- Email: [email protected]
563 speaker LASER DRIVEN ACCELERATORS FOR RADIOBIOLOGY EXPERIMENT
S 230
S YMPOSIUM
some flexibility for treatment with the available static horizontal beam. Development will continue, and in principle there do not seem to be any technical show-stoppers to in time achieving the high gradients and compact injector designs necessary to gantry-mount the machine, but at present there is no published timetable for these developments. [1] The ESTRO Organizers requested the author, who has no connection with the DWA project, to perform an independent assessment of its progress towards readiness as an effective source of beams for proton therapy.
T HURSDAY, M AY 12, 2011
majority of experiments. Conclusion: The successful systematic in vitro cell experiments at laser driven particle beams form an important milestone on the way to the development of clinically applicable laser particle accelerators. Currently, the laser driven proton beam will be improved with respect to maximum energy as well as to spectral and spatial shaping in order to enable radiobiological animal experiments in a subsequent step. This work has been supported by the German Federal Ministry of Education and Research (BMBF), grant no. 03ZIK445.
563 speaker LASER DRIVEN ACCELERATORS FOR RADIOBIOLOGY EXPERIMENT J. Pawelke1 2 , M. Baumann1 , E. Beyreuther2 , T. Burris-Mog2 , T. Cowan2 , Y. Dammene1 , W. Enghardt1 2 , M. Kaluza3 , L. Karsch1 , S. Kraft2 , L. Laschinsky1 , E. Leßmann2 , J. Metzkes2 , D. Naumburger1 , M. Nicolai3 , C. Richter1 2 , H. P. Schlenvoigt3 , U. Schramm2 , M. Schürer1 , J. Woithe1 , K. Zeil2 1 O NCO R AY - N ATIONAL C ENTER FOR R ADIATION R ESEARCH IN O NCOL OGY , Technische Universität Dresden, Dresden, Germany 2 H ELMHOLTZ -Z ENTRUM D RESDEN R OSSENDORF, Institute of Radiation Physics, Dresden, Germany 3 F RIEDRICH -S CHILLER -U NIVERSITÄT, Institute for Optics and Quantum Electronics, Jena, Germany
Objective: The novel technology of particle acceleration based on high intensity lasers promises to reduce the large dimensions and high costs of present hadron (proton and light ion) therapy facilities. However, the therapeutically relevant parameters of laser driven particle beams dramatically differ from those of beams from conventional electromagnetic accelerators: The duty cycle is extremely low, whereas the number of particles and thus the dose rate per pulse is very high. Laser accelerated particle beams show a broad energy spectrum and substantial intensity fluctuations from pulse to pulse. The consequences of these properties on (i) dosimetry, (ii) radiobiological effectiveness, (iii) solutions for therapy beam deliveries, and (iv) therapy quality assurance have to be investigated systematically. With this purpose as well as to develop a compact high power laser system delivering therapeutic particle beams with a range of 30 cm in water at a dose rate exceeding 2 Gy/(min l) as the main technical challenge, the German research project onCOOPtics was started. Material and Methods: In a first step of the translational chain for developing the laser based technology towards applicability in radiation therapy, radiobiological in vitro cell experiments were established. At first, electron pulses were generated using the Titanium:Sapphire 10 terawatt laser system JeTi at Friedrich-Schiller-University Jena. Laser pulses (80 fs duration, 0.8 J energy, 2.5 Hz repetition rate) were focused into a helium gas jet, accelerating electrons to energies of up to a few ten MeV. In order to perform proton experiments, the increased laser intensity of the 150 terawatt laser system Draco, recently installed at the Helmholtz-Zentrum Dresden Rossendorf, was necessary. Laser pulses (30 fs duration, 3.5 J energy, 0.1 Hz repetition rate) were focused to a focal spot of 3 mm diameter on a 2 mm thick Ti foil, accelerating protons to a maximum energy of up to 20 MeV. Before starting irradiation experiments, the laser accelerator systems had to be extensively tuned and optimized with respect to intensity, energy distribution, spot size, stability and reliability of the particle beams. Furthermore, beam filtering and transport to an in-air irradiation site were developed and realised. At this, compact magnetic dipole beam filters together with special aperture setups were used to shape the particle distribution appropriate for the cell irradiation experiments and to efficiently suppress particles with energies below a lower cut-off energy and background radiation at the cell sample position. The particle beams were controlled and monitored in real-time by means of an ionization chamber and an in-house Faraday Cup for defined dose delivery of the prescribed