- Email: [email protected]
84 Simultaneous infield boost with helical tomotherapy for patients with 1-3 brain metastases: A planning study
$26
September 7-10
84 Simultaneous Infield Boost with Helical Tomotherapy for Patients with 1-3 Brain Metastases: A Planning Study G. Bauman 1, S. Yartsev l, B. Fisher~, T. Kron 2, J. Van Dyk 1 London Regional Cancer Program, University of Western Ontario, London, Ontariol; Peter MacCallum Cancer Centre, Melbourne, Australia 2 Aggressive treatment of brain oligometastases may be associated with palliative and survival benefits in selected patients with controlled systemic disease and good performance status. We modelled the use of an image guided simultaneous infield boost (SIB) to individual metastases during a course of whole brain radiotherapy delivered using helical tomotherapy as an alternative to conventional radiosurgery boost. Planning CT data for 3 patients who received conventional fractionated stereotactic radiotherapy were replanned using the helical tomotherapy treatment planning system. Critical structures (eyes, brainstem, optic nerve/chiasm, brain) were contoured and normal tissue constraints assigned. Whole brain radiotherapy to 30 Gy in 10 fractions was planned with SIB to individual lesions up to a total dose of 60 Gy in 10 fractions (isoeffective to a 18 Gy radiosurgery boost). An anthropomorphic phantom was scanned and two and three simulated brain lesions were planned in the same fashion in phantom. Accuracy of alignment and treatment of the phantom on the helical tomotherapy was measured using film dosimetry and internal fiducials. In all cases image guided helical tomotherapy allowed dose escalation to the individual brain metastases to doses of 60 Gy in 10 fractions while maintaining critical structures within assigned normal tissue limits. Estimated radiation delivery time at the highest dose level was 20 minutes per fraction. Planning and treatment of the head phantom was associated with an overall positioning accuracy of <2 mm. Based on this study, use of an image guided helical tomotherapy SIB combined with whole brain radiotherapy for treatment of oligometastatic brain disease seems feasible. Potential advantages of this approach include the use of frameless stereotaxis, efficient delivery, radiobiologic advantages of fractionation and shorter overall treatment duration. A phase I dose escalation trial to test this concept is being conducted. 85 Helical Tomotherapy at the London Regional Cancer Program: Initial Clinical Experience G. Bauman, S. Yartsev, G. Rodrigues, V.M. Venkatesan, F. Perera, R. Ash, N. Read, B. Fisher, J. Gilchrist, R. Dar, K. Paton, C. Lewis, J. Battista, J. Van Dyk, E. Yu London Regional Cancer Program, University of Western Ontario, London, Ontario Helical tomotherapy (HT) incorporates the ring gantry design of a helical CT scanner combined with the delivery of intensitymodulated megavoltage x-rays in a fan beam geometry. Onboard megavoltage CT scan (MV CT) capabilities allows daily positioning correction on the basis of cross sectional anatomy and will also be used for verification of delivered dose distribution in-vivo. A HT unit (TomoTherapy Inc.) was installed at the LRCP in the summer of 2004 and has been used for clinical treatments since September 2004. Two clinical protocols were opened for patient accrual: a radical protocol using a prescription of 50-70 Gy/25-35 fractions and a palliative protocol using a prescription of 30 Gy/10 fractions. Accrual of 36 patients on each protocol was planned, with the primary endpoints being unit reliability and safety. Secondary endpoints were patient and staff satisfaction, dosimetric comparisons between HT and 3DCRT plans, measurement of setup variance and accuracy of MV CT image registration. As of February 2005, 17 patients have commenced treatment: 9 on the palliative protocol and 8 on the radical protocol. The most common anatomic sites treated were pelvis and head and neck. For the patients treated to date, the average treatment volume was 680 cc; average treatment length 11 cm; median fan-beam
CARO 2005
width 2.5 cm, median pitch factor of 0.25. Average beam delivery time was 5 minutes and average "in room" time (including positioning and pre-treatment imaging) was 25 minutes. In-phantom verification of plan dosimetry has been successful for all patients and in all cases the tomotherapy plan was equivalent or superior to the comparative 3DCRT plan. Coregistration of a tomotherapy MVCT and planning kilovoltage CT allowed optimization of patient position pre-treatment for all fractions delivered with tomotherapy. Updated results for patients accrued on these trials including the primary and secondary endpoints and sample cases will be presented. 86 Cobalt-Based Tomotherapy: State-of-the-art Radiotherapy Without a Linac M. Brundage, A. Kerr, G. Salomons, W. Macki//op, J. Schre/ner Cancer Centre of Southeastern Ontario at Kingston General Hospital, Queen's Cancer Research Institute, Queen's University, Kingston, Ontario
