Sumida, Iori | Search NASA

DOE OSTI2016

High-Dose-Rate Brachytherapy as Monotherapy for Intermediate- and High-Risk Prostate Cancer: Clinical Results for a Median 8-Year Follow-Up

Purpose: To present mature results of high-dose-rate brachytherapy (HDR-BT) as monotherapy for intermediate- and high-risk prostate cancer. Methods and Materials: From 1995 through 2012, 190 patients, 79 with intermediate-risk and 111 with high-risk prostate cancer, were treated with HDR-BT alone using 48 Gy/8 fractions, 54 Gy/9 fractions, or 45.5 Gy/7 fractions over 4 to 5 days. Neoadjuvant with or without adjuvant androgen deprivation therapy was administered to 139 patients, 35 intermediate- and 104 high-risk. Results: Median follow-up time was 92 months (range, 10-227 months), with a minimum of 2 years for surviving patients. Respective rates of cause-specific survival, overall survival, metastasis-free survival, and biochemical no evidence of disease for the intermediate-risk patients were 100%, 100%, 96%, and 93% at 5 years, and 100%, 96%, 91%, and 91% at 8 years. Corresponding rates for the high-risk patients were 97%, 93%, 84%, and 81% at 5 years, and 93%, 81%, 74%, and 77% at 8 years. The cumulative incidence of late grade 2 to 3 genitourinary toxicity was 5% at 5 years and 10% at 8 years, and that of late grade 3 was 0 at 5 years and 1% at 8 years. The cumulative incidence of late grade 2-3 gastrointestinal toxicity was 4% at 5 years and 6% at 8 years, and that of late grade 3 was 0 at 5 years and 2% at 8 years. No grade 4 or 5 toxicity was detected. Conclusions: Our single-institution study with a median 8-year follow-up showed that HDR-BT as monotherapy was safe and effective for patients with intermediate- and high-risk prostate cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2015

Reference respiratory waveforms by minimum jerk model analysis

Purpose: CyberKnife{sup ®} robotic surgery system has the ability to deliver radiation to a tumor subject to respiratory movements using Synchrony{sup ®} mode with less than 2 mm tracking accuracy. However, rapid and rough motion tracking causes mechanical tracking errors and puts mechanical stress on the robotic joint, leading to unexpected radiation delivery errors. During clinical treatment, patient respiratory motions are much more complicated, suggesting the need for patient-specific modeling of respiratory motion. The purpose of this study was to propose a novel method that provides a reference respiratory wave to enable smooth tracking for each patient. Methods: The minimum jerk model, which mathematically derives smoothness by means of jerk, or the third derivative of position and the derivative of acceleration with respect to time that is proportional to the time rate of force changed was introduced to model a patient-specific respiratory motion wave to provide smooth motion tracking using CyberKnife{sup ®}. To verify that patient-specific minimum jerk respiratory waves were being tracked smoothly by Synchrony{sup ®} mode, a tracking laser projection from CyberKnife{sup ®} was optically analyzed every 0.1 s using a webcam and a calibrated grid on a motion phantom whose motion was in accordance with three pattern waves (cosine, typical free-breathing, and minimum jerk theoretical wave models) for the clinically relevant superior–inferior directions from six volunteers assessed on the same node of the same isocentric plan. Results: Tracking discrepancy from the center of the grid to the beam projection was evaluated. The minimum jerk theoretical wave reduced the maximum-peak amplitude of radial tracking discrepancy compared with that of the waveforms modeled by cosine and typical free-breathing model by 22% and 35%, respectively, and provided smooth tracking for radial direction. Motion tracking constancy as indicated by radial tracking discrepancy affected by respiratory phase was improved in the minimum jerk theoretical model by 7.0% and 13% compared with that of the waveforms modeled by cosine and free-breathing model, respectively. Conclusions: The minimum jerk theoretical respiratory wave can achieve smooth tracking by CyberKnife{sup ®} and may provide patient-specific respiratory modeling, which may be useful for respiratory training and coaching, as well as quality assurance of the mechanical CyberKnife{sup ®} robotic trajectory.

60 APPLIED LIFE SCIENCES↗