dose. Moreover, EBT radiochromic film was used for retrospective precise determination of absolute dose delivered to the cell monolayer and for verification of a homogeneous dose distribution at the target. Cell irradiations with doses in the range of 0.3 to 10 Gy have been performed for squamous cell carcinoma and non malignant cell lines. Following irradiation, the dose-dependent cellular survival was measured using the clonogenic survival assay. Additionally, the immunohistochemical detection of co-localized gH2AX and 53BP1 molecules was applied to analyze DNA double-strand breaks which remain in the cells 24 hours post-irradiation. Reference irradiation with a continuous beam from conventional accelerator, a clinical electron LINAC and a proton tandem accelerator, respectively, was performed in parallel with experiments at the laser accelerated pulses. Results: All the key requirements for systematic radiobiological cell experiments have been fulfilled, such as the supply of a reasonably stable and reproducible laser-accelerated particle beam providing homogeneous dose delivery on a desired macroscopic irradiation field in an appropriate irradiation time, online dose monitoring for irradiation control and the precise determination of the absolute particle dose delivered to the cells. All components and methods have proven their stability and reliability in systematic studies over months. Moreover, dose response curves have been measured for the chosen endpoints and cell lines showing no significant differences in radiobiological response between pulsed and continuous particle beams for the vast
Guidelines and protocols in the radiotherapy department 564 speaker STAFFING AND EQUIPMENT OF RT CENTRES: COMPARING THE EORTC, ESTRO AND DUTCH GUIDELINES C. Hurkmans1 1 C ATHARINA Z IEKENHUIS, Department of Radiation Oncology, Eindhoven, Netherlands
Purpose: First, to compare the guidelines on staffing and equipment from the EORTC ROG from 2009 to the ESTRO 2005 and the Dutch 2010 guidelines. Second, to suggest a common framework for future guidelines. Materials and methods: The guidelines and associated underlying data from the three surveys were analysed. For the Dutch guidelines, the guidelines were recalculated to number of patients per Full-Time-Equivalent (or per equipment unit). Results: Both EORTC and ESTRO have based their workload definitions on the number of patients that receive radiotherapy. The Dutch NVRO guidelines refined the workload calculations by introducing 4 radiotherapy complexity classes for teletherapy and 5 classes of brachytherapy. Using this latter refinement, a more than merely patient numbers related workload increase could be foreseen, which stimulated timely planning of investments. The more recent EORTC and Dutch guidelines are similar to the slightly older ESTRO guidelines (see table). However, an increase of throughput for CT scanners/simulators is foreseen, reflecting the increased replacement of conventional simulators by time efficient CT scanners. The ESTRO guidelines are based on a survey of national guidelines, whereas the EORTC and Dutch guidelines are based on actual infrastructure information. Although all three surveys collected data on technologist staffing and treatment planning equipment, no guidelines were formulated for these important topics by the ESTRO and the EORTC. However, minimum requirements have been set in the EORTC and Dutch (in brackets) guidelines as follows: MV units: 2 (4); radiation oncologists: 3 (8); and clinical physicists: 2 (3). IT-specialists: - (1.5)
Conclusion: The various guidelines are reasonably similar but figures for technologists and infrastructure other than MV units are missing. The suggested set ofminimum facility requirements for a department varies much more, reflecting the huge variance throughout Europe. Overall, there exists a need for more comprehensive guidelines that closely follow trends in technology and workload. 565 speaker USE OF PRE-TREATMENT IMAGING PROTOCOLS FOR MOTION ESTIMATION B. Bak1 1 G REATER P OLAND C ANCER C ENTRE, 2nd Radiotherapy Department, Poznan, Poland
Modern techniques of the imaging and dose delivering during irradiation allow to separate the tumor volume from normal tissue with almost surgical precision. This allow for the reduction in treatment toxicity with the potential for dose escalation and thus improved tumour control. Precision and accuracy of our actions becomes crucial so it is necessary to carefully define target volume and to precisely deliver the daily treatment. Currently the standard method of imaging for the treatment planning process is the CT. Continuous evolution including improvements in morphological (eg.
