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Proton and Ion Beam Radiation Therapy: A Microscopic Dosimetry System for Radiobiology and Treatment
S54
International Journal of Radiation Oncology Biology Physics
Author Disclosure: C. Min: None. X. Zhu: None. B. Winey: None. K. Grogg: None. G.E. Fakhri: None. T. Bortfeld: None. H. Paganetti: None. H.A. Shih: None.
imaging system to improve the accuracy in proton beam treatment planning and the positioning of patients. We investigated the feasibility of proton tomosynthesis as a preliminary study of proton CT and compared the results with photon tomosynthesis as an alternative to conventional portal imaging or on-board cone-beam computed tomography. Materials/Methods: Dedicated photon-like proton beam using the passively scattered proton beams was generated for proton imaging. The eleven projections were acquired over 30 degree with 3 degree increment in order to investigate the performance of proton tomosynthesis. The cylinder blocks and resolution phantom were used to evaluate imaging performance. The solid water, breast, bone, adipose, lung, muscle, and liver, which were tissue equivalent inserts, were positioned around the resolution phantom. The images were reconstructed by Feldkamp-Davis-Kress (FDK), expectationmaximization (EM), projection onto convex sets (POCS) algorithms and total variation minimization (TVM) methods. The Gafchromic EBT films were utilized for measuring the photon-like proton beams as a proton detector. In addition, the photon tomosynthesis images were obtained for a comparison with proton tomosynthesis images. The same angular sampling data were acquired for both proton and photon tomosynthesis. Results: In the resolution phantom image obtained proton tomosynthesis, down to 1.6 mm diameter rods were resolved visually, although the separation between adjacent rods was less distinct. In contrast, down to 1.2 mm diameter rods were resolved visually in the reconstructed image obtained photon tomosynthesis. The signal-to-noise ratio (SNR) of a highdensity tissue equivalent insert reconstructed by FDK, EM, and TVM was found to be 6.94, 9.93, and 3.40, respectively. The contrast-to-noise ratio (CNR) of the tissue equivalent inserts was summarized in the Table.
133 Proton and Ion Beam Radiation Therapy: A Microscopic Dosimetry System for Radiobiology and Treatment J. Osinga,1,2 M. Niklas,1 G. Klimpki,1,3 M. Akselrod,4 O. Jaekel,1,5 and S. Greilich1; 1German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Martin-Luther University Halle-Wittenberg, Halle/Saale, Germany, 3Ruprecht-Karls-University, Heidelberg, Germany, 4Landauer Inc., Stillwater, OK, 5Heidelberger University Hospital, Heidelberg, Germany Purpose/Objective(s): Many aspects of the physical and biological advantages of proton and ion beam radiation therapy arise from very large local fluctuations in energy deposition. To better understand the fundamental mechanism of radiation therapy this calls for dosimetry systems that are able to work accurately on these small scales. The determination of single particle tracks, track-structure features, steep fluence or dose gradients, energy deposition patterns as well as their precise spatial correlation with cellular response is highly desirable. Materials/Methods: The fluorescent nuclear track detector (FNTD) technology is based on Al2O3:C,Mg-single crystals combined with laser scanning microscopy. They allow the detection and visualization of local dose through the volume of the detector with diffraction-limited (i.e., approx. 300 nm) resolution. For LET greater than approx. 0.2 keV/mm, their detection efficiency is close to 100% and individual charged particle tracks can be investigated in detail. Detector read-out can be implemented on commercial microscopes similar to those available in many life-science environments. FNTD are biocompatible, robust, stable in recorded signal, allow for multiple read-outs, and have no need for chemical postprocessing. Results: We investigated the application of FNTDs in high accuracy fluence, dose, and particle range determination to measure steep gradients in small fields. Gradients in ion beams could be assessed down on mm scale. Ranges of individual tracks were measured in very good (
134 Applications of Proton Digital Tomosynthesis in Proton Beam Therapy B. Min,1 J. Kwak,2 J. Lee,3 S. Cho,3 S. Park,4 S. Lee,1 D. Shin,1 and J. Kim1; 1Proton Therapy Center, National Cancer Center, Goyang-si, Republic of Korea, 2Department of Radiation Oncology, Asan Medical Center, Seoul, Republic of Korea, 3Department of Nuclear and Quantum Engineering, KAIST, Daejeon, Republic of Korea, 4McLaren Cancer Institute, Flint, MI Purpose/Objective(s): Proton beam therapy is a precise form of cancer therapy, which requires the accurate knowledge of the dose delivered to the patients. There has been a steadily increasing interest in the use of proton
Oral Scientific Abstract 134; Table tissue equivalent inserts
Bone Adipose Lung Muscle Trabecular Liver Water Breast
The contrast-to-noise ratio (CNR) of the
EM
FDK
POCS-TVM
13.24 47.88 17.42 52.83 51.36 52.07 41.53 47.33
29.97 17.00 12.53 29.48 27.05 22.39 25.84 3.34
21.81 16.38 17.05 16.74 22.72 19.73 16.73 19.05
Conclusions: In this work, proton tomosynthesis for treatment planning in proton therapy was investigated and compared three representative algorithms for evaluating their performances in proton tomosynthesis. Our results demonstrated that proton tomosynthesis could make it possible to provide comparable tomography imaging to photon tomosynthesis for positioning as determined by manual registration of high-density materials. Author Disclosure: B. Min: None. J. Kwak: None. J. Lee: None. S. Cho: None. S. Park: None. S. Lee: None. D. Shin: None. J. Kim: None.
