Adaptation of the Calypso 4D Localization System to Accommodate Complex Treatment Geometry
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transmitter. A standardized set-up for implant transmitter positioning was used to perform using 2000 random positions in a water tank (saline solution). Dose measurement using a Varian accelerator at Sahlgrenska University Hospital (Field 10x10cm; 2Gy= 120mu at 100 cm) in 5 steps of 100mU from 100uMmU was performed using a Hermes 5 electrometer (Mimator, Sweden). At gantry angles 45, 90, 135 and 180 degrees 100 mU was given to evaluate changes in dose sensitivity due to the direction of irra- diation. Results: Positioning showed mean error of 0.38mm (SD: 0.18 mm). Measurement of dose was linear 100mU - 53nC; 200mU - 106nC; 300mU - 158nC; 400mU - 210nC; 500mU - 262nC and independent of positioning measurements in realtime (or vice versa). Irradiation measurement using 100mU at different gantry angles showed 53nC (+/- 1nC). Conclusions: This is the first report of a new multifunctional implantable transmitter for tumor tracking both new implant mea- suring dose and position in real time. This study shows that neither the dose nor the positioning components of the implant trans- mitter interfere with each other. The implantable transmitter is suitable for real-time dose and positioning measurements during radiotherapy. Author Disclosure: B. Lennerna ¨s, shareholder, E. Ownership Interest; Member of the board, E. Ownership Interest. 2929 Adaptation of the Calypso 4D Localization System to Accommodate Complex Treatment Geometry S. Eulau, T. Zeller, M. K. N. Afghan Swedish Medical Center, Seattle, WA Purpose/Objective(s): The Calypso 4D Localization System and Beacon transponders are FDA cleared devices to localize and track tumor motion during external beam radiation therapy of prostate cancer. The system is designed to accurately localize and track targets when radiation is delivered with a linear accelerator couch set to its default orientation of 180 degrees. We report our initial clinical experience with enabling the Calypso System to accommodate treatment geometries which require that the couch be rotated off baseline. Materials/Methods: Fourteen patients were enrolled on an IRB-approved study to evaluate the feasibility of using the Calypso 4D Localization System to localize and track targets in patients undergoing external beam accelerated partial breast irradiation (APBI). As part of the APBI protocol, radiation is delivered with the linear accelerator couch rotated from its default position of 180 degrees. These rotations, known as ‘‘couch kicks’’, enable field geometries that optimize tumor coverage and/or minimize radiation to uninvolved normal tissues, but can result in more complex verification of correct treatment setup. Such rotations also alter the spatial coordinates of the implanted fiducials, requiring ‘‘re-definition’’ of the transponder coordinates for use in the Calypso System. A MATLAB routine was developed to transform the coordinates of the implanted transponders at the de- fault couch position to that required by the couch kick, thereby creating a new ‘‘Calypso plan’’ for each couch rotation required by the plan. A total of 20 Calypso ‘‘couch kick plans’’ were generated in order to accommodate the couch kick requirements for these patients. Results: The Calypso System was able to accommodate a wide range of couch angles varying between 90 to 270 degrees and the system was successfully used to localize and track during all 20 couch kick plans for fields requiring off-axis couch rotations. The RTT user feedback was favorable. Ease of use for setup and tracking during couch kicks is reported as intuitive and quick. How- ever, target position offsets were not optimized for couch rotations. Conclusions: A practical system has been developed to enable the Calypso 4D Localization System to localize and track a target when treatment geometry mandates couch kicks. This method will be presented in detail and its broad applicability discussed. Author Disclosure: S. Eulau, None; T. Zeller, Tricia Zeller’s position was supported by a research grant from Calypso, B. Research Grant; M.K.N. Afghan, None. 2930 Validating Fiducial Markers for Image Guided Radiation Therapy for Accelerated Partial Breast Irradiation in Early Stage Breast Cancer Treatment J. Pritz, G. Zhang, K. M. Forster, E. E. R. Harris