Peter Wust
Research interests
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InterestsRadiotherapy, Intensity-Modulated Radiotherapy, Conformal Radiotherapy, Computer-Assisted Radiotherapy Planning, Computer-Assisted Radiotherapy
Publications
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4.59Impact points
Contribution of (68)Ga-DOTATOC PET/CT to Target Volume Delineation of Skull Base Meningiomas Treated With Stereotactic Radiation Therapy.
International journal of radiation oncology, biology, physics. 05/2012;
PURPOSE: To investigate the potential impact of (68)Ga-DOTATOC positron emission tomography ((68)Ga-DOTATOC-PET) in addition to magnetic resonance imaging (MRI) and computed tomography (CT) for retrospectively assessing the gross tumor volume (GTV) delineation of meningiomas of the skull base in pat... [more] PURPOSE: To investigate the potential impact of (68)Ga-DOTATOC positron emission tomography ((68)Ga-DOTATOC-PET) in addition to magnetic resonance imaging (MRI) and computed tomography (CT) for retrospectively assessing the gross tumor volume (GTV) delineation of meningiomas of the skull base in patients treated with fractionated stereotactic radiation therapy (FSRT). METHODS AND MATERIALS: The study population consisted of 48 patients with 54 skull base meningiomas, previously treated with FSRT. After scans were coregistered, the GTVs were first delineated with MRI and CT data (GTV(MRI/CT)) and then by PET (GTV(PET)) data. The overlapping regions of both datasets resulted in the GTV(common), which was enlarged to the GTV(final) by adding volumes defined by only one of the complementary modalities (GTV(MRI/CT-added) or GTV(PET-added)). We then evaluated the contribution of conventional imaging modalities (MRI, CT) and (68)Ga-DOTATOC-PET to the GTV(final), which was used for planning purposes. RESULTS: Forty-eight of the 54 skull base lesions in 45 patients showed increased (68)Ga-DOTATOC uptake and were further analyzed. The mean GTV(MRI/CT) and GTV(PET) were approximately 21 cm(3) and 25 cm(3), with a common volume of approximately 15 cm(3). PET contributed a mean additional GTV of approximately 1.5 cm(3) to the common volume (16% ± 34% of the GTV(common)). Approximately 4.5 cm(3) of the GTV(MRI/CT) was excluded from the contribution to the common volume. The resulting mean GTV(final) was significantly smaller than both the GTV(MRI/CT) and the GTV(PET). Compared with the initial GTV(MRI/CT), the addition of (68)Ga-DOTATOC-PET resulted in more than 10% modification of the size of the GTV(final) in 32 (67%) meningiomas CONCLUSIONS: (68)Ga-DOTATOC-PET/CT seems to improve the target volume delineation in skull base meningiomas, often leading to a reduction of GTV compared with results from conventional imaging (MRI and CT).
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1.81Impact points
Percutaneous Computed Tomography-guided High-Dose-Rate Brachytherapy Ablation of Breast Cancer Liver Metastases: Initial Experience with 80 Lesions.
Journal of vascular and interventional radiology : JVIR. 05/2012; 23(5):618-26.
To analyze initial experience with computed tomography-guided high-dose-rate brachytherapy (CT-HDRBT) ablation of breast cancer liver metastases (BCLM). Between January 2008 and December 2010, 37 consecutive women with 80 liver metastases were treated with CT-HDRBT in 56 sessions. Mean age was 58.6 ... [more] To analyze initial experience with computed tomography-guided high-dose-rate brachytherapy (CT-HDRBT) ablation of breast cancer liver metastases (BCLM). Between January 2008 and December 2010, 37 consecutive women with 80 liver metastases were treated with CT-HDRBT in 56 sessions. Mean age was 58.6 years (range, 34-83 y). Treatment was performed by CT-guided applicator placement and high-dose-rate brachytherapy with an iridium-192 source. The mean radiation dose was 18.57 Gy (standard deviation 2.27). Tumor response was evaluated by gadoxetic acid-enhanced liver magnetic resonance (MR) imaging performed before treatment, 6 weeks after treatment, and every 3 months thereafter. Two patients were lost to follow-up; the remaining 35 patients were available for MR imaging evaluation for a mean follow-up time of 11.6 months (range 3-32 mo). Mean tumor diameter was 25.5 mm (range 8-74 mm). Two (2.6%) local recurrences were observed after local tumor control for 10 months and 12 months. Both local progressions were successfully retreated. Distant tumor progression (new metastases or enlargement of nontreated metastases) occurred during the follow-up period in 11 (31.4%) patients. Seven (20%) patients died during the follow-up period. Overall survival ranged from 3-39 months (median 18 months). CT-HDRBT is a safe and effective ablative therapy, providing a high rate of local tumor control in patients with BCLM.
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1.26Impact points
Interfraction rotation of the prostate as evaluated by kilovoltage X-ray fiducial marker imaging in intensity-modulated radiotherapy of localized prostate cancer.
