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Motion Likelihood Over Spine Radiosurgery Treatments—An Intrafraction Motion Analysis
E678
International Journal of Radiation Oncology Biology Physics
Results: The maximum difference for target D90 between the reference plan and plans with applicator rotation was 0.2%, 24.2%, 30.8% for 1) circumferential, 2) anterior, and 3) lateral target, respectively. For bladder D2cc, the maximum difference was 2.7%, 11.0%, 26.1% for 1), 2), and 3), respectively. Similarly, for rectum D2cc, it was 3.2 %, 5.0%, 24.7%, for 1), 2), and 3), respectively. Compared to circumferential target, anterior and one-sided lateral target had larger differences. Dosimetric differences > 5% occurred at 15 degree rotation (or 2.6mm radial shift) for anterior target and 10 degree rotation (or 1.7mm radial shift) for lateral target. For the lateral target, there was a substantial difference between symmetric rotations clockwise and counter-clockwise rotations, while anterior and circumferential target dosimetry did not differ significantly between the two directions. Conclusion: We have demonstrated significant variation in the degree of impact based on location of tumor. In order to achieve a dosemtric deviation of less than 5%, rotational error must be limited to less than 10-15%. Quality assurance measures should be taken to avoid rotation between planning and treatment. Author Disclosure: H. Kim: None. S.M. Glaser: None. S. Beriwal: None.
Radiation Oncology, Asan Medical Center, Seoul, Korea, Republic of (South), 2Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea, Republic of (South), 3Radiosurgery center, Asan Medical Center, Seoul, Korea, Republic of (South)
3617 Motion Likelihood Over Spine Radiosurgery TreatmentsdAn Intrafraction Motion Analysis J. Kim, A.T. Hsia, Z. Xu, and S. Ryu; Radiation Oncology, Stony Brook University Hospital, Stony Brook, NY Purpose/Objective(s): To estimate the intra-treatment spinal motion during single fraction radiosurgery treatment. Materials/Methods: A total of 33 spinal lesions encompassing 1-3 vertebral levels were retrospectively reviewed. The lesions were located in Cervical (4), Thoracic (18), Lumbar (7), and Sacral (4) levels. All lesions were treated in one fraction using VMAT on Varian Edge unit. For each lesion, the pre-, mid-, and post-treatment IGRT images of either CBCT or kV-kV orthogonal pairs were analyzed. The number of IGRT images used in this analysis were 33 images for pre-treatment, 15 for mid-treatment, and 4 for post-treatment. Their automatic registration results were collected as a means to measure spine shifts. Per our institutional protocol, a minimum of two CBCT images were acquired prior to radiation delivery. For this study, only the second CBCT images were used for the pretreatment motion analysis. In order to quantitatively estimate the magnitude of motion per unit time, the time durations between imaging were collected as well. The square root of each directional components were calculated to measure shifts in translations and rotations. Results: The mean1SD translational shifts for pre-, mid-, and posttreatments were respectively 2.9 3.5 mm, 1.60.6 mm, and 1.30.7 mm, and the respective rotational shifts were 1.21.1 deg, 0.40.3 deg, and 0.30.0 deg. The corresponding average durations for such motions were 7.53.0 min, 11.72.4 min, and 7.32.8 min. Therefore, the probable motions per unit time were 0.4 mm/min, 0.13 mm/min, and 0.18 mm/min, respectively. The results indicate that the patient movements were larger before the start of beam delivery, and that the average treatment time (including mid-treatment imaging, but excluding pre-treatment imaging) was 19 min and the potential magnitude of motion was approximately 0.15 mm/min during treatment. The rotational shifts were small. Conclusion: The preliminary results in this study indicates that the potential magnitude of motion during spine radiosurgery is 0.15 mm/min, which results in total 3 mm motion over 20 minute treatment duration. A mid-treatment imaging may be beneficial to reduce potential adverse events for spine radiosurgery. A study with larger population is in need for further evaluation. Author Disclosure: J. Kim: None. A. Hsia: None. Z. Xu: None. S. Ryu: Honoraria; Varian. Speaker’s Bureau; Varian. Advisory Board; Varian. ; International Stereotactic Radiosurgery Society.
