Helical tomotherapy has been developed at the University of Wisconsin, and 'Hi-Art II' clinical machines are now commercially manufactured. At the core of each machine lies a ring-gantry-mounted short linear accelerator which generates x-rays that are collimated into a fan beam of intensity-modulated radiation by a binary multileaf, the modulation being variable with gantry angle. Patients are treated lying on a couch which is translated continuously through the bore of the machine as the gantry rotates. Highly conformal dose-distributions can be delivered using this technique, which is the therapy equivalent of spiral computed tomography. The approach requires synchrony of gantry rotation, couch translation, accelerator pulsing and the opening and closing of the leaves of the binary multileaf collimator used to modulate the radiation beam. In the course of clinically implementing helical tomotherapy, we have developed a quality assurance (QA) system for our machine. The system is analogous to that recommended for conventional clinical linear accelerator QA by AAPM Task Group 40 but contains some novel components, reflecting differences between the Hi-Art devices and conventional clinical accelerators. Here the design and dosimetric characteristics of Hi-Art machines are summarized and the QA system is set out along with experimental details of its implementation. Connections between this machine-based QA work, pre-treatment patient-specific delivery QA and fraction-by-fraction dose verification are discussed. 相似文献
Background: To evaluate if TNF inhibitor serum drug levels (DL) or anti-drug antibodies (ADAb) can predict successful dose reduction (in patients with high DL) or discontinuation (in patients with no/low DL or ADAb) in rheumatoid arthritis (RA) patients.
Research design and methods: RA patients that were using adalimumab (n = 42), etanercept (n = 76) or infliximab (n = 51) and were doing well, were tapered until discontinuation or flare (1–1.5 year follow up). Random timed DL for adalimumab and etanercept and trough DL for infliximab were measured before dose reduction: Receiver-Operator-Curves (ROC) analyses with optimal cut-off DL were determined.
Results: No predictive value of adalimumab and infliximab DL for all outcomes were found, except for an inverse association of lower etanercept DL and higher chance for successful dose reduction (Area Under the Curve (AUC) 0.36, 95% CI 0.23–0.49; cut-off <2.6 mg/l). In sub analyses, higher adalimumab trough DL predicted successful dose reduction (AUC 0.86, 0.58–1.00; cut-off >7.8). ADAb were infrequent and not predictive of successful discontinuation.
Conclusions: No predictive value of baseline adalimumab, etanercept and infliximab DL or ADAb for successful dose reduction or discontinuation in RA was found in this context, with the possible exception of high adalimumab trough levels for successful dose reduction. 相似文献
The Film Digital Radiography System (FilmDRS) is a device with a laser optical film digitizer, 2,000 X 2,000 X 12-bit memory, and a 1,000-line video display. To evaluate the adequacy of this device for general radiography of the chest, four readers independently analyzed both radiographs and the corresponding video display of the digitized chest images of 150 patients, consisting of 100 images of abnormalities and 50 normal images. The overall results indicate equal sensitivity for the two systems. The FilmDRS, with interactive windowing, proved superior in the detection of hilar and mediastinal disease. X-ray film was superior in allowing detection of hyperlucent states. There was equivalent sensitivity for other disease categories. Superior specificity was achieved with conventional radiographs. 相似文献
The systemic administration of IFN-alpha/beta was previously found to
suppress inflammation in rats with experimental autoimmune uveoretinitis
(EAU); however, an effect on the systemic immune response was not
identified. In order to investigate an immunological basis for suppression
at the intraocular level, rats immunized with interphotoreceptor
retinoid-binding protein (IRBP) were administered daily intramuscular
injections of 10(5) IU IFN-alpha/beta and cytokines were measured by ELISA
in intraocular extracts prepared by ultrasonification at various timepoints
throughout the course of EAU. In control EAU, intraocular concentrations of
IFN-gamma were found to be non-detectable on day 8 before the onset of
inflammation, significantly elevated on day 12 at peak inflammation
(182+/-106 pg/ml), then non-detectable again on day 16 after inflammation
had begun to subside. In contrast, intraocular IFN-gamma in IFN-alpha/beta-
treated rats remained non-detectable or low at all timepoints. Measurement
of intraocular IL-2 revealed no difference between the two groups of rats.
Intraocular IL-4 concentrations were elevated in rats treated with
IFN-alpha/beta, although this cytokine was also detected in the same range
in controls as well as normal rats. Finally, intraocular IL-10 was
non-detectable on day 8, significantly elevated at peak inflammation on day
12 (588+/-139 pg/ml), then decreased to low levels on day 16 in control EAU
rats, while remaining non-detectable or low in IFN-alpha/beta-treated rats.
These results suggest that acute inflammation in IRBP-induced EAU in rats
involves both IFN-gamma and IL- 10 at the local intraocular level, and that
systemic administration of IFN-alpha/beta inhibits EAU via a mechanism that
involves suppression of both cytokines.
相似文献
Summary— In order to test whether the β-adrenoceptor activity in rheumatic heart valvular disease depends on the ventricular load conditions, we determined their density and binding affinity to [125I]-iodocyanopindolol in lymphocytes, as well as plasma catecholamine and cAMP levels in 69 patients with regurgitant and stenotic lesions of the aortic and mitral valves. The patients were classified as having left ventricular pressure overload (LVP), left ventricular volume overload (LVV), mixed lesions (MOL) or right ventricular pressure overload (RVP). The β-adrenoceptor activity was determined by radioligand binding methods, catecholamines by high performance liquid chromatography using an electrochemical detector and cAMP by radioimmunoassay. The mean β-adrenoceptor density (Bmax) of the control group was 60.1 ± 9.5 /mol ( n = 29) per 106 lymphocytes. In the study population, the density was decreased by 83% in LVP, 78% in LVV, 87% in MOL and 86% in RVP. Plasma norepinephrine was elevated by 89% in LVP and 60% in MOL, epinephrine by 43% in LVP, 50% in VOL, 115% in MOL and 20% in RVP, while dopamine was not significantly changed, and cAMP was slightly elevated in all four groups. Screening for activating mutational changes in the Gsα-protein gave negative results, possibly dissociating the elevation in plasma cAMP from stimulatory effects of such abnormalities in the Gs-protein signaling. These results show a significant attenuation in lymphocyte β-adrenoceptor density of patients with rheumatic heart valvular disease, irrespective of the type of the prevailing ventricular load conditions. The reduction in receptor density is accompanied by a significant increase in plasma norepinephrine levels in patients with a left ventricular pressure overload and epinephrine in those with volume overload. 相似文献
A mixed B-cell type centroblastic lymphoma with extraordinarily many histiocytes in a 68-year-old man is reported. Multiple skin tumours were the only clinical manifestation during the first 5 months. The disease then progressed to the lymph nodes, spleen, and parenchymal organs, but the bone marrow remained unaffected until death, 11 months after the onset of signs. C3d receptors were the only surface markers of the centroblasts. The histiocytes were normal with respect to morphology, muramidase staining, and Fc and C3b receptors. This highly unusual spread from skin to lymphoid and parenchymal organs is discussed in the light of lymphoid cell kinetics. 相似文献