Biomedical subjects

N Zamboglou

Publications and source records attributed to N Zamboglou.

At least 19 recordsLinked to original sources

PubMed2003

A hybrid evolutionary algorithm for multi-objective anatomy-based dose optimization in high-dose-rate brachytherapy.

Multiple objectives must be considered in anatomy-based dose optimization for high-dose-rate brachytherapy and a large number of parameters must be optimized to satisfy often competing objectives. For objectives expressed solely in terms of dose variances, deterministic gradient-based algorithms can be applied and a weighted sum approach is able to produce a representative set of non-dominated solutions. As the number of objectives increases, or non-convex objectives are used, local minima can be present and deterministic or stochastic algorithms such as simulated annealing either cannot be used or are not efficient. In this case we employ a modified hybrid version of the multi-objective optimization algorithm NSGA-II. This, in combination with the deterministic optimization algorithm, produces a representative sample of the Pareto set. This algorithm can be used with any kind of objectives, including non-convex, and does not require artificial importance factors. A representation of the trade-off surface can be obtained with more than 1000 non-dominated solutions in 2-5 min. An analysis of the solutions provides information on the possibilities available using these objectives. Simple decision making tools allow the selection of a solution that provides a best fit for the clinical goals. We show an example with a prostate implant and compare results obtained by variance and dose-volume histogram (DVH) based objectives.

Algorithms↗

PubMed2003

Management of locally advanced prostate cancer: a European consensus.

This report summarises the findings of a European Consensus Group review of current standards of care in locally advanced prostate cancer defined as (a) untreated cancer extending clinically beyond the prostatic capsule in patients with no evidence of lymph node invasion or distant metastases, and (b) residual disease remaining after local treatment with positive surgical margins, seminal vesicle invasion, persistent prostate-specific antigen (PSA) and/or secondary PSA relapse. There was no overall consensus as to the standard of care in clinically apparent locally advanced prostate cancer. It was agreed, however, that hormonal therapy (e.g. with a gonadotrophin releasing hormone analogue [GnRHa]) represents a valid treatment in these patients. Treatment practices and regimens vary considerably between European countries, but GnRHa is widely used, either alone or in combination with antiandrogens. Hormonal therapy alone is a valid option, though the optimal modality, timing and duration of treatment remain to be defined. Adjuvant therapy with a GnRHa has been shown to improve survival in patients undergoing external beam radiotherapy. It is a viable option after prostatectomy in patients with persistent or secondary relapsing PSA. It was determined that optimal treatment will be different according to PSA, clinical staging and Gleason score, and the treatment of locally advanced disease should be individually tailored after discussion between physician and patient. In many instances, patients prefer and expect some form of treatment in preference to watchful waiting. Treatment nomograms such as the Kattan nomograms provide precise, comprehensive and invaluable tools for everyday use and may be used to predict outcomes and guide treatment decisions.

Androgen Antagonists↗

PubMed2002

Multiobjective anatomy-based dose optimization for HDR-brachytherapy with constraint free deterministic algorithms.

In high dose rate (HDR) brachytherapy, conventional dose optimization algorithms consider multiple objectives in the form of an aggregate function that transforms the multiobjective problem into a single-objective problem. As a result, there is a loss of information on the available alternative possible solutions. This method assumes that the treatment planner exactly understands the correlation between competing objectives and knows the physical constraints. This knowledge is provided by the Pareto trade-off set obtained by single-objective optimization algorithms with a repeated optimization with different importance vectors. A mapping technique avoids non-feasible solutions with negative dwell weights and allows the use of constraint free gradient-based deterministic algorithms. We compare various such algorithms and methods which could improve their performance. This finally allows us to generate a large number of solutions in a few minutes. We use objectives expressed in terms of dose variances obtained from a few hundred sampling points in the planning target volume (PTV) and in organs at risk (OAR). We compare two- to four-dimensional Pareto fronts obtained with the deterministic algorithms and with a fast-simulated annealing algorithm. For PTV-based objectives, due to the convex objective functions, the obtained solutions are global optimal. If OARs are included, then the solutions found are also global optimal, although local minima may be present as suggested.

Algorithms↗

PubMed2002

Brachytherapy dose-volume histogram computations using optimized stratified sampling methods.

