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Efficacy of Stereotactic Radiation Therapy for Brain Metastases Using Dynamic Jaws Technology in the Helical Tomotherapy System: Planning and Clinical Studies
E568
International Journal of Radiation Oncology Biology Physics
the width at D5 from IMRT was found to be slightly larger than from VMAT [0.59 vs 0.54 (pZ1.0)]. WCA showed similar results [D95: 3.28 vs 3.00 (pZ0.65); D5: 1.68 vs 1.95 (pZ0.36)]. RVH showed the AUC from IMRT to be slightly smaller than from VMAT [1.13 vs 1.15 (pZ0.57)]. RVH represents the relative volume (y) on the vertical axis and the RMSD (x) on the horizontal axis. Similar to DVH assessing the nominal dose, this means that y% of the volume of the indicated structure has the RMSD at least x Gy. Conclusion: VMAT plan robustness is comparable to IMRT plan robustness. The plan robustness conclusions from WCA and DVHB are DVH parameter and patient dependent. On the other hand RVH captures the overall effect of uncertainties on the dose to a volume of interest. Author Disclosure: W. Liu: Research Grant; NIH, The Fraternal Order of Eagles Cancer Research, The Lawrence W. and Marilun W Matteson Fund, The Kemper Marley Foundation, ASU. S.H. Patel: None. J. Shen: None. J. Stoker: None. X. Ding: None. Y. Hu: None. W.W. Wong: None. M. Halyard: None. G.A. Ezzell: None. S.E. Schild: None. M. Bues: None.
City Hospital, Okazaki, Japan, 3Department of Radiology and Radiation Oncology, Aichi Medical University, Nagakute, Japan, 4Nanbu Tokushukai Hospital, Shimajiri-gun Yaese-machi, Japan, 5Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
3425 Real Time 3D Beam Visualization for Monitoring External Beam Radiation Therapy C.H. Jenkins,1 D.J. Naczynski,2 S.J. Yu,2 and L. Xing1; 1Stanford University School of Medicine, Stanford, CA, 2Stanford University, Stanford, CA Purpose/Objective(s): The administration of radiation therapy has advanced steadily throughout its history. However, in spite of large advances in planning accuracy and motion tracking techniques, the actual administration of radiation continues to be a blind procedure. We propose that a system consisting of a flexible scintillation sheet and an array of digital cameras can be used to simultaneously visualize the patient surface and the delivered radiation beam in three dimensions and in real time. Materials/Methods: For the proof of concept system, scintillating sheets were made by mixing Gd2O2S:Tb (GOS) with silicone and casting the mixture into a thin sheet. The sheet was placed on a solid water phantom and irradiated with therapeutic photon beams from a medical linear accelerator (LINAC). The light emitted from the sheet was collected using a pair of cameras calibrated as a stereo pair. Custom designed image processing software was used to reconstruct the 3D scene and extract the beam profile. The shape and location of the extracted profile was compared to known collimator settings for validation. Results: The system was capable of acquiring high quality images of both the phantom and the beam under various levels of ambient room lighting including those most commonly used during therapy. Images were obtained at a rate of 20 fps. The system demonstrated sub-millimeter resolution and accuracy in identifying both the shape and location of radiation beams. The intensity of the beam profile was found to be linear with dose rate and correlated to the expected surface dose as beam energy changes. Conclusion: A system consisting of digital cameras and a flexible scintillation sheet is capable of three dimensional visualization of external beam radiation therapy in real-time. The accuracy of the data is sufficient that further development of the system may provide the ability to verify the accuracy of treatment as it is occurring and provide a record for posttreatment analysis. Author Disclosure: C.H. Jenkins: None. D.J. Naczynski: None. S. Yu: None. L. Xing: None.
