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R Krempien

Publications and source records attributed to R Krempien.

At least 19 recordsLinked to original sources
PubMed2006

Piezosurgery--a new safe technique in cranial osteoplasty?

All surgical interventions on the neurocranium bear the risk of injury of the dura mater and development of a cerebrospinal fluid fistula. Therefore, despite careful preparation, damage to the dura mater cannot always be omitted. Especially after surgery and in patients with increased intracranial pressure (craniosynostoses) there is a high risk of perforating the dura. In this article a new surgical technique for osteotomy (Piezosurgery) that avoids perforation of the dura is presented. Ultrasonic microvibrations allow a selective cut of only mineralized structures without damage to the soft tissue. Even in case of accidental contact the dura remains undamaged. This advantage is also useful for bone splitting, to separate the tabula externa from the tabula interna in situ, without any risk of dura perforation even in case of the very thin bones in an infantile skull. The present work shows the applicability of piezoelectric surgery in high-risk patients after osteotomy, avoiding perforation of the dura mater.

Brain Injuries↗
PubMed2006

Clinical application of cone beam digital volume tomography in children with cleft lip and palate.

OBJECTIVES: The diagnostic advantages of digital volume tomography (DVT) over conventional imaging and computed tomography are demonstrated in terms of the respective radiation exposure. The potential role for three-dimensional imaging in cleft lip and palate patients is illustrated on the basis of clinical examples. METHODS: The radiation exposure resulting from scans using a cone beam DVT (NEW TOM QR-DVT 9000, Marburg, Germany) was measured with an Alderson-Rando-Phantom (The Phantom Laboratory, New York, NY) and compared with that resulting from other standard imaging modalities. The patient sample consisted of young children with cleft lip and palate on whom orthodontic and surgical treatment was planned on an interdisciplinary basis at the University-Hospital of Heidelberg. RESULTS: Digital volume tomography allows high-quality three-dimensional imaging of the premaxilla region, with an effective equivalent investigation dose of (110 kV, 5.4 mA) 0.342 mSv based on ICRP recommendations. While the effective equivalent investigation dose for DVT is higher than that for standard imaging techniques (for example digital panoramic radiograph Orthophos Plus DS Ceph (66 kV, 8 mA) 0.016 mSv), it is much lower than that for a normal CT scan (e.g. Picker International Inc., Highland Heights, OH) adjusted at (spiral 130 kV, 125 mA, and 30 mA, 1.5 s) 2.27 mSv. Digital volume tomography provides extensive data important in clinical decision making. CONCLUSIONS: The clinical examples show the good applicability of DVT with a reduced radiation dose.

Child, Preschool↗
PubMed2005

Randomized phase II--study evaluating EGFR targeting therapy with cetuximab in combination with radiotherapy and chemotherapy for patients with locally advanced pancreatic cancer--PARC: study protocol [ISRCTN56652283].

