Technical note: RabbitCT--an open platform for benchmarking 3D cone-beam reconstruction algorithms.

PURPOSE: Fast 3D cone beam reconstruction is mandatory for many clinical workflows. For that reason, researchers and industry work hard on hardware-optimized 3D reconstruction. Backprojection is a major component of many reconstruction algorithms that require a projection of each voxel onto the projection data, including data interpolation, before updating the voxel value. This step is the bottleneck of most reconstruction algorithms and the focus of optimization in recent publications. A crucial limitation, however, of these publications is that the presented results are not comparable to each other. This is mainly due to variations in data acquisitions, preprocessing, and chosen geometries and the lack of a common publicly available test dataset. The authors provide such a standardized dataset that allows for substantial comparison of hardware accelerated backprojection methods. METHODS: They developed an open platform RabbitCT (www.rabbitCT.com) for worldwide comparison in backprojection performance and ranking on different architectures using a specific high resolution C-arm CT dataset of a rabbit. This includes a sophisticated benchmark interface, a prototype implementation in C++, and image quality measures. RESULTS: At the time of writing, six backprojection implementations are already listed on the website. Optimizations include multithreading using Intel threading building blocks and OpenMP, vectorization using SSE, and computation on the GPU using CUDA 2.0. CONCLUSIONS: There is a need for objectively comparing backprojection implementations for reconstruction algorithms. RabbitCT aims to provide a solution to this problem by offering an open platform with fair chances for all participants. The authors are looking forward to a growing community and await feedback regarding future evaluations of novel software- and hardware-based acceleration schemes.

Ontario Child Health Study. I. Methodology.

We developed the methodology for a community survey to determine the prevalence of emotional and behavioral disorders among children 4 to 16 years of age in Ontario, Canada. Our discussion includes the objectives of the survey, the measurement of disorder, sampling methods and survey design, and a description of the data collected and instrumentation. Among 2052 households with eligible children, 1869 (91%) participated in the survey. The results can be used to help plan the future allocation of mental health resources in Ontario.

[Hard-x-ray therapy. The position between orthovolt- and ultra hard ray therapy (author's transl)]. / Röntgen-Hartstrahl-Therapie (Ihre Stellung zwischen Orthovolt und Ultrahartstrahltherapie).

The special position of "hard-ray therapy" (RT 305, 300 kV) between the orthovolt-therapy and the ultra-hard-ray therapy is described in physical respect and clinical practicability. In comparison with the orthovolt-therapy there is an advantage in better skin tolerance, the absence of bone shadows and the possibility to increase the depth-dose up to 50%. The main indications are given in the intermediate therapy and the short distance therapy of greater tumors. The palliative deep therapy is administered under better conditions as with the conventional x-ray irradiation.

[Hard x-ray therapy with special reference to postoperative irradiation of breast carcinoma]. / Die Röntgen-Hartstrahltherapie unter besonderer Berücksichtigung der postoperativen Bestrahlung des Mammakarizonoms

Five-year-experiences have shown that a considerably intensified tolerance of the skin and an absorption equability of tissues and bones and muscles are obtained with the hard ray roentgen irradiator, RT 305, for half-value depths from 20 mm to 70 mm H-2O and half-value thickness to about 7 mm Cu. By means of a rod anode tube of 300 kV with a super-normal filtration to 3.5 mm Pb, a hard and nearly monochromatic radiation, which already possesses the above mentioned advantages of the ultra-hard ray therapy with an effective energy about 0.2 MeV, appears. The application of this hard ray therapy is given preferably for disease foci in the environment of bone tissues, i.e. in the head and throat, the vertebral column, the osseous pelvic ring and the extremities and as the conventional roentgen therapy ist not able to give it. The hard ray therapy seems to be particularly adapted for the postoperative irradiation of the cancer of the breast with the ribs lying in the region of the irradiation fields, with the sternum and the bones of the shoulder girdle. With regard to these radiotherapeutic possibilities, corresponding cases are demonstrated.