3 results on '"M Ehmann"'
Search Results
2. COVID's Impact on Radiation Oncology: A Latin American Survey Study.
- Author
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Martinez D, Sarria GJ, Wakefield D, Flores C, Malhotra S, Li B, Ehmann M, Schwartz DL, and Sarria GR
- Subjects
- COVID-19, Humans, Latin America, Coronavirus Infections epidemiology, Pandemics, Pneumonia, Viral epidemiology, Radiation Oncology statistics & numerical data, Surveys and Questionnaires
- Abstract
Purpose: The impact of the COVID-19 pandemic on Latin American radiation therapy services has not yet been widely assessed. In comparison to centers in Europe or the United States, the scarcity of data on these terms might impair design of adequate measures to ameliorate the pandemic's potential damage. The first survey-based analysis revealing regional information is herein presented., Methods and Materials: From May 6 to May 30, 2020, the American Society for Radiation Oncology's COVID-19 Survey was distributed across Latin America with support of the local national radiation therapy societies. Twenty-six items, including facility demographic and financial characteristics, personnel and patient features, current and expected impact of the pandemic, and research perspectives, were included in the questionnaire., Results: Complete responses were obtained from 115 (50%) of 229 practices across 15 countries. Only 2.6% of centers closed during the pandemic. A median of 4 radiation oncologists (1-27) and 9 (1-100) radiation therapists were reported per center. The median number of new patients treated in 2019 was 600 (24-6200). A median 8% (1%-90%) decrease in patient volume was reported, with a median of 53 patients (1-490) remaining under treatment. Estimated revenue reduction was 20% or more in 53% of cases. Shortage of personal protective equipment was reported in 51.3% of centers, and 27% reported personnel shortage due to COVID-19. Reported delays in treatment for low-risk entities included early stage breast cancer (42.6%), low-risk status prostate cancer (67%), and nonmalignant conditions (42.6%). Treatment of COVID-19 patients at designated treatment times and differentiated bunkers were reported in 22.6% and 10.4% of centers, respectively. Telehealth initiatives have been started in 64.3% of facilities to date for on-treatment (29.6%) and posttreatment (34.8%) patients., Conclusions: Regional information regarding COVID-19 pandemic in Latin America may help elucidate suitable intervention strategies for personnel and patients. Follow-up surveys will be performed to provide dynamic monitoring the pandemic's impact on radiation therapy services and adoption of ameliorating measures., (Copyright © 2020 Elsevier Inc. All rights reserved.)
- Published
- 2020
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3. Determination of Intrafraction Prostate Motion During External Beam Radiation Therapy With a Transperineal 4-Dimensional Ultrasound Real-Time Tracking System.
- Author
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Sihono DSK, Ehmann M, Heitmann S, von Swietochowski S, Grimm M, Boda-Heggemann J, Lohr F, Wenz F, and Wertz H
- Subjects
- Aged, Aged, 80 and over, Computer Systems, Humans, Male, Middle Aged, Organ Size, Prostate pathology, Prostatic Neoplasms pathology, Retrospective Studies, Time Factors, Imaging, Three-Dimensional methods, Organ Motion, Prostate diagnostic imaging, Prostatic Neoplasms diagnostic imaging, Prostatic Neoplasms radiotherapy, Radiation Dose Hypofractionation, Radiotherapy, Intensity-Modulated methods, Ultrasonography, Interventional methods
- Abstract
Purpose/objective: To determine intrafraction prostate motion during volumetric modulated arc therapy (VMAT) using transperineal ultrasound (US) real-time tracking., Methods and Materials: 770 US monitoring sessions in 38 prostate cancer patients' VMAT treatment series were retrospectively evaluated. Intrafraction motion assessment of the prostate was based on continuous position monitoring with a 4-dimensional US system along the 3 directions: left-right (LR), anterior-posterior (AP), and inferior-superior (SI). The overall mean values and standard deviations (SD) along with random and systematic errors were calculated., Results: The mean duration of each monitoring session was 254 s. The mean (μ), the systematic error (Σ), and the random error (σ) of intrafraction prostate displacement were μ = (0.01, -0.08, 0.15) mm, Σ = (0.30, 0.34, 0.23) mm, and σ = (0.59, 0.73, 0.64) mm in the LR, AP and SI directions, respectively. The percentage of treatments for which prostate displacement was ≤2 mm was 97.01%, 92.24%, and 95.77% in the LR, AP, and SI directions, respectively. At 60 s, a vector length of prostate displacement >2 mm was present in 0.67% of the data. The percentage increased to 2.42%, 6.14%, and 9.35% at 120 s, 180 s, and 240 s, respectively., Conclusions: The magnitudes of intrafraction prostate motion along the SI and AP directions were comparable. On average, the smallest motion was in the LR direction and the largest in AP direction. Most of the prostate displacements were within a few millimeters. However, with increasing treatment time (eg, during hypofractionation), larger 3-dimensional prostate displacements up to 18.30 mm could be observed. Shortening treatment time can reduce the impact of intrafraction motion and potentially allows smaller safety margins., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
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