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Marius Treutwein

Publications and source records attributed to Marius Treutwein.

2 recordsLinked to original sources

Clinical results of intracoronary brachytherapy (ICBT) for multiple in-stent restenosis.

BACKGROUND AND PURPOSE: Treatment of in-stent restenosis (ISR) with percutaneous coronary intervention (PCI) alone is often followed by early re-restenosis. The present study focused on the effect of intracoronary brachytherapy (ICBT) on multiple in-stent restenosis (MISR) after repeated PCI. PATIENTS AND METHODS: 40 patients (27 male, 13 female, age: 66 +/- 9 years) with MISR (two to six ISRs, median three ISRs) were retrospectively analyzed. All patients were treated by using the Novoste((R)) Beta-Cathtrade mark 3.5F System after PCI. The target vessel received 18.4-25.3 Gy of radiation at a depth of 2 mm from the center of the source. The restenosis-free survival and overall survival were calculated by Kaplan-Meier analysis (log-rank). The time interval between last PCI without ICBT and the consecutive recurrence was compared with the follow-up time after PCI with ICBT. RESULTS: The 3-year overall survival rate after ICBT was 93%. The 0.5-, 1-, 2-, and 3-year ISR-free survival rates after PCI + ICBT were 81%, 72%, 52%, and 38%, respectively. After PCI alone, the 0.5-, 1-, and 2-year ISR-free survival rates were 30%, 13%, and 0%, respectively. This difference was highly significant (p < 0.0001). Patients with more than three ISRs before ICBT had a better outcome (3-year ISR-free survival: 80%) than patients with only two or three ISRs before ICBT (3-year ISR-free survival: 25%; p < 0.05). CONCLUSION: ICBT is highly effective and safe in patients with ISR. The results of this study are in accordance with the WRIST and BETA-WRIST data. After 6 months both studies revealed an ISR-free survival rate of 86% (WRIST) and 66% (BETA-WRIST), respectively. The ISR rates in the own control group (70%) were comparable to the placebo groups in WRIST (68%) and BETA-WRIST (72%). Interestingly, patients with more than three ISRs before ICBT had the lowest ISR rate after ICBT.

Aged↗

Verification of IMRT: techniques and problems.

PURPOSE: IMRT (intensity-modulated radiotherapy) verification techniques are reviewed together with investigations demonstrating the intrinsic verification problems. MATERIAL AND METHODS: Different IMRT verification procedures for either class solutions or individual patients are demonstrated. Among the latter are techniques like fluence or three-dimensional (3-D) dose distribution verification within a transfer phantom. Different radiographic films and absolute dose probes are investigated for their suitability. Finally, Monte Carlo techniques (XVMC/VEF) are used for error detection and IMRT verification. RESULTS: During introduction of clinical IMRT for head and neck (H and N) tumors, we concurrently applied fluence, relative, and absolute dose measurement. While fluence and relative dose are in rather good agreement with calculations, absolute dose is always low when compared to the TPS (TMS 6.1A, Nucletron B.V.) by 5-7%. This deviation seems to depend not on the number of segments, but can strongly depend on MLC misalignment. Further investigations have revealed the importance of a detailed commissioning of the TPS down to the small-field range using diamond or diode probes and its detailed verification. In addition, simple tests have shown that dose calculation approximations in the IMRT option of TMS are one major source of the dose deviation. XVMC/VEF does not use such approximations. CONCLUSION: The procedure starts with a detailed TPS commissioning and verification process. Different verification methods are recommended during clinical IMRT implementation phase, in order to locate sources of error. Later on, a minimal program could consist of a fluence or relative dose verification procedure with few films and absolute dose measurement, followed by an intensive MLC quality assurance (QA). Inverse Monte Carlo systems, like IMCO(++)/IKO or Hyperion, seem to be able to reduce the effort.

Head and Neck Neoplasms↗