Medical dosimetry : official journal of the American Association of Medical Dosimetrists. 04/2012;
To quantify the daily rotation of the prostate during a radiotherapy course using stereoscopic kilovoltage (kV) x-ray imaging and intraprostatic fiducials for localization and positioning correction. From 2005 to 2009, radio-opaque fiducial markers were inserted into 38 patients via perineum into th... [more] To quantify the daily rotation of the prostate during a radiotherapy course using stereoscopic kilovoltage (kV) x-ray imaging and intraprostatic fiducials for localization and positioning correction. From 2005 to 2009, radio-opaque fiducial markers were inserted into 38 patients via perineum into the prostate. The ExacTrac/Novalis Body X-ray 6-day image acquisition system (ET/NB; BrainLab AG, Feldkirchen, Germany) was used to determine and correct the target position. During the first period in 10 patients we recorded all rotation errors but used only Y (table) for correction. For the next 28 patients we used for correction all rotational coordinates, i.e., in addition Z (superior-inferior [SI] or roll) and X (left-right [LR] or tilt/pitch) according to the fiducial marker position by use of the Robotic Tilt Module and Varian Exact Couch. Rotation correction was applied above a threshold of 1° displacement. The systematic and random errors were specified. Overall, 993 software-assisted rotational corrections were performed. The interfraction rotation errors of the prostate as assessed from the radiodense surrogate markers around the three axes Y, Z, and X were on average 0.09, -0.52, and -0.01° with standard deviations of 2.01, 2.30, and 3.95°, respectively. The systematic uncertainty per patient for prostate rotation was estimated with 2.30, 1.56, and 4.13° and the mean random components with 1.81, 2.02, and 3.09°. The largest rotational errors occurred around the X-axis (pitch), but without preferring a certain orientation. Although the error around Z (roll) can be compensated on average by a transformation with 4 coordinates, a significant error around X remains and advocates the full correction with 6 coordinates. Rotational errors as assessed via daily stereoscopic online imaging are significant and dominate around X. Rotation possibly degrades the dosimetric coverage of the target volume and may require suitable strategies for correction.
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Magnetic resonance imaging, computed tomography, and 68Ga-DOTATOC positron emission tomography for imaging skull base meningiomas with infracranial extension treated with stereotactic radiotherapy - a case series.
Head & face medicine. 01/2012; 8(1):1.
ABSTRACT: Magnetic resonance imaging (MRI) and computed tomography (CT) with 68Ga-DOTATOC positron emission tomography (68Ga-DOTATOC-PET) were compared retrospectively for their ability to delineate infracranial extension of skull base (SB) meningiomas treated with fractionated stereotactic radiothe... [more] ABSTRACT: Magnetic resonance imaging (MRI) and computed tomography (CT) with 68Ga-DOTATOC positron emission tomography (68Ga-DOTATOC-PET) were compared retrospectively for their ability to delineate infracranial extension of skull base (SB) meningiomas treated with fractionated stereotactic radiotherapy. Fifty patients with 56 meningiomas of the SB underwent MRI, CT, and 68Ga-DOTATOC PET/CT prior to fractionated stereotactic radiotherapy. The study group consisted of 16 patients who had infracranial meningioma extension, visible on MRI ± CT (MRI/CT) or PET, and were evaluated further. The respective findings were reviewed independently, analyzed with respect to correlations, and compared with each other. Within the study group, SB transgression was associated with bony changes visible by CT in 14 patients (81%). Tumorous changes of the foramen ovale and rotundum were evident in 13 and 8 cases, respectively, which were accompanied by skeletal muscular invasion in 8 lesions. We analysed six designated anatomical sites of the SB in each of the 16 patients. Of the 96 sites, 42 had infiltration that was delineable by MRI/CT and PET in 35 cases and by PET only in 7 cases. The mean infracranial volume that was delineable in PET was 10.1 ± 10.6 cm3, which was somewhat larger than the volume detectable in MRI/CT (8.4 ± 7.9 cm3). 68Ga-DOTATOC-PET allows detection and assessment of the extent of infracranial meningioma invasion. This method seems to be useful for planning fractionated stereotactic radiation when used in addition to conventional imaging modalities that are often inconclusive in the SB region.
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3.59Impact points
Hepatocellular carcinoma: computed-tomography-guided high-dose-rate brachytherapy (CT-HDRBT) ablation of large (5-7 cm) and very large (>7 cm) tumours.
