[Stereotactic radiosurgery of brain tumors]. / Agyi daganatos elváltozások sztereotaxiás besugárzása.

Stereotactic radiosurgery is today a well-established treatment modality for various intracranial pathologies. The principle of high dose focused intracranial radiation guided by stereotactic technique ("Gamma Knife") was introduced by the Swedish neurosurgeon Prof. Lars Leksell in 1968. After the advent of CT and later MR imaging, stereotactic radiosurgery evolved rapidly regarding indications, and new technical solutions made it possible for linear accelerator systems to perform radiosurgery. A huge number of patients are treated yearly worldwide with this technology. In this article we overview the major indications, advantages and possible complications of stereotactic radiosurgery.

[The clinical impact of amino acid positron emission tomography measurements in the treatment of primary malignant brain tumors]. / Az aminosav-pozitronemissziós tomográfiás mérések klinikai jelentosége a primer rosszindulatú agydaganatok kezelésében.

Despite the large-scale diagnostic and therapeutic progress of recent years, the heterogeneity and therapeutic management of adult primary malignant brain tumors pose a significant challenge to the attending physician. Based on the research and experience accumulated over the past two decades, the range of patients who can benefit the most from complex oncology treatment has been outlined, and it has been confirmed that a reliable complex diagnostic background is essential for adequate therapeutic management. However, after some necessary therapeutic steps, the "gold standard" magnetic resonance imaging (MRI) is not always able to accurately assess and diagnose post-therapeutic conditions. Thanks to the collaboration of the nuclear medicine and neuro-oncology professions, more and more types of radiotracer compounds are now available in more and more centers, including amino acid ligands and thus, positron emission tomography (PET) examinations with the radiopharmaceutical O-(2-[18F]fluoroethyl)-L-tyrosine. The metabolic state, as a kind of fourth dimension of imaging, is an essential part of adequate modern diagnostics. Combining advanced MRI techniques and PET-based (PET/CT, PET/MRI) measurements with a suitable tracer can place therapeutic decisions on a reliable basis. We present the clinical significance of amino acid-PET-based hybrid nuclear medicine imaging studies in the therapeutic management of these patients by reviewing the literature data on the practice of the method in Hungary and abroad and presenting the results of our retrospective summary research so far. Orv Hetil. 2023; 164(32): 1247-1255.

Therapy Defining at Initial Diagnosis of Primary Brain Tumor-The Role of 18F-FET PET/CT and MRI.

Primary malignant brain tumors are heterogeneous and infrequent neoplasms. Their classification, therapeutic regimen and prognosis have undergone significant development requiring the innovation of an imaging diagnostic. The performance of enhanced magnetic resonance imaging depends on blood-brain barrier function. Several studies have demonstrated the advantages of static and dynamic amino acid PET/CT providing accurate metabolic status in the neurooncological setting. The aim of our single-center retrospective study was to test the primary diagnostic role of amino acid PET/CT compared to enhanced MRI. Emphasis was placed on cases prior to intervention, therefore, a certain natural bias was inevitable. In our analysis for newly found brain tumors 18F-FET PET/CT outperformed contrast MRI and PWI in terms of sensitivity and negative predictive value (100% vs. 52.9% and 36.36%; 100% vs. 38.46% and 41.67%), in terms of positive predictive value their performance was roughly the same (84.21 % vs. 90% and 100%), whereas regarding specificity contrast MRI and PWI were superior (40% vs. 83.33% and 100%). Based on these results the superiority of 18F-FET PET/CT seems to present incremental value during the initial diagnosis. In the case of non-enhancing tumors, it should always be suggested as a therapy-determining test.

The Role of Stereotactic Radiotherapy in the Management of Melanoma, A Retrospective Single Institute Preliminary Study of 30 Patients.

Cutaneous melanoma is the third most common type of skin cancer in the world. The incidence of melanoma is increasing in most countries, however, mortality seems to be slowly decreasing. The treatment of advanced cutaneous melanoma changed radically since 2011. The new therapeutic modalities, such as immuno- and targeted therapies give a chance to successfully reach more prolonged progression-free survival (PFS) and overall survival (OS) in patients with metastatic melanoma. Despite the great therapeutic benefit, most patients eventually develop resistance to these therapies, and the disease will progress. In some cases oligoprogression develops. In those cases local therapy, such as stereotactic radiotherapy can make it possible to continue the previously applied effective medical treatment for the benefit of patients. In our study of a total of 30 patients-20 of them received pre-treatment with systemic medical therapy-received stereotactic radiotherapy using various systems, in the National Institute of Oncology, Hungary, Budapest. We managed to prolong the systemic therapy for 12.5 months median period with the assistance of CyberKnife technique. Therapy related adverse events were mostly tolerable with only 3% of Grade 3 toxicity. We concluded that stereotactic radiotherapy and stereotactic radiosurgery, are safe, and effective therapeutic modalities for regional tumor control in cases of oligoprogression.