Moffitt Cancer Center and Research Institute, Tampa, FL Purpose/Objective(s): Image guided radiation therapy (IGRT) using fiducials as reference points during daily localization accu- rately positions the radiation fields at the target volume. The aim of this study was to validate the use of intraparenchymal gold fiducials in breast tissue as stable markers throughout the course of radiation treatment in patients receiving accelerated partial breast irradiation (APBI). Materials/Methods: All patients were enrolled on a prospective IRB-approved protocol. Three or four gold fiducials were placed in the periphery of the tumor bed intraoperatively. Patients were treated with 3D conformal APBI to total dose of 3850 cGy in 10 fractions of 385 cGy each given twice daily. Prior to each treatment, lateral and anterior- posterior megavoltage (MV) portal images were taken. Set up variation was calculated as the motion of the center of mass (COM) of the fiducial sets with respect to the isocenter. The distance of fiducials to the isocenter and the distance of the isocenter to vertebral body reference points were measured in order to calculate relative motion (motion of the individual fiducials with respect to one another) and absolute motion (motion with respect to vertebral body reference points). Results: A total of 17 patients treated with APBI were analyzed. A total of 55 fiducials were measured and the motion of each was tracked individually. All fiducials were readily identifiable on MV portal imaging. Set-up variation during the course of the treat- ment was 0.38 cm (standard deviation (SD)=0.1 cm). For an individual marker, the motion relative to another was found vary from 0 cm to 0.81 cm, with an average movement of 0.15 cm (SD=0.14 cm). The absolute motion of individual fiducials ranged from 0 cm to 1.98 cm, with an average of 0.4 cm (SD=0.31 cm). The absolute motion of the COM displayed an average motion of 0.31 cm (SD= 0.23 cm; range 0.01 to 1.22 cm). The center of mass of the fiducials moved more than 0.5 cm relative to the reference point in 18% of measured images. S598 I. J. Radiation Oncology d Biology d Physics Volume 75, Number 3, Supplement, 2009
Transcript of Adaptation of the Calypso 4D Localization System to Accommodate Complex Treatment Geometry
S598 I. J. Radiation Oncology d Biology d Physics Volume 75, Number 3, Supplement, 2009
transmitter. A standardized set-up for implant transmitter positioning was used to perform using 2000 random positions in a watertank (saline solution). Dose measurement using a Varian accelerator at Sahlgrenska University Hospital (Field 10x10cm; 2Gy=120mu at 100 cm) in 5 steps of 100mU from 100uMmU was performed using a Hermes 5 electrometer (Mimator, Sweden). Atgantry angles 45, 90, 135 and 180 degrees 100 mU was given to evaluate changes in dose sensitivity due to the direction of irra-diation.
Results: Positioning showed mean error of 0.38mm (SD: 0.18 mm). Measurement of dose was linear 100mU - 53nC; 200mU -106nC; 300mU - 158nC; 400mU - 210nC; 500mU - 262nC and independent of positioning measurements in realtime (or viceversa). Irradiation measurement using 100mU at different gantry angles showed 53nC (+/- 1nC).
Conclusions: This is the first report of a new multifunctional implantable transmitter for tumor tracking both new implant mea-suring dose and position in real time. This study shows that neither the dose nor the positioning components of the implant trans-mitter interfere with each other. The implantable transmitter is suitable for real-time dose and positioning measurements duringradiotherapy.
Author Disclosure: B. Lennernas, shareholder, E. Ownership Interest; Member of the board, E. Ownership Interest.
2929 Adaptation of the Calypso 4D Localization System to Accommodate Complex Treatment Geometry
S. Eulau, T. Zeller, M. K. N. Afghan
Swedish Medical Center, Seattle, WA
Purpose/Objective(s): The Calypso 4D Localization System and Beacon transponders are FDA cleared devices to localize andtrack tumor motion during external beam radiation therapy of prostate cancer. The system is designed to accurately localizeand track targets when radiation is delivered with a linear accelerator couch set to its default orientation of 180 degrees. We reportour initial clinical experience with enabling the Calypso System to accommodate treatment geometries which require that the couchbe rotated off baseline.
