Arpád Viola

Iodine-125 Brachytherapy of Brain Stem Tumors

Purpose:To report on iodine-125 (125I) interstitial irradiation in the treatment of brain stem tumors.Patients and Methods:Two patients with brain stem tumors were treated with CT- and image fusion-guided 125I stereotactic brachytherapy.Results:By March 2003, the patients had been followed up for 47 and 13 months, respectively. In case 1, the tumor volume was 1.98 cm3 on the control CT, indicating a 65.5% shrinkage as compared to a target volume of 5.73 cm3 at the time of brachytherapy. In case 2, shrinkage was more distinct. After irradiation, the cyst volume was 0.16 cm3 on the control MRI, indicating a 97.4% shrinkage as compared to a target volume of 6.05 cm3 at the time of brachytherapy, i. e., the metastasis had virtually disappeared.Conclusion:CT- and image fusion-guided 125I stereotactic brachytherapy can be performed during the biopsy session. The procedure can be well planned dosimetrically and is surgically precise.Ziel:Beschreibung der interstitiellen Jod-125-(125I-)Brachytherapie bei der Behandlung von Hirnstammtumoren.Patienten und Methodik:Bei zwei Patienten mit Hirnstammtumoren wurde eine durch CT und Fusionsbild gesteuerte interstitielle 125I-Brachytherapie durchgeführt.Ergebnisse:Bis März 2003 betrugen die Nachuntersuchungszeiten der beiden Patienten 47 bzw. 13 Monate. Im ersten Fall lag das Tumorvolumen auf dem Kontroll-CT bei 1,98 cm3, was eine Schrumpfung um 65,5% anzeigte. Im zweiten Fall fiel diese Änderung deutlicher aus. Das Kontroll-MRT ergab eine Schrumpfung von 97,4%, d. h., die Metastase war praktisch verschwunden.Schlussfolgerung:Die durch CT und Fusionsbild gesteuerte interstitielle 125I-Brachytherapie lässt sich dosimetrisch gut planen, und die Methode ist chirurgisch präzise.

Stereotactic Intracavitary Irradiation of Cystic Craniopharyngiomas with Yttrium-90 Isotope

The authors analyzed data from nearly 30-year follow-up period to assess the value of intracavitary irradiation with stereotactically implanted beta-emitting radioisotope yttrium- 90 (90Y) silicate colloid for the treatment of cystic craniopharyngiomas. Seventy-three cysts in 60 patients were selected for retrospective analysis. The cumulative dose aimed at the inner surface of the cyst wall was 300 Gy. An average of 79% (mean 88.3%) shrinkage of the initial cyst volume was observed. In 47 cysts, the reduction was more than 80%, and the cyst disappeared totally in 29 out of those 47 cases, usually within a year. Mean survival duration after intracavitary irradiation was 9.4 years. Neuroophthalmological prognosis was only favorable when the optic disc was normal or nearly normal at the time of the treatment. In the presence of preexisting optic atrophy, visual damage proved to be irreversible. The long-term results support the view that intracavitary 90Y irradiation is a noninvasive and effective method for the treatment of craniopharyngioma cysts. Because of the mean penetration pathway of beta irradiation is 3.6mm in the soft tissues (maximum 11 mm) it cannot influence the solid part of the tumor; therefore, the best result can be expected in solitary cysts.

Image Fusion-Guided Stereotactic Iodine-125 Interstitial Irradiation of Inoperable and Recurrent Gliomas

Between 1996 and 2004, 27 patients with low grade gliomas (WHO grade I-II), 10 patients with WHO grade III gliomas and 6 patients with glioblastoma multiforme (WHO grade IV) were treated with stereotactic brachytherapy using low-dose rate iodine-125 (125I) isotope seeds at the Department of Neurosurgery, St. Johns Hospital, Budapest, Hungary. In all 43 cases, brachytherapy was used for surgically inoperable gliomas: in 32 cases for recurrent gliomas and in 11 cases as a primary treatment. Results of this study suggest that 125I brachytherapy for inoperable and recurrent gliomas is an effective method and offers a chance for longer-term survival.