Supplementary valproate therapy for glioma patients: An alternative opportunity to enhance the efficiency of radio-chemotherapy / A valproátterápia túlélésre gyakorolt hatása gliomás betegekben: Alternatív terápiás lehetoség a radiokemoterápia eredményességének javítására

Összefoglaló. Bevezetés: A gliomák, ezen belül a glioblastoma kezelése továbbra is megoldatlan onkológiai problémát jelent. A szekunder szimptómás epilepsziabetegség megjelenése pozitív prognosztikai faktornak tekintheto a korai diagnosztizálás és az antiepileptikumok potenciális tumorellenes hatásának köszönhetoen. A valproát túlélést hosszabbító hatása már több mint 20 éve az alap- és klinikai kutatások tárgyát képezi. Napjainkban ismert citotoxikus, proapoptotikus, antiangiogenetikus és hiszton-deacetiláz-gátló hatásmechanizmusa. Célkituzés: Kutatásunk célja a valproát túlélést hosszabbító hatásának vizsgálata egy hazai gliomás betegcsoportban. Módszer: Egycentrumos, retrospektív klinikai vizsgálatot végeztünk. A vizsgálatba 122 felnott beteget vontunk be, akiknél 2000 januárja és 2018 januárja között supratentorialis glioma miatt mutét történt, és rohamtevékenység miatt antiepileptikumot (valproát, levetiracetám, karbamazepin) szedtek. Egyúttal gyógyszert nem szedo kontrollcsoportot is kialakítottunk. A populációt vizsgálati és kontrollcsoportokra osztottuk 28 : 52 arányban. Leíró statisztikai, Kaplan-Meier- és log-rank analízist végeztünk. Eredmények: A vizsgált szövettani kategóriák túlélési analízise az irodalmi adatokkal megegyezo értékeket mutatott. A progressziómentes (PFS: p = 0,031) és a teljes (OS: p = 0,027) túlélés tekintetében is szignifikáns eltérés mutatkozott a különbözo antiepileptikumot szedo betegcsoportok között, amely még kifejezettebbé vált a valproátot és az egyéb antiepileptikumot szedo betegek túlélési idejének összehasonlítása során (PFS: p = 0,006; OS: p = 0,015). Következtetés: Vizsgálatunkban a valproát betegeink PFS- és OS-idejének meghosszabbodását eredményezte. Az irodalmi adatok és kutatásunk alapján megfontolandónak tartjuk a valproát elso vonalban történo alkalmazását onkoterápiában részesülo, epilepsziás, agyi gliomás betegekben. Orv Hetil. 2021; 162(24): 960-967. INTRODUCTION: Gliomas still prove to be a serious oncological problem. The presence of epilepsy may present a favorable prognosis due to early diagnosis and the potential antitumor effects of antiepileptic drugs. The survival prolongation effect of valproate has been studied for more than 20 years, nowadays its proapoptotic, anti-angiogenetic, cytotoxic and histone deacetylase inhibitory effects are well known. OBJECTIVE: Our goal was to investigate the survival-enhancing effects of valproate in a Hungarian patient cohort of primary brain tumors. METHOD: A single-center based retrospective clinical trial was designed. In our study, we included 122 patients harboring supratentorial glioma who underwent surgery and experienced seizures between 2000 January and 2018 January. The patients were grouped by the antiepileptic therapies and survival analysis was performed. RESULTS: The Kaplan-Meier curves of the histological categories showed the survival values consistent with the data of the literature. The progression-free (PFS: p = 0.031) and the overall (OS: p = 0.027) survival of the antiepileptic drug categories were significantly different. It was performed by comparing the valproate group and the population formed by the other groups which also showed a significant increase in the survival values (PFS: p = 0.006; OS: p = 0.015). CONCLUSION: Our results show that valproate increases the PFS and OS period of glioma patients in comparison to other antiepileptic drugs. Our data suggest that the use of valproic acid should be considered as a first-line antiepileptic agent in certain well-selected epileptic patients with glioma as a supplement to the oncotherapy. Orv Hetil. 2021; 162(24): 960-967.