European radiology. 12/2011;
OBJECTIVES: Evaluate the clinical outcome of CT-guided high-dose-rate-brachytherapy (CT-HDRBT) of hepatocellular carcinoma (HCC) larger than 5 cm in diameter with the goal of local tumour control (LTC). METHODS: Thirty-five patients with 35 unresectable HCCs ranging in size from 5 to 12 cm (mean: 7.... [more] OBJECTIVES: Evaluate the clinical outcome of CT-guided high-dose-rate-brachytherapy (CT-HDRBT) of hepatocellular carcinoma (HCC) larger than 5 cm in diameter with the goal of local tumour control (LTC). METHODS: Thirty-five patients with 35 unresectable HCCs ranging in size from 5 to 12 cm (mean: 7.1 cm) were treated with CT-HDRBT. Tumours were classified into two groups according to diameter: "large lesions" (5-7 cm) and "very large lesions" (>7 cm). Tumour response was evaluated by Gd-EOB-DTPA-enhanced liver magnetic resonance imaging (MRI) performed before, 6 weeks after, and then every 3 months after treatment. Endpoints included local tumour control (LTC), progression-free survival (PFS) and overall survival (OS). RESULTS: Nineteen tumours were classified as "large" and 16 as "very large". Complete tumour enclosure was achieved in all patients after the first CT-HDRBT session. Five patients were lost to follow-up. At a mean follow-up of 12.8 months, two patients had local progression (6.7%), one in each group. Nine patients (30%) experienced distant progression, five (26.3%) in the "large" and four (25%) in the "very large" group. No patients died during the follow-up period. No major complications were recorded. CONCLUSIONS: CT-HDRBT is a promising therapy for HCCs that exceed indications for thermal ablation. KEY POINTS: • Computed Tomography guided high-dose-rate brachytherapy offers new therapeutic options for hepatocellular carcinoma • CT-HDRBT can be safely practised in HCCs exceeding 5 cm in diameter • CT-HDRBT offers high rate of local control where thermal ablation is impossible • CT-HDRBT could be a valid alternative to TACE for intermediate stage HCC.
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4.32Impact points
Computed tomography-guided brachytherapy for liver cancer.
Seminars in radiation oncology. 10/2011; 21(4):287-93.
Limitations of thermal liver cancer ablation have led to the development of percutaneous, catheter-based brachytherapy for the treatment of liver malignancies. Computed tomography (CT)-guided brachytherapy has been used to treat primary and metastatic liver cancers, including very large tumors >1... [more] Limitations of thermal liver cancer ablation have led to the development of percutaneous, catheter-based brachytherapy for the treatment of liver malignancies. Computed tomography (CT)-guided brachytherapy has been used to treat primary and metastatic liver cancers, including very large tumors >10 cm. Cooling effects by adjacent blood vessels are not a concern in brachytherapy, and the method may be used safely in tumors unsuitable for thermal ablation that are close to the liver hilum due to the relatively high radiation tolerance of bile duct. CT scanning is used for dosimetry planning after catheter implantation and also to guide the catheter placement itself. Major complications, including postinterventional bleeding, are rare despite frequent application of this technique in a salvage situation. Patients with liver cirrhosis have an increased risk for complications. Prospective trials of CT-guided brachytherapy have been performed with promising survival rates for liver metastases and hepatocellular carcinoma, respectively. In this article, the radiobiological and technical properties of CT-guided brachytherapy, appropriate patients for treatment, and prospective trials that have been published to date are reviewed.
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1.95Impact points
Erratum to: Computed Tomography-Guided Interstitial HDR Brachytherapy (CT-HDRBT) of the Liver in Patients with Irresectable Intrahepatic Cholangiocarcinoma.
Cardiovascular and interventional radiology. 09/2011;
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2.53Impact points
In vivo assessment of catheter positioning accuracy and prolonged irradiation time on liver tolerance dose after single-fraction 192Ir high-dose-rate brachytherapy.
Radiation oncology (London, England). 09/2011; 6:107.
To assess brachytherapy catheter positioning accuracy and to evaluate the effects of prolonged irradiation time on the tolerance dose of normal liver parenchyma following single-fraction irradiation with 192Ir. Fifty patients with 76 malignant liver tumors treated by computed tomography (CT)-guided ... [more] To assess brachytherapy catheter positioning accuracy and to evaluate the effects of prolonged irradiation time on the tolerance dose of normal liver parenchyma following single-fraction irradiation with 192Ir. Fifty patients with 76 malignant liver tumors treated by computed tomography (CT)-guided high-dose-rate brachytherapy (HDR-BT) were included in the study. The prescribed radiation dose was delivered by 1 - 11 catheters with exposure times in the range of 844 - 4432 seconds. Magnetic resonance imaging (MRI) datasets for assessing irradiation effects on normal liver tissue, edema, and hepatocyte dysfunction, obtained 6 and 12 weeks after HDR-BT, were merged with 3D dosimetry data. The isodose of the treatment plan covering the same volume as the irradiation effect was taken as a surrogate for the liver tissue tolerance dose. Catheter positioning accuracy was assessed by calculating the shift between the 3D center coordinates of the irradiation effect volume and the tolerance dose volume for 38 irradiation effects in 30 patients induced by catheters implanted in nearly parallel arrangement. Effects of prolonged irradiation were assessed in areas where the irradiation effect volume and tolerance dose volume did not overlap (mismatch areas) by using a catheter contribution index. This index was calculated for 48 irradiation effects induced by at least two catheters in 44 patients. Positioning accuracy of the brachytherapy catheters was 5-6 mm. The orthogonal and axial shifts between the center coordinates of the irradiation effect volume and the tolerance dose volume in relation to the direction vector of catheter implantation were highly correlated and in first approximation identically in the T1-w and T2-w MRI sequences (p = 0.003 and p < 0.001, respectively), as were the shifts between 6 and 12 weeks examinations (p = 0.001 and p = 0.004, respectively). There was a significant shift of the irradiation effect towards the catheter entry site compared with the planned dose distribution (p < 0.005). Prolonged treatment time increases the normal tissue tolerance dose. Here, the catheter contribution indices indicated a lower tolerance dose of the liver parenchyma in areas with prolonged irradiation (p < 0.005). Positioning accuracy of brachytherapy catheters is sufficient for clinical practice. Reduced tolerance dose in areas exposed to prolonged irradiation is contradictory to results published in the current literature. Effects of prolonged dose administration on the liver tolerance dose for treatment times of up to 60 minutes per HDR-BT session are not pronounced compared to effects of positioning accuracy of the brachytherapy catheters and are therefore of minor importance in treatment planning.
