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Prostate Localization Using Serrated Gold Coil Markers
I. J. Radiation Oncology d Biology d Physics
S382
Volume 69, Number 3, Supplement, 2007
Seven men met the ASTRO consensus definition of PSA failure. Four of these men also met the Phoenix definition of failure with a PSA rise greater than 2.0 ng/ml above nadir. Overall survival and bRFS curves were estimated by the Kaplan-Meier method using the ASTRO definition of failure. The Cox-Mantel test was used to compare survival distributions. The overall 5-year estimate of bRFS was 93.5%, with a 5-year overall survival rate of 88.9%. With respect to mean EUD, the 5year estimate of bRFS was 100% if mean EUD was .168 Gy, and 88.3% if mean EUD was \168 Gy, (p = 0.014). With respect to D90, the 5-year estimate of bRFS was 100% if D90 was .140 Gy, and 89.4% if D90 was \140 Gy, (p = 0.027). A value of 140 Gy was used rather than the median dose for analysis as previously published work has demonstrated a correlation with bRFS at doses above and below this value. With respect to V100, the 5-year estimate of bRFS was 100% if V100 was .87%, and 88.4% if V100 was \87%, (p = 0.014). There was no statistically significant correlation with any of these factors with overall survival. Conclusions: The post-implant dosimetric quantifiers used in our post-implant analysis, mean EUD . 168 Gy, D90 . 140 Gy, V100 . 87%, did predict for a statistically significant increase in bRFS after LDRPB in our cohort. Author Disclosure: E. Miles, None; A. Alkaissi, None; S. Das, None; R. Clough, None; M. Anscher, None; J. Oleson, None.
2319
Prostate Localization Using Serrated Gold Coil Markers 1
L. L. Gates , D. J. Gladstone1, M. S. Kasibhatla2, J. F. Marshall1, J. D. Seigne1, E. Hug3, A. C. Hartford1 1 Dartmouth-Hitchcock Medical Center, Lebanon, NH, 2Duke University Medical Center, Durham, NC, 3Paul Scherrer Institut, Zurich, Switzerland
Purpose/Objective(s): We investigated the positioning reproducibility of serrated gold coils (VisicoilTM) implanted within the prostate glands of patients undergoing definitive external beam radiotherapy for prostate cancer. Materials/Methods: Radiopaque VisicoilsTM of diameter 0.75 mm and median length 3 cm (range 2–4 cm) were implanted, one into each lobe of the prostate glands of 30 patients planned for external beam treatment. A transperineal approach with ultrasound guidance was used. The coils were visualized on treatment planning CT scans performed before therapy (SIM) and again after 25 fractions of treatment (5 weeks, W5). For localization purposes five points were specified along the length of each coil. For each patient the SIM and 5WK scans were fused using a computer algorithm that mapped these specified points from the SIM scan onto the 5WK scan. The magnitude and direction of changes in relative coil positions from the original CT scan were determined. Results: Data from 30 patients were studied, of whom 19 also received androgen ablation therapy. The average change in the distance between the two coils over 5 weeks of treatment was 1.0 mm (± 0.6 mm), with a maximum of 2.5 mm in one patient. Average residual errors (standard deviations) for the positions of individual coil segments after 5 weeks of therapy were only 0.5 mm LR, 0.6 mm AP, and 0.4 mm IS. For all parameters tested, differences between patients undergoing and those not undergoing hormonal therapy were not statistically significant. Conclusions: In this study of 30 patients, the average change in distance between the coils over 5 weeks of treatment, at 1.0 mm with a maximum of 2.5 mm, compared favorably with published data regarding marker seed stability.1 One study, for example, demonstrated an average seed migration of 1.2 mm, with a maximum change in inter-seed distance during a course of therapy greater than 6 mm in a pool of only 10 patients.2 Possible volume changes due to androgen ablation treatment did not significantly affect VisicoilTM fiducial accuracy. Overall, excellent stability of the implanted VisicoilTM was observed, with average residual errors (standard deviations) of 0.4–0.6 mm in the AP, lat, and sup-inf directions. These data lead us to expect that at treatment planning the safety margins needed to account for coil position uncertainty, encompassing 95% of cases (two standard deviations), would be less than two millimeters. References: 1. Litzenberg D, et al. Daily prostate targeting using implanted radiopaque markers. Int. J. Radiation Oncology Biol. Phys. 2002; 52: 699–703. 2. Poggi MM et al. Marker seed migration in prostate localization. Int. J. Radiation Oncology Biol. Phys. 2003; 56: 1248–51. Author Disclosure: L.L. Gates, None; D.J. Gladstone, None; M.S. Kasibhatla, None; J.F. Marshall, None; J.D. Seigne, None; E. Hug, None; A.C. Hartford, None.