[Early experience with CyberKnife treatment in case of intra-, suprasellar hypernephroma metastasis]. / Korai tapasztalataink CyberKnife-kezeléssel suprasellarisan is terjedo hypernephroma-áttét esetén.

Among tumours found in the suprasellar region metastases are very rare and the most frequent primary tumours are lung and breast cancer. Data of a patient with clear cell renal carcinoma with intra-suprasellar metastasis will be discussed. As in most of the tumours in the sellar region, the first symptom was visual deterioration with visual field defect. A transsphenoidal debulking of the tumour was performed and the residual tumor was treated by CyberKnife hypofractionated stereotactic radiotherapy. Both our patient's visual acuity and visual field impairment improved after the surgery and CyberKnife treatment. At 6-month after irradiation, MR of the sella showed a complete remission of the tumour. This was the first treatment with CyberKnife in our country in case of a tumour close to the optic chiasm. According to our best knowledge, there are 21 cases in the literature with renal cell carcinoma metastasis in the suprasellar region.

[The effect of bevacizumab monotherapy on progression free survival in recurrent glioblastoma]. / A bevacizumab-monoterápia hatása a progressziómentes túlélésre rekurrens glioblastomában szenvedo betegek esetében.

BACKGROUND AND PURPOSE: Glioblastoma, WHO grade IV is the most frequent primary malignant brain tumor in adults. There are few articles and result about the efficacy of bevacizumab monotherapy. The aim of our paper is to examine the effect of bevacizumab therapy on progression free and overall survival in an extended database of recurrent glioblastoma patients. METHODS: In our retrospective study, patients with recurrent glioblastoma treated with bevacizumab had been collected. All of our patients received first line chemo-irradiation according the Stupp protocol treatment. The histological diagnosis was primary or secondary glioblastoma in every patient. The prognostic features of primary and secondary glioblastomas were statistically analyzed. RESULTS: Eighty-six patients were selected into the retrospective analysis. The histological diagnosis was primary glioblastoma in 65 patients (75.6%) and secondary glioblastoma in 21 patients (24.4%). The mean follow up period was 36.5 months. The mean second progression free survival beside bevacizumab therapy was 6.59 months and the mean overall survival was 24.55 months. In secunder glioblastoma cases, the mean second progression free survival was 6.16 months and the mean overall survival was 91.94 months. CONCLUSION: The bevacizumab therapy is a safe option in recurrent glioblastoma patients. Bevacizumab therapy has a positive effect both on progression free and overall survival and our results confirm the findings in the literature. There is no statistically significant difference in the second progression free survival between glioblastoma subtypes.

Intensity modulated operating mode of the rotating gamma system.

PURPOSE: The purpose of this work was to explore two novel operation modalities of the rotating gamma systems (RGS) that could expand its clinical application to lesions in close proximity to critical organs at risk (OAR). METHODS: The approach taken in this study consists of two components. First, a Geant4-based Monte Carlo (MC) simulation toolkit is used to model the dosimetric properties of the RGS Vertex 360™ for the normal, intensity modulated radiosurgery (IMRS), and speed modulated radiosurgery (SMRS) operation modalities. Second, the RGS Vertex 360™ at the Rotating Gamma Institute in Debrecen, Hungary is used to collect experimental data for the normal and IMRS operation modes. An ion chamber is used to record measurements of the absolute dose. The dose profiles are measured using Gafchromic EBT3 films positioned within a spherical water equivalent phantom. RESULTS: A strong dosimetric agreement between the measured and simulated dose profiles and penumbra was found for both the normal and IMRS operation modes for all collimator sizes (4, 8, 14, and 18 mm diameter). The simulated falloff and maximum dose regions agree better with the experimental results for the 4 and 8 mm diameter collimators. Although the falloff regions align well in the 14 and 18 mm collimators, the maximum dose regions have a larger difference. For the IMRS operation mode, the simulated and experimental dose distributions are ellipsoidal, where the short axis aligns with the blocked angles. Similarly, the simulated dose distributions for the SMRS operation mode also adopt an ellipsoidal shape, where the short axis aligns with the angles where the orbital speed is highest. For both modalities, the dose distribution is highly constrained with a sharper penumbra along the short axes. CONCLUSIONS: Dose modulation of the RGS can be achieved with the IMRS and SMRS modes. By providing a highly constrained dose distribution with a sharp penumbra, both modes could be clinically applicable for the treatment of lesions in close proximity to critical OARs.

