Boris Pokrajac

Vienna General Hospital, Wien, Vienna, Austria

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Publications (65)207.4 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Recurrent disease (restenosis) after endovascular treatment of the superficial femoral artery (SFA) remains a major problem. We evaluated the efficacy of beta-endovascular brachytherapy using the CORONA centering catheter in patients with SFA restenosis in a single-arm Phase II trial. A total of 28 patients (mean age 70 years; 16 female, 12 male) with recurrent SFA stenosis were treated, and in-stent restenosis was present in 17 patients (61%). Brachytherapy was performed with strontium-90 beta source using a 7-French CO(2)-filled one-segment centering catheter. New stents had to be applied in two cases. Mean interventional length was 129 mm (range 20-240 mm). A dose of 14 Gy in vessel radius (postinterventional) plus 2 mm was applied in 24 patients and 18.4 Gy in four patients. Treatment time was 7 min 32 s per radiation segment. No major adverse events occurred. Patients were followed by ankle-brachial index and duplex sonography for a median of 42 months. Cumulative restenosis rates at 1, 2, and 3 years were 9%, 28%, and 40%, respectively. Target vessel revascularization was performed in seven cases (25%). In comparison to literature data, the treatment of SFA restenosis with beta brachytherapy may improve long-term patency.
    Cardiovascular revascularization medicine: including molecular interventions 01/2009; 10(3):162-5.
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    ABSTRACT: In previous studies, razoxane and vindesine together with radiotherapy was proved to be effective in soft tissue sarcomas (STS). Because razoxane leads to a redifferentiation of pathological tumor blood vessels, it was of particular interest to study the influence of this drug combination in vascular soft tissue sarcomas. This open multicenter Phase II study was performed by the Austrian Society of Radiooncology. Among 13 evaluable patients (10 angiosarcomas and 3 hemangio-pericytomas), 9 had unresectable measurable disease, 3 showed microscopic residuals, and 1 had a resection with clear margins. They received a basic treatment with razoxane and vindesine supported by radiation therapy. Outcome measures were objective response rates, survival time, and the incidence of distant metastases. In nine patients with measurable vascular soft tissue sarcomas (eight angiosarcomas and one hemangiopericytoma), 6 complete remissions, 2 partial remissions, and 1 minor remission were achieved, corresponding to a major response rate of 89%. A maintenance therapy with razoxane and vindesine of 1 year or longer led to a suppression of distant metastases. The median survival time from the start of the treatment is 23+ months (range, 3-120+) for 12 patients with macroscopic and microscopic residual disease. The progression-free survival at 6 months was 75%. The combined treatment was associated with a low general toxicity, but attention must be given to increased normal tissue reactions. This trimodal treatment leads to excellent response rates, and it suppresses distant metastases when given as maintenance therapy.
    International journal of radiation oncology, biology, physics 12/2008; 74(1):187-91. · 4.59 Impact Factor
  • Cardiovascular Revascularization Medicine. 01/2008; 9(3):205-205.
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    ABSTRACT: Background. The purpose of this investigation was to evaluate feasibility, safety and efficacy of 3D-conformal radiotherapy (3D-RT) for inoperable non-small-cell lung cancer (NSCLC). Time to progression (TTP), including local recurrence and/or distant metastasis, local control rate (LCR), time to death (TTD) and side effects were evaluated. Patients and methods. From 1997 to 2002, a total of 84 patients with inoperable NSCLC were treated with 3D-RT according to a prospective protocol at our institution. Depending on performance status, lung function and dose-volume constraints, radiation doses of either 66-70 Gy or 50-60 Gy +/-platin-based chemotherapy were applied. Results. The treatment was well tolerated and the rate of side effects was low. Only one grade 4 pneumo-nitis was observed, the rate of grade 3 pneumonitis was 6% and 13% for grade 2. Two patients developed a grade 4 oesophagitis and no grade 3 oesophageal toxicity was observed. The analysis of dose-volume histograms (DVH) found a mean V 20 (lung volume that receives 20 Gy) for the ipsilateral lung (IL) of 42%, a mean V 20 for the contralateral lung (CL) of 14% and a mean lung dose IL of 25 Gy. The mean V 20 IL in patients developing a pneumonitis grade 2-4 was 53.3%. The mean follow-up was 24 month. There was no difference in TTP (median 15 months) in the different treatment groups. Patients receiving higher radiation doses (66-70 Gy) had a benefit in an overall survival (OS) when the additional chemotherapy was applied (28 month vs. 16 month). Local control rates of mean 22% after 2 years were low. Conclusions. The application of radiation doses up to 70 Gy is feasible and safe, also in combination with chemotherapy. Still, the local control and OS is poor. Thus, further trials to investigate the possibility of dose escalation in the lung without increasing lung toxicity significantly, also in more advanced tumour stages, are mandatory.
