The impact of the ClearRT™ upgrade on target motion tracking accuracy in Radixact® Synchrony® lung treatments.

Background: The objective was to investigate the change in segmentation error of Radixact® Synchrony® lung treatment after its kV imaging system was upgraded from Generation 1 to Generation 2 in the ClearRT™ installation. Materials and methods: Radixact® Lung Synchrony® plans were created for the Model 18023 Xsight® Lung Tracking "XLT" Phantom combined with different lung target inserts with densities of 0.280, 0.500, 0.943 and 1.093 g/cc. After Radixact® Synchrony® treatment delivery using the Generation 1 and Generation 2 kV systems according to each plan, the tracking performance of the two kV systems on each density insert was compared by calculating the root mean square (RMS) error (δRMS) between the Synchrony-predicted motion in the log file and the known phantom motion and by calculating δ95%, the maximum error within a 95% probability threshold. Results: The δRMS and δ95% of Radixact® Synchrony® treatment for Gen1 kV systems deteriorated as the density of the target insert decreased, from 1.673 ± 0.064 mm and 3.049 ± 0.089 mm, respectively, for the 1.093 g/cc insert to 8.355 ± 5.873 mm and 15.297 ± 10.470 mm, respectively, for the 0.280 g/cc insert. In contrast, no such trend was observed in the δRMS or δ95% of Synchrony® treatment using the Gen2 kV system. The δRMS and δ95%, respectively, fluctuated slightly from 1.586 to 1.687 mm and from 2.874 to 2.971 mm when different target inserts were tracked by the Gen2 kV system. Conclusion: With improved image contrast in kV radiographs, the Gen2 kV imaging system can enhance the ability to track targets accurately in Radixact® Lung Synchrony® treatment and reduce the segmentation error. Our study showed that lung targets with density values as low as 0.280 cc/g could be tracked correctly in Synchrony treatment with the Gen2 kV imaging system.

Clinical presentation, treatment and outcome of Takayasu's arteritis in southern Chinese: a multicenter retrospective study.

To study the clinical presentation, treatment and outcome of southern Chinese patients with Takayasu's arteritis (TA). This is a retrospective chart review study of 78 patients managed in 14 public hospitals in Hong Kong between the years 2000 and 2010. Patients were identified from the hospital registry using the ICD-10 diagnostic code of the disease. The classification of TA was based on the American College of Rheumatology (ACR) or modified Ichikawa's criteria. Demographic data, clinical presentation, angiographic findings, pattern of vascular involvement (Numano's classification), treatment and outcome of these patients were presented. 78 patients were studied (82% women, age at presentation 34.2 ± 14 years). The estimated point prevalence of TA was 11/million population. The commonest initial manifestations were hypertension (62%) and vascular ischemic symptoms (38%). Systemic symptoms occurred in nine (12%) patients only. The proportion of patients fulfilling the angiographic subtypes of the Numano's classification was: types I (13%), IIa (4%), IIb (12%), III (12%), IV (20%) and V (39%), respectively. Thirty-two patients (41%) were treated with high-dose glucocorticoids (GCs) and 22 patients (28%) received additional non-GC immunosuppressive drugs. Vascular complications occurred in 26 (33%) patients and revascularization surgery was performed in 23(29%) patients. Three (4%) patients died of vascular complication at a median of 8 years after disease onset. TA is rare in southern Chinese patients of Hong Kong. Most patients present with ischemic symptoms during the stenotic phase of the disease. Although mortality is low, a significant proportion of patients developed vascular stenosis that required surgical interventions. More awareness of TA as a differential diagnosis of non-specific systemic symptoms with elevated inflammatory markers in younger patients is needed for earlier diagnosis.

New immunoassay platform utilizing yeast surface display and direct cell counting.

In this study, we report a new immunoassay platform using yeast cell surface display. This method holds promise for very low limit of detection (LOD) and is suitable for 2-Plex antibody recognition. Instead of adopting a conventional enzyme linked immunosorbent assay (ELISA) protocol by detecting the enzymatic activities or other physicochemical properties of the labeled analytes, this approach determines the quantity of an antibody analyte by directly counting the amount of "modified" yeast cells bound with antibody on the cell surface. c-myc and hemagglutinin (HA) tags were employed as an epitope model to demonstrate our approach. This yeast surface display based cell counting immunoassay (abbreviated as YSD-CCI) for anti-c-myc has a detection limit of 0.2 ng/mL, which is about 80 times higher than that of a conventional yeast ELISA under a similar condition. Moreover, the YSD-CCI's capability for 2-Plex antibody detection was demonstrated by simultaneous detection of anti-c-myc and anti-HA using engineered yeast cells expressing intracellular enhanced green fluorescent protein (EGFP) and mCherry, respectively. This proof-of-concept study paves the way for a new ultrasensitive multiplexed immunoassay method for diagnostic applications.