3426 Efficacy of Stereotactic Radiation Therapy for Brain Metastases Using Dynamic Jaws Technology in the Helical Tomotherapy System: Planning and Clinical Studies T. Murai,1 A. Hayashi,2 Y. Mori,3 M. Yoshihiko,4 T. Yanagi,1 M. Matsuo,1 T. Takaoka,1 Y. Ogawa,5 T. Kondo,5 and Y. Shibamoto1; 1Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan, 2Okazaki
Purpose/Objective(s): Stereotactic radiation therapy (SRT) for brain metastases (BMs) can be performed using helical tomotherapy. Recently, a new dynamic jaws (DJs) technology has been introduced into tomotherapy. In the new system, jaw sizes are optimized during sweeping across the target, and reduction of treatment time and improvement in dose distribution may be expected using this system. To evaluate the DJs system in SRT for brain metastases, we first conducted a planning study to compare 2 treatment plans with and without the DJs system. As a second step, the efficacy was evaluated in actual patients. Materials/Methods: In the planning study, imaginary spherical PTVs with a diameter of 10-22 mm were contoured on 5 patients’ head CT images. Treatment plans were calculated for the following 2 conditions: 1-cm field width with fixed jaws (FJs) and 2.5-cm field width with DJs. Prescribed dose was 30 Gy/3 fr. Evaluated parameters were the treatment time, homogeneity index and conformity index (CI) for PTV, and D20Gy and D10Gy (cc) for the brain. To evaluate clinical efficacy, we conducted a study of tomotherapy SRT using DJs or FJs for BM patients. Demographic, treatment and outcome data were analyzed. Results: In the planning study, irrespective of the PTV diameter, 2.5-cm field width DJs plans could shorten treatment time and had almost the same dose distribution as in 1.0-cm field-width FJs plans. Treatment time decreased to 73% in 2.5-cm field-width DJs plans compared to 1cm field-width plans (p< 0.0001). Homogeneity index and CI in 2.5-cm field-width DJs plans were comparable to 1-cm field-width FJs plans. V20Gy and V10Gy did not differ significantly between the two plans. In total, 27 patients (performance status; 0-2) were treated with tomotherapy as the first line therapy. Among them, 7 were treated with whole brain radiation (No of BMs > 4) and excluded from this analysis. Twenty patients with 31 BMs underwent SRT (30 Gy/3 fr or 35 Gy/5 fr) (No of BMs 4). All patients were RPA class II. Primary tumor site was the lung in 13 patients, breast in 2, and others in 5. Three fractions were applied to 5 BMs and 5 fractions to 26 BMs. The local control (LC) rate was 87% at 12 months. Median overall survival was 11 months. Ten patients with 15 BMs underwent SRT using 2.5-cm field-width DJs and others using 1.0-cm field-width FJs. PTV (cc) did not differ significantly between the DJs and FJs groups (11.4 cc vs. 13.9 cc). In patients treated with the DJs system, the treatment time was 75% shorter and the LC rate was 100% at 12 months. Brain necrosis (Grade 2) was observed in 2 patients; one had been treated with DJs and the other with FJs. Conclusion: The DJs system offers treatment time reduction and dose distribution comparable to that obtained by the FJs system using a smaller jaw width. Clinical results are favorable and further studies are warranted. Author Disclosure: T. Murai: None. A. Hayashi: None. Y. Mori: None. M. Yoshihiko: None. T. Yanagi: None. M. Matsuo: None. T. Takaoka: None. Y. Ogawa: None. T. Kondo: None. Y. Shibamoto: None.