    Radiol Oncol Vienna; Austria. 01/2007; 41:133-43.
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    ABSTRACT: Intracoronary brachytherapy was the primary therapeutic option for the treatment of in-stent restenosis (ISR) during the last years. Especially for the treatment of diffuse ISR (lesions >10mm), beta-source brachytherapy was significantly superior to singular balloon angioplasty. Despite lacking clinical database, the implantation of drug eluting stents recently became a common procedure for the treatment of ISR. This randomized trial aimed to compare the efficacy of beta-brachytherapy with beta-radioisotopes (90)Sr/(90)Y and paclitaxel-eluting stent implantation for the treatment of diffuse ISR. Thirty-seven patients with diffuse ISR were randomly assigned to beta-brachytherapy after balloon angioplasty (Beta-Cath in 17 patients) or paclitaxel-eluting stent implantation (Taxus-Express2 in 20 patients). Six-month clinical follow-up was obtained for all patients, while angiographic follow-up was available for 30 patients. Binary ISR (restenosis >50%) within target segment was observed in three patients treated with Beta-Cath, of which one needed target segment revascularisation for recurrent ISR, whereas no significant restenosis occurred in the patients treated with Taxus-Express2 (P=0.037). No further major adverse cardiac (target segment revascularisation, myocardial infarction, death) was found in either group (P=NS). Stent implantation was the more time-saving (31+/-11 min versus 60+/-23 min, P<0.001) procedure. Although this trial revealed a significant reduction of binary restenosis in the Taxus-Express2 arm, we found no difference in clinical outcome after implantation of paclitaxel-eluting stents for the treatment of diffuse ISR when compared to beta-brachytherapy.
    Radiotherapy and Oncology 01/2007; 82(1):18-23. · 4.52 Impact Factor
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    ABSTRACT: Induction chemotherapy may improve clinical outcome of locally advanced non-small cell lung cancer (NSCLC). To further pursue this, the Austrian Association for the Study of Lung Cancer (AASLC) performed a multi-center phase II trial with TIP induction chemotherapy (Taxol 175 mg/m2 over 3h on day 1, ifosfamide 1000 mg/m2 daily on days 1-3, cisplatin 60 mg/m2 on day 1, and prophylactic filgrastim 5 microg/kg daily on days 4-13). Treatment cycles were repeated every 3 weeks for 3 cycles. Then patients were re-staged and selected for local treatment. Forty-seven patients (33 male, 14 female; median age 58 years, range 36-78; 22 cIIIA, 25 cIIIB; 26 adenocarcinomas, 14 squamous cell carcinomas, 4 large cell carcinomas, 3 undifferentiated carcinomas) were included in this trial. Forty-five patients were evaluable for response and toxicity. An overall response rate of 43% (complete remission 4.5% and partial remission 38%) was achieved. Stable disease and progressive disease were seen in 38 and 15% of the patients, respectively. Down-staging occurred in 36% of the patients. The toxicities of the chemotherapy were mild and, in particular, no severe hematotoxicity was observed. Surgery was performed in 24 (51%) patients and resulted in complete tumor resection in 19 patients. Twenty-four patients received thoracic radiotherapy, 10 patients after surgery. Median survival was 10.3 months for the total population, 13.5 months for patients with cIIIA and 10 months for patients with clinical cIIIB. Survival was longer for patients with down-staging as compared to those without (median not reached versus 10 months, p=0.005) and for patients with complete tumor resection as compared to the remaining patients (27 months versus 10 months, p=0.05). In conclusion, the TIP regimen shows activity and good tolerance as induction chemotherapy in patients with locally advanced NSCLC.
