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Background: Precise immobilisation of a patient during extracranial stereotactic 3-D navigation is essential in order to minimize the patient's movement during CT data recording and needle application. In this paper we report the first results of needle positioning accuracy in various body regions, using a 3-D navigation system for brachytherapy and a new patient immobilisation system., Patients and Methods: Six patients with different manifestations of neoplastic diseases were immobilized by a special vacuum system and treated with stereotactic 3-D navigational interstitial brachytherapy., Results: The comparison of the simulated stereotactic needle positions with the actual needle positions resulted in a mean positioning deviation varying from 3.4 to 6.5 mm for 29 needles. The maximum positioning deviation lay between 5.7 and 13 mm., Conclusion: The results of our study show that, despite effective patient immobilisation, an increase in needle positioning accuracy is limited by the method of stereotactic 3-D navigation. Effects such as modification of body shape caused by the needle application morphologic alterations, and inherent inaccuracies within the navigation system have an important influence upon accuracy, which it is not yet possible to calculate.

Interstitial brachytherapy was first applied using radium needles, with minimum protection of physicians and nurses. Modern techniques involve the use of radionuclide (192)Ir as the source used in computer-controlled remote afterloading machines, which can deliver a high dose rate (HDR). Treatment planning is also undertaken with the use of computers and anatomical cross-section images using CT, ultrasound and MRI. This review presents these modern techniques for tumors of a series of body sites: prostate, head and neck, breast, bladder, brain, and for soft-tissue sarcomas. Low dose rate (LDR) interstitial brachytherapy techniques are also included in this review since in some body sites there is a choice between HDR and LDR., (Copyright 2001 S. Karger GmbH, Freiburg)

Purpose: Development, application and evaluation of a CT-guided implantation technique and a fully CT-based treatment planning procedure for brachytherapy., Methods and Materials: A brachytherapy procedure based on CT-guided implantation technique and CT-based treatment planning has been developed and clinical evaluated. For this purpose a software system (PROMETHEUS) for the 3D reconstruction of brachytherapy catheters and patient anatomy using only CT scans has been developed. An interface for the Nucletron PLATO BPS treatment planning system for optimization and calculation of dose distribution has been devised. The planning target volume(s) are defined as sets of points using contouring tools and are used for optimization of the 3D dose distribution. Dose-volume histogram based analysis of the dose distribution (COIN analysis) enables a clinically realistic evaluation of the brachytherapy application to be made. The CT-guided implantation of catheters and the CT-based treatment planning procedure has been performed for interstitial brachytherapy and for different tumor sites in 197 patients between 1996 and 1997., Results: The accuracy of the CT reconstruction was tested using first a quality assurance phantom and second, a simulated interstitial implant of 12 needles. These were compared with the results of reconstruction using radiographs. Both methods gave comparable results with regard to accuracy, but the CT based reconstruction was faster. Clinical feasibility was proved in pre-irradiated recurrences of brain tumors, in pretreated recurrences or metastatic disease, and in breast carcinomas. The tumor volumes treated were in the range 5.1 to 2,741 cm3. Analysis of implant quality showed a slightly significant lower COIN value for the bone implants, but no differences with respect to the planning target volume., Conclusions: The Offenbach system, incorporating the PROMETHEUS software for interstitial HDR brachytherapy has proved to be extremely valuable in routine clinical practice for many tumor sites. Our CT-guided implantation technique together with a fully CT-based planning system has enabled conformal brachytherapy treatment to become routine.

Purpose: To propose a new index (COIN) that can be easily understood and computed to assess high dose rate (HDR) brachytherapy interstitial implant quality and dose specification and is an improvement on existing indexes., Methods and Materials: The COIN index is based on an extension of dose-volume histograms and employs an analogous concept to that of cost-benefit analysis, which has already been applied to quality-of-life assessments for two alternative treatment protocols. The COIN index calculation methodology is shown for two cases: with and without critical structures. An analysis is given of dose distributions for two planning treatment volumes (PTV) of simple geometrical shape, applying both the rules of the Paris system and that of the "Offenbach" system. 40 patients who have received interstitial implants form the clinical material. With current HDR brachytherapy technology both for dose delivery, using remote afterloaders, and for three-dimensional (3D) treatment planning, it is now possible to relatively easily plan conformal brachytherapy treatments that would have been impossible with manual afterloading techniques and two-dimensional (2D) treatment planning., Results: Examples of the use of the COIN index are presented for experimental and clinical data., Conclusions: The results show that COIN is a useful and practical index to improve the quality of treatment of interstitial brachytherapy implants. Further work will be undertaken with a larger population of implanted cancer patients and a subdivision of the results by treatment site.

Purpose: To test the feasibility of recombinant human granulocyte colony stimulating factor application during large-field radiotherapy., Methods and Materials: Fifteen patients with clinically and histologically proven malignancy who received large-field radiotherapy entered this study. Administration of recombinant granulocyte colony stimulating factor (G-CSF) at a dose of 300 microgram subcutaneously was started on Friday and was continued on Saturday and Sunday after the first radiotherapy treatment, which began on the Monday before. In this way four courses of G-CSF were applied every Friday, Saturday, and Sunday during the radiotherapy period. Absolute neutrophil cell (ANC) and blood counts were monitored twice a week and compared to a second group of 15 patients who received large-field radiotherapy without G-CSF. Before and at the end of every cycle of G-CSF, ANC, blood counts, and biochemistry were measured. We compared the myelotoxicity of the patients treated with G-CSF with 15 patients without G-CSF treated at the same period with large-field radiotherapy, in match pair technique., Results: G-CSF increased the ANC throughout the period of irradiation, and the treatment time needed for competing radiotherapy was shorter in the group who received G-CSF. Fourteen of 15 patients who received G-CSF treatment completed large-field radiotherapy without pause. Only 1 of 15 patients not receiving G-CSF was able to receive radiation treatment on schedule. Patients receiving G-CSF completed treatment with the mantle-field technique in 24 days and those with the abdominal bath technique in 26.5 days. Conversely, patients treated without G-CSF completed treatment with the mantle-field technique in 30.5 days and those with the abdominal bath technique in 36 days. The most frequent side effect was musculoskeletal pain., Conclusion: The prophylactic application of G-CSF during large-field radiotherapy before the onset of neutropenia was feasible in this schedule. Whether or not this shortening of treatment duration will translate into an improvement in efficacy is not clear.