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ABSTRACT: IMPORTANCE The present study intended to analyze the suitability of single-dose stereotactic radiotherapy in the treatment of uveal melanoma that cannot be handled with ruthenium-brachytherapy and therefore is a challenge for ophthalmologists concerning local tumor control, as well as preservation of the eye and visual function. OBJECTIVES To evaluate local tumor control, eye preservation, visual course, radiation complications, metastases, and death after single-dose stereotactic radiotherapy (SDRT) applied exclusively or combined with tumor resection in uveal melanomas that are neither suitable nor favorably located for ruthenium brachytherapy. DESIGN Retrospective, observational case series. SETTING Primary care center. PARTICIPANTS Seventy-eight patients with uveal melanoma were treated. INTERVENTION Between June 3, 2003, and March 18, 2008, patients with uveal melanoma received SDRT monotherapy (group 1, 60 patients) or SDRT combined with tumor resection (group 2, 18 patients). Radiotherapy was performed with a tumor-surrounding dose of 25 Gy on a linear accelerator. MAIN OUTCOME MEASURES Local tumor control, eye preservation, visual results, and radiation complications. RESULTS Within a median follow-up of 33.7 months (range, 0.13-81.13 months), 6 recurrences occurred in group 1; none recurred in group 2. The Kaplan-Meier estimate for local control was 85% at 3 years in group 1 and 100% in group 2 (P = .22). Eye preservation rate was 77% vs 87% at 3 years (groups 1 and 2, respectively) (P = .82). Visual acuity decreased with a median loss of -18 Snellen lines (group 1) and -22 Snellen lines (group 2). More retinopathies (P = .07), opticopathies (P = .27), and rubeotic glaucomas (P = .10) occurred in group 1. No significant difference was observed in the development of metastases (P = .33). The groups differed in overall survival because of 2 deaths occurring shortly after surgery in group 2 for unexplained reasons (P = .06). CONCLUSIONS AND RELEVANCE Survival analysis suggested that SDRT with combined tumor resection might be associated with increased tumor control and fewer radiation complications than SDRT as monotherapy. Both groups had similar eye retention rates and were comparable concerning the decrease in visual function in most eyes. However, the protocol was stopped after 3 unexplainable deaths after surgery.
JAMA ophthalmology. 03/2013;
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Dominik Ketelsen, Markus Buchgeister,
Andreas Korn,
Michael Fenchel,
Bernhard Schmidt,
Thomas G Flohr,
Christoph Thomas,
Christoph Schabel,
Ilias Tsiflikas,
Roland Syha,
Claus D Claussen,
Martin Heuschmid
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ABSTRACT: Purpose. To estimate effective dose and organ equivalent doses of prospective ECG-triggered high-pitch CTCA. Materials and Methods. For dose measurements, an Alderson-Rando phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a second-generation dual-source scanner (SOMATOM Definition Flash, Siemens Medical Solutions, Germany). The following scan parameters were used: 320 mAs per rotation, 100 and 120 kV, pitch 3.4 for prospectively ECG-triggered high-pitch CTCA, scan range of 13.5 cm, collimation 64 × 2 × 0.6 mm with z-flying focal spot, gantry rotation time 280 ms, and simulated heart rate of 60 beats per minute. Results. Depending on the applied tube potential, the effective whole-body dose of the cardiac scan ranged from 1.1 mSv to 1.6 mSv and from 1.2 to 1.8 mSv for males and females, respectively. The radiosensitive breast tissue in the range of the primary beam caused an increased female-specific effective dose of 8.6%±0.3% compared to males. Decreasing the tube potential, a significant reduction of the effective dose of 35.8% and 36.0% can be achieved for males and females, respectively (P < 0.001). Conclusion. The radiologist and the CT technician should be aware of this new dose-saving strategy to keep the radiation exposure as low as reasonablly achievable.
Radiology research and practice. 01/2012; 2012:724129.
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ABSTRACT: To evaluate radiation exposure and image quality in thoracic computed tomography (CT) using a new dose-saving algorithm to protect radiosensitive organs.