Comparison of 125I Stereotactic Brachytherapy and LINAC Radiosurgery Modalities based on Physical Dose Distribution and Radiobiological Efficacy

Abstract Viola, A., Major, T. and Julow, J. Comparison of 125I Stereotactic Brachytherapy and LINAC Radiosurgery Modalities based on Physical Dose Distribution and Radiobiological Efficacy. Radiat. Res. 165, 695–702 (2006). The goal of this study was to make a comparison between stereotactic brachytherapy implants and linear accelerator-based radiosurgery of brain tumors with respect to physical dose distributions and radiobiological efficacy. Twenty-four treatment plans made for irradiation of brain tumors with low-dose-rate 125I brachytherapy and multiple-arc LINAC-based radiosurgery were analyzed. Using the dose–volume histograms and the linear-quadratic model, the brachytherapy doses were compared to the brachytherapy-equivalent LINAC radiosurgery doses with respect to the predicted late effects of radiation on normal brain tissue. To characterize the conformity and homogeneity of dose distributions, the conformal index, external volume index, and relative homogeneity index were calculated for each dose plan and the mean values were compared. The average tumor volume was 5.6 cm3 (range: 0.1–19.3 cm3). At low doses, the calculated radiobiological late effect on normal tissue was equivalent for external-beam and brachytherapy dose delivery. For brachytherapy at doses greater than 30 Gy, the calculated equivalent dose to normal tissues was less than for external-beam radiosurgery. However, the dose-calculated homogeneity was better for the LINAC radiosurgery, with a mean relative homogeneity index of 0.62 compared to the calculated value of 0.19 for the brachytherapy (P = 0.0002). These results are only predictions based on calculations concerning normal tissue tolerance. More data and research are needed to understand the clinical relevance of these findings.

Image fusion analysis of volumetric changes after interstitial low-dose-rate iodine-125 irradiation of supratentorial low-grade gliomas.

Abstract Julow, J., Major, T., Mangel, L., Bajzik, L. and Viola, A. Image Fusion Analysis of Volumetric Changes after Interstitial Low-Dose-Rate Iodine-125 Irradiation of Supratentorial Low-Grade Gliomas. Radiat. Res. 167, 438–444 (2007). The aim of this study was to compare the volumes of tumor necrosis, reactive zone and edema with the three-dimensional dose distributions after brachytherapy treatments of gliomas. The investigation was performed an average of 14.2 months after low-dose-rate 125I interstitial irradiation of 25 inoperable low-grade gliomas. The prescribed dose was 50–60 Gy to the tumor surface. Dose planning and image fusion were performed with the BrainLab-Target 1.19 software. In the CT/ MRI images, the “triple ring” (tumor necrosis, reactive ring and edema) developing after the interstitial irradiation of the brain tumors was examined. The images with the triple ring were fused with the planning images, and the isodose curves were superimposed on them. The volumes of the three regions were measured. The average dose at the necrosis border was determined from the isodose distribution. For quantitative assessment of the dose distributions, the dose nonuniformity ratio (DNR), homogeneity index (HI), coverage index (CI) and conformal index (COIN) were calculated. The relative volumes of the different parts of the triple ring after the interstitial irradiation compared to the reference dose volume were the following: necrosis, 40.9%, reactive zone, 47.1%, and edema, 367%. The tumor necrosis developed at 79.1 Gy on average. The average DNR, HI, CI and COIN were 0.45, 0.24, 0.94 and 0.57, respectively. The image fusion analysis of the volume of tumor necrosis, reactive ring and edema caused by interstitial irradiation and their correlation with the dose distribution provide valuable information for patient follow-up, treatment options, and effects and side effects of radio therapy.

Az ismételt frakcionált külsô sugárkezelés (reirradiáció) elsôdleges 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.