Dabrafenib Therapy in 30 Patients with Melanoma Metastatic to the Brain: a Single-centre Controlled Retrospective Study in Hungary.

Dabrafenib is a potent BRAF inhibitor, which showed intracranial tumor activity. The purpose of our retrospective analysis was to evaluate the efficacy of dabrafenib for patients with melanoma brain metastasis (BM). We studied 30 BRAF mutant melanoma patients with BM, who received dabrafenib after local control of the brain between 2014 and 2017. Eastern Cooperative Oncology Group Performance Status (ECOG) was 0-2. The control arm consisted of 204 melanoma patients from our institutional melanoma database with BM and ECOG 0-2 treated with local therapies and/or chemotherapy, between 2003 and 2015. We found the intracranial disease control rate (DCR) was 83% including four (13%) complete remissions (CR), nine (30%) partial remissions (PR) and twelve (40%) stable diseases (SD) in contrast to five (17%) progressive diseases (PD). With a median follow-up of 14 months, median progression-free survival (PFS) and overall survival (OS) were 5.5 months, and 8.8 months, respectively. If calculated from BM onset, the OS turned to be 11.8 months on the dabrafenib arm, while it was only 6.0 months in the control arm (HR = 0.45, p = 0.0014). Higher risk of progression was observed with increasing ECOG (HR =4.06, p = 0.00027) and if more than 2 extracranial organs were involved (HR = 3.4, p = 0.0077). Elevated lactate dehydrogenase (LDH) was non-significantly associated with worse clinical outcome. Remarkable intracranial activity of dabrafenib in real practice was confirmed by our analysis.

[RADIOSURGERY OF INTRACEREBRAL CAVERNOMAS--CURRENT INTERNATIONAL TRENDS]. / AZ INTRACEREBRALIS CAVERNOMÁK SUGÁRSEBÉSZETE--HOL TART MA A VILÁG?

Although still a controversial management option, radio-surgery of intracranial cavernomas has become increasingly popular world-wide during the last decade. Microsurgery is a safe and effective treatment for symptomatic hemispheric cavernomas. However, the indication for microsurgical resection of deep eloquent cavernomas is relatively limited even in experienced hands. The importance of radiosurgery has recently been appreciated in parallel with increasing positive experiences both in terms of effectiveness and safety, especially for cases high risk for surgical resection, in the brainstem, thalamus and basal ganglia. While radiosurgery was earlier indicated mainly for surgically inaccessible lesions that had bled multiple times, a more proactive policy has recently become more accepted. In our opinion preventive treatment with the low morbidity radiosurgery serves the patients' interest especially for deep eloquent lesions that had bled not more than once, due to the cumulative morbidity of repeated hemorrhages. Despite our increasing knowledge on natural history, there is currently no available treatment algorithm for cavernomas. Arguments for all three treatment modalities (observation, microsurgery and radiosurgery) are established, but their indication criteria are yet to be defined. It is time to organize a prospective population based data collection in Hungary, which appears to be the most realistic way to clarify indication criteria.

[RADIOSURGERY OF INTRACEREBRAL CAVERNOMAS--CURRENT HUNGARIAN PRACTICE]. / AZ INTRACEREBRALIS CAVERNOMÁK SUGÁRSEBESZETE--HOL TART MAGYARORSZÁG?