For dose measurements, an Alderson RANDO phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to the International Commission on Radiologic Protection 103. Exposure was performed on a second-generation dual-source CT. The following parameters for thoracic CT were used: 160 effective mAs, 120 kV, scan range of 30 cm, collimation of 128 × 0.6 mm. For the acquisition, the tube current modulation type XCare was used, which reduces the tube current for anterior tube position to minimize direct exposure to anterior located organs. To compare differences, scans with and without XCare were performed. Objective signal-to-noise measurements were evaluated, and the subjective noise perception was rated in a 3-point scale (1: excellent, 3: affecting diagnostic accuracy) in 30 patients with a standard thoracic examination and a follow-up using XCare.
A substantial dose reduction in radiosensitive tissues was evident using the dose-saving algorithm XCare. Specifically, reductions of 35.2% for the female breast and 20.1% for the thyroid gland were measured, resulting in a decreasing effective whole-body dose of 8.0% and 14.3% for males and females, respectively. The objective and subjective evaluation of image quality showed no significant differences between both scan protocols (P > 0.05). Mean signal-to-noise ratio was 1.3 ± 0.2 and 1.2 ± 0.2 in scan protocols without and with XCare, respectively. The subjective scores at the level of the pulmonary trunk were 1.2 ± 0.4 and 1.4 ± 0.5 in standard chest scan and scans with the dose-saving algorithm XCare, respectively.
The XCare technique protects radiosensitive organs like the female breast and the thyroid gland without affecting image quality. Therefore, this dose-saving algorithm may be used in thoracic CT examinations in male and female patients.
Investigative radiology 09/2011; 47(2):148-52. · 4.85 Impact Factor
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ABSTRACT: CT has become an important role in the differential diagnosis of acute chest pain to exclude an aortic dissection, pulmonary embolism and acute coronary artery syndrome. However, the additional radiation exposure is a cause of concern and dose saving strategies should be applied, if possible.
To estimate effective dose of retrospective gated and prospective ECG-triggered triple-rule-out computed tomography angiography (TRO-CTA).
An Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a 128-slice single source scanner. The following scan parameters were used (retrospective ECG-gated): 120 kV, 190 mAs/rot., collimation 128x0.6 mm, rotation time 0.3 s. Protocols with a simulated heart rate (HR) of 60 and 100 bpm were performed using the standard ECG-pulsing as well as MinDose. Additionally, a prospective triggered TRO-CTA was acquired (HR 60 bpm).
The estimated effective dose of retrospective ECG-gated TRO-CTA ranged from 7.4-13.4 mSv and from 10.1-17.5 mSv for men and women, respectively. Due to radiosensitive breast tissue, women received a significant increased effective dose of up to 64.7% ± 0.03% (p = 0.028) compared to men. MinDose reduces radiation exposure of up to 33.0% ± 6.5% in comparison to standard ECG-pulsing (p < 0.001). The effective dose increased significantly with lower heart rates (p < 0.001). Prospective ECG-triggered TRO-CTA showed an effective dose of 5.9 mSv and 8.2 mSv for men and women, respectively. Compared to retrospective ECG-gated TRO-CTA a significant dose reduction was observed (p < 0.001).
Due to the significant different dose exposure, scan protocols should be specifically adapted in a patient- and problem-oriented manner.
Acta Radiologica 03/2011; 52(7):762-6. · 1.37 Impact Factor
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ABSTRACT: To estimate the effective dose of cardiac CT with different dose saving strategies dependent on varying heart rates.
For dose measurements, an Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a 128-slice single source scanner providing a rotation time of 0.30s and standard protocols with 120 kV and 160 mAs/rot. Protocols were evaluated without ECG-pulsing, with two different ECG-pulsing techniques, and automated exposure control with a simulated heart rate of 60 and 100 beats per minute.
Depending on different dose saving techniques and heart rate, the effective whole-body dose of a cardiac scan ranged from 2.8 to 9.5 mSv and from 4.3 to 16.0 mSv for males and females, respectively. The radiation-sensitive breast tissue in the primary scan range results in an increased female dose of 66.7 ± 6.0%. Prospective triggering has the greatest potential to reduce the effective dose to 27.8%, compared to a comparable scan protocol with retrospective ECG-triggering with no ECG-pulsing. Furthermore, the heart rate influences the radiation exposure by increasing significantly at lower heart rates.
Due to this broad variability in radiation exposure of a cardiac CT, the radiologist and the CT technician should be aware of the different dose reduction strategies.
