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J Debus

Publications and source records attributed to J Debus.

At least 37 records · Page 2Linked to original sources
PubMed2005

Stereotactically guided fractionated re-irradiation in recurrent glioblastoma multiforme.

PURPOSE: To assess the feasibility, efficacy and toxicity of fractionated stereotactic radiotherapy in the treatment of recurrent glioblastoma multiforme. PATIENTS AND METHODS: From January 1995 to July 2003, 53 patients with histologically proven glioblastoma multiforme were treated at recurrence with fractionated stereotactic radiation therapy. A median dose of 36 Gy using a median fractionation of 5 x 2 Gy/week was applied. RESULTS: Median overall survival was 21 months, and median overall survival from the time point of re-irradiation was 8 months. The median time interval between primary and secondary radiation therapy was 10 months. In this patient population, no variables predicting longer overall survival could be determined. However, neurosurgical resection at relapse was associated with increased survival after re-irradiation (p=0.04), but left progression-free survival unaltered. Treatment was well-tolerated and no severe toxicities developed. CONCLUSION: Stereotactically guided fractionated re-irradiation is a safe and effective treatment modality in selected cases of recurring glioblastoma multiforme. Since this is not a randomized study, further evaluation in larger patient collectives is warranted. Also, based on recent results of radiochemotherapy in the treatment of primary glioblastoma multiforme, concomitant chemotherapy at relapse might be considered in the future.

Brain Neoplasms↗
PubMed2005

Daytime pulsed dose rate brachytherapy as a new treatment option for previously irradiated patients with recurrent oesophageal cancer.

The aim of this study was to evaluate the feasibility, effects, and toxicity of pulsed dose rate (PDR) brachytherapy for re-irradiation of oesophageal carcinoma. A total of 16 patients (median age 67 years) with inoperable recurrences from oesophageal cancer after primary radio-(chemo)-therapy (median 50 Gy) were re-irradiated using PDR brachytherapy ((192)Ir, 37 GBq). Treatment was carried out on an outpatient basis applying a weekly 5 Gy daytime schedule (0.5 Gy pulse(-1) h(-1), total dose 15-20 Gy). The dose was prescribed 10 mm from the mid-dwell position and encompassed the clipped tumour extension with 2 cm margins. The use of clips for delineation of tumour extent and catheter movement during irradiations was evaluated. All 61 PDR treatments were applied safely. The median catheter movement was 5 mm, range 2-12 mm. After a median follow-up of 8 months, three patients had a complete and five a partial remission. Body weight increased in 5 of 16 (31%) and was stable in 4 of 16 (25%) patients, respectively. The median grade 2 (RTOG/EORTC) dysphagia-free survival was 17 months. Seven patients experienced grade 1, five grade 2, and one grade 3 late toxicity. Three patients with uncontrolled locoregional disease showed grade 4 complications (oesophago-tracheal fistulae (n=2), fatal arterial bleeding (n=1). Daytime PDR brachytherapy proved to be feasible and provided effective palliation. Toxicity remains a major problem. Thus, total dose should be restricted to <15 Gy in this palliative situation.

Aged↗
PubMed2004

Influence of intra-fractional breathing movement in step-and-shoot IMRT.

Efforts have been made to extend the application of intensity-modulated radiotherapy to a variety of organs. One of the unanswered questions is whether breathing-induced organ motion may lead to a relevant over- or underdosage, e.g., in treatment plans for the irradiation of lung cancer. Theoretical considerations have been made concerning the different kinds of IMRT but there is still a lack of experimental data. We examined 18 points in a fraction of a clinical treatment plan of a NSCLC delivered in static IMRT with a new phantom and nine ionization chambers. Measurements were performed at a speed of 12 and 16 breathing cycles per minute. The dose differences between static points and moving target points ranged between -2.4% and +5.5% (mean: +0.2%, median: -0.1%) when moving with 12 cycles min(-1) and between -3.6% and +5.0% (mean: -0.4%, median: -0.6%) when moving with 16 cycles min(-1). All differences of measurements with and without movements were below 5%, with one exception. In conclusion, our results underline that at least in static IMRT breathing effects (concerning target dose coverage) due to interplay effects between collimator leaf movement and target movement are of secondary importance and will not reduce the clinical value of IMRT in the step-and-shoot technique for irradiation of thoracic targets.

Body Burden↗
PubMed2004

[Noninvasive measurement of relative cerebral blood flow with the blood bolus MRI arterial spin labeling: basic physics and clinical applications].