3618 Development of 3D Printed Applicator in Brachytherapy for Gynecologic Cancer S.W. Kim,1 C. Jeong,1 K.H. Chang,1 Y.S. Ji,1 B. Cho,2 D. Lee,3 Y.S. Kim,2 S.Y. Song,2 S.W. Lee,2 and J. Kwak1; 1Department of
Purpose/Objective(s): Variety commercial applicators are used to treat Gynecologic(GYN) cancer in brachytherapy. A cylinder and ovoid type commercial applicators are commonly used to treat post hysterectomy adjuvant brachytherapy. When these patients treated with brachytherapy, the applicator design (length, diameter and number of source path) is one of the important factor to decide dose distribution and patient comfort. However, the standard commercial applicators only provide little opportunities to optimize dose distribution and patient comfort. In this study, the homemade applicator which reflects patient body structures and position of tumor was developed to provide better dose distribution and fixation. Materials/Methods: To provide better dose distributions to patient, the isotope path ways (single channel, multi- channel, ring with single channel) of applicator were considered. The PLA(PolyLactic Acid) which processed with nontoxic plant component was used for 3D printer filament material for clinical usage. OSLD(Optical Stimulated Luminescence Detector), Gafchromic EBT3 film, Epson Expression 10000XL and FilmQApro software were used to measure and analyze the absorbed dose and dose distribution. To measure the absorbed dose the OSLDs were located at 2 cm apart from superior side of applicator and the films were located at 1 cm apart to posterior, 0 and 0.5 cm apart to superior direction from the surface of applicator with solid water phantom to measure dose distributions. The TPS(Treatment Planning System) calculation and film measurement dose distributions were evaluated with gamma method. Results: The homemade applicators were created using 3D printing technique to adjust various isotope moving paths. The absorbed dose of Multi channel and ring with single channel applicator from TPS is calculated 89.8 to 102.5 and 70.2 to 80.6 cGy at 2.1 to 2.3 cm apart from center of each applicator surface and the measured absorbed dose is 106.62 and 70.42 cGy with 1.85 and 2.35 standard deviation. The dose distributions are evaluated with gamma method (3%, 3 mm) at 1 posterior and 2 superior side(0 and 0.5 cm apart) and the passing rates of each position are 100, 98.56, 99.01% at multi channel and 98.6, 99.13, 99.45% at ring with single channel. Conclusion: 3D printing technique offers a capability of various nontoxic custom applicators design in brachytherapy as provide the diversity of isotope moving path, length and diameter change. This study shows that we could provide better dose distribution and fixation to postoperative vaginal cancer patient using the applicator which reflect patient body structures and position of tumors. Author Disclosure: S. Kim: None. C. Jeong: None. K. Chang: None. Y. Ji: None. B. Cho: None. D. Lee: None. Y. Kim: None. S. Song: None. S. Lee: None. J. Kwak: None.
