Eike Rietzel

..The average registration error for five landmarks for each of five patients was 2.1 mm. This level of accuracy is acceptable for most radiotherapy applications...

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..We used four-dimensional computed tomography (4DCT) to characterize tumor motion and create treatment volumes in 10 patients with lung cancer. These were compared with standard treatment volumes...

..To assess the accuracy of maximum-intensity volumes (MIV) for fast contouring of lung tumors including respiratory motion...

..To describe approaches to four-dimensional (4D) treatment planning, including acquisition of 4D-CT scans, target delineation of spatio-temporal image data sets, 4D dose calculations, and their analysis...

..This calibration can cause relevant differences between treatment planning and treatment delivery...

..Residual motion artifacts in the resulting 4DCT volumes are reduced and allow use of the 4D imaging studies for treatment planning...

..Even limited compensation precision (standard deviation approximately 2 mm), introduced to simulate possible limitations of real-time target tracking, resulted in less than 3% loss in dose homogeneity...

..We describe the methods of our 4D treatment planning approach and demonstrate functionality of the system for phantom as well as patient data...

..Scanned ion beam therapy of intra-fractionally moving tumors requires motion mitigation. GSI proposed beam tracking and performed several experimental studies to analyse the dosimetric precision of the system for scanned carbon beams...

..The inter-fractional variation of the daily mean positions of the markers, which indicates the uncertainty in the set-up procedure, was within +8.3 mm/-4.5 mm (95% range) in the SI direction for this case...

..A protocol for 4DCT scanning was evaluated and clinically implemented at the MGH. Patient data are presented to elucidate how additional patient specific parameters can impact 4DCT imaging...

..Intrafractional motion results in local over- and under-dosage in particle therapy with a scanned beam. Scanned beam delivery offers the possibility to compensate target motion by tracking with the treatment beam...

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..We compared different treatment planning strategies for lung tumors that compensate for respiratory motion...

..The results demonstrate the feasibility/proof of the proposed range adaptation method for beam tracking from the beam quality point of view...

..Statistical analyses of the mismatch of the homologous points before and after registration demonstrated improved overall accuracy for both algorithms...

..To demonstrate mitigation of the interplay effects of scanned particle beams and residual target motion within a gating window by increased overlap of pencil beams...

..The purpose of this project was the implementation of continuous (four-dimensional [4D]) Monte Carlo simulation to study the irradiation of tumors under respiratory motion...

..These calculation codes should be verified against suitable measurements. We performed simulations and measurements to validate calculation of the film response in the presence of target motion...

..Imaging before treatment (image guidance) improves accuracy of radiation delivery, and recording transmission images can provide a means of verifying gated delivery...

..We are studying approaches to targeting moving tumors throughout the entire treatment process, from treatment planning to beam delivery...

..For example, 5 mm water equivalence (WE) longitudinal beam tracking results in accuracy of 1.08 and 0.48 mm WE in root mean square for time windows of 10 and 50 ms, respectively...

..A prototype setup for 3D online motion compensation (3D-OMC) with a scanned particle beam is described, transferring the full potential of volume conformal irradiation to moving targets...

..An alternative to the use of margins is to do the planning based on blurred dose distributions...

..Smoothing beam profiles either based on a single scan or over the different breathing phases was not beneficial for reducing this shift...

..However, especially for small fraction numbers, e.g. hypo-fractionation, treatment of moving targets with scanned particle beams requires motion mitigation techniques such as rescanning, gating, or tracking...

..It contributes a substantial basis for the experimental research on the irradiation of moving target volumes with scanned ion beams at GSI which will be presented in upcoming papers...

..We have applied the scanning and registration methods on phantom, animal and patients, and initial results suggest the applicability of both the scanning and the registration methods...

..Dose gradients and dose to surrounding areas were in good agreement. The motion tracking system successfully preserved dose distributions delivered to moving targets and maintained target conformity...