A stratified sampling method for the efficient repeated computation of dose-volume histograms (DVHs) in brachytherapy is presented as used for anatomy based brachytherapy optimization methods. The aim of the method is to reduce the number of sampling points required for the calculation of DVHs for the body and the PTV. From the DVHs are derived the quantities such as Conformity Index COIN and COIN integrals. This is achieved by using partial uniform distributed sampling points with a density in each region obtained from a survey of the gradients or the variance of the dose distribution in these regions. The shape of the sampling regions is adapted to the patient anatomy and the shape and size of the implant. For the application of this method a single preprocessing step is necessary which requires only a few seconds. Ten clinical implants were used to study the appropriate number of sampling points, given a required accuracy for quantities such as cumulative DVHs, COIN indices and COIN integrals. We found that DVHs of very large tissue volumes surrounding the PTV, and also COIN distributions, can be obtained using a factor of 5-10 times smaller the number of sampling points in comparison with uniform distributed points.

Brachytherapy↗

PubMed2001

[Intraoperative radiotherapy--progress with a CT-assisted navigation system].

INTRODUCTION: The fact that conventional intraoperative radiotherapy (IORT) does not give the opportunity for exact documentation of the applied radiation volume and dose distribution has been criticised. We would like to introduce a system for surgical navigation and documentation of the flab positioning for intraoperative brachytherapy in afterloading flab technique. METHODS: Our system consists of an electromagnetic 3D digitizer and a PC workstation. Preoperatively taken spiral CT scans of the tumour region are used for navigation and documentation of the flab positioning, analogous to the procedure in neuronavigation. Registration is done via an external reference system attached to the iliac bone of the patient. RESULTS: The mean accuracy of digitalization of the 100 spheres in a pelvis model is about 2.6 +/- 0.5-3.7 +/- 0.9 mm. Mean navigation accuracy is 2.4 +/- 0.8-3.3 +/- 0.8 mm. These figures correspond to the clinical experience of our surgeons. CONCLUSIONS: The optimization of the flab positioning by CT-guided navigation and the more accurate documentation of the dose volume and distribution in the patient is an important step towards improving the quality of individual radiotherapy. We are of the opinion that surgical navigation in the pelvic region should be subject to additional investigation in order to optimize the procedure.

Brachytherapy↗

PubMed2001

Predictive factors in radiotherapy for non-small cell lung cancer: present status.

PURPOSE: To evaluate the predictive factors for radiation response in non-small cell lung cancer (NSCLC) and the role of such factors in guiding high dose radiation therapy. METHODS: The first International Workshop on Prognostic and Predictive Factors in Lung Cancer was organized by the Hellenic Cooperative Oncology Group and held in Athens, Greece under the auspices of the International Association for the Study of Lung Cancer. Presentations at this meeting provided the outline of this report, which has also been supplemented with available data from the current literature. RESULTS: The predictive factors for both the natural history and the therapy outcome of NSCLC are grouped as follows: (1) tumor related factors (anatomic factors); the extent of tumor (tumor stage) is one of most important prognostic factors affecting the therapy outcome. Tumor size (T stage), anatomical structures involved (T4 vs. T3 lesion), and the presence of regional lymph node metastasis have a significant impact on both prognosis and response to appropriate therapy; (2) host-related factors (clinical factors) that are important in therapy response include performance status, weight loss of more than 10% of body weight in the previous 6 months, and associated co-morbidities, i.e. pulmonary and cardiac diseases; (3) technical factors of radiation therapy which play a decisive role in successful outcome. The target volume should be defined accurately using modern imaging studies. The radiation dose fractionation schedule, in terms of the dose intensity and total dose, should be high enough to provide local tumor control in the majority of patients. Three-dimensional (3-D) conformal planning is an essential tool in dose escalation studies to determine the maximum tolerated dose of radiation; (4) biological/radiobiological/metabolic factors. Biologic markers resulting from genetic lesions in lung cancer are grouped as follows: (a) oncogene amplification and overexpression (aberrant gene expression) and mutated tumor suppressor genes -- ras gene, myc gene, HER-2/neu and survivin gene, p53 and mutated beta-tubulin gene; (b) tumor biologic/radiobiologic factors -- tumor cell proliferation kinetics, hypoxia, intrinsic cellular radiosensitivity, gamma factor, and DNA content; (c) enzymes and hormones: neuron-specific enolase, serum lactate dehydrogenase, and enhanced glucose metabolic rate supported by increased glucose transporter protein. The surviving fraction of tumor cells at 2.0 Gy of radiation (SF2) as a measure of intrinsic tumor cell radiosensitivity, potential doubling time (T(Pot)) as a measure of the rate of tumor cell proliferation and gamma factor representing the slope of the survival curve at 50% survival rate are being investigated as potential predictors for therapy response. Enhanced glucose utilization, a hallmark of malignant transformation, is being studied as a potential monitor for therapy response by using PET-FDG. CONCLUSION: Current data indicate that there is a dose-response relationship between radiation dose and local tumor control, and also between local tumor control and survival in stage III NSCLC. Therapeutic factors, i.e. total radiation dose, fractionation schedule and dose intensity, and use of 3-D conformal radiation to secure the optimum therapeutic ratio are important for improved local tumor control and survival. Future research should be directed towards radiation dose escalation using 3-D conformal therapy to determine the maximum tolerated dose (MTD) of radiation in chemo-radiotherapy, and the use of this MTD for improved local tumor control and survival. Radiobiological, molecular, and metabolic markers may have potential for monitoring tumor response and optimizing radiation therapy.