3427 Whole-Brain Radiation Therapy With Hypothalamic-Pituitary Axis and Hippocampus Avoiding: A Planning Study X. Fan; Fudan University Shanghai Cancer Center, Shanghai, China Purpose/Objective(s): Hypothalamus-pituitary axis, the vital organs for endocrine regulation, is sensitive for irradiation and associated with cognitive impairments, somnolence syndrome, and fatigue after brain irradiation. The purpose was to evaluate the feasibility of delivering wholebrain radiation therapy (WBRT) with hypothalamic-pituitary axis and hippocampus avoiding (HPA-HA-WBRT). Materials/Methods: Ten lung cancer patients with brain metastases underwent planning using linear accelerator based intensity modulated
International Journal of Radiation Oncology Biology Physics
the width at D5 from IMRT was found to be slightly larger than from VMAT [0.59 vs 0.54 (pZ1.0)]. WCA showed similar results [D95: 3.28 vs 3.00 (pZ0.65); D5: 1.68 vs 1.95 (pZ0.36)]. RVH showed the AUC from IMRT to be slightly smaller than from VMAT [1.13 vs 1.15 (pZ0.57)]. RVH represents the relative volume (y) on the vertical axis and the RMSD (x) on the horizontal axis. Similar to DVH assessing the nominal dose, this means that y% of the volume of the indicated structure has the RMSD at least x Gy. Conclusion: VMAT plan robustness is comparable to IMRT plan robustness. The plan robustness conclusions from WCA and DVHB are DVH parameter and patient dependent. On the other hand RVH captures the overall effect of uncertainties on the dose to a volume of interest. Author Disclosure: W. Liu: Research Grant; NIH, The Fraternal Order of Eagles Cancer Research, The Lawrence W. and Marilun W Matteson Fund, The Kemper Marley Foundation, ASU. S.H. Patel: None. J. Shen: None. J. Stoker: None. X. Ding: None. Y. Hu: None. W.W. Wong: None. M. Halyard: None. G.A. Ezzell: None. S.E. Schild: None. M. Bues: None.
City Hospital, Okazaki, Japan, 3Department of Radiology and Radiation Oncology, Aichi Medical University, Nagakute, Japan, 4Nanbu Tokushukai Hospital, Shimajiri-gun Yaese-machi, Japan, 5Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
3425 Real Time 3D Beam Visualization for Monitoring External Beam Radiation Therapy C.H. Jenkins,1 D.J. Naczynski,2 S.J. Yu,2 and L. Xing1; 1Stanford University School of Medicine, Stanford, CA, 2Stanford University, Stanford, CA Purpose/Objective(s): The administration of radiation therapy has advanced steadily throughout its history. However, in spite of large advances in planning accuracy and motion tracking techniques, the actual administration of radiation continues to be a blind procedure. We propose that a system consisting of a flexible scintillation sheet and an array of digital cameras can be used to simultaneously visualize the patient surface and the delivered radiation beam in three dimensions and in real time. Materials/Methods: For the proof of concept system, scintillating sheets were made by mixing Gd2O2S:Tb (GOS) with silicone and casting the mixture into a thin sheet. The sheet was placed on a solid water phantom and irradiated with therapeutic photon beams from a medical linear accelerator (LINAC). The light emitted from the sheet was collected using a pair of cameras calibrated as a stereo pair. Custom designed image processing software was used to reconstruct the 3D scene and extract the beam profile. The shape and location of the extracted profile was compared to known collimator settings for validation. Results: The system was capable of acquiring high quality images of both the phantom and the beam under various levels of ambient room lighting including those most commonly used during therapy. Images were obtained at a rate of 20 fps. The system demonstrated sub-millimeter resolution and accuracy in identifying both the shape and location of radiation beams. The intensity of the beam profile was found to be linear with dose rate and correlated to the expected surface dose as beam energy changes. Conclusion: A system consisting of digital cameras and a flexible scintillation sheet is capable of three dimensional visualization of external beam radiation therapy in real-time. The accuracy of the data is sufficient that further development of the system may provide the ability to verify the accuracy of treatment as it is occurring and provide a record for posttreatment analysis. Author Disclosure: C.H. Jenkins: None. D.J. Naczynski: None. S. Yu: None. L. Xing: None.