Background: Tomotherapy is a rotational implementation of IMRT based on the modulation of a fan beam of radiation from a source resulting in a highly conformal distribution. An additional benefit is the ability to perform in situ megavoltage CT imaging to confirm patient set-up and for treatment planning. Presently, linear accelerators provide the radiation in all implementations of tomotherapy. Objectives: To explore replacing the linear accelerator used for tomotherapy with a Cobalt 60 radiation source. The purpose of doing so is to provide the dosimetry benefits of conformal therapy while reducing the technical requirements to run and maintain the tomotherapy unit, thereby extending the availability of the technique to cancer centres throughout the world. Methods: We report the results of a series of experiments to characterize the capabilities of Co 60 tomotherapy. Dose delivery and CT imaging data were obtained using a benchtop Co 60 tomotherapy unit attached to a Theratron T780 clinical system. Inverse treatment planning was performed via inhouse optimization software based on a fast conjugate gradient search algorithm with a Milan-Bentley dose engine. CT image reconstruction utilized the method of filtered back-projection of transmission data from fan-beam and pencil beam geometries. Results: Findings from both computer simulations and dose measurements with film and with three-dimensional gel dosimeters demonstrated that Co 60 tomotherapy provides the conformal dose delivery required of modern IMRT techniques. Dose-area histograms of measured dose distribution show excellent correspondence with predicted distributions. Imaging results have shown that Co 60 CT provides sufficient contrast (3% low-contrast sensitivity) and resolution (3 mm currently) for image guidance with a Co 60 tomotherapy unit. Implications: The physics of the Co 60 beam are well suited to tometherapy applications; clinical implement-ations of Co 60 tomotherapy warrant development, 87 Application of Helical Tomotherapy to Palliative and Radical Genitourinary Malignancies G. Rodrigues, R. Ash, S. Yartsev, G. Bauman, 7-. Coad, K. Trinka, J. Harriman-Duke, B. Wart, L. Murphy, M. Lock London Regional Cancer Program, University of Western Ontario, London, Ontario
Introduction: Helical Tomotherapy (HT) is an innovative approach to the delivery of intensity-modulated radiation therapy which combines the elements of helical computed tomography (CT) with megavoltage linear accelerator treatment. The purpose of this study is to describe the simulation, comparative planning, and treatment experience with Helical Tomotherapy (HT) as it applies to palliative and radical genitourinary malignancies. Methods: Genitourinary patients enrolled on both a general palliative (30 Gy/10 fractions) and radical (50-70 Gy/25-35
September 7-10
84 Simultaneous Infield Boost with Helical Tomotherapy for Patients with 1-3 Brain Metastases: A Planning Study G. Bauman 1, S. Yartsev l, B. Fisher~, T. Kron 2, J. Van Dyk 1 London Regional Cancer Program, University of Western Ontario, London, Ontariol; Peter MacCallum Cancer Centre, Melbourne, Australia 2 Aggressive treatment of brain oligometastases may be associated with palliative and survival benefits in selected patients with controlled systemic disease and good performance status. We modelled the use of an image guided simultaneous infield boost (SIB) to individual metastases during a course of whole brain radiotherapy delivered using helical tomotherapy as an alternative to conventional radiosurgery boost. Planning CT data for 3 patients who received conventional fractionated stereotactic radiotherapy were replanned using the helical tomotherapy treatment planning system. Critical structures (eyes, brainstem, optic nerve/chiasm, brain) were contoured and normal tissue constraints assigned. Whole brain radiotherapy to 30 Gy in 10 fractions was planned with SIB to individual lesions up to a total dose of 60 Gy in 10 fractions (isoeffective to a 18 Gy radiosurgery boost). An anthropomorphic phantom was scanned and two and three simulated brain lesions were planned in the same fashion in phantom. Accuracy of alignment and treatment of the phantom on the helical tomotherapy was measured using film dosimetry and internal fiducials. In all cases image guided helical tomotherapy allowed dose escalation to the individual brain metastases to doses of 60 Gy in 10 fractions while maintaining critical structures within assigned normal tissue limits. Estimated radiation delivery time at the highest dose level was 20 minutes per fraction. Planning and treatment of the head phantom was associated with an overall positioning accuracy of <2 mm. Based on this study, use of an image guided helical tomotherapy SIB combined with whole brain radiotherapy for treatment of oligometastatic brain disease seems feasible. Potential advantages of this approach include the use of frameless stereotaxis, efficient delivery, radiobiologic advantages of fractionation and shorter overall treatment duration. A phase I dose escalation trial to test this concept is being conducted. 