Biomarkers, Tumor↗

PubMed2001

Randomized comparison of early versus late hyperfractionated thoracic irradiation concurrently with chemotherapy in limited disease small-cell lung cancer: a randomized phase II study of the Hellenic Cooperative Oncology Group (HeCOG).

BACKGROUND: Concurrent platinum etoposide chemotherapy given in combination with hyperfractionated thoracic radiation therapy (HTRT) in limited disease (LD) small cell lung cancer (SCLC) is associated with a high response rate and significant prolongation of survival. Given these results, the Hellenic Cooperative Oncology Group (HeCOG) performed a multicenter randomized phase II study in patients with LD SCLC to evaluate the timing of HTRT (early vs. late) when given concurrently with chemotherapy. PATIENTS AND METHODS: To be eligible for the study, patients were required to have histologically or cytologically proven LD SCLC, confined to one hemithorax and/or ipsilateral mediastinal or supraclavicular lymphnodes and absence of pleural effusion or controlateral supraclavicular lymphnode involvement. Moreover, patients had to have a good performance status and adequate haematological, liver and renal function. Patients with LD SCLC were randomized to receive HTRT either concurrently with the first (Group A) or with the fourth (Group B) cycle of chemotherapy. Chemotherapy consisted of carboplatin administered at an AUC of six given as an i.v. 1-hour-infusion immediately followed by etoposide at a dose of 100 mg/m2 i.v. as a two-hour infusion for three consecutive days every three weeks up to a total of six cycles. Prophylactic cranial irradiation was also given to patients achieving a complete response. RESULTS: 42 and 39 patients, were eligible for efficacy evaluation in group A and B respectively. The overall response rate was 76% in group A and 92.5% in group B (P = 0.07) with a complete response rate of 40.5% and 56.5%, respectively. After a median follow-up of 35 months, time to progression was 9.5 months in group A and 10.5 in group B (NS) while overall median survival was 17.5 and 17 months respectively (NS). The 2-year survival was 36% in group A and 29% in group B (NS) and the 3-year survival 22% and 13%, respectively (NS). The distant relapse rate was 38% in group A and 61% in group B (P = 0.046). Severe grade 3 4 anemia was recorded in 19% of group A and 12.5% of group B (NS), while severe leucopenia was recorded in 35.5% and 20.5% (P = 0.09) and neutropenic fever in 5% and 2.5% (NS), respectively. Severe thrombocytopenia did not differ significantly between the two treatment groups being 21.5% and 23%, respectively. Severe grade 2-3 esophageal toxicity was 19% in group A and 23% in group B (NS), while grade 3 lung toxicity was 5% and 7.5% (NS), respectively. No toxicity-related deaths were recorded. CONCLUSION: Concurrent administration of HTRT with carboplatin etoposide is associated with a high response and survival rate. Although a trend for higher response rate was recorded in the group of patients who received late HTRT, the overall median, 2-year and 3-year survival rates did not differ significantly between the two treatment groups. The toxicity of this promising therapeutic approach was acceptable. Comparative phase III studies with an adequate number of patients are recommended in order to answer this question.

