Large vapour cloud explosions, with particular reference to that at Buncefield

This paper first briefly surveys the energy releases in some major accidents. It then examines the analyses of the explosion at the Buncefield fuel storage site in the UK, one of the most intense accidental explosions in recent times. This followed the release of approximately 300 tonnes of winter-grade gasoline, when a 15 m high storage tank was overfilled for about 40 min before ignition of the resulting flammable mixture. The ensuing explosion was of a severity that had not been identified previously in a major hazard assessment of this type of facility. It was therefore imperative to investigate the event thoroughly and develop an understanding of the underlying mechanisms to inform future prevention, mitigation and land-use planning issues. The investigation of the incident was overseen by the Buncefield Major Incident Investigation Board. A separate Explosion Mechanism Advisory Group examined the evidence and reported on the severity of the explosion. It concluded that additional work was necessary and recommended that a two-stage project be initiated, phase 1 of which has been completed. The analyses of the damage and the derivation of explosion over-pressures are described. Possible explosion mechanisms and the evidence for them at Buncefield are discussed, in the light of other major incidents. Mechanisms that are reviewed include high-speed turbulent combustion, quasi-detonations, fully developed detonations, the generation of fireballs, flame instabilites, radiative heat transfer and aspects of two-phase burning. Of particular importance is the acceleration of turbulent flames along the line of trees and hedgerows. A number of conclusions are drawn and suggestions made for further research.

Hot electron measurements in ignition relevant Hohlraums on the National Ignition Facility

On the National Ignition Facility (NIF), hot electrons generated in laser heated Hohlraums are inferred from the >20 keV bremsstrahlung emission measured with the time integrated FFLEX broadband spectrometer. New high energy (>200 keV) time resolved channels were added to infer the generated >170 keV hot electrons that can cause ignition capsule preheat. First hot electron measurements in near ignition scaled Hohlraums heated by 96-192 NIF laser beams are presented.

Modeling of neutron induced backgrounds in x-ray framing cameras

Fast neutrons from inertial confinement fusion implosions pose a severe background to conventional multichannel plate (MCP)-based x-ray framing cameras for deuterium-tritium yields >10(13). Nuclear reactions of neutrons in photosensitive elements (charge coupled device or film) cause some of the image noise. In addition, inelastic neutron collisions in the detector and nearby components create a large gamma pulse. The background from the resulting secondary charged particles is twofold: (1) production of light through the Cherenkov effect in optical components and by excitation of the MCP phosphor and (2) direct excitation of the photosensitive elements. We give theoretical estimates of the various contributions to the overall noise and present mitigation strategies for operating in high yield environments.

Measuring symmetry of implosions in cryogenic Hohlraums at the NIF using gated x-ray detectors (invited)

Ignition of imploding inertial confinement capsules requires, among other things, controlling the symmetry with high accuracy and fidelity. We have used gated x-ray imaging, with 10 μm and 70 ps resolution, to detect the x-ray emission from the imploded core of symmetry capsules at the National Ignition Facility. The measurements are used to characterize the time dependent symmetry and the x-ray bang time of the implosion from two orthogonal directions. These measurements were one of the primary diagnostics used to tune the parameters of the laser and Hohlraum to vary the symmetry and x-ray bang time of the implosion of cryogenically cooled ignition scale deuterium/helium filled plastic capsules. Here, we will report on the successful measurements performed with up to 1.2 MJ of laser energy in a fully integrated cryogenics gas-filled ignition-scale Hohlraum and capsule illuminated with 192 smoothed laser beams. We will describe the technique, the accuracy of the technique, and the results of the variation in symmetry with tuning parameters, and explain how that set was used to predictably tune the implosion symmetry as the laser energy, the laser cone wavelength separation, and the Hohlraum size were increased to ignition scales. We will also describe how to apply that technique to cryogenically layered tritium-hydrogen-deuterium capsules.

