A novel range telescope concept for proton CT.

Proton beam therapy can potentially offer improved treatment for cancers of the head and neck and in paediatric patients. There has been a sharp uptake of proton beam therapy in recent years as improved delivery techniques and patient benefits are observed. However, treatments are currently planned using conventional x-ray CT images due to the absence of devices able to perform high quality proton computed tomography (pCT) under realistic clinical conditions. A new plastic-scintillator-based range telescope concept, named ASTRA, is proposed here to measure the proton's energy loss in a pCT system. Simulations conducted using GEANT4 yield an expected energy resolution of 0.7%. If calorimetric information is used the energy resolution could be further improved to about 0.5%. In addition, the ability of ASTRA to track multiple protons simultaneously is presented. Due to its fast components, ASTRA is expected to reach unprecedented data collection rates, similar to 108protons/s. The performance of ASTRA has also been tested by simulating the imaging of phantoms. The results show excellent image contrast and relative stopping power reconstruction.

[Patient compliance and efficacy of diagnostic procedures in the surveillance of colorectal cancer: experience from a cancer center]. / Patientencompliance und Stellenwert diagnostischer Verfahren in der Tumornachsorge beim kolorektalen Karzinom: Erfahrungen aus einem Tumorzentrum.

Postoperative surveillance is an important part of the curative therapy of colorectal cancer patients. The effort and effectiveness of these surveillance programs are controversially discussed. We analyzed the practiced follow-up of patients who had undergone a curative resection of colorectal cancer to demonstrate the difficulty to validate the performed surveillance program and to point out possible improvements. For a follow-up period of 37 months (median) we included 530 patients with at least one postoperative examination. 70 patients ended the follow-up prematurely - out of these 56 % quit the surveillance during the first 18 months. Another 68 patients died during the follow-up period. Cancer recurred in 28 % of the patients (n = 109 metastasis, n = 26 local recurrences, 18 patients developed a secondary cancer). 90 % of these recurrences occurred within the first three years. 3525 follow-up examinations took place within 79 months. Patient histories and physical examinations were not helpful for the diagnosis of local recurrences; neither were laboratory routine screenings meaningful. Carcinoembryonic antigen (CEA) and CA 19 - 9 tests, ultrasonographic studies, chest XD-rays and colonoscopic procedures had a higher diagnostic value on the other hand. We demonstrated the problematic nature of the evaluation of different follow-up tests concerning their validity as they were part of a complex postoperative surveillance program. It is also important to point out that the success of the postoperative surveillance depends strongly on the compliance of the patients. To increase this compliance we suggest that the follow-up of patients should be more strongly oriented towards the incidence of recurrences.

Genetic variation at the short tandem repeat loci HumvWA, HumFXIIIB, and HumFES/FPS in the Egyptian and Yemenian populations.

The short tandem repeat systems (STRs) HumvWA, HumFXIIIB, and HumFES/FPS were amplified in a triplex polymerase chain reaction (PCR) on blood samples from 100 unrelated Yemenians and 100 unrelated Egyptians. The samples were analyzed by native horizontal discontinual electrophoresis. No deviations from Hardy-Weinberg equilibrium were detected. The mean exclusion chances for Egyptians and Yemenians were 0.634 and 0.591 (vWA), 0.530 and 0.531 (FXIIIB), and 0.573 and 0.583 (FES); the discriminating powers were 0.937 and 0.924 (vWA), 0.900 and 0.899 (FXIIIB), and 0.918 and 0.921 (FES); and the observed heterozygosity rates were 0.84 and 0.72 (vWA), 0.73 and 0.83 (FXIIIB), and 0.81 and 0.80 (FES). No significant differences were found between the two Arab populations, but the differences between both Arab populations and a European population for HumFES and FXIIIB and between the Yemenian sample and a European sample for vWA were significant. No evidence of linkage disequilibrium between any of the three STRs tested was found.