BACKGROUND: Pancreatic cancer is the fourth commonest cause of death from cancer in men and women. Advantages in surgical techniques, radiation therapy techniques, chemotherapeutic regimes, and different combined-modality approaches have yielded only a modest impact on the prognosis of patients with pancreatic cancer. Thus there is clearly a need for additional strategies. One approach involves using the identification of a number of molecular targets that may be responsible for the resistance of cancer cells to radiation or to other cytotoxic agents. As such, these molecular determinants may serve as targets for augmentation of the radiotherapy or chemotherapy response. Of these, the epidermal growth factor receptor (EGFR) has been a molecular target of considerable interest and investigation, and there has been a tremendous surge of interest in pursuing targeted therapy of cancers via inhibition of the EGFR. METHODS/DESIGN: The PARC study is designed as an open, controlled, prospective, randomized phase II trial. Patients in study arm A will be treated with chemoradiation using intensity modulated radiation therapy (IMRT) combined with gemcitabine and simultaneous cetuximab infusions. After chemoradiation the patients receive gemcitabine infusions weekly over 4 weeks. Patients in study arm B will be treated with chemoradiation using intensity modulated radiation therapy (IMRT) combined with gemcitabine and simultaneous cetuximab infusions. After chemoradiation the patients receive gemcitabine weekly over 4 weeks and cetuximab infusions over 12 weeks. A total of 66 patients with locally advanced adenocarcinoma of the pancreas will be enrolled. An interim analysis for patient safety reasons will be done one year after start of recruitment. Evaluation of the primary endpoint will be performed two years after the last patient's enrollment. DISCUSSION: The primary objective of this study is to evaluate the feasibility and the toxicity profile of trimodal therapy in pancreatic adenocarcinoma with chemoradiation therapy with gemcitabine and intensity modulated radiation therapy (IMRT) and EGFR-targeted therapy using cetuximab and to compare between two different methods of cetuximab treatment schedules (concomitant versus concomitant and sequential cetuximab treatment). Secondary objectives are to determine the role and the mechanism of cetuximab in patient's chemoradiation regimen, the response rate, the potential of this combined modality treatment to concert locally advanced lesions to potentially resectable lesions, the time to progression interval and the quality of life.

Antibodies, Monoclonal↗
PubMed2005

Phase III trial of postoperative cisplatin, interferon alpha-2b, and 5-FU combined with external radiation treatment versus 5-FU alone for patients with resected pancreatic adenocarcinoma -- CapRI: study protocol [ISRCTN62866759].

UNLABELLED: After surgical intervention with curative intention in specialised centres the five-year survival of patients with carcinoma of the exocrine pancreas is only 15%. The ESPAC-1 trial showed an increased five-year survival of 21% achieved with adjuvant chemotherapy. Investigators from the Virginia Mason Clinic have reported a 5-year survival rate of 55% in a phase II trial evaluating adjuvant chemotherapy, immunotherapy and external-beam radiation. DESIGN: The CapRI study is an open, controlled, prospective, randomised multi-centre phase III trial. Patients in study arm A will be treated as outpatients with 5-Fluorouracil; Cisplatin and 3 million units Interferon alpha-2b for 5 1/2 weeks combined with external beam radiation. After chemo-radiation the patients receive continuous 5-FU infusions for two more cycles. Patients in study arm B will be treated as outpatients with intravenous bolus injections of folinic acid, followed by intravenous bolus injections of 5-FU given on 5 consecutive days every 28 days for 6 cycles. A total of 110 patients with specimen-proven R0 or R1 resected pancreatic adenocarcinoma will be enrolled. An interim analysis for patient safety reasons will be done one year after start of recruitment. Evaluation of the primary endpoint will be performed two years after the last patients' enrollment. DISCUSSION: The aim of this study is to evaluate the overall survival period attained by chemo-radiotherapy including interferon alpha 2b administration with adjuvant chemotherapy. The influence of interferon alpha on the effectiveness of the patients' chemoradiation regimen, the toxicity, the disease-free interval and the quality of life are analysed. Different factors are tested in terms of their potential role as predictive markers.

Adenocarcinoma↗
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

[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↗
PubMed2002

[Ultrasonography of tumors of the locomotor system].

Sonography is an integral part of primary tumor diagnosis and follow-up for the great majority of organ systems. However, its value in the field of space-occupying processes of the locomotor system, especially of malignant bone tumors, has mostly been underestimated. The sonographic examination has to investigate the whole tumor region and the corresponding lymph nodes statically and dynamically. The examination procedure should be standardized and the documentation reliable. Evaluation criteria are the localization, dimensions, and volume of the tumors, echogenicity and homogeneity, peri- and intratumoral vascularization (vessel density and architecture), borders of the tumor, and neighboring structures. Pathologic changes not only of the soft tissues but also of the bones can be evaluated sonographically. Even subtle analysis does not permit definitive assessment of tumor status. Taking its physical limitations into consideration, high-resolution sonography, enhanced by color/PowerDoppler and three-dimensional techniques, is a valuable adjunct to improve diagnosis, therapy planning, monitoring, and posttherapeutic care of tumors of the locomotor system.

