Guillaume Landry1, Fabian Dörringer1, Salim Si-Mohamed2,3, Philippe Douek2,3, Juan F P J Abascal3, Françoise Peyrin3,4, Isabel P Almeida5, Frank Verhaegen5, Ilaria Rinaldi6,7,8, Katia Parodi1, Simon Rit3. 1. Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Munich, Germany. 2. Radiology Department, Centre Hospitalier Universitaire, Lyon, France. 3. Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint-Étienne, CNRS, Inserm, CREATIS, UMR 5220, U1206, F-69373, Lyon, France. 4. ESRF, The European Synchrotron, Grenoble, France. 5. Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands. 6. Department of Radiation Therapy and Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. 7. CNRS/IN2P3 and Lyon 1 University, UMR 5822, Villeurbanne, France. 8. MAASTRO Clinic, Dr. Tanslaan 12, 6229 ET, Maastricht, The Netherlands.
Abstract
PURPOSE: The objective of this technical note was to investigate the accuracy of proton stopping power relative to water (RSP) estimation using a novel dual-layer, dual-energy computed tomography (DL-DECT) scanner for potential use in proton therapy planning. DL-DECT allows dual-energy reconstruction from scans acquired at a single x-ray tube voltage V by using two-layered detectors. METHODS: Sets of calibration and evaluation inserts were scanned at a DL-DECT scanner in a custom phantom with variable diameter D (0 to 150 mm) at V of 120 and 140 kV. Inserts were additionally scanned at a synchrotron computed tomography facility to obtain comparative linear attenuation coefficients for energies from 50 to 100 keV, and reference RSP was obtained using a carbon ion beam and variable water column. DL-DECT monoenergetic (mono-E) reconstructions were employed to obtain RSP by adapting the Yang-Saito-Landry (YSL) method. The method was compared to reference RSP via the root mean square error (RMSE) over insert mean values obtained from volumetric regions of interest. The accuracy of intermediate quantities such as the relative electron density (RED), effective atomic number (EAN), and the mono-E was additionally evaluated. RESULTS: The lung inserts showed higher errors for all quantities and we report RMSE excluding them. RMSE for μ from DL-DECT mono-E was below 1.9%. For the evaluation inserts at D = 150 mm and V = 140 kV, RED RMSE was 1.0%, while for EAN it was 2.9%. RSP RMSE was below 0.8% for all D and V, which did not strongly affect the results. CONCLUSIONS: In this investigation of RSP accuracy from DL-DECT, we have shown that RMSE below 1% can be achieved. It was possible to adapt the YSL method for DL-DECT and intermediate quantities RED and EAN had comparable accuracy to previous publications.
PURPOSE: The objective of this technical note was to investigate the accuracy of proton stopping power relative to water (RSP) estimation using a novel dual-layer, dual-energy computed tomography (DL-DECT) scanner for potential use in proton therapy planning. DL-DECT allows dual-energy reconstruction from scans acquired at a single x-ray tube voltage V by using two-layered detectors. METHODS: Sets of calibration and evaluation inserts were scanned at a DL-DECT scanner in a custom phantom with variable diameter D (0 to 150 mm) at V of 120 and 140 kV. Inserts were additionally scanned at a synchrotron computed tomography facility to obtain comparative linear attenuation coefficients for energies from 50 to 100 keV, and reference RSP was obtained using a carbon ion beam and variable water column. DL-DECT monoenergetic (mono-E) reconstructions were employed to obtain RSP by adapting the Yang-Saito-Landry (YSL) method. The method was compared to reference RSP via the root mean square error (RMSE) over insert mean values obtained from volumetric regions of interest. The accuracy of intermediate quantities such as the relative electron density (RED), effective atomic number (EAN), and the mono-E was additionally evaluated. RESULTS: The lung inserts showed higher errors for all quantities and we report RMSE excluding them. RMSE for μ from DL-DECT mono-E was below 1.9%. For the evaluation inserts at D = 150 mm and V = 140 kV, RED RMSE was 1.0%, while for EAN it was 2.9%. RSP RMSE was below 0.8% for all D and V, which did not strongly affect the results. CONCLUSIONS: In this investigation of RSP accuracy from DL-DECT, we have shown that RMSE below 1% can be achieved. It was possible to adapt the YSL method for DL-DECT and intermediate quantities RED and EAN had comparable accuracy to previous publications.
Authors: Friderike K Longarino; Antonia Kowalewski; Thomas Tessonnier; Stewart Mein; Benjamin Ackermann; Jürgen Debus; Andrea Mairani; Wolfram Stiller Journal: Front Oncol Date: 2022-04-20 Impact factor: 5.738
Authors: Friderike K Longarino; Thomas Tessonnier; Stewart Mein; Semi B Harrabi; Jürgen Debus; Wolfram Stiller; Andrea Mairani Journal: J Appl Clin Med Phys Date: 2021-11-01 Impact factor: 2.102