53%, with a median value of 24%. Only six patients reported grade 2, and 16 patients grade 3 pneumonitis. Two patients developed fatal, grade 5 pneumonitis. No correlation between pneumonitis score and V20Gy or other possible predictive factors was found. CONCLUSION: The 15% grade 2-5 pneumonitis rate we document is at the lower end of the spectrum reported in other studies. This suggests that using published data on limiting V20Gy values to reduce the risk of radiation pneumonitis can be extrapolated to planning treatment with non-conventionally fractionated radiotherapy.

Aged↗
PubMed2004

Search for doubly charged Higgs bosons decaying to dileptons in pp collisions at square root of s=1.96 TeV.

We present the results of a search for doubly charged Higgs bosons (H+/-+/-) decaying to dileptons (ll(')) using approximately 240 pb(-1) of pp collision data collected by the CDF II experiment at the Fermilab Tevatron. In our search region, given by same-sign ll(') mass m(ll('))>80 GeV/c(2) (100 GeV/c(2) for ee channel), we observe no evidence for H+/-+/- production. We set limits on sigma(pp -->H++H---->l(+)l('+)l(-)l('-)) as a function of the mass of the H+/-+/- and the chirality of its couplings. Assuming exclusive same-sign dilepton decays, we derive lower mass limits on H(+/-+/-)(L) of 133, 136, and 115 GeV/c(2) in the ee, mumu, and emu channels, respectively, and a lower mass limit of 113 GeV/c(2) on H(+/-+/-)(R) in the mumu channel, all at the 95% confidence level.

Journal Article↗
PubMed2004

Inclusive double-pomeron exchange at the fermilab tevatron p p collider.

We report results from a study of events with a double-Pomeron exchange topology produced in p p collisions at sqrt[s]=1800 GeV. The events are characterized by a leading antiproton and a large rapidity gap on the outgoing proton side. We find that the differential production cross section agrees in shape with predictions based on Regge theory and factorization, and that the ratio of double-Pomeron exchange to single diffractive production rates is relatively unsuppressed as compared to the O(10) suppression factor previously measured in single diffractive production.

Journal Article↗
PubMed2004

Measurement of the tt production cross section in pp collisions at sqrt[s]=1.96 TeV using dilepton events.

We report a measurement of the tt production cross section using dilepton events with jets and missing transverse energy in pp collisions at a center-of-mass energy of 1.96 TeV. Using a 197+/-12 pb(-1) data sample recorded by the upgraded Collider Detector at Fermilab, we use two complementary techniques to select candidate events. We compare the number of observed events and selected kinematical distributions with the predictions of the standard model and find good agreement. The combined result of the two techniques yields a tt production cross section of 7.0(+2.4)(-2.1)(stat)+1.6-1.1(syst)+/-0.4(lum) pb.

Journal Article↗
PubMed2004

Inclusive search for anomalous production of high-pT like-sign lepton pairs in pp collisions at square root s = 1.8 TeV.

We report on a search for anomalous production of events with at least two charged, isolated, like-sign leptons, each with pT > 11 GeV/c using a 107 pb(-1) sample of 1.8 TeV pp collisions collected by the CDF detector. We define a signal region containing low background from standard model processes. To avoid bias, we fix the final cuts before examining the event yield in the signal region using control regions to test the Monte Carlo predictions. We observe no events in the signal region, consistent with an expectation of 0.63(+0.84)(-0.07) events. We present 95% confidence level limits on new physics processes in both a signature-based context as well as within a representative minimal supergravity (tanbeta = 3) model.

Journal Article↗
PubMed2004

Search for B0s-->micro+micro- and B0d-->micro+micro- decays in pp collisions at square root s = 1.96 TeV.

We report on a search for B(0)(s)-->micro(+)micro(-) and B(0)(d)-->micro(+)micro(-) decays in pp collisions at square root of s=1.96 TeV using 171 pb(-1) of data collected by the CDF II experiment at the Fermilab Tevatron Collider. The decay rates of these rare processes are sensitive to contributions from physics beyond the standard model. One event survives all our selection requirements, consistent with the background expectation. We derive branching ratio limits of B(B(0)(s)-->micro(+)micro(-))<5.8x10(-7) and B(B(0)(d)-->micro(+)micro(-))<1.5x10(-7) at 90% confidence level.

Journal Article↗
PubMed2004

Search for Kaluza-Klein graviton emission in pp collisions at square root[s] = 1.8 TeV using the missing energy signature.

We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 pb(-1) of ppmacr; collisions at sqrt[s]=1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a (3+1+n)-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for n=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.

Journal Article↗
PubMed2004

Search for pair production of scalar top quarks in R-parity violating decay modes in pp collisions at square root of s=1.8 TeV.

We present the results of a search for pair production of scalar top quarks (t(1)) in an R-parity violating supersymmetry scenario in 106 pb(-1) of pp collisions at square root of s=1.8 TeV collected by the Collider Detector at Fermilab. In this mode each t(1) decays into a tau lepton and a b quark. We search for events with two tau's, one decaying leptonically (e or mu) and one decaying hadronically, and two jets. No candidate events pass our final selection criteria. We set a 95% confidence level lower limit on the t(1) mass at 122 GeV/c(2) for Br(t(1)-->tau b)=1.

Journal Article↗
PubMed2003

Search for lepton flavor violating decays of a heavy neutral particle in p(-)p collisions at sqrt[s]=1.8 TeV.

We report on a search for a high mass, narrow width particle that decays directly to emu, etau, or microtau. We use approximately 110 pb(-1) of data collected with the Collider Detector at Fermilab from 1992 to 1995. No evidence of lepton flavor violating decays is found. Limits are set on the production and decay of sneutrinos with R-parity violating interactions.

Journal Article↗
PubMed2003

Central pseudorapidity gaps in events with a leading antiproton at the fermilab tevatron pp collider.

We report a measurement of the fraction of events with a large pseudorapidity gap deltaeta within the pseudorapidity region available to the proton dissociation products X in p+p-->p+X. For a final state p of fractional momentum loss xi(p) and 4-momentum transfer squared t(p) within 0.06 3 is found to be 0.246+/-0.001 (stat)+/-0.042 (syst) [0.184+/-0.001 (stat)+/-0.043 (syst)]. Our results are compared with gap fractions measured in minimum bias pp collisions and with theoretical expectations.

Journal Article↗
PubMed2003

Search for the supersymmetric partner of the top quark in dilepton events from pp collisions at square root of s=1.8 TeV.

We have searched for pair production of the supersymmetric partner of the top quark (stop) in 107 pb(-1) of pp collisions at square root of s=1.8 TeV collected by the Collider Detector at Fermilab (CDF). Each stop is assumed to decay into a lepton, bottom quark, and supersymmetric neutrino. Such a scenario would give rise to events with two leptons, two hadronic jets, and a substantial imbalance of transverse energy. No evidence of such a stop signal has been found. We exclude stop masses in the region (80</=m(t)</=135 GeV/c(2)) in the mass plane of stop versus sneutrino.

Journal Article↗