    Lung Cancer 11/2006; 54(1):63-7. · 3.39 Impact Factor
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    ABSTRACT: To report the 5-year results from the prospective randomized Vienna-2 trial, which was designed to evaluate the safety and effectiveness of adjunctive endovascular brachytherapy (EBT) compared with no further treatment after successful revascularization in patients with long-segment femoropopliteal lesions. Each patient gave written informed consent to participate in the study, which was approved by the hospital's ethics committee. One hundred two patients (men, 53.9%; mean age, 72.1 years +/- 8.7 [standard deviation]; lesion length, 8.1 cm +/- 4.9) underwent percutaneous transluminal angioplasty (PTA) without further stent implantation. Patients were then assigned to either receive EBT (n = 51) by using an iridium 192 source, with a prescribed dose of 12 Gy at 3 mm from the source axis, or no further treatment (n = 51). Radiation was delivered without a centering catheter. Data were analyzed by using a Student t test for continuous values and a chi(2) test to compare categorical values. A Cox proportional hazards regression analysis was performed to evaluate predictors of recurrence at follow-up. After 6 months, the restenosis rate for the 102 patients with completed 5-year follow-up was significantly reduced for the PTA plus EBT group versus the PTA alone group (29.4% vs 56.9%, P < .05). During follow-up we observed a late catch-up phenomenon, and after 5 years the recurrence rate was comparable in both groups (72.5% vs 72.5%, P > .99). Time to recurrence, however, was significantly delayed in the PTA plus EBT group (17.5 months +/- 14.7 vs 7.4 months +/- 6.8 for the PTA alone group, P < .05). At 5-year follow-up, PTA followed by gamma radiation EBT with a dose of 12 Gy resulted in a delay but not an inhibition of restenosis when compared with that of PTA alone.
    Radiology 09/2006; 240(3):878-84. · 6.34 Impact Factor
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    ABSTRACT: We report a double-blind, randomized clinical trial of intracoronary beta-radiation for prevention of restenosis after stent implantation in native coronary de novo lesions in diabetic patients. After successful stent implantation in native coronary de novo lesions, 106 lesions in 89 diabetic patients were randomly allocated to treatment with beta-radiation with 18 Gy at 1 mm vessel depth (n = 53) or placebo treatment (n = 53). Angiographic analysis at 9 month follow-up revealed a late lumen loss of 0.7+/-0.9 mm in the radiotherapy group versus 1.2+/-0.8 mm in the control group at the injured segment (P = 0.006), 0.9+/-1.0 versus 1.3+/-0.7 mm at the radiated segment (P = 0.02), and 0.9+/-1.0 versus 1.3+/-0.7 mm at the target segment (P = 0.04) (defined as active source length plus 5mm on proximal and distal sites). Binary restenosis rates were significantly lower in the radiation group in all subsegments (injured segment: 10.9 versus 37.3%, P = 0.003; radiated segment: 21.7 versus 49.0%, P = 0.005; target segment: 23.9 versus 49.0%, P = 0.01). Target lesion revascularization for restenosis was required in nine lesions (17.6%) in the radiotherapy group versus 18 (34.0%) in the placebo group (P = 0.05). Late thrombosis occurred in four radiated patients (after premature discontinuation of antiplatelet therapy in all), resulting in a major adverse clinical event rate of 37.2% in the brachytherapy group versus 38.6% in the placebo group (P = ns). In diabetic patients with de novo coronary lesions, intracoronary radiation after stent implantation significantly reduced restenosis. However, this clinical benefit was reduced by the frequent occurrence of late thrombosis.