Bone Neoplasms↗
PubMed2002

[3D-ultrasound: a valuable adjunct for therapy planning and follow-up of head and neck tumours].

AIM: The three-dimensional visualization of orofacial tumours and adjacent organs at risk of infiltration is an important requirement for staging, therapy planning and follow-up. Artifacts from the mandible or metal implants often reduce the diagnostic power of computed tomography (CT). The value of 3D-ultrasound (3D-US) in respect to the standard methods CT and magnetic resonance imaging (MRI) was therefore analyzed. METHOD: Between 9/97 and 10/99 the visualization of orofacial tumours in 243 patients by 3D-US was examined, classified on a five-point scale and compared to the corresponding CT and MRI scans. RESULTS: Complete visualization of the tumours was possible in 85.6 % by 3D-US, whereas the rates of MRI and CT were lower with 77.4 % and 61.3 % respectively, mainly because of artifacts. The best combinations of methods, 3D-US + CT (96.7 %) and 3D-US + MRI (95.1 %) gave almost equivalent results, whereas CT + MRI (83.5 %) was inferior. In 2.5 % of the cases none of the methods produced adequate results. CONCLUSION: By free selection of sectional planes and direct correlation to the clinical findings 3D-ultrasound can improve staging, therapy planning and follow-up of orofacial tumours, especially in the case of small tumour size, dental crowns/inlays, metal implants or contraindications to MRI.

Head and Neck Neoplasms↗
PubMed2002

Radiation recall dermatitis from docetaxel.

BACKGROUND: Experiences with inflammatory skin reactions after treatment with docetaxel and prior exposure to radiotherapy like a recall phenomenon are very rare. We present the case of an uncommon and severe skin reaction after docetaxel application and prior radiotherapy. PATIENT AND METHODS: A 40-year-old female was treated with an upper body irradiation with electrons because of relapsed breast cancer. In addition, because of metastases of brain and bone she received radiotherapy on the whole brain and the left pelvis. One week after radiotherapy weekly chemotherapy with docetaxel was started. RESULTS: Radiotherapy was well tolerated. There was a cutaneous erythema RTOG grade 1. After second application of docetaxel the patient developed a severe skin erythema, after fourth application confluent desquamations exactly demarcated the previously irradiated skin area. After discontinuation of docetaxel and after antiinflammatory treatment the skin reactions improved rapidly. CONCLUSION: In our opinion the severe skin reaction was clearly associated with the application of docetaxel like a recall phenomenon after previous radiotherapy. In case of severe skin reaction after this therapy it is important to know the possibility of recall phenomenon.

Adult↗
PubMed2002

[Computer-assisted reconstruction of coronary vessels].

End stage coronary artery disease with linear stenosis of the main vessels despite several coronary interventions is a current challenge for surgical treatment. As the long term results are mainly determined by the pathology of the coronary vessels a simple revascularisation with arterial or venous grafts provides no adequate solution of the problem. An exactly controlled 3D-reconstruction of the coronary vessels enabling selective thrombendarteriectomy (TEA) seems to be a new approach, that may be limited by neointimal hyperproliferation of the coronary vessels. Intraoperative brachytherapy may be a tool to inhibit this process.

Atherectomy, Coronary↗
PubMed2002

[Processing medical image data for head surgery].

Three-dimensional models of the patient's anatomy are the basis for modern applications in computer-assisted surgery or radiology. To create these models the data is processed in a series of steps that transforms the initial raw data (generally CT/MRT volume images) into the three-dimensional models (e.g. triangle meshes). In doing so, a multitude of parameters adjustments, interactions and decisions are necessary to be made by the physician in order to create the models adapted to the specific needs of the patient and to the surgery. The quality of the models therefore strongly depends on that process chain. As a result of the high requirements on the quality and security of a clinical application the quality of the models itself and the capability to use them flexibly are essential. This work present a method to adjust and optimise the creation of the models and to asses their quality afterwards.