European journal of radiology 02/2011; 81(2):e153-7. · 2.65 Impact Factor
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ABSTRACT: To determine and compare cyclo-oxygenase-2 (COX-2) expression in photon-radiated and non-radiated malignant uveal melanomas and to analyse the correlation between COX-2 expression and prognosis.
Immunohistochemical staining for COX-2 was performed on 21 uveal melanomas that were endoresected after prior stereotactic radiotherapy with photons and on 22 tumours that were treated by endoresection without prior radiotherapy. COX-2 staining was further analysed in respect to cell type, maximal prominence, time interval between radiotherapy and surgery, apoptotic index (AI), proliferative index (PI) and the development of metastatic disease.
There was no difference in COX-2 expression between radiated and non-radiated melanomas (P>0.15). COX-2 staining correlated with neither the tumour prominence (P>0.40) nor the AI or the PI (both P>0.35). Tumours with high COX-2 expression were significantly more likely to develop metastasis (P=0.022).
Radiotherapy with photons does not induce COX-2 expression in malignant melanomas of the uvea. But high COX-2 expression may be a marker for poor prognosis.
Acta ophthalmologica 04/2009; 88(5):582-7. · 2.44 Impact Factor
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Dominik Ketelsen,
Marie H Luetkhoff,
Christoph Thomas,
Matthias Werner, Markus Buchgeister,
Ilias Tsiflikas,
Anja Reimann,
Christof Burgstahler,
Andreas F Kopp,
Claus D Claussen,
Martin Heuschmid
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ABSTRACT: The aim of the study was to evaluate radiation exposure of a chest pain protocol with ECG-gated dual-source computed tomography (DSCT). An Alderson Rando phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a dual-source computed tomography system with a standard protocol for chest pain evaluation (120 kV, 320 mAs/rot) with different simulated heart rates (HRs). The dose of a standard chest CT examination (120 kV, 160 mAs) was also measured. Effective dose of the chest pain protocol was 19.3/21.9 mSv (male/female, HR 60), 17.9/20.4 mSv (male/female, HR 80) and 14.7/16.7 mSv (male/female, HR 100). Effective dose of a standard chest examination was 6.3 mSv (males) and 7.2 mSv (females). Radiation dose of the chest pain protocol increases significantly with a lower heart rate for both males (p = 0.040) and females (p = 0.044). The average radiation dose of a standard chest CT examination is about 36.5% that of a CT examination performed for chest pain. Using DSCT, the evaluated chest pain protocol revealed a higher radiation exposure compared with standard chest CT. Furthermore, HRs markedly influenced the dose exposure when using the ECG-gated chest pain protocol.
European Radiology 01/2009; 19(1):37-41. · 3.22 Impact Factor
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Dominik Ketelsen,
Christoph Thomas,
Matthias Werner,
Marie H Luetkhoff, Markus Buchgeister,
Ilias Tsiflikas,
Anja Reimann,
Christof Burgstahler,
Harald Brodoefel,
Andreas F Kopp,
Claus D Claussen,
Martin Heuschmid
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ABSTRACT: The aim of the study was to estimate radiation exposure of coronary calcium scoring and angiography using ECG-gated and ECG-triggered dual-source computed tomography.
An Alderson Rando phantom equipped with thermoluminescent dosimeters was used for all dose measurements. Effective dose was calculated according to ICRP 103. Radiation exposure was performed on a dual-source computed tomography (DSCT) scanner with standard protocols for calcium scoring (DSCT-Ca) and coronary angiography (DSCTA) at different heart rates (40-100 beats/min). Furthermore, a scanning protocol with ECG-triggering as well as a standard chest CT scan were evaluated.
Depending on gender, heart rate and ECG-pulsing, the effective dose of a complete cardiac DSCT (DSCT-Ca and DSCTA) scan varies from 10.2 to 32.6mSv. The effective radiation dose increased significantly with lower heart rates (p<0.035). ECG-pulsing reduced the radiation exposure significantly in DSCTA (p<0.001). Due to breast tissue in the primary scan range, females' doses showed an increase up to 69.9% compared to males in scan protocols without ECG-pulsing. Prospective ECG-triggered DSCTA resulted in estimated effective doses from 2.8mSv (males) to 4.1mSv (females).