135 Experimental Evaluation of the Interplay Effect and Motion Management by Respiratory Gating in Synchrotron-based Spot Scanning Proton Beam Delivery T. Yoshikazu,1 N. Sahoo,2 F. Poenisch,2 M. Umezawa,3 T.M. Briere,2 R.X. Zhu,2 R. Mohan,2 and L. Dong4; 1Graduate School of Biomedical Sciences, University of Texas at Houston, Houston, TX, 2Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 3Hitachi Ltd., Hitachi Research Laboratory, Houston, TX, 4 Scripps Proton Therapy Center, San Diego, CA Purpose/Objective(s): To evaluate the dosimetric impact caused by motion in spot scanning beam delivery and to evaluate the feasibility of utilizing respiratory gated spot scanning beam delivery by experiment. Materials/Methods: A 10 x 10 cm2 uniform square field was delivered using a 173.7 MeV beam (20 cm2/g in water) with an approximately s Z 8 mm
International Journal of Radiation Oncology Biology Physics
Author Disclosure: C. Min: None. X. Zhu: None. B. Winey: None. K. Grogg: None. G.E. Fakhri: None. T. Bortfeld: None. H. Paganetti: None. H.A. Shih: None.
imaging system to improve the accuracy in proton beam treatment planning and the positioning of patients. We investigated the feasibility of proton tomosynthesis as a preliminary study of proton CT and compared the results with photon tomosynthesis as an alternative to conventional portal imaging or on-board cone-beam computed tomography. Materials/Methods: Dedicated photon-like proton beam using the passively scattered proton beams was generated for proton imaging. The eleven projections were acquired over 30 degree with 3 degree increment in order to investigate the performance of proton tomosynthesis. The cylinder blocks and resolution phantom were used to evaluate imaging performance. The solid water, breast, bone, adipose, lung, muscle, and liver, which were tissue equivalent inserts, were positioned around the resolution phantom. The images were reconstructed by Feldkamp-Davis-Kress (FDK), expectationmaximization (EM), projection onto convex sets (POCS) algorithms and total variation minimization (TVM) methods. The Gafchromic EBT films were utilized for measuring the photon-like proton beams as a proton detector. In addition, the photon tomosynthesis images were obtained for a comparison with proton tomosynthesis images. The same angular sampling data were acquired for both proton and photon tomosynthesis. Results: In the resolution phantom image obtained proton tomosynthesis, down to 1.6 mm diameter rods were resolved visually, although the separation between adjacent rods was less distinct. In contrast, down to 1.2 mm diameter rods were resolved visually in the reconstructed image obtained photon tomosynthesis. The signal-to-noise ratio (SNR) of a highdensity tissue equivalent insert reconstructed by FDK, EM, and TVM was found to be 6.94, 9.93, and 3.40, respectively. The contrast-to-noise ratio (CNR) of the tissue equivalent inserts was summarized in the Table.