BACKGROUND AND PURPOSE: Radiosurgery is an increasingly popular treatment option especially for deep eloquent intracerebral cavernomas that are often too risky for surgical removal, but their re-bleed carries significant risk for persisting neurological deficit. Gamma-radiation based radiosurgery has been being available since 2007 in Hungary in Debrecen. Our aim is to summarize our experience accumulated during the first five years of treatment and to compare it to the international experience. PATIENT SELECTION AND METHODS: We retrospectively analyzed 51 cavernomas in 45 patients treated between 2008 and 2012 in terms of localization, natural history, and the effect of radiosurgery on re-bleed risk and epilepsy, and its side effects. RESULTS: We treated 26.5% deep eloquent (brainstem, thalamic/basal ganglia) and 72.5% superficial hemispheric cavernomas. The median presentation age was 25 years (13-60) for deep, and 45 years (6-67) for superficial cavernomas. They were treated median of 1 year after presentation. 64.5% of deep cavernomas bled before treatment, the annual risk of first hemorrhage was 2%/lesion, re-bleed risk 21.7%, with 44% persisting morbidity. 13.5% of superficial cavernomas bled prior to treatment, the risk of first bleed was 0.3%, there was no re-bleed, and 35% caused epilepsy. We used GammaART-6000TM rotating gamma system for treatment, marginal dose was 14 Gy (10-16), and treatment volume 1.38-1.53 cm3. Re-bleed risk of deep eloquent lesions fell to 4% during the first two years after treatment and to 0% thereafter, and no hemorrhage occurred from superficial lesions after treatment. Persisting morbidity in deep lesions came from adverse radiation effect in 7% and from re-bleed in 7%, and there was no persisting side effect in superficial cavernomas. 87.5% of cases of epilepsy resistant to medical therapy improved. Radiological regression was found in 37.5% and progression in 2% after treatment. CONCLUSIONS: Radiosurgery of cavernomas is safe and effective. Early preventive treatment for deep cavernomas carrying high surgical risk is justified. Moreover, for superficial lesions that are surgically easily accessible radiosurgery also appears to be an attractive alternative.

[Treatment-induced tumor-like lesions in the course of neurooncological therapy]. / Tumort utánzó barrierzavarok a neuroonkológiai terápia során.

The proper interpretation of imaging changes in the course of multimodal neurooncological therapy (neurosurgery, radiotherapy, chemotherapy, stereotactic radiosurgery) is crucial. The appearance of abnormal or new contrast-enhancing lesions does not indicate obvious tumor progression, in the contrary they are frequently induced by the oncological therapy itself. The differentiation of real tumor progression from therapy-induced lesions is essential, since the diagnosis of progressive disease results in the termination of the current regimen and initiation of second or third line therapy, if possible. The most common frequent therapy-induced tumor-like lesions include the followings: pseudoprogression seen at 1-3 months after the completion of concomittant radiochemotherapy of high-grade gliomas, real radiation necrosis which can develop even years after the completion of fractionated external beam radiotherapy of gliomas, and radiation necrosis seen after stereotactic radiosurgery delivered to metastatic brain tumors. The absorbable hemostatic materials applied to the wall of resection cavity during brain tumor surgery might cause delayed disturbancies in the blood brain barrier, inducing abnormal signal changes and contrast enhancement mimicking residual or recurrent tumor. Cerebrovascular ischemic lesions might cause cortical enhancement in the subacute stage, which may be misinterpreted as leptomeningeal tumor spread. The correct assessment of imaging findings requires special knowledge and multidisciplinary consultation, therefore the treatment and follow-up of brain tumor patients should be linked to brain tumor centers staffed by experts in the field of neurosurgery, neurooncology and brain tumor imaging.

[Results of postoperative radiochemotherapy of glioblastoma multiforme]. / Glioblastoma multiforme posztoperatív radio-kemoterápiájának eredményei.

Glioblastoma multiforme has one of the worst prognoses of all cancers. A substantial progression in its treatment has been achieved only eight years ago when a new adjuvant radiochemotherapy regimen containing temozolomid has been introduced to the clinical practice. In this paper we evaluate the treatment results in adjuvant radiochemotherapy of glioblastoma carried out by two neurosurgery and oncology centers in Budapest, Hungary and we compared our results to the data of the reference phase III registration trial of the EORTC/NCIC. We analyzed the data of 210 patients treated for glioblastoma between 2005 and 2013. The primary endpoints of our study were overall survival and side effects. We studied and statistically analyzed the influence of multiple factors on survival. We compared our results with the data of the reference study and other results published in the literature. The median follow-up for the surviving patients in our study was 52 months. The median age of our patients was 58 (18-79) years. Seventy-two women and 138 men have been treated. The median overall survival was 17 (3-96) months, the progression-free survival 11 (3-96) months. The radiochemotherapy phase was completed in 95.2% and the monotherapy phase in 68% of all cases.Univariate analysis showed that age, ECOG status and RPA class had significant influence on survival. In multivariate analysis only RPA class remained statistically significant (RR 1.86, 95% CI 1.14-3.05). The proportion of grade III and worse side effects during the chemoradiation phase was 3.8% and in the monotherapy phase 1.9%. These were hematological side effects only. Serious hematological sequelae occurred nearly exclusively in women. Comparing to the reference study the demographic distribution of the patients was similar in our study but among our patients there were less patients with unfavorable prognosis (ECOG 2 or RPA V), and it resulted in a longer median survival than in the original trial (17 vs. 14.6 months). With this analysis of our patients treated according to the Stupp-protocol for glioblastoma multiforme we validated the results of the original EORTC/NCIC study in a Hungarian patient population. Moreover, this comparison proves that the comprehensive Hungarian neuro-oncology service is not at all inferior when compared to any of the developed countries in Europe.