3426 Efficacy of Stereotactic Radiation Therapy for Brain Metastases Using Dynamic Jaws Technology in the Helical Tomotherapy System: Planning and Clinical Studies T. Murai,1 A. Hayashi,2 Y. Mori,3 M. Yoshihiko,4 T. Yanagi,1 M. Matsuo,1 T. Takaoka,1 Y. Ogawa,5 T. Kondo,5 and Y. Shibamoto1; 1Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan, 2Okazaki
Purpose/Objective(s): Stereotactic radiation therapy (SRT) for brain metastases (BMs) can be performed using helical tomotherapy. Recently, a new dynamic jaws (DJs) technology has been introduced into tomotherapy. In the new system, jaw sizes are optimized during sweeping across the target, and reduction of treatment time and improvement in dose distribution may be expected using this system. To evaluate the DJs system in SRT for brain metastases, we first conducted a planning study to compare 2 treatment plans with and without the DJs system. As a second step, the efficacy was evaluated in actual patients. Materials/Methods: In the planning study, imaginary spherical PTVs with a diameter of 10-22 mm were contoured on 5 patients’ head CT images. Treatment plans were calculated for the following 2 conditions: 1-cm field width with fixed jaws (FJs) and 2.5-cm field width with DJs. Prescribed dose was 30 Gy/3 fr. Evaluated parameters were the treatment time, homogeneity index and conformity index (CI) for PTV, and D20Gy and D10Gy (cc) for the brain. To evaluate clinical efficacy, we conducted a study of tomotherapy SRT using DJs or FJs for BM patients. Demographic, treatment and outcome data were analyzed. Results: In the planning study, irrespective of the PTV diameter, 2.5-cm field width DJs plans could shorten treatment time and had almost the same dose distribution as in 1.0-cm field-width FJs plans. Treatment time decreased to 73% in 2.5-cm field-width DJs plans compared to 1cm field-width plans (p< 0.0001). Homogeneity index and CI in 2.5-cm field-width DJs plans were comparable to 1-cm field-width FJs plans. V20Gy and V10Gy did not differ significantly between the two plans. In total, 27 patients (performance status; 0-2) were treated with tomotherapy as the first line therapy. Among them, 7 were treated with whole brain radiation (No of BMs > 4) and excluded from this analysis. Twenty patients with 31 BMs underwent SRT (30 Gy/3 fr or 35 Gy/5 fr) (No of BMs 4). All patients were RPA class II. Primary tumor site was the lung in 13 patients, breast in 2, and others in 5. Three fractions were applied to 5 BMs and 5 fractions to 26 BMs. The local control (LC) rate was 87% at 12 months. Median overall survival was 11 months. Ten patients with 15 BMs underwent SRT using 2.5-cm field-width DJs and others using 1.0-cm field-width FJs. PTV (cc) did not differ significantly between the DJs and FJs groups (11.4 cc vs. 13.9 cc). In patients treated with the DJs system, the treatment time was 75% shorter and the LC rate was 100% at 12 months. Brain necrosis (Grade 2) was observed in 2 patients; one had been treated with DJs and the other with FJs. Conclusion: The DJs system offers treatment time reduction and dose distribution comparable to that obtained by the FJs system using a smaller jaw width. Clinical results are favorable and further studies are warranted. Author Disclosure: T. Murai: None. A. Hayashi: None. Y. Mori: None. M. Yoshihiko: None. T. Yanagi: None. M. Matsuo: None. T. Takaoka: None. Y. Ogawa: None. T. Kondo: None. Y. Shibamoto: None.
3427 Whole-Brain Radiation Therapy With Hypothalamic-Pituitary Axis and Hippocampus Avoiding: A Planning Study X. Fan; Fudan University Shanghai Cancer Center, Shanghai, China Purpose/Objective(s): Hypothalamus-pituitary axis, the vital organs for endocrine regulation, is sensitive for irradiation and associated with cognitive impairments, somnolence syndrome, and fatigue after brain irradiation. The purpose was to evaluate the feasibility of delivering wholebrain radiation therapy (WBRT) with hypothalamic-pituitary axis and hippocampus avoiding (HPA-HA-WBRT). Materials/Methods: Ten lung cancer patients with brain metastases underwent planning using linear accelerator based intensity modulated