2320
3D Magnetic Resonance Spectroscopy Without Endorectal Coil in Prostate Cancer Patients Undergoing Androgen Deprivation and External Beam Radiation Therapy
G. Sasso1,2, A. Zapotoczna3, N. Gibson4, A. Mohd Tahir1, D. Pryor1, O. Bigault1, P. J. Fon1, J. Dass1, S. Cooper1, J. Simpson3 1 Radiation Oncology Department, Townsville Teaching Hospital, Townsville, Queensland, Australia, 2Faculty of Medicine, Health and Molecular Sciences, James Cook University, Townsville, Queensland, Australia, 3Medical Physics Department, Townsville Teaching Hospital, Townsville, Queensland, Australia, 4Medical Imaging Department, Townsville Teaching Hospital, Townsville, Queensland, Australia Sensitivity and specificity of 3D MRS [magnetic resonance spectroscopy] for prostate studies increased significantly in the last few years causing interest for its potential role for definition of target sub-volumes at higher risk of failure following radical radiotherapy. Similarly to other tumour sites, prostate MRS can also be a non-invasive predictive factor of treatment outcome. We present the early results of a prospective, non randomized study aiming to evaluate MRS changes in response to neo-adjuvant androgen deprivation therapy [AD] prior to radiotherapy in patients affected by high risk localised prostate cancer (clinical stage T3 and/or Gleason score .7). Secondary endpoints of the study are: 1) determination of optimal guidelines for MRS use in clinical routine; 2) feasibility of performing MRS with diagnostic results without endorectal [ER] coil; 3) value of MRS for radiotherapy planning with special interest in dose escalation to the dominant intra-prostatic lesion; 4) potential of MRS for improving treatment cost-efficiency.
S382
Volume 69, Number 3, Supplement, 2007
Seven men met the ASTRO consensus definition of PSA failure. Four of these men also met the Phoenix definition of failure with a PSA rise greater than 2.0 ng/ml above nadir. Overall survival and bRFS curves were estimated by the Kaplan-Meier method using the ASTRO definition of failure. The Cox-Mantel test was used to compare survival distributions. The overall 5-year estimate of bRFS was 93.5%, with a 5-year overall survival rate of 88.9%. With respect to mean EUD, the 5year estimate of bRFS was 100% if mean EUD was .168 Gy, and 88.3% if mean EUD was \168 Gy, (p = 0.014). With respect to D90, the 5-year estimate of bRFS was 100% if D90 was .140 Gy, and 89.4% if D90 was \140 Gy, (p = 0.027). A value of 140 Gy was used rather than the median dose for analysis as previously published work has demonstrated a correlation with bRFS at doses above and below this value. With respect to V100, the 5-year estimate of bRFS was 100% if V100 was .87%, and 88.4% if V100 was \87%, (p = 0.014). There was no statistically significant correlation with any of these factors with overall survival. Conclusions: The post-implant dosimetric quantifiers used in our post-implant analysis, mean EUD . 168 Gy, D90 . 140 Gy, V100 . 87%, did predict for a statistically significant increase in bRFS after LDRPB in our cohort. Author Disclosure: E. Miles, None; A. Alkaissi, None; S. Das, None; R. Clough, None; M. Anscher, None; J. Oleson, None.
