We have used a monoclonal antibody-based ELISA for plasma prothrombin fragment 1.2 (F1.2) to establish appropriate sample collection and storage conditions for this biomarker of thrombin generation. F1.2 concentrations were not altered by exogenous factor Xa, thrombin, or thromboplastin if blood was collected by routine venipuncture into tubes containing heparin as anticoagulant (but not citrate, acid-citrate-dextrose, EDTA, or oxalate) and if plasma antithrombin III concentration was > or = 30% of normal. Heparinized plasma F1.2 was stable for > or = 8 h at 20-25 degrees C, and if premixed with a stabilizing reagent, for > or = 4 years at -70 degrees C. Mean values for heparinized plasma F1.2 collected and stored by recommended procedures were increased in patients with thrombosis and conditions of increased thrombotic risk, and were sensitive to heparin and oral anticoagulant therapies. We conclude that plasma obtained by routine venipuncture into tubes with heparin as anticoagulant is an appropriate specimen for F1.2 measurements for most patients.

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Purpose: Development of a novel on‐line dosimetry tool is needed to move toward patient‐specific quality assurance measurements for Ir‐192 HDR brachytherapy to verify accurate dose delivery to the intended location. This work describes the development and use of a nano‐crystalline yttrium oxide inorganic scintillator based optical‐fiber detector capable of acquiring real‐time high‐precision dose measurements during tandem and ovoid (T&O) gynecological (GYN) applicator Ir‐192 HDR brachytherapy procedures. Methods: An optical‐fiber detector was calibrated by acquiring light output measurements in liquid water at 3, 5, 7, and 9cm radial source‐detector‐distances from an Ir‐192 HDR source. A regression model was fit to the data to describe the relative light output per unit dose (TG‐43 derived) as a function of source‐detector‐distance. Next, the optical‐fiber detector was attached to a vaginal balloon fixed to a Varian Fletcher‐Suit‐Delclos‐style applicator (to mimic clinical setup), and localized by acquiring high‐resolution computed tomography (CT) images. To compare the physical point dose to the TPS calculated values (TG‐43 and Acuros‐BV), a phantom measurement was performed, by submerging the T&O applicator in a liquid water bath and delivering a treatment template representative of a clinical T&O procedure. The fiber detector collected scintillation signal as a function of time, and the calibration data was applied to calculate both real‐time dose rate, and cumulative dose. Results: Fiber cumulative dose values were 100.0cGy, 94.3cGy, and 348.9cGy from the tandem, left ovoid, and right ovoid dwells, respectively (total of 443.2cGy). A plot of real time dose rate during the treatment was also acquired. The TPS values at the fiber location were 458.4cGy using TG‐43, and 437.6cGy using Acuros‐BV calculated as Dm,m (per TG‐186). Conclusion: The fiber measured dose value agreement was 3% vs TG‐43 and −1% vs Acuros‐BV. This fiber detector opens up new possibilities for performing patient‐specific quality assurance for Ir‐192 HDR GYN procedures. Funding from Coulter Foundation, Duke Bio‐medical Engineering. Company is being created around the detector technology. Duke holds patents on the technology.

Our results show that automated kilovoltage software is effective for reducing the radiation dose to the lens of the eye in pediatric patients. Furthermore, the image quality by CNR remained acceptable within 11% of the baseline for all kilovoltage settings used.

A computer program was formulated and verified experimentally to predict the optical density on an image receptor for any given set of radiographic variables including tube kilovoltage, milliamperage, and wave form; x-ray beam filtration; nature of filters and absorbers, and type of x-ray film.