Knowledge of tumor blood flow is important for diagnosis and follow-up of brain tumors after therapy, especially to discriminate necrosis from tumor recurrence after radiation or chemotherapy. Meanwhile, perfusion and diffusion MRI, besides MR-angiography, are state of the art in stroke imaging. Until now, perfusion imaging was mostly performed using the first-pass dynamic susceptibility-weighted contrast-enhanced (DSC) MRI. The MRI-based arterial spin labeling technique (ASL) is a novel approach for measuring relative cerebral blood flow (rCBF) without using extrinsic contrast agents, by labeling spins of flowing arterial blood as intrinsic contrast agent. This article describes physical basics of ASL and shows clinical examples in neuroimaging such as in meningeoma, glioblastoma, oligodendroglioma, and cerebral ischemia, using the Q2TIPS ASL technique. Gray matter is clearly visible, while the observed white matter signal obtained by Q2TIPS is only slightly higher than background noise. Venous blood causes artefacts in the sagittal sinus and other large superficial veins in the subarachnoid space. Meningeoma and glioblastoma show elevated rCBF, whereas oligodendroglioma and cerebral ischemia have reduced rCBF values. Arterial-spin-labeling techniques are noninvasive tools for measuring rCBF within 5 min, using a standard MRI scanner.

Blood Flow Velocity↗
PubMed2004

[Stereotactic irradiation of lung tumors].

Stereotactic irradiation of lung tumors is a relatively new technique aiming at increased applicable radiation doses by a reduction of normal tissue involvement. As a result of adequate patient immobilization, three dimensional treatment planning and highly precise target point definition, the safety margins generally used in conventional radiotherapy can be reduced significantly. Increased fraction doses, which have an amplified biological effect, can be used and lead to a shortening of the overall treatment time. Especially for localized early-stage non-small-cell lung cancer the achieved dose escalation is proven to correlate with an increased local tumor control. But also the utilization for the therapy of lung metastases of solid tumors is possible. In spite of small patient cohorts and limited long-term data compared to conventional radiotherapy the results are promising.

Dose Fractionation, Radiation↗
PubMed2004

Radiation therapy of mesothelioma: the Heidelberg experience and future aspects.

Pleural mesothelioma is a rare but fatal tumour. Numerous attempts to find effective treatment approaches have, in general, been disappointing. To date, the most promising treatment is surgery, or surgery in combination with radio and chemotherapy as a part of a multidisciplinary approach. Preliminary results from clinical trials evaluating intensity modulated radiotherapy are encouraging. Further randomised trials are proposed.

Clinical Trials as Topic↗
PubMed2004

Treatment planning for carbon ion radiotherapy in Germany: review of clinical trials and treatment planning studies.

The GSI carbon ion radiotherapy facility established the first completely active beam shaping system for heavy ions, using energy variation on the synchrotron and pencil beam scanning. The introduction of an active beam shaping system for carbon ions has considerable impact on the design of the treatment planning system (TPS). The TPS has to account for the capability of the beam delivery and the biological modelling, which is needed to calculate the RBE for the resulting varying depth dose modulation. The TPS used in clinical routine with carbon ions is described and its use in treatment planning studies are outlined. A clinical trial with carbon ion therapy as primary therapy for chordoma and chondrosarcoma of the base of skull has been completed in 2001. Currently, carbon ion therapy as a boost treatment together with conventional conformal photon therapy or IMRT is under investigation in clinical trials for adenoid cystic carcinoma, chordoma and chondrosarcoma of the cervical spine and sacrococcygeal chordoma. Treatment planning studies comparing carbon ion therapy with IMRT, using optimization of combination therapy, and optimization of beam-line design have already been completed. Analysis of uncertainties in treatment planning has been started with the investigation of range uncertainties stemming from CT imaging. Uncertainties coming from the beam delivery play only a minor role. An attempt to asses the uncertainties introduced in treatment plans by the biological modelling, was done, using phantom verification of calculated cell survival levels. The clinical trials and planning studies are of special importance for the upcoming new clinical ion facility of the Heidelberg university hospital.

Carbon↗
PubMed2004

The Heidelberg Ion Therapy Center.

The ion beam therapy facility presently under construction at the Department of Clinical Radiology, University of Heidelberg, Germany, will be the first dedicated and hospital-based irradiation facility for protons and heavier ions in Europe. A capacity of more than 1000 patient treatments per year is planned. The facility comprises two horizontally-fixed beamlines for patient treatments plus a fixed-beam experimental area. In addition, the world-wide first scanning ion gantry is under construction. The facility fully relies on an active beam delivery method, the intensity-controlled rasterscan technique. The availability of different ion species ranging from protons to oxygen under identical conditions optimally supports clinical trials aiming to clarify the question of which particle species is best suited for the individual indications. A linac-synchrotron combination will deliver libraries of energy-, focus- and intensity-variable pencil-beams for each ion species to the dose-delivering scanning systems at each treatment station. The available energies correspond to water-equivalent ranges from 2 cm to 30 cm. The intensity-controlled rasterscan technique allows for the administration of inversely planned and biologically optimized dose distributions having utmost precision. The facility will be equipped with state-of-the-art imaging modalities as well as an in-situ Positron-Emission-Tomography (PET). The commissioning of the different sections is scheduled for 2006. The pre-clinical operation will start early in 2007 followed by the routine patient treatment.