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1.95Impact points
Computed Tomography-Guided Interstitial HDR Brachytherapy (CT-HDRBT) of the Liver in Patients with Irresectable Intrahepatic Cholangiocarcinoma.
Cardiovascular and interventional radiology. 08/2011;
PURPOSE: This study was designed to investigate the clinical outcome of patients with irresectable, intrahepatic cholangiocarcinoma (IHC) treated with computed tomography (CT)-guided HDR-brachytherapy (CT-HDRBT) for local tumor ablation. METHOD: Fifteen consecutive patients with histologically prove... [more] PURPOSE: This study was designed to investigate the clinical outcome of patients with irresectable, intrahepatic cholangiocarcinoma (IHC) treated with computed tomography (CT)-guided HDR-brachytherapy (CT-HDRBT) for local tumor ablation. METHOD: Fifteen consecutive patients with histologically proven cholangiocarcinoma were selected for this retrospective study. Patients were treated by high-dose-rate internal brachytherapy (HDRBT) using an Iridium-192 source in afterloading technique through CT-guided percutaneous placed catheters. A total of 27 brachytherapy treatments were performed in these patients between 2006 and 2009. Median tumor enclosing target dose was 20 Gy, and mean target volume of the radiated tumors was 131 (± 90) ml (range, 10-257 ml). Follow-up consisted of clinical visits and magnetic resonance imaging of the liver every third month. Statistical evaluation included survival analysis using the Kaplan-Meier method. RESULTS: After a median follow-up of 18 (range, 1-27) months after local ablation, 6 of the 15 patients are still alive; 4 of them did not get further chemotherapy and are regarded as disease-free. The reached median local tumor control was 10 months; median local tumor control, including repetitive local ablation, was 11 months. Median survival after local ablation was 14 months and after primary diagnosis 21 months. CONCLUSION: In view of current clinical data on the clinical outcome of cholangiocarcinoma, locally ablative treatment with CT-HDRBT represents a promising and safe technique for patients who are not eligible for tumor resection.
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2.70Impact points
Monte Carlo simulation of contrast-enhanced whole brain radiotherapy on a CT scanner.
Medical physics. 08/2011; 38(8):4672-80.
To perform a feasibility study of contrast-enhanced whole brain radiotherapy for treating patients with multiple brain metastasis using a conventional computed tomography (CT) scanner. The treatment dose was optimized to be applied in a single run using a maximum tube power of 5200 kWs at 140 kV. CT... [more] To perform a feasibility study of contrast-enhanced whole brain radiotherapy for treating patients with multiple brain metastasis using a conventional computed tomography (CT) scanner. The treatment dose was optimized to be applied in a single run using a maximum tube power of 5200 kWs at 140 kV. CT scans of a large and a small head were used as reference. Irradiation geometry, shielding, axial beam collimation, radial beam collimation, gantry tilt, and tube current for beam modulation were optimized using a Monte Carlo simulation and a contrast agent concentration of 5 mg/ml iodine in the tumor. The statistical uncertainty of the Monte Carlo simulation was corrected using back convolution. Using a CT tube with a beam collimation of 28.8 mm, a mean tumor dose of 1.76 +/- 0.13 Gy was achieved, while the head bone dose was 2.61 +/- 0.18 Gy with a normal brain dose of 0.98 +/- 0.06 Gy, eye dose of 0.19 +/- 0.05 Gy, and lens dose of 0.15 +/- 0.03 Gy, respectively. Using a CT tube with dose modulation and a beam collimation of 40.0 mm, the mean tumor dose was 2.00 +/- 0.11 Gy with a head bone dose of 1.96 +/- 0.14 Gy, normal brain dose of 1.13 +/- 0.08 Gy, eye dose of 0.21 +/- 0.05 Gy, and lens dose of 0.16 +/- 0.02 Gy, respectively. Thus a standard CT scanner enables an effective tumor dose of 37.0 Gy to be administered in 13 fractions, while exposing healthy brain to an effective dose of 17.2 Gy and head bone to 69.3 Gy. Additional radial collimation implemented in the hardware improves the therapeutic tumor dose by 25.2% in relation to the bone dose. Contrast-enhanced total brain radiotherapy is feasible using a conventional CT tube with optimized dose application.