Adult↗

PubMed2001

[MR mammography of response-control in primary chemo-brachytherapy in BCT-inoperable breast cancer].

PURPOSE: To evaluate (1) if neoadjuvant chemo-brachytherapy interferes with MR imaging, (2) if MR can predict the size of the remaining tumor after therapy and (3) if MR can give prognostic information after the onset of therapy. MATERIALS/METHODS: 14 patients enrolled in a preoperative tumor-reduction protocol (4 cycles of chemotherapy combined with interstitial radiotherapy) were examined by dynamic contrast enhanced MR mammography (1 T, temporal resolution 93 s, spatial resolution 1.9 min, 0.1 mmol/kg GdDTPA), before therapy, after the first two cycles of chemotherapy, after radiotherapy and the third cycle, and after completion of therapy. MR findings were evaluated for (1) artificial enhancement after radiotherapy, (2) correlation of enhancement after therapy with histology and (3) changes in enhancement dynamics after the first 2 cycles. RESULTS: (1) 54% of patients had diffuse enhancement that occurred after radiotherapy but vanished before the end of therapy. (2) 4 patients had complete histological remissions after therapy, 3 had dispersed single tumor cells, 7 had remaining nodular tumor. While MR could not differentiate between complete remission and single tumor cells, it accurately predicted the diameter of remaining nodular tumor, except for one case that showed false-positive enhancement. (3) MR dynamics after the first cycles of chemotherapy could not predict overall response. CONCLUSIONS: MR is an accurate tool in assessing tumor response after neoadjuvant chemobrachytherapy. Negative effects from radiotherapy are only transient.

Adult↗

PubMed2001

Long-term effects on the intelligence of children treated for acute lymphoblastic leukemia.

The purpose of this study was to investigate whether the intelligence quotient (IQ) in children treated for leukemia decreases in the years following whole brain irradiation. Twenty-seven leukemic children were assessed following a mean time lapse between radiotherapy and IQ measurement of 9 years. The IQ test used was the Hamburg Weschsler Intelligence Test for Adults. The IQ results did not differ significantly, p > 0.05, from the IQs of the general population. It was found that age and dose were not predictors of a decrease in IQ. The only predictor was time lapse between irradiation and IQ measurement, which we found to be indicative of an IQ decrease even after 9 years. Time lapse between irradiation is a useful predictor of IQ.

Adult↗

PubMed2001

A new algorithm for autoreconstruction of catheters in computed tomography-based brachytherapy treatment planning.

This paper describes innovative software for automatic reconstruction, which we term autoreconstruction, of plastic and metallic brachytherapy catheters using computed tomography (CT) data. No such automatic facility has previously existed in any treatment planning software. The patient data consists of a set of post-implantation CT images with the catheters in situ in their final positions. This new software solves those difficulties which arise when the catheters are intersecting or when loop techniques are used. With the software algorithms, catheter reconstruction time is significantly reduced and accuracy is also improved when compared with that achieved using the classical manual method of CT-slice-by-CT-slice reconstruction.

Algorithms↗

PubMed2001

Correcting organ motion artifacts in x-ray CT systems based on tracking of motion phase by the spatial overlap correlator. II. Experimental study.

This paper presents the experimental part of an investigation on tracking and eliminating organ motion artifacts in x-ray CT cardiac applications with emphasis on imaging coronary calcification. The system methodology consists of a software implementation of the spatial overlap correlator (SSOC) concept in x-ray CT scanners to track the net amplitude and phase of organ motion during the CT data acquisition process. A coherent sinogram synthesis (CSS) method is then used to identify the repeated phases of a periodic organ motion from the information provided by the SSOC process and hence synthesize a new sinogram with no motion effects. Since the SSOC scheme is capable of tracking cardiac motion, it identifies also the projection points associated with minimum amplitude cardiac motion effects. These points are used to identify a 180 degrees plus the fan angle sinogram for image reconstruction. This leads to a retrospective gating (RG) scheme that is based on the output of the SSOC process. Performance comparison of the proposed methodology with the retrospective ECG gating using real data sets with phantoms and human patients provides a performance assessment of the merits of the proposed methods. Real results demonstrate that the new methodology eliminates the requirement for ECG gating. Moreover, the CSS and the new RG methods do not require breath holding and they can be implemented in x-ray CT scanners to image coronary calcification and the heart's ventricles.