85 Helical Tomotherapy at the London Regional Cancer Program: Initial Clinical Experience G. Bauman, S. Yartsev, G. Rodrigues, V.M. Venkatesan, F. Perera, R. Ash, N. Read, B. Fisher, J. Gilchrist, R. Dar, K. Paton, C. Lewis, J. Battista, J. Van Dyk, E. Yu London Regional Cancer Program, University of Western Ontario, London, Ontario Helical tomotherapy (HT) incorporates the ring gantry design of a helical CT scanner combined with the delivery of intensitymodulated megavoltage x-rays in a fan beam geometry. Onboard megavoltage CT scan (MV CT) capabilities allows daily positioning correction on the basis of cross sectional anatomy and will also be used for verification of delivered dose distribution in-vivo. A HT unit (TomoTherapy Inc.) was installed at the LRCP in the summer of 2004 and has been used for clinical treatments since September 2004. Two clinical protocols were opened for patient accrual: a radical protocol using a prescription of 50-70 Gy/25-35 fractions and a palliative protocol using a prescription of 30 Gy/10 fractions. Accrual of 36 patients on each protocol was planned, with the primary endpoints being unit reliability and safety. Secondary endpoints were patient and staff satisfaction, dosimetric comparisons between HT and 3DCRT plans, measurement of setup variance and accuracy of MV CT image registration. As of February 2005, 17 patients have commenced treatment: 9 on the palliative protocol and 8 on the radical protocol. The most common anatomic sites treated were pelvis and head and neck. For the patients treated to date, the average treatment volume was 680 cc; average treatment length 11 cm; median fan-beam
CARO 2005
width 2.5 cm, median pitch factor of 0.25. Average beam delivery time was 5 minutes and average "in room" time (including positioning and pre-treatment imaging) was 25 minutes. In-phantom verification of plan dosimetry has been successful for all patients and in all cases the tomotherapy plan was equivalent or superior to the comparative 3DCRT plan. Coregistration of a tomotherapy MVCT and planning kilovoltage CT allowed optimization of patient position pre-treatment for all fractions delivered with tomotherapy. Updated results for patients accrued on these trials including the primary and secondary endpoints and sample cases will be presented. 86 Cobalt-Based Tomotherapy: State-of-the-art Radiotherapy Without a Linac M. Brundage, A. Kerr, G. Salomons, W. Macki//op, J. Schre/ner Cancer Centre of Southeastern Ontario at Kingston General Hospital, Queen's Cancer Research Institute, Queen's University, Kingston, Ontario
Background: Tomotherapy is a rotational implementation of IMRT based on the modulation of a fan beam of radiation from a source resulting in a highly conformal distribution. An additional benefit is the ability to perform in situ megavoltage CT imaging to confirm patient set-up and for treatment planning. Presently, linear accelerators provide the radiation in all implementations of tomotherapy. Objectives: To explore replacing the linear accelerator used for tomotherapy with a Cobalt 60 radiation source. The purpose of doing so is to provide the dosimetry benefits of conformal therapy while reducing the technical requirements to run and maintain the tomotherapy unit, thereby extending the availability of the technique to cancer centres throughout the world. Methods: We report the results of a series of experiments to characterize the capabilities of Co 60 tomotherapy. Dose delivery and CT imaging data were obtained using a benchtop Co 60 tomotherapy unit attached to a Theratron T780 clinical system. Inverse treatment planning was performed via inhouse optimization software based on a fast conjugate gradient search algorithm with a Milan-Bentley dose engine. CT image reconstruction utilized the method of filtered back-projection of transmission data from fan-beam and pencil beam geometries. Results: Findings from both computer simulations and dose measurements with film and with three-dimensional gel dosimeters demonstrated that Co 60 tomotherapy provides the conformal dose delivery required of modern IMRT techniques. Dose-area histograms of measured dose distribution show excellent correspondence with predicted distributions. Imaging results have shown that Co 60 CT provides sufficient contrast (3% low-contrast sensitivity) and resolution (3 mm currently) for image guidance with a Co 60 tomotherapy unit. Implications: The physics of the Co 60 beam are well suited to tometherapy applications; clinical implement-ations of Co 60 tomotherapy warrant development, 87 Application of Helical Tomotherapy to Palliative and Radical Genitourinary Malignancies G. Rodrigues, R. Ash, S. Yartsev, G. Bauman, 7-. Coad, K. Trinka, J. Harriman-Duke, B. Wart, L. Murphy, M. Lock London Regional Cancer Program, University of Western Ontario, London, Ontario
Introduction: Helical Tomotherapy (HT) is an innovative approach to the delivery of intensity-modulated radiation therapy which combines the elements of helical computed tomography (CT) with megavoltage linear accelerator treatment. The purpose of this study is to describe the simulation, comparative planning, and treatment experience with Helical Tomotherapy (HT) as it applies to palliative and radical genitourinary malignancies. Methods: Genitourinary patients enrolled on both a general palliative (30 Gy/10 fractions) and radical (50-70 Gy/25-35