Heavy Ion Radiotherapy↗
PubMed2004

[Reirradiation of chest wall local recurrences from breast cancer].

OBJECTIVE: The aim of this article was to describe the radio-therapeutic treatment options in previously irradiated patients suffering from breast cancer local recurrences and to review the literature. MATERIAL AND METHODS: Reirradiation of the chest wall can be performed using electron beams or alternatively CLDR/PDR (continuous/pulsed low dose rate) brachytherapy techniques with large skin moulds. With both techniques high doses can be applied to the chest wall while deeper-seated organs (lung, heart) can be spared to a large extent. Electron-beam therapy is readily available and the depth of treatment can be easily controlled by selecting the appropriate energy. The protracted irradiation schedule of CLDR/PDR brachytherapy results due to radiobiological reasons in a broad therapeutic ratio and safe treatment time. RESULTS: In the literature, more than 250 cases being reirradiated for chest wall local recurrences have been published. After retreatment using electron beams complete remissions were obtained in 41-74 % of the patients (brachytherapy 79-82 %). Severe grade IV complications (RTOG/EORTC) occurred in less than 10 % of the patients. CONCLUSIONS: With regard to the limited treatment options reirradiation of chest wall local recurrences resulted in high local control rates while toxicity remained acceptable. These data weaken the radio-therapeutic dogma that reirradiation of the chest wall may not be possible.

Brachytherapy↗
PubMed2003

Monitoring individual response to brain-tumour chemotherapy: proton MR spectroscopy in a patient with recurrent glioma after stereotactic radiotherapy.

Since antineoplastic activity varies, sensitive methods for individual assessment of efficacy are needed. We demonstrate the clinical value of MR spectroscopy in monitoring chemotherapy in a patient with recurrent glioma after stereotactic radiotherapy. Diagnostic imaging before and after chemotherapy included contrast-enhanced MRI, single-voxel proton MR spectroscopy ((1)H MRS), (1)H MR spectroscopic imaging ((1)H SI), and fluorodeoxyglucose (FDG) positron-emission tomography (PET). A significant decrease in choline signal intensity was observed 2 months after chemotherapy indicating tumour chemosensitivity, in line with tumour shrinkage on MRI and decreased uptake of FDG. Assessment of early response by MRS may help to improve treatment protocols in other patients.

Adult↗
PubMed2003

Treatment planning intercomparison for spinal chordomas using intensity-modulated photon radiation therapy (IMRT) and carbon ions.

Spinal chordomas cannot be treated with an effective dose using conventional radiation therapy (RT) without exceeding the tolerance dose of the spinal cord while ensuring sufficient target coverage at the same time. In this study we investigate the potential physical advantages of combined photon intensity-modulated radiation therapy (IMRT) and raster-scanned carbon ion RT over photon IMRT alone. For a representative patient we generated a carbon ion RT plan and a photon IMRT plan. Additionally, combined plans consisting of both carbon ions and photon IMRT were calculated using ratios of 20:40 GyE, 30:30 GyE and 40:20 GyE. The best target coverage was obtained using carbon ions alone. Using a combination of photon IMRT and carbon ions, the target coverage was better than with photon IMRT alone. Due to the applied dose constraints, the sparing of the spinal cord was comparable for all plans. Using carbon ions alone, the non-target tissue volume irradiated to at least 30 GyE/50.4 GyE was reduced by 72%/84% compared to photon IMRT alone. These advantages were evident even with combined techniques. The actually delivered dose distribution is expected to be more dependent on patient misalignment with carbon ions compared with photon IMRT. A combination of carbon ions and photon IMRT might be preferable in order to profit by the physical advantages of carbon ions while ensuring a safe treatment.

Carbon Radioisotopes↗
PubMed2003

[Monitoring of irradiated brain metastases using MR perfusion imaging and 1H MR spectroscopy].