    Radiotherapy and Oncology 02/2006; 78(1):60-6. · 4.52 Impact Factor
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    ABSTRACT: To prospectively evaluate the effectiveness of endovascular brachytherapy in the prevention of restenosis after femoropopliteal stent implantation in high-risk patients. Patients provided written informed consent to participate in this study, which was approved by the ethics committee. A total of 88 patients (mean age, 67.7 years +/- 10.1; 57 men [65%], 31 women [35%]) with femoropopliteal lesions (mean treatment length, 16.8 cm +/- 7.3) were included. Patients underwent percutaneous transluminal angioplasty (PTA) and stent implantation and were randomized in a double-blind fashion to undergo either gamma brachytherapy with an iridium 192 source or treatment with nonradioactive seeds. A 14-Gy dose of iridium 192 was prescribed at 2 mm into the arterial wall (target depth equals vessel radius plus 2 mm). The primary end point of the study was angiographic binary restenosis of more than 50% at 6-month follow-up. Secondary end point was either percutaneous or surgical target lesion revascularization after 6 months. Continuous data are presented as mean +/- standard deviation. Categorical data are expressed as percentages. Student t test was used to compare continuous data; chi(2) test was used to compare categorical values. Survival function was calculated with the Kaplan-Meier method. Multivariate Cox proportional hazard regression analysis was performed to enable evaluation of multivariate predictors of recurrence at 6- and 12-month follow-up. Variables included brachytherapy, clinical stage, lesion length, de novo and recurrent lesion, vessel run off, prior stenosis or occlusion, diabetes mellitus, and stent model. Revascularization and brachytherapy were accomplished successfully in all patients. The overall 6-month recurrence rate was 35% in patients who underwent only stent implantation and 33% in patients who underwent both stent implantation and brachytherapy (P = .89). Nine (10%) patients developed early reocclusion in the segment treated with a stent (two patients [4%] in the stent group and seven [17%] in the stent and brachytherapy group); of these patients, three in the stent and brachytherapy group experienced reocclusion within 24 hours of the intervention. Late (>30 days after intervention) thrombotic occlusion was observed in three patients (7%) in the stent and brachytherapy group. Brachytherapy does not improve 6-month patency after femoropopliteal stent implantation in high-risk patients because of a high incidence of early and late thrombotic occlusion.
    Radiology 08/2005; 236(1):343-51. · 6.34 Impact Factor
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    ABSTRACT: To determine the effectiveness of endovascular brachytherapy in the prevention of restenosis in recurrent versus de novo femoropopliteal lesions. Ethics committee approval and patient informed consent were obtained. After they had undergone femoropopliteal angioplasty, 199 patients (mean age, 71.9 years +/- 9.6; 115 men, 84 women) were treated with either percutaneous transluminal angioplasty (PTA) and brachytherapy (n = 100) or PTA alone (n = 99). The patients were part of prospective randomized trials, the Vienna 2 and 3 trials, and were evaluated according to the stratification criterion of de novo or recurrent disease. Sixty-six of 134 patients with a de novo lesion and 34 of 65 patients with a recurrent lesion were randomly assigned to the PTA and brachytherapy arm; the remaining patients were treated with PTA alone. Outcomes were compared between the groups. The Student t test or one-way analysis of variance was used to compare continuous variables, and the chi2 test or Fisher exact test was used to assess dichotomous variables. Kaplan-Meier curves were calculated, and the log-rank test was performed to determine freedom from recurrence at 12 months in both groups. A multivariate Cox proportional hazard regression analysis was performed to evaluate the multivariate predictors of recurrence at 12-month follow-up. For patients with de novo lesions, the frequency of recurrence at 12 months was not significantly different between those who underwent brachytherapy and PTA and those who underwent PTA alone (24 [36%] of 66 patients vs 30 [44%] of 68 patients, P = .32). For patients with recurrent lesions, however, the 12-month recurrence rate was significantly lower in those who received brachytherapy than in those who did not (nine [26%] of 34 patients vs 22 [71%] of 31 patients, P = .004). Endovascular brachytherapy with gamma radiation significantly reduces the restenosis rate after femoropopliteal angioplasty of recurrent but not de novo lesions.
    Radiology 08/2005; 236(1):338-42. · 6.34 Impact Factor
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    ABSTRACT: To investigate 3D-conformal external beam radiotherapy for prevention of recurrent instent restenosis after carotid artery angioplasty. Between Oct 2000 and Sep 2001 five patients with recurrent carotid artery in-stent restenosis of more than 50% lumen loss diagnosed with duplex sonography were enrolled. After successful revascularization, radiotherapy treatment planning was performed, which was based on the angioplasty protocol and all images documenting the intervention. A single dose of 5 Gy was prescribed to the 100% isodose. The treatment started on day one after angioplasty. In total, 4 fractions were given within 3 days. All patients tolerated the treatment well. No acute radiotherapy associated side effects were observed. Two patients developed recurrence within four months after therapy. In both cases, late total occlusion of the stent was noticed. One patient died and one developed a severe stroke. The other three patients remained asymptomatic with evidence of less than 50% restenosis. 3D-conformal radiotherapy is a feasible treatment option for highly selected patients with carotid artery in-stent restenosis. These preliminary results from a very small group of patients do show some potential for radiotherapy to prevent restenosis. However, due to the risk of late stent thrombosis, radiotherapy for the prevention of recurrent carotid artery in-stent restenosis is not recommended.
