The first atmospheric Cherenkov telescope of VERITAS (the Very Energetic Radiation Imaging Telescope Array System) has been in operation since February 2005. We present here a technical description of the instrument and a summary of its performance. The calibration methods are described, along with the results of Monte Carlo simulations of the telescope and comparisons between real and simulated data. The analysis of TeV γ-ray observations of the Crab Nebula, including the reconstructed energy spectrum, is shown to give results consistent with earlier measurements. The telescope is operating as expected and has met or exceeded all design specifications.

No abstract

In 1971, Cancer and Leukemia Group B (CALGB) mounted a study of acute lymphocytic leukemia (ALL) that compared the effects of the two steroid hormones dexamethasone and prednisone. Six-hundred-forty-six children and adolescents with ALL were randomized to receive either prednisone or dexamethasone as part of their remission induction therapy. The 493 evaluable patients who achieved complete remission received the same steroid as pulses throughout remission. Specific central nervous system (CNS) therapy was randomized to either six injections of intrathecal methotrexate (IT MTX) alone or to six injections of IT MTX with cranial radiation (2,400 cGy). Both cranial radiation and dexamethasone offered increased protection against CNS relapse as the first site of failure over IT MTX alone. There were 30 CNS relapses among 238 patients (12.6%) receiving cranial radiation plus IT MTX, whereas there were 70 CNS relapses among 225 (P less than 0.001) (22.5%) in those who received IT MTX alone. Similarly, there were 33 CNS relapses among 231 (14.3%) children treated with dexamethasone, whereas there were 67 CNS relapses among 262 (25.6%) treated with prednisone (P = 0.017). Both steroids appeared equal in protecting the bone marrow. Recent national studies have shown significant improvements in preventing CNS relapse over the results in the present report. However, this finding warrants further investigation and, with further documentation, could lead to the substitution of prednisone by dexamethasone to aid further in preventing CNS relapse. This may be particularly important in patients at higher risk for CNS relapse.

A comparison of the late effects on intellectual and neuropsychologic function of three different CNS "prophylaxis" regimens was conducted in 104 patients treated for childhood acute lymphocytic leukemia. Of the children studied, 33 were randomized to treatment with intrathecal (IT) methotrexate alone, 36 to IT methotrexate plus 2,400 rad cranial irradiation, and 35 to IT methotrexate plus intravenous intermediate dose methotrexate. All patients were in their first (complete) continuous remission, were a minimum of one year post-CNS prophylaxis and had no evidence of CNS disease at the time of evaluation. In contrast to the other two treatment groups, children whose CNS prophylaxis included cranial irradiation attained significantly lower mean Full Scale IQs (P less than .001), performed more poorly on the Wide Range Achievement Test, a measure of school abilities, and exhibited a greater number of difficulties on a variety of other neuropsychologic measures. The poorer performance of the irradiated group was independent of sex of the patient, time since treatment and age at diagnosis. These data suggest that the addition of 2,400 rad cranial irradiation to CNS prophylaxis in ALL puts these children at greater risk for mild global loss in intellectual and neuropsychologic ability.

A randomized trial of combined modality therapy employing combination chemotherapy (cyclophosphamide (CTX) and methotrexate (MTX), CTX, MTX and Vincristine (VCR) and CTX, VCR and high-dose MTX with citrovorum rescue) and radiation therapy was compared to cyclophosphamide and radiation therapy in 258 patients with pulmonary small cell carcinoma. Patients were also rendomized: 1) to determine the effects of prophylactic whole brain irradiation; and 2) to establish the effects of maintenance chemotherapy. Survival, frequency of response and site of relapse were different in patients with limited disease (LD) (disease confined to lung, mediastinum and supraclavicular lymph nodes) when compared with disease spread beyond these sites (extensive disease) (ED). No survival advantage was seen in LD when combination chemotherapy was employed, although the frequency of complete remission was greater with three drugs than with one or two drugs (40% vs. 32%). In ED frequency of response was greater for three drugs than for one and two drugs (60% vs. 40%), but there was no survival advantage. The median survival time for complete responders was similar for limited or extensive disease (12.1 months), but 23.8% were alive at 24 months with LD compared to none with ED. Maintenance chemotherapy significantly prolonged survival by 16.8 months with 33% alive at 24 months compared to 9% who were unmaintained. Prophylactic while brain irradiation prevented brain metastases with only 4% developing this complication as compared to 18% of control subjects, but did not influence survival.