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1.43Impact points
CT-guided high-dose-rate brachytherapy of metachronous ovarian cancer metastasis to the liver: initial experience.
Anticancer research. 08/2011; 31(8):2597-602.
Hepatic resection for hepatic ovarian cancer metastases remains controversial. The purpose of this study was to evaluate the clinical outcome of CT-guided high dose rate brachytherapy (CT-HDRBT) for minimally invasive cytoreduction of isolated metachronous ovarian cancer metastases to the liver. Sev... [more] Hepatic resection for hepatic ovarian cancer metastases remains controversial. The purpose of this study was to evaluate the clinical outcome of CT-guided high dose rate brachytherapy (CT-HDRBT) for minimally invasive cytoreduction of isolated metachronous ovarian cancer metastases to the liver. Seven patients with 12 isolated ovarian cancer metastases to the liver were treated with CT-HDRBT. To evaluate tumor response a gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced liver MRI was performed before, six weeks after and every third month after treatment. The mean MRI-follow-up period was 15.4 months. Tumors ranged from 13 to 120 mm in diameter. Complete ablation was achieved for all lesions. No complications occurred. No local progression was observed in any of the included patients. Overall survival was 100% after 12 months. Two patients died after 14 and 25 months, respectively. CT-HDRBT is a safe and valid technique for performing minimally invasive cytoreduction of metachronous isolated liver metastases from ovarian cancer.
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2.75Impact points
Efficacy and safety of intratumoral thermotherapy using magnetic iron-oxide nanoparticles combined with external beam radiotherapy on patients with recurrent glioblastoma multiforme.
Journal of neuro-oncology. 06/2011; 103(2):317-24.
Therapy options at the time of recurrence of glioblastoma multiforme are often limited. We investigated whether treatment with a new intratumoral thermotherapy procedure using magnetic nanoparticles improves survival outcome. In a single-arm study in two centers, 66 patients (59 with recurrent gliob... [more] Therapy options at the time of recurrence of glioblastoma multiforme are often limited. We investigated whether treatment with a new intratumoral thermotherapy procedure using magnetic nanoparticles improves survival outcome. In a single-arm study in two centers, 66 patients (59 with recurrent glioblastoma) received neuronavigationally controlled intratumoral instillation of an aqueous dispersion of iron-oxide (magnetite) nanoparticles and subsequent heating of the particles in an alternating magnetic field. Treatment was combined with fractionated stereotactic radiotherapy. A median dose of 30 Gy using a fractionation of 5 × 2 Gy/week was applied. The primary study endpoint was overall survival following diagnosis of first tumor recurrence (OS-2), while the secondary endpoint was overall survival after primary tumor diagnosis (OS-1). Survival times were calculated using the Kaplan-Meier method. Analyses were by intention to treat. The median overall survival from diagnosis of the first tumor recurrence among the 59 patients with recurrent glioblastoma was 13.4 months (95% CI: 10.6-16.2 months). Median OS-1 was 23.2 months while the median time interval between primary diagnosis and first tumor recurrence was 8.0 months. Only tumor volume at study entry was significantly correlated with ensuing survival (P < 0.01). No other variables predicting longer survival could be determined. The side effects of the new therapeutic approach were moderate, and no serious complications were observed. Thermotherapy using magnetic nanoparticles in conjunction with a reduced radiation dose is safe and effective and leads to longer OS-2 compared to conventional therapies in the treatment of recurrent glioblastoma.
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4.34Impact points
Treatment of hepatic metastases of breast cancer with CT-guided interstitial brachytherapy - a phase II-study.
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. 04/2011; 100(2):314-9.