The ECG-pulsing technique has proven its effectiveness to reduce effective dose in coronary CT angiography and is recommended for all patients with regular heart rates. The patient's heart rate influences the radiation exposure with a significant decrease at higher heart rates. Due to its lower dose, ECG-triggered DSCTA should be implemented for special indications, i.e. for diagnosis of pathologies of the aortic root and the ascending aorta.
European journal of radiology 12/2008; 73(2):274-9. · 2.65 Impact Factor
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ABSTRACT: Measurement of the radiation dose of different radiotherapy techniques with a phantom at the position of the uterus of a pregnant patient with and without a special radiation shielding.
A special radiation shielding for the radiation therapy of a pregnant patient was constructed in the shape of a tunnel over the abdomen from 1 cm thick lead to reduce scatter radiation to the uterus and the fetus therein. The reduction of the scatter radiation to the lower abdomen was measured for three typical cases (cerebrum with lateral opposed fields, 6-MV photons; tangential fields for mamma irradiation, 6 MV; and anteroposterior-posteroanterior [AP-PA] opposed fields of 15 MV for treatment of the mediastinum) at an anthropomorphic Alderson phantom with thermoluminescence dosimeters in different depths and with an ionization chamber positioned in an RW3 solid water phantom. In the case of lateral opposed fields, a movable lead wall was additionally positioned next to the accelerator's head to reduce the scatter radiation from this source.
Depending on the geometry of the radiation fields and on the photon energy, a reduction of the dose to the lower abdomen averaged over the depths of 6, 9, and 12 cm from 16% (15 MV, mediastinum case) to 51% (6 MV, cerebrum with additional lead wall) was achieved. The absolute scattered dose with shielding in place for a 2-Gy fraction dose results to 3.85 mGy and 0.27 mGy, respectively.
National and international recommendations on the radiation dose to a fetus of a pregnant patient state limits of 200 mSv (DGMP report no. 7) and 100 mGy (ICRP 84), below which an abortion should not be considered and above which an indication for termination of the pregnancy could be given, respectively. The dose to the fetus can be kept below these limits with the shielding described in this work. Therefore, a radiation therapy of a pregnant patient is possible when these special precautions to reduce the scatter radiation to the fetus are met.
Strahlentherapie und Onkologie 03/2008; 184(2):80-5. · 3.56 Impact Factor
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ABSTRACT: A modified swim goggle holding a light spot as an optical guide for actively aligning the eye in a reproducible orientation has been constructed to perform radiotherapy of ocular tumors. This device is compatible with computed tomography (CT) and magnetic resonance imaging systems. Image fusion of these data sets yielded clinically acceptable results. The reproducibility of the eye's positioning is tested by repeated CT. The eye's alignment during radiotherapy is monitored by an infrared TV camera with individual markings of the eye's position on the TV-monitor screen. From 2003-2006, 50 patients were treated with this fixation aid by radiosurgery with good patient compliance.
Medical Physics 01/2008; 34(12):4649-53. · 2.83 Impact Factor
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ABSTRACT: To evaluate the effectiveness of stereotactic fractionated radiotherapy (SFRT) in the treatment of optic nerve sheath meningioma (ONSM). METHODS AND MARERIALS: Between 1994 and 2000, a total of 39 patients with either primary (n = 15) or secondary (n = 24) ONSM were treated with SFRT and received a median total tumor dose of 54 Gy using 1.8 Gy/fraction.
The radiographic response to SFRT was documented in all patients as stable disease (no change) except for 1 patient with a partial response. After a median follow-up of 35.5 months, all patients with ONSM were alive without recurrence. The visual fields and visual acuity were improved in 6 of 15 and 1 of 16 examined eyes in patients with primary ONSM, respectively, and in 6 of 24 and 7 of 26 examined eyes in patients with secondary ONSM, respectively. Stable visual fields and visual acuity was observed in 8 of 14 and 15 of 16 patients with primary ONSM, respectively, and in 17 of 24 and 19 of 26 patients with secondary ONSM, respectively. Except for reversible alopecia and erythema, no other SFRT-related toxicity was observed.
SFRT represents a very effective and low-toxic treatment modality for ONSM. Despite a median follow-up of 3 years, this series of primary ONSM holds promise for future studies. It adds substantial evidence that SFRT may definitely become a standard treatment approach in selected cases of ONSM.