    Wiener klinische Wochenschrift 05/2005; 117(7-8):293-6. · 0.81 Impact Factor
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    ABSTRACT: To evaluate the feasibility, effectiveness, and long-term bowel function of preoperative hyperfractionated accelerated radiotherapy in primary resectable rectal cancer. A total of 184 consecutive patients (median age 65 years, male : female=2 : 1) with clinical T3Nx rectal adenocarcinoma received preoperative pelvic radiation therapy with single fractions of 2.5 Gy twice daily (interval 6 h between fractions) to a total dose of 25 Gy within 1 week. Surgery was conducted the following week. Postoperative histology revealed UICC stage I in 33%, stage II in 26%, stage III in 34%, and stage IV in 7% of the patients. Median follow-up was 43 months (53 months for surviving patients). The actuarial 4-year-local-recurrence rate was 2.1%, overall recurrence 23%. Disease-specific and disease-free survivals at 4 years (excluding stage IV) were 82 and 69%, respectively. Overall survival for 4 years was 68%. Postoperative mortality was 0.5% (one patient), early anastomotic leakage occurred in 11.4%, and anastomotic stenosis requiring treatment in 6%, of 132 patients with primary anastomosis. Seven of 184 patients (3.8%) died of abdominal complications, all within the first year. Bowel function was satisfactory after more than 5 years. Local control in primarily resectable rectal cancer after 10 x 2.5 Gy is excellent, warranting further evaluation of this treatment.
    British Journal of Cancer 05/2005; 92(7):1209-14. · 5.08 Impact Factor
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    ABSTRACT: The aim of the trial was to investigate the effect of Iridium-192 gamma endovascular brachytherapy on reduction of restenosis after femoropopliteal angioplasty. Between Oct, 1998 and Jul, 2001 a total of 134 patients have been randomized after successful angioplasty to brachytherapy or sham irradiation in a prospective, randomized, multicenter, double blind controlled trial. Patients with de novo lesion of at least 5 cm or recurrent lesion of any length after prior angioplasty have been enrolled. Brachytherapy was performed with 7F centering catheter. Mean lesion length was 9.1cm (1.5-25 cm) and mean intervention length 13.6 cm (4-27.5 cm) in brachytherapy cohort. In placebo cohort mean lesion length was 10.3 cm (2-25 cm) and mean intervention length 14.1 cm (2-29 cm). A dose of 18 Gy was prescribed 2 mm from the surface of centering balloons. Analyzed (based on angiography) on intention to treat basis the binary restenosis rate at 12 months was 41.7% (28/67) in brachytherapy cohort and 67.1% (45/67) in placebo cohort (chi2 test, P<0.05). Corresponding data for as treated analysis (A total of 38 patients was excluded from analysis due to lack of follow-up, early recurrence within 30 days and >30% residual stenosis after angioplasty) have been 23.4% in the brachytherapy and 53.3% in the placebo group (P<0.05), respectively. The cumulative patency rates after 24 months on intention to treat analysis were 54% in the brachytherapy and 27% in the placebo group (P<0.005). Corresponding data for as treated analysis were 77% in the brachytherapy and 39% in the placebo group (P<0.001). Late thrombosis was not seen. Significant reduction of restenosis rate was obtained with endovascular gamma brachytherapy after femoropopliteal angioplasty.
    Radiotherapy and Oncology 02/2005; 74(1):3-9. · 4.52 Impact Factor
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    ABSTRACT: To determine dosimetric parameters, such as radial and longitudinal dose profiles, for beta and gamma devices in peripheral endovascular brachytherapy. An (192)Ir high-dose rate stepping source, a (90)Sr source train, and a (32)P-coated radiation balloon were investigated. The treatment-planning software PLATO, Monte Carlo code EGSnrc, and GafChromic film dosimetry were used to analyze the dose distribution of these devices. For a 5-mm-diameter vessel, the ratio between the dose at 2 mm depth and the dose at the lumen surface was 1.8, 3.4, and 16.2 for the (192)Ir, (90)Sr, and (32)P devices, respectively. The dose variation at the reference depth of 2 mm into the vessel wall was 7-18 Gy, for different analyzed dose prescriptions. The reference lumen dose was different by a factor >8. For all three devices, the reference isodose length was not <5 mm on the proximal and distal edge of the active source length. A complete set of dose parameters for beta and gamma sources has to be considered for appropriate treatment planning and performance, including reporting of reference depth dose, reference lumen dose, and reference isodose length.