[Role of the intraoperative electrical brain stimulation in conserving the speech and language function in neurosurgical procedures on conscious patients]. / Az intraoperatív elektromos agyi stimuláció szerepe a nyelvi és beszédfunkciók megorzése céljából éber betegeken végzett idegsebészeti beavatkozások során.

AIM OF THE STUDY: To summarize the results gained with awake craniotomies, which were performed in either low grade glioma patients or epilepsy surgical patients whose tumor or epileptogenic zone, was in the vicinity of eloquent, mostly language, cortices. PATIENT SELECTION AND METHODS: In our retrospective study we selected 16 patients who were operated awake between 1999-2011 at the Neurosurgical Department of MAV Kórház Budapest, or at the National Institute of Neurosciences in Budapest, or at the Neurosurgical Department of the University of Debrecen in Debrecen. In the presurgical evaluation if it was possible we performed functional magnetic resonance imaging, tractography and detailed neuropsychological testing. At the National Institute of Neurosciences all patients were operated with the aid of MR guided neuronavigation. RESULTS: Anesthesia was carried out without complications in all of the 16 cases. Monitoring of sleep deepness has significantly contributed to the safety of anesthesia during the superficial anesthezied states of the operation. The intraoperative neuropsychological tasks used for testing language were sensitive enough to judge the little disturbances in speech during stimulation. Stimulation evoked seizures could be adequately managed during surgery and did not influence the outcome of the procedures. The use of neuronavigation helped significantly by planning the optimal place for the craniotomy and by intraoperative orientation. CONCLUSIONS: Awake craniotomies require well practiced surgical teams, which requires the cooperation of neuro-anesthesiologits, neurosurgeons, neuropsychologist and electrophysiologists. It has two goals, first to reduce the time of surgery to minimize surgical complications, secondly the detailed intraoperative mapping of cognitive and motor functions to avoid any neurological deficit. The intraoperative anatomical data provided by the neuronavigation and the functional data provided by awake intraoperative stimulation of the patient together serve the safety of the patient which is essential in the neurologically minimal invasive neurosurgical approach of the 21st century.

The pre-requisite of a second-generation glioma PET biomarker.

UNLABELLED: Since the introduction of FDG into the field of molecular imaging with positron emission tomography (PET) more than three decades ago, FDG has been the tracer of choice for oncology PET imaging. Despite the relative disadvantages of FDG and the relative benefits of its challengers, FDG remains the most commonly used glioma tracer nowadays. The present article surveys the expectations of the field and gives a concise summary of recent developments; including the issues pertaining to the continued search for an optimal second-generation PET biomarker for glioma. MINI-ABSTRACT: The present article gives a concise summary of recent developments; including the issues pertaining to the continued search for an optimal PET biomarker for glioma.

Neuronavigation and fluoroscopy-assisted subdural strip electrode positioning: a simple method to increase intraoperative accuracy of strip localization in epilepsy surgery.

For localization of the epileptogenic zone in cases of focal epilepsy, detailed clinical investigations, imaging studies, and electrophysiological methods are used. If the noninvasive presurgical evaluation provides insufficient data, intracranial electrodes are necessary. Computed tomography and MR imaging techniques are the gold standard for localization of the postoperative position of the implanted intracranial electrode contacts. If the electrode strips are inserted through a bur hole, however, the exact localization of the electrode contacts on the patient's brain remains uncertain for the surgeon during insertion. Therefore, the authors developed a simple method to visualize the electrodes during the procedure. In this method they combine neuronavigation and intraoperative fluoroscopy for parallel visualization of the cortex, electrodes, and the navigation probe. The target region is searched with neuronavigation, a bur hole is made over the optimal entry point, and using real-time fluoroscopy the strip electrode is slid to the tip of the navigation probe, which was kept over the area of interest. At the authors' institution 26 strips in 8 patients have been inserted with this technique, and none of the strips had to be repositioned. There were no complications with this procedure and the prolongation of surgery time is acceptable. Compared to previously published electrode placement methods, this one enhances the accuracy of electrode placement at occipital, parietal, frontal, or interhemispheric regions as well. Intraoperative visualization of the electrodes with fluoroscopy combined with neuronavigation during positioning through a bur hole gives the neurosurgeon the ability to control the real position of the electrode over the gyri during the procedure.