The aim of the study was the evaluation of feasibility, safety and effectiveness of interstitial brachytherapy for the treatment of hepatic metastases of breast cancer. Forty-one consecutive patients with 115 unresectable hepatic metastases of breast cancer were included in this phase-II-trial. They... [more] The aim of the study was the evaluation of feasibility, safety and effectiveness of interstitial brachytherapy for the treatment of hepatic metastases of breast cancer. Forty-one consecutive patients with 115 unresectable hepatic metastases of breast cancer were included in this phase-II-trial. They were treated in 69 interventions of CT-guided-interstitial-brachytherapy of the liver. Brachytherapy was applied as a single fraction high-dose-irradiation (15-25Gy (Gray)) using a (192)Ir-source of 10Ci. Nineteen patients presented systemically pretreated extrahepatic tumors. Primary endpoints were complications, local tumor control and progression-free survival. The median tumor diameter was 4.6 cm (1.5-11 cm). The median irradiation time per intervention was 26.5 min (range: 7-47 min). The applied median minimal dose at the CTV (clinical target volume) margin was 18.5 Gy (12-25 Gy). In 69 interventions and during the postinterventional period, one major complication (symptomatic post-interventional bleeding) (1.5%) and six minor complications occurred (8.7%). The median follow-up time was 18 months (range: 1-56). After 6, 12 and 18 months, local tumor control was 97%, 93.5% and 93.5%, intra- and extrahepatic progression free survival was 53%, 40% and 27%, and overall survival was 97%, 79% and 60%, respectively. CT-guided-brachytherapy is safe and effective for the treatment of liver metastases of breast cancer.
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2.53Impact points
Quantitative in vivo assessment of radiation injury of the liver using Gd-EOB-DTPA enhanced MRI: tolerance dose of small liver volumes.
Radiation oncology (London, England). 01/2011; 6:40.
Hepatic radiation toxicity restricts irradiation of liver malignancies. Better knowledge of hepatic tolerance dose is favourable to gain higher safety and to optimize radiation regimes in radiotherapy of the liver. In this study we sought to determine the hepatic tolerance dose to small volume singl... [more] Hepatic radiation toxicity restricts irradiation of liver malignancies. Better knowledge of hepatic tolerance dose is favourable to gain higher safety and to optimize radiation regimes in radiotherapy of the liver. In this study we sought to determine the hepatic tolerance dose to small volume single fraction high dose rate irradiation. 23 liver metastases were treated by CT-guided interstitial brachytherapy. MRI was performed 3 days, 6, 12 and 24 weeks after therapy. MR-sequences were conducted with T1-w GRE enhanced by hepatocyte-targeted Gd-EOB-DTPA. All MRI data sets were merged with 3D-dosimetry data. The reviewer indicated the border of hypointensity on T1-w images (loss of hepatocyte function) or hyperintensity on T2-w images (edema). Based on the volume data, a dose-volume-histogram was calculated. We estimated the threshold dose for edema or function loss as the D90, i.e. the dose achieved in at least 90% of the pseudolesion volume. At six weeks post brachytherapy, the hepatocyte function loss reached its maximum extending to the former 9.4Gy isosurface in median (i.e., ≥9.4Gy dose exposure led to hepatocyte dysfunction). After 12 and 24 weeks, the dysfunctional volume had decreased significantly to a median of 11.4Gy and 14Gy isosurface, respectively, as a result of repair mechanisms. Development of edema was maximal at six weeks post brachytherapy (9.2Gy isosurface in median), and regeneration led to a decrease of the isosurface to a median of 11.3Gy between 6 and 12 weeks. The dose exposure leading to hepatocyte dysfunction was not significantly different from the dose provoking edema. Hepatic injury peaked 6 weeks after small volume irradiation. Ongoing repair was observed up to 6 months. Individual dose sensitivity may differ as demonstrated by a relatively high standard deviation of threshold values in our own as well as all other published data.
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2.70Impact points
Regularized antenna profile adaptation in online hyperthermia treatment.
Medical physics. 10/2010; 37(10):5382-94.
Online optimization of annular-phased-array hyperthermia (HT) is based on planning tools and magnetic resonance (MR) thermometry. Until now, the method has been validated in phantoms. Further developments and extensions are required for clinical purposes. In particular, the problem of deducing the e... [more] Online optimization of annular-phased-array hyperthermia (HT) is based on planning tools and magnetic resonance (MR) thermometry. Until now, the method has been validated in phantoms. Further developments and extensions are required for clinical purposes. In particular, the problem of deducing the electric field distribution inside the patient from MR thermometry is ill-posed, which leads to an amplification of measurement errors. A method to overcome this difficulty is proposed. The authors utilized a regularized Gauss-Newton algorithm with a fast bioheat transfer equation (BHTE) approximation to identify the field parameters. To evaluate the method, simulations with patient models are conducted and a treatment data set obtained from a heat treatment performed in the hybrid HT-MR system at the Charité Medical School is used to visualize the error amplification. The regularization leads to a significantly improved accuracy of the predicted electric fields and temperatures compared to an unregularized approach. The BHTE approximation enables highly accurate temperature predictions in real-time. Regularization proves to be necessary to identify electromagnetic field parameters. The proposed method is able to reproduce measurements without overfitting to the noise in the MR measurements and results in an improved treatment planning.
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3.78Impact points
Residual translational and rotational errors after kV X-ray image-guided correction of prostate location using implanted fiducials.
Strahlentherapie und Onkologie : Organ der Deutschen Röntgengesellschaft ... [et al]. 09/2010; 186(10):544-50.