2319
Prostate Localization Using Serrated Gold Coil Markers 1
L. L. Gates , D. J. Gladstone1, M. S. Kasibhatla2, J. F. Marshall1, J. D. Seigne1, E. Hug3, A. C. Hartford1 1 Dartmouth-Hitchcock Medical Center, Lebanon, NH, 2Duke University Medical Center, Durham, NC, 3Paul Scherrer Institut, Zurich, Switzerland
Purpose/Objective(s): We investigated the positioning reproducibility of serrated gold coils (VisicoilTM) implanted within the prostate glands of patients undergoing definitive external beam radiotherapy for prostate cancer. Materials/Methods: Radiopaque VisicoilsTM of diameter 0.75 mm and median length 3 cm (range 2–4 cm) were implanted, one into each lobe of the prostate glands of 30 patients planned for external beam treatment. A transperineal approach with ultrasound guidance was used. The coils were visualized on treatment planning CT scans performed before therapy (SIM) and again after 25 fractions of treatment (5 weeks, W5). For localization purposes five points were specified along the length of each coil. For each patient the SIM and 5WK scans were fused using a computer algorithm that mapped these specified points from the SIM scan onto the 5WK scan. The magnitude and direction of changes in relative coil positions from the original CT scan were determined. Results: Data from 30 patients were studied, of whom 19 also received androgen ablation therapy. The average change in the distance between the two coils over 5 weeks of treatment was 1.0 mm (± 0.6 mm), with a maximum of 2.5 mm in one patient. Average residual errors (standard deviations) for the positions of individual coil segments after 5 weeks of therapy were only 0.5 mm LR, 0.6 mm AP, and 0.4 mm IS. For all parameters tested, differences between patients undergoing and those not undergoing hormonal therapy were not statistically significant. Conclusions: In this study of 30 patients, the average change in distance between the coils over 5 weeks of treatment, at 1.0 mm with a maximum of 2.5 mm, compared favorably with published data regarding marker seed stability.1 One study, for example, demonstrated an average seed migration of 1.2 mm, with a maximum change in inter-seed distance during a course of therapy greater than 6 mm in a pool of only 10 patients.2 Possible volume changes due to androgen ablation treatment did not significantly affect VisicoilTM fiducial accuracy. Overall, excellent stability of the implanted VisicoilTM was observed, with average residual errors (standard deviations) of 0.4–0.6 mm in the AP, lat, and sup-inf directions. These data lead us to expect that at treatment planning the safety margins needed to account for coil position uncertainty, encompassing 95% of cases (two standard deviations), would be less than two millimeters. References: 1. Litzenberg D, et al. Daily prostate targeting using implanted radiopaque markers. Int. J. Radiation Oncology Biol. Phys. 2002; 52: 699–703. 2. Poggi MM et al. Marker seed migration in prostate localization. Int. J. Radiation Oncology Biol. Phys. 2003; 56: 1248–51. Author Disclosure: L.L. Gates, None; D.J. Gladstone, None; M.S. Kasibhatla, None; J.F. Marshall, None; J.D. Seigne, None; E. Hug, None; A.C. Hartford, None.
2320
3D Magnetic Resonance Spectroscopy Without Endorectal Coil in Prostate Cancer Patients Undergoing Androgen Deprivation and External Beam Radiation Therapy
G. Sasso1,2, A. Zapotoczna3, N. Gibson4, A. Mohd Tahir1, D. Pryor1, O. Bigault1, P. J. Fon1, J. Dass1, S. Cooper1, J. Simpson3 1 Radiation Oncology Department, Townsville Teaching Hospital, Townsville, Queensland, Australia, 2Faculty of Medicine, Health and Molecular Sciences, James Cook University, Townsville, Queensland, Australia, 3Medical Physics Department, Townsville Teaching Hospital, Townsville, Queensland, Australia, 4Medical Imaging Department, Townsville Teaching Hospital, Townsville, Queensland, Australia Sensitivity and specificity of 3D MRS [magnetic resonance spectroscopy] for prostate studies increased significantly in the last few years causing interest for its potential role for definition of target sub-volumes at higher risk of failure following radical radiotherapy. Similarly to other tumour sites, prostate MRS can also be a non-invasive predictive factor of treatment outcome. We present the early results of a prospective, non randomized study aiming to evaluate MRS changes in response to neo-adjuvant androgen deprivation therapy [AD] prior to radiotherapy in patients affected by high risk localised prostate cancer (clinical stage T3 and/or Gleason score .7). Secondary endpoints of the study are: 1) determination of optimal guidelines for MRS use in clinical routine; 2) feasibility of performing MRS with diagnostic results without endorectal [ER] coil; 3) value of MRS for radiotherapy planning with special interest in dose escalation to the dominant intra-prostatic lesion; 4) potential of MRS for improving treatment cost-efficiency.