Cellular Response of the Rabbit Eye to Primary Intravitreal Injection of Neisseria meningitidis

New Zealand White rabbits were injected intravitreally with approximately 2,500 viable or heat-killed meningococci. The rabbits were killed at intervals from 30 min to 14 days after injection. None of the rabbits produced detectable antibodies. Local antibody production by uveal tract, spleen, or preauricular lymph node cells was not demonstrated. Viable organisms were recovered from the vitreous at periods from 30 min to 48 hr after injection. Failure to recover viable organisms could be correlated with the appearance of large numbers of polymorphonuclear neutrophiles (PMN) throughout the vitreous. Animals injected with viable meningococci demonstrated a progressive inflammatory reaction characterized by an early accumulation of PMN in the vitreous, limbus, and conjunctiva. The cellular infiltrate gradually became mononuclear. By the 14th day postinjection only a few residual inflammatory cells remained at the limbus. This extensive cellular response was lacking in recipients of heat-killed organisms. The defense of the rabbit against intraocular introduction of meningococci therefore seems to be predominantly a cellular mechanism.

Effect of window level on target volume delineation in treatment planning

In radiotherapy the efficacy of medical imaging is central to the selection and delineation of target volume. Of note is that target volume is intended to be larger than tumour volume, including a geometric margin that accounts for the possible uncertainties in patient set-up. However this reduces potential tissue sparing, irradiating not only the target but also normal tissue. Additionally, features of the object that appear in the 2D image display may be influenced by the appropriate window level selection. This is especially critical for target volume delineation in radiotherapy. The present work seeks to assess the effect of window level selection on feature size in CT, MR and PET images, use being made of a NEMA body phantom and ProSoma 3D simulation software. In general, the window level produced discrepancies of up to +/-2 mm in all imaging modalities.

Maintenance sunitinib postchemotherapy (CT) in patients (pts) with advanced urothelial carcinoma (UC): A randomized placebo controlled phase II trial

5073

Background: Although response to CT is common in pts with advanced UC it is rarely durable. Sunitinib is an oral small molecule inhibitor of receptor tyrosine kinases regulating angiogenesis including VEGFR-1, -2, -3, and PDGFR-α, -β with demonstrated antitumor activity in a variety of solid tumors. Inhibition of angiogenesis following CT may delay disease progression. Therefore, we are evaluating maintenance sunitinib in a phase II study. Methods: Pts with advanced UC, > stable disease (SD) after 4–6 cycles of CT, a performance status (PS) 0–2, adequate organ function and < 42 days from last CT dose were randomized to sunitinib 50 mg or placebo; 4 weeks (wks) on 2 off in 6 wk cycles. Pts were stratified by response to CT. Disease was assessed every 12 wks. Pts were unblinded for progression or unacceptable adverse events (AEs), with placebo pts offered open label sunitinib. The primary end point is 6 month progression rate using a modified version of the randomized selection design (Simon 1985). 42 pts/arm are to be accrued to allow selection of the superior arm with 90% probability. Other endpoints include safety, response rate (RR), time to progression, median survival, RR to open label sunitinib and correlation of changes in serum VEGF and sVEGFR-2 levels with outcome. Results: To date, 28 pts have been registered and 26 have completed > 12 wks of therapy. Median age is 69 years (48–81) and PS is 1 (37% PS 0, 52% PS 1). 12% had a complete response (CR) to prior CT, 46% a partial response (PR) and 42% SD. 14 pts have progressed after a median of 2 cycles (range 1–12). 7 pts received open label sunitinib at progression, 1/7 remains on treatment. Median duration on open label therapy is 2.2 months (11 days-15 months). Best response to open label therapy to date is progressive disease (2 pts), SD (2 pts) for 24 wks, PR in 1 pt through 60 weeks and 2 pts have not reached first assessment. Grade 3 AEs on open label sunitinib included: bladder hemorrhage, increased creatinine, fatigue, thrombocytopenia and hand-and-foot syndrome. No grade 4 or 5 AEs were observed. Conclusions: Preliminary results indicate that maintenance sunitinib post CT is feasible in advanced UC pts and is associated with clinical activity. Supported by Pfizer.