Artifacts↗
PubMed2002

Intraoperative guidance of pre-planned bone deformations with a surface scanning system.

Computer- and robot-based systems to support interventions become more and more important in modem surgery. In general these systems provide methods to plan an intervention pre-operatively and to execute it with support from a autonomous robot-system. Due to the principle restriction of a robot to comparatively simple work steps, there are some complex work steps which the surgeon may plan but which he/she has to execute manually. In craniofacial surgery osteotomised bone segments are deformed by hand to a shape given by the planning system. We support the execution of pre-planned deformation by comparison of the actual shape of an object with the target shape. The actual shape is obtained intra-operatively with a surface scanning device, the deviation from the target shape are visualised by projecting colour-coded error values directly on the object to be deformed. The surgeon uses these projections to adjust further deformation steps. The system is therefore able to validate the correct execution of planned deformations, especially of bony structures.

Computer Simulation↗
PubMed2002

Creating a statistical atlas of the cranium.

Normative data is very important for simulation procedures in craniofacial surgery. While treating e.g. a malformed skull the surgeon seeks to reconstruct its natural and harmonic shape. Atlas or normative data of the skull could support the surgeon in this effort, as it would provide a standard model of the skull which gives an idea of the natural shape. We create a standard skull by averaging regularly formed skulls in a shape space spanned by spherical harmonics. While state-of-the-art methods use landmarks to define the shape and mean shapes, this method is deterministic, i.e. it manages averaging without landmarks and it provides a complete description of the shape. In addition the shape space can be used to classify shapes to identify different types of an anatomy.

Cephalometry↗
PubMed2002

Daily patient set-up control in radiation therapy by coded light projection.

Advances in conformal radiation therapy to control disease via dose escalation are challenged by set-up uncertainties. Recently, techniques have been developed to use surface features to evaluate the patient's position and correct it where necessary. The aim of this study was to use the patient's surface as a tool for daily set-up control and monitoring. We use a surface scanner based on the projection of coded light to receive--in a daily routine--a large amount of surface points which enables us to register the CT-based planning data with the patients current position. By superimposing current and planned volumes, a volume of congruency was obtained. An error below 1 mm was considered acceptable. In cases where set-up was not satisfactory a map of the surface comparison was evaluated showing the areas of missing alignment. According to this information a manual repositioning was performed. This procedure was repeated until the error was acceptable. No more then 3 repetitions where necessary to obtain an acceptable result. The whole procedure including registration, calculation and visualization took about 20 sec for one repetition. The use of structured light projection in the daily set-up control and monitoring proved to be a noninvasive, easy, quick, inexpensive and reliable solution.

Data Collection↗
PubMed2002

Integration of intraoperative radiotherapy (IORT) dose distribution into the postoperative CT-based external beam radiotherapy (EBRT) treatment planing.

In the treatment of malignant disease external beam radiation therapy (EBRT) is often combined with surgery. Intraoperative radiotherapy (IORT) improves the local control by dose escalation. For reasons of recording, improvement and security of the intervention, it would be necessary to merge the IORT-dose distribution with the postoperative CT-based EBRT-planing. The aim of this work was to develop a method to reconstruct the IORT field and register it with the postoperative planing CT. This enables the reconstruction of the IORT dose distribution and merge it with the CT-based EBRT planing data. We use a surface scanner to receive a large amount of surface points which enables us reconstruct the IORT-field and to register it with the CT-based EBRT planning data. Scanning and calculation time is not over 2 seconds, depending mainly on the CPU power. The error of a single point is below 1 mm. The density of the point cloud is approx. 4 per mm2. In this paper we give an overview of our experimental setup and the accuracy of the method.

Brachytherapy↗