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93 Lymphatic target volume delineation using magnetic resonance imaging with ultrasmall particles of superparamagnetic iron oxide in carcinoma of the prostate
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September 7-10
64 (range 49-88). Patients were treated according to their risk category at presentation. Patients were divided into low, intermediate and high risk categories dependant on the presence of one, or two or more of the following factors; PSA >10, T-stage >2b, and Gleason score >6. Eight patients in the low risk category received HDR-BT as monotherapy to a prescribed dose of 3,800 cGy in 4 fractions over 3 days using a single implant. 65 patients in the intermediate risk group, and 40 patients in the high risk group received combined HDR-BT to a prescribed dose of 1,800 cGy in 3 fractions + adjuvant hormonal therapy. The fractionation schedule was recently changed: 2,000 cGy in 2 fractions HDR-BT and 4,000 cGy in 20 fractions EBRT. Results: Treatment was well tolerated with <5% grade 3 genitourinary and gastrointestinal toxicity. 3% of patients were discharged with a catheter following the HDR-BT implant and no patient required a catheter for longer than 1 month. There have been no cases of urethral stenosis. 3 failures have occurred; 2 PSA failures (ASTRO definition), and 1 died with bone metastases. Data is not mature enough to perform a meaningful survival analysis. Conclusions: The results of this preliminary study appear favourable; the analysis shows that the acute and chronic toxicity of patients with prostate cancer treated with HDR-BT is acceptable. 92 D o s i m e t r i c Feasibility of a Two Phase versus a S i m u l t a n e o u s lrntegrated Boost T e c h n i q u e for Dose Escalated P r o s t a t e R a d i o t h e r a p y J. Meng, D. Wilke, J. Clancey, J. MacArthur, R. Rut/edge Nova Scotia Cancer Centre, Dalhousie University, Halifax, Nova Scotia Objective: To investigate the feasibility of delivering 60 Gy in 20 fractions or 78 Gy in 39 fractions using 3D conformal radiotherapy, comparing a two-phase (TP) or simultaneous integrated boost (SIB) delivery technique. Methods: CT data from 10 patients was used. Planning target volumes (PTV) were defined as follows: PTV1 = GI-V + 11 mm, except 7 mm posterior. PTV2 = G'IV + 7 mm. The TP technique utilized a 4-field box technique with conformal shielding for Phase I, and a 6-field technique for Phase II. Phase I dose for the 60 Gy arm was 36 Gy in 12 fractions. Phase I dose for the 78 Gy arm was 46 Gy in 23 fractions. Normal tissue constraints (NTC) were taken from published literature on these two fractionation schemes. For the SIB technique, in-house computer software was developed with the following optimization capabilities: Gantry angle, beam weight and field shape. Cumulative Dose Volume Histograms for PTV coverage and normal tissues were generated. Results for the two treatment techniques were compared using the paired T-test. The type I error rate was corrected for multiple pairwise comparisons. Results: For all ten cases tested, the SIB plans met the PTV and NTC, for both the 60 Gy and 78 Gy dose levels. For the TP technique, 40% of plans exceeded the rectal NTC for the 60 Gy dose fractionation, and 10% of the plans exceeded the femoral head NTC. At all thresholds of dose, the SIB plans treated less volume of rectum and femoral head, with a relative reduction in volume from 11 to 38% (all comparisons statistically significant, p<0.016). The TP technique did not deliver the minimum desired dose to P-I-V1 in any case with either the 60 Gy or 78 Gy fractionation schemes. Conclusion: The SIB technique can achieve the desired constraints with either the 60 Gy in 20 or 78 Gy in 38 fractionation schemes, while demonstrating the ability to simultaneously address microscopic extracapsular spread and gross disease.