Algorithms↗

PubMed2001

Beta versus gamma dosimetry close to Ir-192 brachytherapy sources.

The relative importance of the dose rate component owing to the beta spectrum emitted by 192Ir brachytherapy sources at the short radial distances of interest in intravascular and endobronchial applications is investigated. Separate dosimetric calculations, using Monte Carlo simulations, were performed for the gamma and beta dose rate components of an 192Ir ideal point source as well as real 192Ir source designs used in clinical practice including wire and seed sources and both Nucletron and Varian, old and new, high dose rate (HDR) source designs. A significant dose rate enhancement due to the beta spectrum emitted by 192Ir, greater than 50% for radial distances r<2 mm, was observed for an ideal point source. For real source designs, however, the magnitude of this enhancement was found to depend strongly on the sources' geometric as well as compositional details of the active core and encapsulation. A detectable effect was found for the majority of the investigated sources at radial distances less than 1 mm, but overall findings suggest that the contribution of beta particles is not significant in 192Ir clinical intravascular applications that are currently carried out. However, since treatment of vessels with smaller diameters, in the future, may lead to the development of 192Ir sources and catheters of reduced diameters, the potential effect of the beta spectrum in terms of dose enhancement to tissues in close proximity to 192Ir sources should not be ignored.

Beta Particles↗

PubMed2001

CT-based navigation systems for intraoperative radiotherapy using the afterloading-flab technique.

INTRODUCTION: The fact that conventional intraoperative radiotherapy does not give the opportunity to exactly document the radiation volume applied and the dose distribution has been criticized in many ways. We would like to introduce a system for surgical navigation and documentation of flap positioning in intraoperative brachytherapy using the afterloading flap technique. METHODS: Our system consists of an electromagnetic 3D-digitizer and a PC workstation. Spiral CT scans of the tumor region taken preoperatively are used for navigation and documentation of flap positioning, analogous to the procedure in neuronavigation. Registration is done via an external reference system which is attached to the iliac bone of the patient. RESULTS: The mean accuracy of digitalization of the 100 spheres in a pelvis model is about 2.6 +/- 0.5 to 3.7 +/- 9.9 mm. The mean navigation accuracy is 2.4 +/- 0.8 to 3.3 +/- 0.8 mm. These figures correspond to the clinical experience of our surgeons. DISCUSSION: The optimization of flab positioning by CT-guided navigation and the more accurate documentation of the dose volume and distribution in the patient is an important step on the way to improving the quality of individual radiation therapy. We are of the opinion that surgical navigation in the pelvic region should be subject to additional investigation in order to optimize the procedure.

Brachytherapy↗

PubMed2001

Role of interstitial brachytherapy in the treatment of malignant disease.

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.

Brachytherapy↗

PubMed2001

Radiation therapy for the prevention of heterotopic ossification at the elbow.

We present nine patients (five men and four women) who underwent surgical excision of clinically significant heterotopic ossification at the elbow. They also received perioperative radiation therapy using total doses between 600 and 1000 cGy. Five received fractionated radiotherapy, with two fractions of 500 cGy applied on the first two postoperative days, and the remaining four were irradiated with single doses of 600 and 700 cGy. After a mean period of observation of 7.7 months (6 to 13) none had radiological recurrence of heterotopic ossification and eight showed clinical improvement. Assessment of the functional outcome showed a mean improvement in the Morrey score from 33.3 to 84.5 points indicating a high therapeutic efficacy of prophylactic irradiation.

Adult↗

PubMed2001

[Radiotherapy in vertebral hemangioma].