3619 The Novel Method to Reconstruct ThreeDimensional Target Motion From Body Surface Motion for Dynamic Moving Phantom S. Kito, K. Karasawa, K. Nihei, Y. Suda, M. Kanda, T. Okano, Y. Nakajima, T. Furuya, and S. Hashimoto; Tokyo Metropolitan Cancer and Infectious diseases Center Komagome Hospital, 3-18-22, Bunkyo-ku, Tokyo, Japan Purpose/Objective(s): We have developed the new dynamic moving phantom (DMP) with three axis drives to reproduce three-dimensional(3D) target motion plus one axis drive for body surface motion. The motion data for operating this phantom is able to be acquired by rehearsing dynamic tracking therapy (DTT) of a patient. In this study, the novel approach which reconstructs the 3D long time information from respiratory motion (RPM) data on the body surface during planning CT and the target motion measured by 4DCT is developed. Materials/Methods: First, the RPM data on body surface during planning CT in each patient was obtained by laser ranger (u(t)). Then, the average wave of u(t) when 4DCT are scanned was calculated and 3D target
International Journal of Radiation Oncology Biology Physics
Results: The maximum difference for target D90 between the reference plan and plans with applicator rotation was 0.2%, 24.2%, 30.8% for 1) circumferential, 2) anterior, and 3) lateral target, respectively. For bladder D2cc, the maximum difference was 2.7%, 11.0%, 26.1% for 1), 2), and 3), respectively. Similarly, for rectum D2cc, it was 3.2 %, 5.0%, 24.7%, for 1), 2), and 3), respectively. Compared to circumferential target, anterior and one-sided lateral target had larger differences. Dosimetric differences > 5% occurred at 15 degree rotation (or 2.6mm radial shift) for anterior target and 10 degree rotation (or 1.7mm radial shift) for lateral target. For the lateral target, there was a substantial difference between symmetric rotations clockwise and counter-clockwise rotations, while anterior and circumferential target dosimetry did not differ significantly between the two directions. Conclusion: We have demonstrated significant variation in the degree of impact based on location of tumor. In order to achieve a dosemtric deviation of less than 5%, rotational error must be limited to less than 10-15%. Quality assurance measures should be taken to avoid rotation between planning and treatment. Author Disclosure: H. Kim: None. S.M. Glaser: None. S. Beriwal: None.
Radiation Oncology, Asan Medical Center, Seoul, Korea, Republic of (South), 2Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea, Republic of (South), 3Radiosurgery center, Asan Medical Center, Seoul, Korea, Republic of (South)
3617 Motion Likelihood Over Spine Radiosurgery TreatmentsdAn Intrafraction Motion Analysis J. Kim, A.T. Hsia, Z. Xu, and S. Ryu; Radiation Oncology, Stony Brook University Hospital, Stony Brook, NY Purpose/Objective(s): To estimate the intra-treatment spinal motion during single fraction radiosurgery treatment. Materials/Methods: A total of 33 spinal lesions encompassing 1-3 vertebral levels were retrospectively reviewed. The lesions were located in Cervical (4), Thoracic (18), Lumbar (7), and Sacral (4) levels. All lesions were treated in one fraction using VMAT on Varian Edge unit. For each lesion, the pre-, mid-, and post-treatment IGRT images of either CBCT or kV-kV orthogonal pairs were analyzed. The number of IGRT images used in this analysis were 33 images for pre-treatment, 15 for mid-treatment, and 4 for post-treatment. Their automatic registration results were collected as a means to measure spine shifts. Per our institutional protocol, a minimum of two CBCT images were acquired prior to radiation delivery. For this study, only the second CBCT images were used for the pretreatment motion analysis. In order to quantitatively estimate the magnitude of motion per unit time, the time durations between imaging were collected as well. The square root of each directional components were calculated to measure shifts in translations and rotations. Results: The mean1SD translational shifts for pre-, mid-, and posttreatments were respectively 2.9 3.5 mm, 1.60.6 mm, and 1.30.7 mm, and the respective rotational shifts were 1.21.1 deg, 0.40.3 deg, and 0.30.0 deg. The corresponding average durations for such motions were 7.53.0 min, 11.72.4 min, and 7.32.8 min. Therefore, the probable motions per unit time were 0.4 mm/min, 0.13 mm/min, and 0.18 mm/min, respectively. The results indicate that the patient movements were larger before the start of beam delivery, and that the average treatment time (including mid-treatment imaging, but excluding pre-treatment imaging) was 19 min and the potential magnitude of motion was approximately 0.15 mm/min during treatment. The rotational shifts were small. Conclusion: The preliminary results in this study indicates that the potential magnitude of motion during spine radiosurgery is 0.15 mm/min, which results in total 3 mm motion over 20 minute treatment duration. A mid-treatment imaging may be beneficial to reduce potential adverse events for spine radiosurgery. A study with larger population is in need for further evaluation. Author Disclosure: J. Kim: None. A. Hsia: None. Z. Xu: None. S. Ryu: Honoraria; Varian. Speaker’s Bureau; Varian. Advisory Board; Varian. ; International Stereotactic Radiosurgery Society.