CARO 2005
93 L y m p h a t i c T a r g e t V o l u m e D e l i n e a t i o n using M a g n e t i c Resonance Zmaging with Ultrasmall Particles of S u p e r p a r a m a g n e t i c Zron Oxide in C a r c i n o m a o f t h e Prostate R. Dinniwel/, P. Chan, M. Haider, A. Fyles, A. Kir#ova, A. Syed, D. Jaffray, M. Milosevic Princess Margaret Hospital, University of Toronto, Toronto, Ontario Purpose: To examine the patterns of lymph node metastases in prostate cancer using Magnetic Resonance Imaging (MRI) with a lymphotrophic ultra-small superparamagnetic iron oxide and generate a nodal clinical target volume comprised of the nodal basins at risk of tumor spread. Methods: A single centre trial was undertaken with patients undergoing pre- and post- contrast MRI studies over two consecutive days. Ferumoxtran-10 (Combidex®: Advanced Magnetics, Inc, Cambridge, MA) was administered (2.6 mg/Kg) on the first day. Axial images were obtained at 3 mm intervals through the pelvis. The pelvic vasculature and lymph nodes were delineated using 3D modeling and image processing software (3D-DOCTOR®: Able Software Corp., Lexington, MA). Lymph node frequency and location relative to the adjacent vascular segments were analyzed. Nodes were ascertained to have metastases using previously demonstrated criteria (Harisinghani et at. NEJM 2003; 348: 2491-9). Results: 30 patients were enrolled. The patients ranged in age from 47 to 81 years (median 71). There were: 12 Tlc, 4 T2a, 8 T2b, 5 T3a and 1 T3b tumors. All patients had biopsy proven adenocarcinomas with Gleason scores ranging from 6 to 9 (median 7). The median PSA was 11.56 (range 3.41 to 90.40). 39 malignant nodes were identified. Metastases were situated in the following locations or vascular segments: obturator fossa (7); internal lilac (3); external lilac (11); common lilac (5); aortic/aortocaval (3); pararectal (6); and sacral (4). Conclusion: Nodal metastases appeared to be primarily localized in proximity to the major pelvic vessels. However, radial expansion around the major pelvic vessels to define a radiotherapy target volume for IMRT may not encompass all of the nodes at risk of harboring disease. Specific knowledge of the distribution of nodal metastases in prostate cancer as well as a better understanding of the pathways of pelvic lymphatic drainage will help in the delineation of nodal target volumes. 94 Stereotactic Fractionated Radiotherapy for the T r e a t m e n t of Benign M e n i n g i o m a s - C u r r e n t Results and Future Perspectives C. Candish, M. McKenzie, B. Clark, E. Vol/ans, R. Ma, R. Lee, E. Gete, M. Martin British Columbia Cancer Agency, Vancouver, British Columbia Background and Purpose: Stereotactic fractionated radiotherapy (SRT) is used for the treatment of benign meningiomas. This study reviewed the feasibility, efficacy and toxicity of SRT using static conformat fields, and investigated the possible therapeutic gain of dynamic arc or intensity modulated SRT. M e t h o d s and :Materials: A retrospective review and dosimetric analysis of 38 patients undergoing SRT was performed (1999-2004). Following this, 20 cases of base of skull meningioma were re-planned with dynamic arc and intensity modulated SRT. Comparison for conformality, homogeneity and dose to normal tissues was undertaken. Results: Of 34 patients (36 tumours) assessed, the median age was 53 years. The indication was primary treatment in 26 cases (no histology) and post-operative in 10 cases. The most common sites were cavernous sinus (17), optic nerve (6), and cerebellopontine angle (5). The median gross target volume and planning target volume were 8.9 cc and 18.9 cc respectively. Stereotactic treatment was delivered with static conformal fields (median number 6 with custom made blocks, 9 patients and micro-multileaf collimator, 25 patients). The
September 7-10