Vertebral hemangiomas are the most common benign spinal tumors with an incidence range of 10-12%. Approximately 1-2% of the cases develop clinically significant symptoms causing the necessity for treatment. Based on our own results and a review of the literature we discuss the role of radiotherapy in the management of symptomatic vertebral hemangiomas. A total dose of 30.0 Gy given in five weekly fractions of 2.0 Gy has been proven as effective for the primary treatment and postsurgical irradiation for the prevention of a recurrence. In the literature review the results are summarized of 59 reports in the period of 1929-2000 for a total of 327 cases. The analysis of 55 studies reporting results in 210 cases which underwent primary radiotherapy or combinations with other methods of treatment demonstrated that in 54% occurred a complete relief of symptoms (CR), in 32% a partial relief (PR), and 11% were non-responders (NR). The analysis of 21 reports of 63 cases which were treated with radiotherapy as the sole measure of treatment demonstrated that 57% had a complete remission of symptoms (CR), 32% a partial remission (PR), and 11% did not respond to radiotherapy (NR). We conclude that radiation therapy is very effective in the management of symptomatic vertebral hemangiomas. With regard on the delayed effects of the irradiation, cases with an acute compression of the spinal cord should be treated primarily with a surgical procedure and a postsurgical irradiation is recommended to prevent a relapse of symptoms. In order to minimise acute or late toxicity and the risk of radiation-induced neoplasms the total dose should not exceed 30 Gy.

Adult↗

PubMed2001

Hypofractionated radiotherapy for Graves' orbitopathy.

BACKGROUND: Radiotherapy (RT) has been proven effective in the management of Graves' orbitopathy in numerous studies. Most commonly is the use of conventional fractionated RT and the value of hypofractionated irradiation has not been investigated. MATERIALS AND METHODS: The results in 33 euthyroid cases who underwent RT with a total dose of 21.0 Gy given in three weekly fractions of 3.0 Gy are retrospectively analyzed. The duration of symptoms ranged from 1-84 months and all of the cases had treatment failure after previous administration of corticosteroids. After a mean follow-up period of 33.6 months the overall results were assessed according to the criteria by Donaldson et al. and for evaluation of the clinical outcome a classification with the main criteria being eye-lid changes, exophthalmos, myopathy and eye nerve involvement was used. RESULTS: At follow-up, the overall response to RT was 84.8% (28/33 cases). The analysis with the clinical classification demonstrated that in 19/33 (57.6%) cases occurred a decrease of eye lid changes and exophthalmos and 12/33 (36.4%) had a relief of myopathy. 2/33 cases (6.0%) developed an eye nerve compression causing the necessity of surgical decompression. 3/33 cases (9.0%) had a progression of at least of one of the single criteria of the score and therefore they were classified as non-responders. CONCLUSIONS: Hypofractionated RT has been proven effective for treatment of severe cases of Graves' orbitopathy in cases with a prolongated duration of symptoms. The comparison with literature data demonstrate that the results after hypofractionated RT are comparable to those obtained after conventional fractionated RT.

Adult↗

PubMed2000

Reconstruction and navigation system for intraoperative brachytherapy using the flab technique for colorectal tumor bed irradiation.

PURPOSE: To present the development of a new navigation and reconstruction system based on an electromagnetic free-hand tracker and on CT imaging for treatment planning of intraoperative high-dose-rate brachytherapy (IORT-HDRB) in the sacral region. Our aim is to improve accuracy and to enable individualized treatment planning and dose documentation to be performed for IORT-HDRB using a flab technique. METHODS AND MATERIALS: The material consists of an electromagnetic 3D tracker system, a PC workstation with Microsoft Windows NT 4.0 operating system, and a recognition program for continuous speech. In addition, we designed an external reference system constructed of titanium and Perspex, which is positioned in the pelvis, and a special digitizer pen for reconstruction of the flab geometry. The flab design incorporates a series of silicon 10-mm-diameter spherical pellets. Measurements were made with a pelvic phantom in order to study the accuracy of the system. The reconstruction results are stored and can be exported via network or floppy to our different treatment planning systems. RESULTS: Our results for the reconstruction of a flab with six catheters and a total of 100 spherical pellets give mean errors in the range (2.5 +/- 0.6) mm to (3.5 +/- 0.8) mm depending on the positions of the pelvic phantom and transmitter relative to the operation table. These errors are calculated by comparing the reconstruction results of our system with those using a CT-based reconstruction of the flab geometry. For the accuracy of the navigation system for the pelvic phantom, we obtained mean errors in the range (2.2 +/- 0.7) mm to (3. 1 +/- 1.0) mm. CONCLUSIONS: The new system we have developed enables navigation and reconstruction within the surgical environment with a clinically acceptable level of accuracy. It offers the possibility of individualized treatment planning and effective documentation of the 3D dose distribution in IORT-HDRB using a flab technique.

Brachytherapy↗