S YMPOSIUM
some flexibility for treatment with the available static horizontal beam. Development will continue, and in principle there do not seem to be any technical show-stoppers to in time achieving the high gradients and compact injector designs necessary to gantry-mount the machine, but at present there is no published timetable for these developments. [1] The ESTRO Organizers requested the author, who has no connection with the DWA project, to perform an independent assessment of its progress towards readiness as an effective source of beams for proton therapy.
T HURSDAY, M AY 12, 2011
majority of experiments. Conclusion: The successful systematic in vitro cell experiments at laser driven particle beams form an important milestone on the way to the development of clinically applicable laser particle accelerators. Currently, the laser driven proton beam will be improved with respect to maximum energy as well as to spectral and spatial shaping in order to enable radiobiological animal experiments in a subsequent step. This work has been supported by the German Federal Ministry of Education and Research (BMBF), grant no. 03ZIK445.
563 speaker LASER DRIVEN ACCELERATORS FOR RADIOBIOLOGY EXPERIMENT J. Pawelke1 2 , M. Baumann1 , E. Beyreuther2 , T. Burris-Mog2 , T. Cowan2 , Y. Dammene1 , W. Enghardt1 2 , M. Kaluza3 , L. Karsch1 , S. Kraft2 , L. Laschinsky1 , E. Leßmann2 , J. Metzkes2 , D. Naumburger1 , M. Nicolai3 , C. Richter1 2 , H. P. Schlenvoigt3 , U. Schramm2 , M. Schürer1 , J. Woithe1 , K. Zeil2 1 O NCO R AY - N ATIONAL C ENTER FOR R ADIATION R ESEARCH IN O NCOL OGY , Technische Universität Dresden, Dresden, Germany 2 H ELMHOLTZ -Z ENTRUM D RESDEN R OSSENDORF, Institute of Radiation Physics, Dresden, Germany 3 F RIEDRICH -S CHILLER -U NIVERSITÄT, Institute for Optics and Quantum Electronics, Jena, Germany
Objective: The novel technology of particle acceleration based on high intensity lasers promises to reduce the large dimensions and high costs of present hadron (proton and light ion) therapy facilities. However, the therapeutically relevant parameters of laser driven particle beams dramatically differ from those of beams from conventional electromagnetic accelerators: The duty cycle is extremely low, whereas the number of particles and thus the dose rate per pulse is very high. Laser accelerated particle beams show a broad energy spectrum and substantial intensity fluctuations from pulse to pulse. The consequences of these properties on (i) dosimetry, (ii) radiobiological effectiveness, (iii) solutions for therapy beam deliveries, and (iv) therapy quality assurance have to be investigated systematically. With this purpose as well as to develop a compact high power laser system delivering therapeutic particle beams with a range of 30 cm in water at a dose rate exceeding 2 Gy/(min l) as the main technical challenge, the German research project onCOOPtics was started. Material and Methods: In a first step of the translational chain for developing the laser based technology towards applicability in radiation therapy, radiobiological in vitro cell experiments were established. At first, electron pulses were generated using the Titanium:Sapphire 10 terawatt laser system JeTi at Friedrich-Schiller-University Jena. Laser pulses (80 fs duration, 0.8 J energy, 2.5 Hz repetition rate) were focused into a helium gas jet, accelerating electrons to energies of up to a few ten MeV. In order to perform proton experiments, the increased laser intensity of the 150 terawatt laser system Draco, recently installed at the Helmholtz-Zentrum Dresden Rossendorf, was necessary. Laser pulses (30 fs duration, 3.5 J energy, 0.1 Hz repetition rate) were focused to a focal spot of 3 mm diameter on a 2 mm thick Ti foil, accelerating protons to a maximum energy of up to 20 MeV. Before starting irradiation experiments, the laser accelerator systems had to be extensively tuned and optimized with respect to intensity, energy distribution, spot size, stability and reliability of the particle beams. Furthermore, beam filtering and transport to an in-air irradiation site were developed and realised. At this, compact magnetic dipole beam filters together with special aperture setups were used to shape the particle distribution appropriate for the cell irradiation experiments and to efficiently suppress particles with energies below a lower cut-off energy and background radiation at the cell sample position. The particle beams were controlled and monitored in real-time by means of an ionization chamber and an in-house Faraday Cup for defined dose delivery of the prescribed dose. Moreover, EBT radiochromic film was used