International Journal of Radiation OncologyBiologyPhysics 01/2003; 54(5):1422-9. · 4.11 Impact Factor
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ABSTRACT: To retrospectively investigate the effectiveness of linear accelerator based radiosurgery (RS) in the treatment of brain metastases (BM).
Of 55 patients with a total of 72 BM, 41 patients had a single brain metastasis and 14 patients had two or three metastases. Median tumour dose of 15Gy (range 8-20Gy) was prescribed to a median isodose surface of 90% (range 70-100%) encompassing the target volume.
The median survival time (MST) for all 55 patients was 7 months [95% confidence interval (CI), 5-10 months] and 2-year survival is 18%. There was no significant difference between patients who had one brain metastasis and those with either two or three metastases (log rank P=0.7565). Multivariate analysis in patients with a single BM showed that interval between primary diagnosis (PD) to BM, maximum size of metastasis, and histology (renal cell carcinoma and melanoma versus others) were independent prognostic factors influencing survival. Local control was obtained in 66/72 (92%) metastases. Actuarial local control at 24 months was 52%. Only age (<or=50 years vs >50 years) and histology (renal cell versus others) influenced local control in the univariate analysis in patients with a single BM. In multivariate analysis, size, histology (renal cell and melanoma versus others), activity of extracranial metastatic disease, age, interval from PD to BM and location (midline versus other) independently influenced local control, while the dose was not significant for our patient group. Only one patient developed radiographically suspected RS-induced necrosis after previous whole brain RT.
RS was effective and little toxic in BM. Identification of prognostic factors must be performed to gain knowledge on patients most likely to benefit from this procedure.
Radiotherapy and Oncology 02/2002; 62(2):233-7. · 5.58 Impact Factor
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ABSTRACT: The present paper presents the results of a survey on radiotherapy-treatment planning systems conducted in the summer of 2000. A total of 263 questionnaires of 108 German, 6 Austrian, and 4 Swiss radiotherapy clinics or practices have been evaluated. Most treatment planning systems are used for teletherapy, with nearly all sites using at least one commercial system. The planning systems are mostly networked with CT, partially also with MRI, simulator and R&V systems of the treatment equipment. For brachytherapy planning, usually orthogonal X-ray images are used, but some systems allow already the use of CT data as well. Stereotactic planning dominates the specialized treatment planning, followed by total body irradiation techniques. Commercial systems are well established for stereotactic planning systems, whereas in-house systems are still predominant for total body irradiation. In-house systems predominate also in the case of simple treatment planning systems and plausibility check programs. These simpler dose-calculation programs usually offer variable degrees of correction options.
Zeitschrift für Medizinische Physik 01/2002; 12(3):204-10. · 1.21 Impact Factor
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ABSTRACT: We aimed to estimate the effective dose of 4D-Perfusion-CT protocols of the lung, liver, and pelvis for the assessment of tumor vascularity.
An Alderson-Rando phantom equipped with thermoluminescent dosimeters was used to determine the effective dose values of 4D-Perfusion-CT. Phantom measurements were performed on a 128-slice single-source scanner in adaptive 4D-spiral-mode with bidirectional table movement and a total scan range of 69 mm over a time period of nearly 120 seconds (26 scans). Perfusion measurements were simulated for the lung, liver, and pelvis under the following conditions: lung (80 kV, 60 mAs), liver (80 kV/80 mAs and 80 kV/120 mAs), pelvis (100 kV/80 mAs and 100 kV/120 mAs).
Depending on gender, the evaluated body region and scan protocol, an effective whole-body dose between 2.9-12.2 mSv, was determined. The radiation exposure administered to gender-specific organs like the female breast tissue (lung perfusion) or to the ovaries (pelvic perfusion) led to an increase in the female specific dose by 86% and 100% in perfusion scans of the lung and the pelvis, respectively.
Due to a significant radiation dose of 4D-perfusion-CT protocols, the responsible use of this new promising technique is mandatory. Gender- and organ-specific differences should be considered for indication and planning of tumor perfusion scans.
Korean journal of radiology: official journal of the Korean Radiological Society 11(5):547-52. · 1.32 Impact Factor