3618 Development of 3D Printed Applicator in Brachytherapy for Gynecologic Cancer S.W. Kim,1 C. Jeong,1 K.H. Chang,1 Y.S. Ji,1 B. Cho,2 D. Lee,3 Y.S. Kim,2 S.Y. Song,2 S.W. Lee,2 and J. Kwak1; 1Department of
Purpose/Objective(s): Variety commercial applicators are used to treat Gynecologic(GYN) cancer in brachytherapy. A cylinder and ovoid type commercial applicators are commonly used to treat post hysterectomy adjuvant brachytherapy. When these patients treated with brachytherapy, the applicator design (length, diameter and number of source path) is one of the important factor to decide dose distribution and patient comfort. However, the standard commercial applicators only provide little opportunities to optimize dose distribution and patient comfort. In this study, the homemade applicator which reflects patient body structures and position of tumor was developed to provide better dose distribution and fixation. Materials/Methods: To provide better dose distributions to patient, the isotope path ways (single channel, multi- channel, ring with single channel) of applicator were considered. The PLA(PolyLactic Acid) which processed with nontoxic plant component was used for 3D printer filament material for clinical usage. OSLD(Optical Stimulated Luminescence Detector), Gafchromic EBT3 film, Epson Expression 10000XL and FilmQApro software were used to measure and analyze the absorbed dose and dose distribution. To measure the absorbed dose the OSLDs were located at 2 cm apart from superior side of applicator and the films were located at 1 cm apart to posterior, 0 and 0.5 cm apart to superior direction from the surface of applicator with solid water phantom to measure dose distributions. The TPS(Treatment Planning System) calculation and film measurement dose distributions were evaluated with gamma method. Results: The homemade applicators were created using 3D printing technique to adjust various isotope moving paths. The absorbed dose of Multi channel and ring with single channel applicator from TPS is calculated 89.8 to 102.5 and 70.2 to 80.6 cGy at 2.1 to 2.3 cm apart from center of each applicator surface and the measured absorbed dose is 106.62 and 70.42 cGy with 1.85 and 2.35 standard deviation. The dose distributions are evaluated with gamma method (3%, 3 mm) at 1 posterior and 2 superior side(0 and 0.5 cm apart) and the passing rates of each position are 100, 98.56, 99.01% at multi channel and 98.6, 99.13, 99.45% at ring with single channel. Conclusion: 3D printing technique offers a capability of various nontoxic custom applicators design in brachytherapy as provide the diversity of isotope moving path, length and diameter change. This study shows that we could provide better dose distribution and fixation to postoperative vaginal cancer patient using the applicator which reflect patient body structures and position of tumors. Author Disclosure: S. Kim: None. C. Jeong: None. K. Chang: None. Y. Ji: None. B. Cho: None. D. Lee: None. Y. Kim: None. S. Song: None. S. Lee: None. J. Kwak: None.
3619 The Novel Method to Reconstruct ThreeDimensional Target Motion From Body Surface Motion for Dynamic Moving Phantom S. Kito, K. Karasawa, K. Nihei, Y. Suda, M. Kanda, T. Okano, Y. Nakajima, T. Furuya, and S. Hashimoto; Tokyo Metropolitan Cancer and Infectious diseases Center Komagome Hospital, 3-18-22, Bunkyo-ku, Tokyo, Japan Purpose/Objective(s): We have developed the new dynamic moving phantom (DMP) with three axis drives to reproduce three-dimensional(3D) target motion plus one axis drive for body surface motion. The motion data for operating this phantom is able to be acquired by rehearsing dynamic tracking therapy (DTT) of a patient. In this study, the novel approach which reconstructs the 3D long time information from respiratory motion (RPM) data on the body surface during planning CT and the target motion measured by 4DCT is developed. Materials/Methods: First, the RPM data on body surface during planning CT in each patient was obtained by laser ranger (u(t)). Then, the average wave of u(t) when 4DCT are scanned was calculated and 3D target