To evaluate the residual errors and required safety margins after stereoscopic kilovoltage (kV) X-ray target localization of the prostate in image-guided radiotherapy (IGRT) using internal fiducials. Radiopaque fiducial markers (FMs) have been inserted into the prostate in a cohort of 33 patients. T... [more] To evaluate the residual errors and required safety margins after stereoscopic kilovoltage (kV) X-ray target localization of the prostate in image-guided radiotherapy (IGRT) using internal fiducials. Radiopaque fiducial markers (FMs) have been inserted into the prostate in a cohort of 33 patients. The ExacTrac/Novalis Body™ X-ray 6d image acquisition system (BrainLAB AG, Feldkirchen, Germany) was used. Corrections were performed in left-right (LR), anterior-posterior (AP), and superior-inferior (SI) direction. Rotational errors around LR (x-axis), AP (y) and SI (z) have been recorded for the first series of nine patients, and since 2007 for the subsequent 24 patients in addition corrected in each fraction by using the Robotic Tilt Module™ and Varian Exact Couch™. After positioning, a second set of X-ray images was acquired for verification purposes. Residual errors were registered and again corrected. Standard deviations (SD) of residual translational random errors in LR, AP, and SI coordinates were 1.3, 1.7, and 2.2 mm. Residual random rotation errors were found for lateral (around x, tilt), vertical (around y, table), and longitudinal (around z, roll) and of 3.2°, 1.8°, and 1.5°. Planning target volume (PTV)-clinical target volume (CTV) margins were calculated in LR, AP, and SI direction to 2.3, 3.0, and 3.7 mm. After a second repositioning, the margins could be reduced to 1.8, 2.1, and 1.8 mm. On the basis of the residual setup error measurements, the margin required after one to two online X-ray corrections for the patients enrolled in this study would be at minimum 2 mm. The contribution of intrafractional motion to residual random errors has to be evaluated.
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4.59Impact points
Computed tomography-guided high-dose-rate brachytherapy in hepatocellular carcinoma: safety, efficacy, and effect on survival.
International journal of radiation oncology, biology, physics. 09/2010; 78(1):172-9.
To determine the safety and efficacy of computed tomography (CT)-guided brachytherapy in hepatocellular carcinoma (HCC). A total of 83 patients were recruited, presenting with 140 HCC- lesions. Treatment was performed by CT-guided high-dose-rate (HDR) brachytherapy with an iridium-192 source. The pr... [more] To determine the safety and efficacy of computed tomography (CT)-guided brachytherapy in hepatocellular carcinoma (HCC). A total of 83 patients were recruited, presenting with 140 HCC- lesions. Treatment was performed by CT-guided high-dose-rate (HDR) brachytherapy with an iridium-192 source. The primary endpoint was time to progression; secondary endpoints included local tumor control and overall survival (OS). A matched-pair analysis with patients not receiving brachytherapy was performed. Match criteria included the Cancer of the Liver Italian Program (CLIP) score, alpha-fetoprotein, presence, and extent of multifocal disease. For statistical analysis, Kaplan-Meier and Cox regression were performed. Mean and median cumulative TTP for all patients (n = 75) were 17.7 and 10.4 months. Five local recurrences were observed. The OS after inclusion reached median times of 19.4 months (all patients), 46.3 months (CLIP score, 0), 20.6 months (CLIP score, 1) 12.7 months, (CLIP score, 2), and 8.3 months (CLIP score, >or=3). The 1- and 3-year OS were 94% and 65% (CLIP score, 0), 69% and 12% (CLIP score, 1), and 48% and 19% (CLIP score, 2), respectively. Nine complications requiring intervention were encountered in 124 interventions. Matched-pair analysis revealed a significantly longer OS for patients undergoing CT-guided brachytherapy. Based on our results the study treatment could be safely performed. The study treatment had a beneficial effect on OS in patients with advanced HCC, with respect to (and depending on) the CLIP score and compared with OS in a historical control group. A high rate of local control was also observed, regardless of applied dose in a range of 15 to 25 Gy.
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4.59Impact points
Value of combined PET/CT for radiation planning in CT-guided percutaneous interstitial high-dose-rate single-fraction brachytherapy for colorectal liver metastases.
International journal of radiation oncology, biology, physics. 07/2010; 77(4):1178-85.