133 Proton and Ion Beam Radiation Therapy: A Microscopic Dosimetry System for Radiobiology and Treatment J. Osinga,1,2 M. Niklas,1 G. Klimpki,1,3 M. Akselrod,4 O. Jaekel,1,5 and S. Greilich1; 1German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Martin-Luther University Halle-Wittenberg, Halle/Saale, Germany, 3Ruprecht-Karls-University, Heidelberg, Germany, 4Landauer Inc., Stillwater, OK, 5Heidelberger University Hospital, Heidelberg, Germany Purpose/Objective(s): Many aspects of the physical and biological advantages of proton and ion beam radiation therapy arise from very large local fluctuations in energy deposition. To better understand the fundamental mechanism of radiation therapy this calls for dosimetry systems that are able to work accurately on these small scales. The determination of single particle tracks, track-structure features, steep fluence or dose gradients, energy deposition patterns as well as their precise spatial correlation with cellular response is highly desirable. Materials/Methods: The fluorescent nuclear track detector (FNTD) technology is based on Al2O3:C,Mg-single crystals combined with laser scanning microscopy. They allow the detection and visualization of local dose through the volume of the detector with diffraction-limited (i.e., approx. 300 nm) resolution. For LET greater than approx. 0.2 keV/mm, their detection efficiency is close to 100% and individual charged particle tracks can be investigated in detail. Detector read-out can be implemented on commercial microscopes similar to those available in many life-science environments. FNTD are biocompatible, robust, stable in recorded signal, allow for multiple read-outs, and have no need for chemical postprocessing. Results: We investigated the application of FNTDs in high accuracy fluence, dose, and particle range determination to measure steep gradients in small fields. Gradients in ion beams could be assessed down on mm scale. Ranges of individual tracks were measured in very good (
134 Applications of Proton Digital Tomosynthesis in Proton Beam Therapy B. Min,1 J. Kwak,2 J. Lee,3 S. Cho,3 S. Park,4 S. Lee,1 D. Shin,1 and J. Kim1; 1Proton Therapy Center, National Cancer Center, Goyang-si, Republic of Korea, 2Department of Radiation Oncology, Asan Medical Center, Seoul, Republic of Korea, 3Department of Nuclear and Quantum Engineering, KAIST, Daejeon, Republic of Korea, 4McLaren Cancer Institute, Flint, MI Purpose/Objective(s): Proton beam therapy is a precise form of cancer therapy, which requires the accurate knowledge of the dose delivered to the patients. There has been a steadily increasing interest in the use of proton
Oral Scientific Abstract 134; Table tissue equivalent inserts
Bone Adipose Lung Muscle Trabecular Liver Water Breast
The contrast-to-noise ratio (CNR) of the
EM
FDK
POCS-TVM
13.24 47.88 17.42 52.83 51.36 52.07 41.53 47.33
29.97 17.00 12.53 29.48 27.05 22.39 25.84 3.34
21.81 16.38 17.05 16.74 22.72 19.73 16.73 19.05
Conclusions: In this work, proton tomosynthesis for treatment planning in proton therapy was investigated and compared three representative algorithms for evaluating their performances in proton tomosynthesis. Our results demonstrated that proton tomosynthesis could make it possible to provide comparable tomography imaging to photon tomosynthesis for positioning as determined by manual registration of high-density materials. Author Disclosure: B. Min: None. J. Kwak: None. J. Lee: None. S. Cho: None. S. Park: None. S. Lee: None. D. Shin: None. J. Kim: None.
135 Experimental Evaluation of the Interplay Effect and Motion Management by Respiratory Gating in Synchrotron-based Spot Scanning Proton Beam Delivery T. Yoshikazu,1 N. Sahoo,2 F. Poenisch,2 M. Umezawa,3 T.M. Briere,2 R.X. Zhu,2 R. Mohan,2 and L. Dong4; 1Graduate School of Biomedical Sciences, University of Texas at Houston, Houston, TX, 2Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 3Hitachi Ltd., Hitachi Research Laboratory, Houston, TX, 4 Scripps Proton Therapy Center, San Diego, CA Purpose/Objective(s): To evaluate the dosimetric impact caused by motion in spot scanning beam delivery and to evaluate the feasibility of utilizing respiratory gated spot scanning beam delivery by experiment. Materials/Methods: A 10 x 10 cm2 uniform square field was delivered using a 173.7 MeV beam (20 cm2/g in water) with an approximately s Z 8 mm