PURPOSE: In follow-up examinations of irradiated brain metastases conventional contrast-enhanced morphological MR imaging is often unable to distinguish between transient radiation effects, radionecrosis,and tumor recurrence. To evaluate changes of relative cerebral blood flow (rCBF) in irradiated brain metastases arterial spin-labeling techniques (ASL) were applied and compared to the outcome of (1)H MR spectroscopy and spectroscopic imaging ((1)H MRS, SI). PATIENTS AND METHODS: In 2 patients follow-up examinations of irradiated brain metastases were performed on a 1.5-T tomograph (average single dose: 20 Gy/80% isodose). Relative CBF values of gray matter (GM), white matter (WM),and metastases (Met) were measured by means of the ASL techniques ITS-FAIR and Q2TIPS. (1)H MRS was performed with PRESS 1500/135. RESULTS: In both patients with initially hyperperfused metastases (Met/GM >1) the reduction of rCBF after stereotactic radiosurgery indicated response to treatment--even if the contrast-enhancing region increased--while increasing rCBF values indicated tumor progression. The findings were confirmed by (1)H MRS, SI and subsequent follow-up. CONCLUSION: The ASL techniques ITS-FAIR and Q2TIPS are able to monitor changes of rCBF in irradiated brain metastases. The two cases imply a possible role for ASL-MR perfusion imaging and (1)H MR spectroscopy in differentiating radiation effects from tumor progression.

Aged↗
PubMed2003

[Modern techniques in the radiotherapy of prostate cancer. Non-surgical treatment options for localized stages].

The implementation of computer-assisted three-dimensional radiotherapy treatment planning methods based on computed tomography together with sophisticated beam modeling with individual blocks and multi-leaf-collimators in the 90's enabled the creation of steep dose gradients between the target volume and surrounding radiosensitive normal tissue. For prostate cancer, a clear dose dependence between the treated radiation dose and the treatment success is proven, especially for patients with intermediate and unfavorable prognostic criteria. However, with conventional radiotherapy, rectum and urinary bladder are limiting the applicable dose. New technical methods allow a safe dose escalation without increasing of treatment-related toxicity. An improvement in terms of PSA remission and local control was yielded. This article presents the different established external beam and interstitial treatment techniques and their clinical results.

Brachytherapy↗
PubMed2003

[Focused ultrasound surgery. Basics, current status, and new trends].

There is an increasing interest in high intensity focused ultrasound (HIFU) for thermo ablative tumor therapy. The attractiveness of this method is based on its ability to destroy tumor tissue non invasively while sparing surrounding tissue from outside the body. HIFU induced tissue necroses are sharply circumscribed. Therefore this method was termed focused ultrasound surgery (FUS). The therapeutic potential of FUS is under investigation in several clinical studies. Main objects of these studies are prostate carcinomas, breast kidney and liver tumors. The next innovative step will be the non invasive FUS treatment of brain through the intact skull. Combining FUS with magnetic resonance imaging (MRI) or diagnostic ultrasound allows accurate and online therapy guiding and monitoring. This article gives an overview of the basics, the latest developments and actual clinical studies in the field of focused ultrasound surgery.

Electrocoagulation↗
PubMed2003

Cytosine deaminase versus thymidine kinase: a comparison of the antitumor activity.

The efficacy of single and combination suicide gene therapy was evaluated using a Herpes simplex virus thymidine kinase/ganciclovir system and Escherichia coli cytosine deaminase/5-fluorocytosine system on the rat prostate tumor cell line R3327 AT-1. The wild-type R3327 AT-1 cell line was transfected with a bifunctional fusion gene CDglyTK, which had the advantage that the resulting R3327 AT-1/CDglyTK cell line has the same amount of cytosine deaminase and thymidine kinase molecules. The percentage of viable R3327 AT-1/CDglyTK cells after 96 h incubation with 0.1 micro g/ml ganciclovir or 10 micro g/ml 5-fluorocytosine were 85% and 52% of controls, respectively. The cell viability when both suicide genes systems were activated was 43%. For in vivo analysis, Copenhagen rats were injected subcutaneously with R3327 AT-1 or R3327 AT-1/CDglyTK cells and treated with 30 mg/kg ganciclovir, 500 mg/kg 5-fluorocytosine, or both prodrugs together. A survival of 83% with the thymidine kinase/ganciclovir and 57% with the CD/5-FC could be observed. Only co-administration of thymidine kinase- and cytosine deaminase-specific prodrugs resulted in a 100% recurrence-free survival of the Copenhagen rats with a Dunning R3327 AT-1/CDglyTK prostate tumor and showed an additive cytotoxic effect. Calculation of the degree of activation and the potential of activation can be used to predict the success of a suicide gene therapy. In our case, the cytosine deaminase/5-fluorocytosine system had a low degree of activation (value 40), which is also found in the low response to 5- fluorocytosine in vivo (57% tumor free).

Animals↗