[Table: see text]

Phase I study of vorinostat plus docetaxel in patients with solid tumor malignancies

2528

Background: Vorinostat is an inhibitor of histone deacetylase 6, which results in the acetylation of tubulin and the stabilization of microtubules. Since taxanes bind to stabilized microtubules, the administration of vorinostat followed by docetaxel, we hypothesized, should result in synergistic cytotoxicity. A phase I trial was conducted to determine the dose level of vorinostat plus docetaxel that would result in dose-limiting toxicity (DLT) in ≤ 30% of patients (pts). Methods: Eligible pts had castration-resistant prostate cancer (CRPC) or relapsed urothelial or non-small-cell lung cancer (NSCLC) after ≥1 prior chemotherapy regimen not containing docetaxel, a performance status of 0–2 and adequate organ function. Vorinostat was given orally for 14 days beginning on day 1 of a 21-day cycle. Docetaxel was given intravenously over 1 hour on day 4. The time-to-event continuous reassessment method guided dose escalation. Dose levels (DL) -1, 0, 1 and 2 corresponded to vorinostat 100, 100, 200 and 200 mg plus docetaxel 50, 60, 60, and 75 mg/m2, respectively. Blood was collected on days 1 and 4 of cycle 1 to measure drug levels by HPLC. Results: 12 pts were enrolled: median age 65 yrs (49–74); gender 9M:3F; 4 CRPC, 5 urothelial, 3 NSCLC. The median number of cycles was 2. 2 pts were treated at DL -1, 4 pts at DL 0, 5 pts at DL 1 and 1 pt at DL 2. 5 DLTs occurred in 5 pts: grade 4 neutropenic fever/sepsis (n = 2), anaphylactic reaction (n = 1), myocardial infarction (n = 1) and GI bleed (n = 1). Other toxicities included grade 4 neutropenia (n = 2), pulmonary embolus (n = 1) and GI bleed (n = 1). The estimated probability of DLT for DL -1 was .32 (90% posterior probability interval [PI], .11 to .53) for DL 0, .38 (90% PI, .16 to .58) and for DL 1, .43 (90% PI, .23 to .64). The trial was stopped due to excessive toxicity. No responses were noted. Conclusions: Combination vorinostat plus docetaxel was poorly tolerated with excessive DLTs requiring study termination. PK analysis will be presented. Supported in part by a grant from Merck & Co., Inc.

[Table: see text]

A preliminary analysis of LET effects in the dosimetry of proton beams using PRESAGE and optical CT

PRESAGE is a solid dosimeter based on a clear polyurethane matrix doped with radiochromic components (leuco dyes). On exposure to ionizing radiation a colour change is generated in the dosimeter, and hence an optical absorption or optical density change that can be read out by optical CT. The main focus of present investigations has been to investigate the possible LET dependence of PRESAGE to the dose deposited at the Bragg maxima using proton beam absorbed dose measurements, and the linearity of response of the dosimeter. Proton irradiations were performed using the proton beam facility at the Douglas Cyclotron, Clatterbridge Centre for Oncology (CCO) using a configuration that approximates the one routinely used in treatment of patients with ocular tumours. The samples were irradiated with both monoenergetic and modulated proton beams. Optical tomography measurements were carried out with our in-house CCD-based optical-CT system. Initial results for monoenergetic beams show that in PRESAGE the measured ratio of the Bragg peak dose to entrance dose is approximately 2:1 whereas the true value measured at CCO is approximately 5:1. For range-modulated proton beams, the absorbed dose close to the end of the proton range, i.e. at the Bragg peak, is underestimated by approximately 20% compared to the corresponding diode measurement. Further investigations are necessary to understand and quantify the effect of LET on PRESAGE, and to measure the uncertainties related to our optical CT.

Neoadjuvant docetaxel and capecitabine in patients (Pts) with high-risk prostate cancer (PCa): Final results of a phase II trial