To determine the additional value of fluorodeoxyglucose-positron emission tomography (PET) for clinical target volume definition in the planning of computed tomography (CT)-guided interstitial brachytherapy for liver metastases. A total of 19 patients with liver metastases from colorectal cancer tre... [more] To determine the additional value of fluorodeoxyglucose-positron emission tomography (PET) for clinical target volume definition in the planning of computed tomography (CT)-guided interstitial brachytherapy for liver metastases. A total of 19 patients with liver metastases from colorectal cancer treated in 25 sessions were included in the present study. All patients had undergone fluorodeoxyglucose-PET for patient evaluation before interstitial CT-guided brachytherapy. A contrast-enhanced CT scan of the upper abdomen was obtained for radiation planning. The clinical target volume (CTV) was defined by a radiation oncologist and radiologist. After registration of the CT scan with the PET data set, the target volume was defined again using the fusion images. PET revealed one additional liver lesion that was not visible on CT. The median CT-CTV (defined using CT and magnetic resonance imaging) was 68 cm(3) (range 4-260). The PET/CT-CTV (median, 78 cm(3); range, 4-273) was significantly larger, with a median gain of 24.5% (interquartile range, 2.1-71.5%; p = .022). An increased CTV was observed in 15 cases and a decrease in 6; in 4 cases, the CT-CTV and PET/CT-CTV were equal. Incomplete dose coverage of PET/CT-CTVs was indicative of early local progression (p = .004); however, CT-based radiation plans did not show significant differences in the local control rates when stratified by dose coverage. Retrospective implementation of fluorodeoxyglucose-PET for CTV specification for CT-guided brachytherapy for colorectal liver metastases revealed a significant change in the CTVs. Additional PET-positive tumor regions with incomplete dose coverage could explain unexpected early local progression.
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2.41Impact points
Tumour perfusion assessment during regional hyperthermia treatment: comparison of temperature probe measurement with H(2)(15)O-PET perfusion.
International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group. 04/2010; 26(4):404-11.
Hyperthermia treatment might increase tumour oxygenation and perfusion, as has been reported for experimental tumours. The present study was performed to investigate this hypothesis in patients undergoing regional hyperthermia treatment. Thirteen patients with primary or recurrent pelvic tumours wer... [more] Hyperthermia treatment might increase tumour oxygenation and perfusion, as has been reported for experimental tumours. The present study was performed to investigate this hypothesis in patients undergoing regional hyperthermia treatment. Thirteen patients with primary or recurrent pelvic tumours were included in this study. Prior to and up to one hour after regional hyperthermia, perfusion was quantitatively determined by H(2)(15)O-PET. The fused CT-PET images were used to extract tumour time-activity curves and to identify the catheter position. Perfusion was calculated from the total tumour time-activity curves and for the time-activity curves at the catheter site. Additionally, perfusion was calculated from the temperature-time curves measured using temperature probes. Perfusion values calculated using H(2)(15)O-PET and those deduced from temperature probe measurements are significantly correlated with a correlation coefficient, R = 0.21. The perfusion values deduced from the temperature measured in a body cavity do not provide information about average tumour perfusion. Perfusion values deduced from the temperature are overestimated for very poorly perfused tissues and underestimated for highly perfused tissues. Temperature measurement during hyperthermia may allow only determination of intermediate perfusion values.
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4.59Impact points
Local response and impact on survival after local ablation of liver metastases from colorectal carcinoma by computed tomography-guided high-dose-rate brachytherapy.
International journal of radiation oncology, biology, physics. 03/2010; 78(2):479-85.
To determine local tumor control after CT-guided brachytherapy at various dose levels and the prognostic impact of extensive cytoreduction in colorectal liver metastases. Seventy-three patients were treated on a single-center prospective trial that was initially designed to be randomized to three do... [more] To determine local tumor control after CT-guided brachytherapy at various dose levels and the prognostic impact of extensive cytoreduction in colorectal liver metastases. Seventy-three patients were treated on a single-center prospective trial that was initially designed to be randomized to three dose levels of 15 Gy, 20 Gy, or 25 Gy per lesion, delivered in a single fraction. However, because there was a high rate of cross-over of subjects from higher to lower dose levels, this study is better understood as a prospective trial with three dose levels. No upper size limit for the metastases was applied. We assessed time to local progression, progression-free survival, and overall survival. According to safety constraints cross-over was performed. The final assignment was n = 98, n = 68, and n = 33 in the 15-Gy, 20-Gy, and 25-Gy groups, respectively. Median diameter of the largest tumor lesion in each patient was 5 cm (range, 1-13.5 cm). Estimated mean local recurrence-free survival for all lesions was 34 months (median not reached). The group assigned to 15 Gy after cross-over displayed 34 local recurrences out of 98 lesions; 20 Gy, 15 out of 68 lesions; 25 Gy, 1 out of 33 lesions. The difference between the 25-Gy and the 20-Gy or 15-Gy group was significant (p < 0.05). Repeated local tumor ablations were the most prominent factor for increased survival and dominated additional systemic antitumor treatments. Local tumor control after CT-guided brachytherapy of colorectal liver metastases demonstrated a strong dose dependency. The role of extensive minimally invasive tumor ablation in metastatic colorectal cancer needs to be further established.
Following (29)
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Frank Siebenhaar
Charité Universitätsmedizin Berlin -
Marcus Maurer
Charité Universitätsmedizin Berlin -
Ulrich Dirnagl
Charité Universitätsmedizin Berlin -
Agnieszka Szczepek
Charité Universitätsmedizin Berlin -
Ricarda Seidensticker
Otto-von-Guericke-Universität Magdeburg