    International Journal of Radiation OncologyBiologyPhysics 01/2005; 60(5):1652-9. · 4.52 Impact Factor
  • Wiener Klinische Wochenschrift - WIEN KLIN WOCHENSCHR. 01/2005; 117:293-296.
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    ABSTRACT: To investigate efficacy and feasibility of hyperfractionated accelerated radiotherapy combined with mitomycin C, patients with locally advanced unresectable squamous cell carcinomas of the head and neck region were administered 64-66 Gy in four weeks and mitomycin C (20 mg/m(2)) on day five. Twenty-one consecutive patients were included between November 1997 and June 1999 (median age: 57 years). All tumours were stage T3-4 and 18/21 were N2-3. Eighteen patients experienced grade 3 and three patients grade 2 mucosal toxicity. With median follow up for surviving patients of 42 months, loco-regional control was 55% at three years, overall survival was 33% at three years. This treatment is at the edge of local tolerability, but there is a good curative chance even for very advanced localised tumours, provided a complete remission is induced at primary treatment.
    Radiotherapy and Oncology 12/2004; 73(2):173-7. · 4.52 Impact Factor
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    ABSTRACT: To assess the efficacy of intracoronary brachytherapy with beta-radiation (Sr/Y) for the treatment of long diffuse in-stent restenosis (ISR). As recurrent ISR depends on intimal injury after coronary angioplasty, long in-stent restenotic lesions were defined as lesions with a treatment length >26 mm (lesion length >20 mm plus a treatment margin of 3 mm at each end). Seventy-eight patients with long ISR were treated at our institution with beta-brachytherapy after coronary angioplasty. Patients were irradiated with either an approximate dose of 12 Gy at 1 mm vessel wall depth or with 18 Gy at 1 mm vessel wall depth. Clinical follow-up was available for 69 patients and angiographic follow-up for 65 patients. Late lumen loss (LLL), binary restenosis (stenosis >50%), target lesion revascularization (TLR) and major adverse cardiac events (MACE) were assessed for a follow-up time of 6.6+/-2.2 months. Mean interventional treatment length was 46+/-18 mm. TLR was performed in all 23 patients with binary restenosis (33%). Death of cardiac cause was reported for two patients, one of whom did not undergo TLR. Thus, overall MACE rate was 35%. Recurrent ISR was significantly more frequent in patients with geographic miss. Comparison of the different radiation dose regimens revealed significantly lower LLL in patients irradiated with the higher dose (0.20+/-0.68 mm compared with 0.65+/-0.96 mm, P=0.03). Intracoronary brachytherapy with beta-radiation (Sr/Y) is a safe and effective therapeutic option for the reduction of recurrent ISR in long diffuse lesions. We recommend a high-dose irradiation with 18 Gy at 1 mm vessel wall depth.
    Coronary Artery Disease 09/2004; 15(5):285-9. · 1.11 Impact Factor
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    ABSTRACT: A new method of assessing geographic miss (GM) in endovascular brachytherapy (EVBT) is applied to evaluate the quality of intracoronary brachytherapy treatments, retrospectively. Based on the Vienna experience, recommendations for adequate safety margins are derived to avoid GM. Evaluation is done on 136 vessels of 128 consecutive patients treated between October 1999 and July 2001. The quality of EVBT is assessed using the concept and terminology of the EVA GEC ESTRO task group. Evaluation of GM and/or safety margin is performed by comparing the outermost interventions with the reference isodose length (RIL) of the applied delivering devices on recorded compact disk (CD) angiograms. The RIL is defined as the length of the vessel segment, which receives at least 90% of the reference dose at the reference depth (=1 mm within the vessel). GM is defined as injured vessel segments, which receive a dose lower than 90% of reference dose. Measurements of intervention length (IL) and active source length (ASL) are performed with respect to anatomical landmarks within the vessel in the region of interest (e.g. stent edges), and by using the nominal length of the devices (balloons, sources) as a reference scale. The edges of RIL are determined by subtracting the length of the dose-fall-off zone (specific to the applied delivery devices: (192)Ir 4.5 mm, (90)Sr 2.5 mm, (32)P 2.0 mm) from the edges of ASL. The described method to assess GM is applicable to 128 vessels (94%). GM is found in 23% of proximal edges and 20% of distal edges. 95% of all GM are observed if the total margin (proximal+distal margin) between RIL and IL is shorter than 10.5 mm. GM in intracoronary brachytherapy can be widely avoided by adding an appropriate safety margin to the IL (5-6 mm each edge in this study) in order to determine the necessary RIL for a treatment.