5147

Background: Docetaxel is the most active cytotoxic agent in PCa. Pre-clinically docetaxel increases the expression of thymidine phosphorylase (TP), an enzyme responsible for activation of capecitabine to 5-fluorouracil. We assessed the activity and safety of neoadjuvant docetaxel and capecitabine (DC) in pts with high risk PCa. Methods: Non-metastatic PCa pts with clinical stage >T2, or PSA = 15 ng/ml or biopsy Gleason sum (GS) = 8 received 3–6 cycles of docetaxel (36 mg/m2 IV on days 1, 8, and 15) and capecitabine (1,250 mg/m2/day PO on days 5–18) q 28 days, followed by local therapy. The primary endpoint of this 2-stage phase II trial was rate of = 50% decline in PSA. Secondary endpoints included safety and correlative measures of treatment effect (qualitative changes in histology, tissue TP and survivin expression, and CK18Asp396 [apoptosis marker] in serum). Results: Fifteen pts were enrolled with median age of 58 years, median GS =8 and PSA of 23.2 ng/mL. Five pts met 1, 7 met 2, and 3 met 3 entry criteria. 14 pts completed 3 or more cycles of DC, with a median follow up of 17.5 months (9–34). Six of the 15 patients (40%) experienced a = 50% decline in PSA, which was below the 7 required for expansion of the study. Median testosterone did not change post therapy. Eleven pts underwent radical prostatectomy (RP), with no increase in surgical complications. Six pts had positive margins, and 2 had lymph node involvement. Of the 8 patients who underwent RP alone, 5 developed a biochemical recurrence in a median time of 11 months. Grade 3 or 4 toxicities were diarrhea(3), mucositis(2), hand foot syndrome(1) and neutropenia(2). Post versus pre therapy tissue had only mild chemotherapy-effects (4/7 samples), including focal clear cell changes, apoptosis/pyknosis, and necrosis. While there was no discernable pattern of increased TP expression, 4/7 specimens showed decreased survivin expression, suggesting a possible mechanism for chemotherapy-induced apoptosis. There was no correlation of PSA response and survivin expression and no increase in serum CK18Asp396. Conclusions: Docetaxel and capecitabine in the neoadjuvant setting is well tolerated, but results in modest pathologic and PSA responses. Supported by Sanofi- Aventis.

No significant financial relationships to disclose.

Suberoylanilide hydroxamic acid (vorinostat) post chemotherapy in hormone refractory prostate cancer (HRPC) patients (pts): A phase II trial by the Prostate Cancer Clinical Trials Consortium (NCI 6862)

5132

Background: Histone deacetylases (HDACs) are key regulators of histone acetylation status, which is critical to expression of genes implicated in the regulation of cell survival, proliferation, differentiation and apoptosis. Vorinostat is a potent oral HDAC inhibitor with anti-tumor activity in PC models and in phase I clinical trials. A phase II trial is assessing vorinostat in HRPC pts. Methods: Eligible pts had disease progression on 1 prior chemotherapy for HRPC, a PSA of ≥ 5ng/ml, and adequate organ function. Vorinostat was administered orally at 400 mg daily in 21-day cycles. Response was assessed every 12 weeks. The primary endpoint is proportion of pts without progression at 6 months by objective and biochemical measures. This study is designed to accrue 29 pts (80% power at the 5% significance level to distinguish between a rate of 10% vs 30%). If ≥ 7/29 pts are progression-free at 6 months, the drug will be recommended for further study. Secondary endpoints include safety, rate of PSA decline, objective response rate and overall survival. Correlative studies assessing the effect of vorinostat on serum levels of IL-6, soluble IL-6 receptor and gp130 levels were conducted. Results: To date 23/29 pts have been accrued. Median age is 68 years (range 54–77), 70% had performance status 1 and 78% are white. At registration disease progression was defined by: PSA in 83%, bone in 74% and soft tissue in 43%. Median number of cycles is 2 (range 1–6), 57% of pts required at least 1 dose reduction. At time of this report 39% of pts remain on therapy. 19 pts are toxicity evaluable. Most common treatment related adverse events (AEs) were: fatigue (74%), anorexia (63%), nausea (58%), diarrhea (32%), dehydration, taste alteration and vomiting (26% each). There was 1 grade (G) 4 thrombosis and 11 pts had G 3 AEs, the most common were: fatigue (32%) and nausea and anorexia (11% each). 3/9 response evaluable pts achieved stable disease. Conclusions: Vorinostat is feasible post chemotherapy in pts with HRPC, however it is associated with significant toxicities requiring dose reductions. Final efficacy, safety and correlative studies will be reported. Support: CTEP, N01-CM-62201, PC051375, PC 051382

No significant financial relationships to disclose.

Variant Creutzfeldt-Jakob disease: first two indigenous cases in Republic of Ireland. Case report and perspective

The first two cases of indigenous variant Creutzfeldt-Jakob disease (vCJD) in the Republic of Ireland are reported in two men, neither of whom had lived outside Ireland. Both diagnoses were made ante-mortem based on clinical presentation, brain imaging, positive 14-3-3 protein in one case, and tonsillar biopsy. We discuss some of the clinical aspects of vCJD and the significance of these cases in the Irish context.