for retrospective precise determination of absolute dose delivered to the cell monolayer and for verification of a homogeneous dose distribution at the target. Cell irradiations with doses in the range of 0.3 to 10 Gy have been performed for squamous cell carcinoma and non malignant cell lines. Following irradiation, the dose-dependent cellular survival was measured using the clonogenic survival assay. Additionally, the immunohistochemical detection of co-localized gH2AX and 53BP1 molecules was applied to analyze DNA double-strand breaks which remain in the cells 24 hours post-irradiation. Reference irradiation with a continuous beam from conventional accelerator, a clinical electron LINAC and a proton tandem accelerator, respectively, was performed in parallel with experiments at the laser accelerated pulses. Results: All the key requirements for systematic radiobiological cell experiments have been fulfilled, such as the supply of a reasonably stable and reproducible laser-accelerated particle beam providing homogeneous dose delivery on a desired macroscopic irradiation field in an appropriate irradiation time, online dose monitoring for irradiation control and the precise determination of the absolute particle dose delivered to the cells. All components and methods have proven their stability and reliability in systematic studies over months. Moreover, dose response curves have been measured for the chosen endpoints and cell lines showing no significant differences in radiobiological response between pulsed and continuous particle beams for the vast
Guidelines and protocols in the radiotherapy department 564 speaker STAFFING AND EQUIPMENT OF RT CENTRES: COMPARING THE EORTC, ESTRO AND DUTCH GUIDELINES C. Hurkmans1 1 C ATHARINA Z IEKENHUIS, Department of Radiation Oncology, Eindhoven, Netherlands
Purpose: First, to compare the guidelines on staffing and equipment from the EORTC ROG from 2009 to the ESTRO 2005 and the Dutch 2010 guidelines. Second, to suggest a common framework for future guidelines. Materials and methods: The guidelines and associated underlying data from the three surveys were analysed. For the Dutch guidelines, the guidelines were recalculated to number of patients per Full-Time-Equivalent (or per equipment unit). Results: Both EORTC and ESTRO have based their workload definitions on the number of patients that receive radiotherapy. The Dutch NVRO guidelines refined the workload calculations by introducing 4 radiotherapy complexity classes for teletherapy and 5 classes of brachytherapy. Using this latter refinement, a more than merely patient numbers related workload increase could be foreseen, which stimulated timely planning of investments. The more recent EORTC and Dutch guidelines are similar to the slightly older ESTRO guidelines (see table). However, an increase of throughput for CT scanners/simulators is foreseen, reflecting the increased replacement of conventional simulators by time efficient CT scanners. The ESTRO guidelines are based on a survey of national guidelines, whereas the EORTC and Dutch guidelines are based on actual infrastructure information. Although all three surveys collected data on technologist staffing and treatment planning equipment, no guidelines were formulated for these important topics by the ESTRO and the EORTC. However, minimum requirements have been set in the EORTC and Dutch (in brackets) guidelines as follows: MV units: 2 (4); radiation oncologists: 3 (8); and clinical physicists: 2 (3). IT-specialists: - (1.5)
Conclusion: The various guidelines are reasonably similar but figures for technologists and infrastructure other than MV units are missing. The suggested set ofminimum facility requirements for a department varies much more, reflecting the huge variance throughout Europe. Overall, there exists a need for more comprehensive guidelines that closely follow trends in technology and workload. 565 speaker USE OF PRE-TREATMENT IMAGING PROTOCOLS FOR MOTION ESTIMATION B. Bak1 1 G REATER P OLAND C ANCER C ENTRE, 2nd Radiotherapy Department, Poznan, Poland
Modern techniques of the imaging and dose delivering during irradiation allow to separate the tumor volume from normal tissue with almost surgical precision. This allow for the reduction in treatment toxicity with the potential for dose escalation and thus improved tumour control. Precision and accuracy of our actions becomes crucial so it is necessary to carefully define target volume and to precisely deliver the daily treatment. Currently the standard method of imaging for the treatment planning process is the CT. Continuous evolution including improvements in morphological (eg.