    Radiotherapy and Oncology 07/2004; 71(3):311-8. · 4.52 Impact Factor
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    ABSTRACT: The purpose of this analysis was to evaluate if overdosage during intracoronary irradiation due to overlapped source stepping may result in long-term morphologic changes in vessel anatomy. Baseline angiograms of patients with in-stent restenosis undergoing coronary reintervention followed by intracoronary irradiation with source stepping were analyzed. Overlapping was considered present for the segment with overlapped reference isodose length (RIL) (RIL = segment with > or = 90% of reference dose at 1 mm vessel wall depth). Baseline and 6-months follow-up volumetric intravascular ultrasound (IVUS) analysis were performed for the overlapped segment and for proximal and distal segments of equal length. Overlapping was found in six patients (three patients: (32)P treatment; three patients: (90)Sr/Y treatment); final analysis was performed in four patients. Comparison of the baseline and follow-up IVUS volumetric parameters revealed no significant change in lumen or vessel volumes at segments of overlaps in comparison to proximal and distal reference segments. Increased dosage due to overlapping during source stepping is not associated with morphologic changes in vessel anatomy at follow-up.
    Journal of Interventional Cardiology 06/2004; 17(3):143-9. · 1.50 Impact Factor
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    ABSTRACT: Endovascular brachytherapy is still an important therapy modality with a high number of treated patients per year. Quality assurance of devices used has been addressed already in several publications (AAPM, DGMP, ESTRO, NCS). However, there are no clear recommendations given on test procedures and related equipment. Our experience with four different devices containing beta- ((32)P, (90)Sr/Y) and gamma-sources ((192)Ir), which were used in clinical routine during the last 3 years is described. The incoming check includes leakage radiation, missing catheter interlock, positioning test, timer check, interrupt button check, power-off test and verification of the manual retraction facility. Dose profiles are measured using GafChromic film. Source strength verification is performed using well type chambers or air-kerma measurements. In addition, the proposed reference absorbed dose rate at 2 mm distance from the source centre is measured with a dedicated film dosimetry technique where two additional films are exposed to two known doses in a (60)Co field for calibration. Dosimetrical parameters (dose profiles, source strength) are found to be within +/-10% of the manufacturers specifications. The reference dose rate measured with film is on average +3.1% for 13 (90)Sr seed trains, +8.1% for three (32)P wire sources and -3.7% for one (192)Ir seed ribbon compared to the source certificate. The activity of 30 individual (32)P wire sources measured by using a calibrated well type chamber showed a deviation of mean -0.3%, the activity of 16 (192)Ir seed ribbons determined with air kerma measurements a deviation of mean 2.8%. The QA programme introduced in our department provides methods to verify all relevant parameters proposed by international recommendations. Film dosimetry can be used as independent verification of the reference dose rate within a 10% limit.
    Radiotherapy and Oncology 05/2004; 71(1):91-8. · 4.52 Impact Factor

Publication Stats

388 Citations
207.40 Total Impact Points

Institutions

  • 1998–2009
    • Vienna General Hospital
      Wien, Vienna, Austria
  • 2008
    • State Hospital Feldkirch
      Feldkirch, Vorarlberg, Austria
  • 2002–2008
    • Medical University of Vienna
      • Department of Radiation Oncology
      Linz, Upper Austria, Austria
  • 2001–2004
    • University of Vienna
      • Department of Internal Medicine III
      Vienna, Vienna, Austria