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Real time flat panel detectors based on amorphous selenium (a-Se) have demonstrated to be the most advanced technology for direct conversion X-ray imaging in various medical applications. In continuation of real time detector development, ANRAD Corporation introduce in this paper a large size 14" x 14" active area detector built with an amorphous selenium (a-Se) converter coated on a TFT array. This new detector is a scaled up version of the 9" x 9" presented last year based on a TFT array with 150 µm x 150 µm pixel and a 1000 µm thick a-Se PIN structure operated at 10V/µm. DQE(f=0) measurements were performed in low dose range and demonstrated to be in agreement with a linear model including 2500e of electronic noise. It is also shown that the spatial resolution (MTF) could be controlled by selenium coating process and can almost reach the theoretical limit defined by the pixel pitch. Finally, the first 14" x 14" chest image is presented.

Two patients with thyroid carcinoma infiltrating bilateral internal jugular veins were treated. In reconstruction of the internal jugular vein by implantation of an autogenous venous segment or Gore-Tex artificial vessel, the repaired area soon became obstructed. The repaired area with the Impra-Flex artificial vessel became obstructed again one month after the implantation. In the reconstruction by ipsilateral end-to-end anastomosis between the internal and external jugular veins, good circulation was apparent even 2 years after the operation. The internal-external jugular vein anastomosis is expected to increase the safety of single-stage bilateral excision of the internal jugular vein, as an adjunct to total thyroidectomy, in the surgical treatment of thyroid carcinoma.

Dose-survival curves were obtained for matched samples of peripheral T-lymphocytes and skin fibroblasts from a total of 22 patients who underwent various surgical procedures using loss of colony-forming ability as the end point. The results showed that the mean D10 (dose required to kill 90% of cells) +/- SD was 3.58 +/- 0.21 Gy for T-lymphocytes irradiated in G0 and 3.19 +/- 0.37 Gy for skin fibroblasts irradiated in log phase. The coefficients of variation were found to be 6 and 11%, respectively. Contrary to the expectation, regression analysis of D10 values for the two types of cells revealed no significant correlations. The absence of correlation most probably derives from the fact that the apparent interindividual variability of dose-survival curves is caused primarily by random experimental fluctuations at least in the case of lymphocytes. Possible reasons for the greater variability observed in the fibroblast assay are discussed.

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