Materials/Methods: Fourteen patients were enrolled on an IRB-approved study to evaluate the feasibility of using the Calypso4D Localization System to localize and track targets in patients undergoing external beam accelerated partial breast irradiation(APBI). As part of the APBI protocol, radiation is delivered with the linear accelerator couch rotated from its default position of180 degrees. These rotations, known as ‘‘couch kicks’’, enable field geometries that optimize tumor coverage and/or minimizeradiation to uninvolved normal tissues, but can result in more complex verification of correct treatment setup. Such rotationsalso alter the spatial coordinates of the implanted fiducials, requiring ‘‘re-definition’’ of the transponder coordinates for use inthe Calypso System. A MATLAB routine was developed to transform the coordinates of the implanted transponders at the de-fault couch position to that required by the couch kick, thereby creating a new ‘‘Calypso plan’’ for each couch rotation requiredby the plan. A total of 20 Calypso ‘‘couch kick plans’’ were generated in order to accommodate the couch kick requirements forthese patients.
Results: The Calypso System was able to accommodate a wide range of couch angles varying between 90 to 270 degrees and thesystem was successfully used to localize and track during all 20 couch kick plans for fields requiring off-axis couch rotations. TheRTT user feedback was favorable. Ease of use for setup and tracking during couch kicks is reported as intuitive and quick. How-ever, target position offsets were not optimized for couch rotations.
Conclusions: A practical system has been developed to enable the Calypso 4D Localization System to localize and track a targetwhen treatment geometry mandates couch kicks. This method will be presented in detail and its broad applicability discussed.
Author Disclosure: S. Eulau, None; T. Zeller, Tricia Zeller’s position was supported by a research grant from Calypso, B. ResearchGrant; M.K.N. Afghan, None.
2930 Validating Fiducial Markers for Image Guided Radiation Therapy for Accelerated Partial Breast
Irradiation in Early Stage Breast Cancer TreatmentJ. Pritz, G. Zhang, K. M. Forster, E. E. R. Harris
Moffitt Cancer Center and Research Institute, Tampa, FL
Purpose/Objective(s): Image guided radiation therapy (IGRT) using fiducials as reference points during daily localization accu-rately positions the radiation fields at the target volume. The aim of this study was to validate the use of intraparenchymal goldfiducials in breast tissue as stable markers throughout the course of radiation treatment in patients receiving accelerated partialbreast irradiation (APBI).
Materials/Methods: All patients were enrolled on a prospective IRB-approved protocol. Three or four gold fiducialswere placed in the periphery of the tumor bed intraoperatively. Patients were treated with 3D conformal APBI to totaldose of 3850 cGy in 10 fractions of 385 cGy each given twice daily. Prior to each treatment, lateral and anterior-posterior megavoltage (MV) portal images were taken. Set up variation was calculated as the motion of the centerof mass (COM) of the fiducial sets with respect to the isocenter. The distance of fiducials to the isocenter and thedistance of the isocenter to vertebral body reference points were measured in order to calculate relative motion (motionof the individual fiducials with respect to one another) and absolute motion (motion with respect to vertebral bodyreference points).
Results: A total of 17 patients treated with APBI were analyzed. A total of 55 fiducials were measured and the motion of each wastracked individually. All fiducials were readily identifiable on MV portal imaging. Set-up variation during the course of the treat-ment was 0.38 cm (standard deviation (SD)=0.1 cm). For an individual marker, the motion relative to another was found vary from0 cm to 0.81 cm, with an average movement of 0.15 cm (SD=0.14 cm). The absolute motion of individual fiducials ranged from0 cm to 1.98 cm, with an average of 0.4 cm (SD=0.31 cm). The absolute motion of the COM displayed an average motion of 0.31cm (SD= 0.23 cm; range 0.01 to 1.22 cm). The center of mass of the fiducials moved more than 0.5 cm relative to the reference pointin 18% of measured images.
