No abstract available

[en] Short communication

[en] During a clinical comparison study, 7 nuclear medicine physicians reported on unprocessed and mathematically processed scintigrams of the liver from 50 patients who had previously been diagnosed from biopsy. The evaluation of the quality of the diagnoses was aided by the ''signal detection'' theory. As a measure for the signal detectability, the area under the ROC-curve was used together with the curves' maximum value of information content. The form of the curves and the measured values for signal detectability showed that the diagnostic image quality is significantly improved by the application of the WIENER-filters

[en] Nearly ten years after the advent of CT, there is no more doubt that this imaging technique has not only brought a revolution to medical diagnostics, but also to radiotherapy. Besides the obvious contribution to radiotherapy by improving the detection and localisation of tumours in earlier stages, the whole treatment planning procedure takes advantage of a lot of other aspects of Computerized Tomography. In this paper the author presents a summary of the developments which have been induced by CT in radiation therapy treatment planning during the last decade. (Auth.)

[en] Full text: During the last three decades, 3D imaging with X-ray computerized tomography (CT) and magnetic resonance imaging (MRI) were introduced to characterize tumour morphology for improved delineation of target volumes. At present, the time has come to also start the assessment and correction of the temporal alterations of the target volume. This is leading to 'image guided radiotherapy' (IGRT), which is characterized by the integration of 2D and 3D imaging modalities into the radiotherapy workflow. The vision is to detect deformations and motion between radiotherapy fractions (inter-fractional IGRT) and during beam delivery (intra fractional IGRT). Considering these changes and correcting for them either by gating or tracking of the irradiation beam is leading a step further to 'time adapted radiotherapy' (ART). Many institutions are currently addressing this technical challenge, with the goal of implementing IGRT and ART into radiotherapy as a faster, safer and more efficient treatment technique. Another innovation, which is currently coming up is ^biological adaptive radiotherapy^. The background for this approach is the fact, that the old hypothesis of radiotherapy assuming that the tumor consists of homogenous tissue and therefore a homogeneous dose distribution has to be delivered to the target can no longer be sustained. It is known today, that a tumor may consist of various subvolumes with different radiobiological properties. New methods are currently being developed to characterize these properties more appropriately, e.g. by functional and molecular imaging using new tracers for Positron Emission Tomography (PET) and by functional magnetic resonance imaging (fMRI). The challenge in radiotherapy is to develop concepts to include and integrate this information into radiotherapy planning and beam delivery, first by extending the morphological image content towards a biological planning target volume including subvolumes of different radiosensitivity, and second by delivering appropriate inhomogeneous dose distributions, e.g. with the new tools of photon- and particle-IMRT techniques ('dose painting'). (author)

No abstract available

[en] In the near future, Radiotherapy with photon beams will be extended by inverse treatment planning and intensity modulated radiation therapy (IMRT), thus coming to a physical limit as far as dose conformation is concerned. For a minority of patients due to the complexity, radiation resistance or the close neighbourhood of the target volume to critical organs, even conformal therapy including IMRT will not be sufficient to reach local tumour control. Those patients will be candidates for a radiotherapy with heavy charged particles (e.g. protons or ¹²C-Ion beams). Several institutes are currently working to introduce charged particle beams into clinical practice. (orig.)

[en] The digital interpretation of pictures is the beginning of a new era in radiology. The original objectives of this method, e.g. the automatical analysis of chromosomes, are even now not attained. On the other hand, the utilization of the digital interpretation of pictures in medicine has proved itself to be extremely advantageous-concerning scintillographical pictures as well as ultrasound pictures. The computer-tomography also takes advantages from the digitalized interpretation of the signals received. (orig.)

No abstract available

[en] 3D reconstructions from tomographic images are used in the planning of radiation therapy to study important anatomical structures such as the body surface, target volumes, and organs at risk. The reconstructed anatomical models are used to define to the geometry of the radiation beams. In addition, 3D voxel models are used for the calculation of the 3D dose distributions with an accuracy, previously in possible to achieve. Further uses of 3D reconstructions are in the display and evaluation of 3D therapy plans, and in the transfer of treatment planning parameters to the irradiation situation with the help of digitally reconstructed radiographs. 3D tomographic imaging with subsequent 3D reconstruction must be regarded as a completely new basis for the planning of radiation therapy, enabling tumor-tailored radiation therapy of localized target volumes with increased radiation doses and improved sparing of organs at risk. 3D treatment planning is currently being evaluated in clinical trials in connection with the new treatment techniques of conformation radiotherapy. Early experience with 3D treatment planning shows that its clinical importance in radiotherapy is growing, but will only become a standard radiotherapy tool when volumetric CT scanning, reliable and user-friendly treatment planning software, and faster and cheaper PACS-integrated medical work stations are accessible to radiotherapists. (orig.)