[The possibilities of fractionated external beam repeat irradiation of relapsed primary brain tumours: the first Hungarian experience]. / Az ismételt frakcionált külso sugárkezelés (reirradiáció) elsodleges központi idegrendszeri daganatok kiújulásának kezelésére: az elsô hazai tapasztalatok.

INTRODUCTION: The practice of image-based three dimensional treatment planning and conformal radiotherapy techniques offer the opportunity to elaborate novel treatment forms, e.g. repeat irradiation techniques for primary brain tumours. AIM: The authors analysed the effect on survival and toxicity of fractionated external beam repeat irradiation in brain tumour patients. METHODS: At the National Institute of Oncology, between 2002 and 2006, fractionated external beam repeat irradiation was performed in eleven patients with recurrent primary brain tumour, with total of 50-54 Gy or near total of 34-40 Gy doses. All patients were previously treated with total radiotherapy doses of 50-64 Gy. The intervals between radiotherapy courses were in the range of 7-30 years. All the treatments were carried out with 3D image-based conformal methods, the fractionation was conventional, with 1,8-2,0 Gy daily fractions in all cases. RESULTS: The repeat irradiation was tolerated well in the material. No grade 3-4 acute toxicity was detected, and serious, grade 3 mental deterioration, not related tumour progression was observed in only one case. In one case reoperation was necessary due to histologically verified radio-necrosis with mass-effect, and we believe that late neurotoxicity caused serious functional inabilities in one case. The median progression free survival was 8 (2-33) months, the median survival was 13 (4,5-33) months. Three of our patients were alive at the end of the study. CONCLUSIONS: Based on this experience and current knowledge, in absence of other treatment possibilities, the fractionated external beam repeat irradiation with near total doses could be a therapeutic choice in case of recurrent primary brain tumours, if having appropriate background. To define the optimal treatment strategy and regimens, further clinical trials should be carried out.

[Improvement of the first cerebral stereotactic radiosurgery system of Hungary]. / Az elso hazai sztereotaxiás agyi sugársebészeti rendszer továbbfejlesztése.

OBJECTIVE: The first cerebral stereotactic radiosurgery system in Hungary was built in 1991. This system was based on a Leksell stereotactic head frame and a Neptun 10p linear accelerator. We performed 624 radiosurgery treatments with this system between 1991 and 2000. Our objective was to increase the reliability of operation and to extend the applicability of our radiosurgery system. METHODS AND MATERIALS: We modified our stereotactic floor stand with specially designed adapter plates to make it compatible with the Mevatron KD and Neptun 10p linear accelerators and other stereotactic head frames (Riechert-Mundiger, CRW and BrainLab). We made a new tertiary collimator holder attachable to the Mevatron KD linac. The range of treatable cerebral lesion was increased from 10-30 mm to 5-42.5 mm with additional collimator inserts. With the above modifications our radiosurgery system is compatible simultaneously with the Neptun 10p and the Mevatron KD linear accelerators. This way we were able to increase the reliability of operation of the system, as the treatment can be performed with the Neptun 10p linac in case of breakdown of the Mevatron KD linac after fixation of the head frame to a patient's skull. RESULTS: The measured diameter of the radiation isocenter defined by the new radiosurgery collimator was less than 1 mm with the Mevatron KD linac. According to the Lutz-test the distance between the radiosurgery isocenter and the rotation axis of ZIV treatment table was less than 0.5 mm. Results of phantom test showed that the overall spatial precision of our modified radiosurgery system was better than 1.3 mm with Leksell head frame. CONCLUSIONS: On the basis of experiences with 662 patients' radiosurgery treatments, the extension of our first cerebral radiosurgery system to Mevatron KD linear accelerator resulted in a more reliable operation. In accordance with our phantom tests the extension of the original system did not worsen its overall spatial precision.