64 (range 49-88). Patients were treated according to their risk category at presentation. Patients were divided into low, intermediate and high risk categories dependant on the presence of one, or two or more of the following factors; PSA >10, T-stage >2b, and Gleason score >6. Eight patients in the low risk category received HDR-BT as monotherapy to a prescribed dose of 3,800 cGy in 4 fractions over 3 days using a single implant. 65 patients in the intermediate risk group, and 40 patients in the high risk group received combined HDR-BT to a prescribed dose of 1,800 cGy in 3 fractions + adjuvant hormonal therapy. The fractionation schedule was recently changed: 2,000 cGy in 2 fractions HDR-BT and 4,000 cGy in 20 fractions EBRT. Results: Treatment was well tolerated with <5% grade 3 genitourinary and gastrointestinal toxicity. 3% of patients were discharged with a catheter following the HDR-BT implant and no patient required a catheter for longer than 1 month. There have been no cases of urethral stenosis. 3 failures have occurred; 2 PSA failures (ASTRO definition), and 1 died with bone metastases. Data is not mature enough to perform a meaningful survival analysis. Conclusions: The results of this preliminary study appear favourable; the analysis shows that the acute and chronic toxicity of patients with prostate cancer treated with HDR-BT is acceptable. 92 D o s i m e t r i c Feasibility of a Two Phase versus a S i m u l t a n e o u s lrntegrated Boost T e c h n i q u e for Dose Escalated P r o s t a t e R a d i o t h e r a p y J. Meng, D. Wilke, J. Clancey, J. MacArthur, R. Rut/edge Nova Scotia Cancer Centre, Dalhousie University, Halifax, Nova Scotia Objective: To investigate the feasibility of delivering 60 Gy in 20 fractions or 78 Gy in 39 fractions using 3D conformal radiotherapy, comparing a two-phase (TP) or simultaneous integrated boost (SIB) delivery technique. Methods: CT data from 10 patients was used. Planning target volumes (PTV) were defined as follows: PTV1 = GI-V + 11 mm, except 7 mm posterior. PTV2 = G'IV + 7 mm. The TP technique utilized a 4-field box technique with conformal shielding for Phase I, and a 6-field technique for Phase II. Phase I dose for the 60 Gy arm was 36 Gy in 12 fractions. Phase I dose for the 78 Gy arm was 46 Gy in 23 fractions. Normal tissue constraints (NTC) were taken from published literature on these two fractionation schemes. For the SIB technique, in-house computer software was developed with the following optimization capabilities: Gantry angle, beam weight and field shape. Cumulative Dose Volume Histograms for PTV coverage and normal tissues were generated. Results for the two treatment techniques were compared using the paired T-test. The type I error rate was corrected for multiple pairwise comparisons. Results: For all ten cases tested, the SIB plans met the PTV and NTC, for both the 60 Gy and 78 Gy dose levels. For the TP technique, 40% of plans exceeded the rectal NTC for the 60 Gy dose fractionation, and 10% of the plans exceeded the femoral head NTC. At all thresholds of dose, the SIB plans treated less volume of rectum and femoral head, with a relative reduction in volume from 11 to 38% (all comparisons statistically significant, p<0.016). The TP technique did not deliver the minimum desired dose to P-I-V1 in any case with either the 60 Gy or 78 Gy fractionation schemes. Conclusion: The SIB technique can achieve the desired constraints with either the 60 Gy in 20 or 78 Gy in 38 fractionation schemes, while demonstrating the ability to simultaneously address microscopic extracapsular spread and gross disease.
CARO 2005
93 L y m p h a t i c T a r g e t V o l u m e D e l i n e a t i o n using M a g n e t i c Resonance Zmaging with Ultrasmall Particles of S u p e r p a r a m a g n e t i c Zron Oxide in C a r c i n o m a o f t h e Prostate R. Dinniwel/, P. Chan, M. Haider, A. Fyles, A. Kir#ova, A. Syed, D. Jaffray, M. Milosevic Princess Margaret Hospital, University of Toronto, Toronto, Ontario Purpose: To examine the patterns of lymph node metastases in prostate cancer using Magnetic Resonance Imaging (MRI) with a lymphotrophic ultra-small superparamagnetic iron oxide and generate a nodal clinical target volume comprised of the nodal basins at risk of tumor spread. Methods: A single centre trial was undertaken with patients undergoing pre- and post- contrast MRI studies over two consecutive days. Ferumoxtran-10 (Combidex®: Advanced Magnetics, Inc, Cambridge, MA) was administered (2.6 mg/Kg) on the first day. Axial images were obtained at 3 mm intervals through the pelvis. The pelvic vasculature and lymph nodes were delineated using 3D modeling and image processing software (3D-DOCTOR®: Able Software Corp., Lexington, MA). Lymph node frequency and location relative to the adjacent vascular segments were analyzed. Nodes were ascertained to have metastases using previously demonstrated criteria (Harisinghani et at. NEJM 2003; 348: 2491-9). Results: 30 patients were enrolled. The patients ranged in age from 47 to 81 years (median 71). There were: 12 Tlc, 4 T2a, 8 T2b, 5 T3a and 1 T3b tumors. All patients had biopsy proven adenocarcinomas with Gleason scores ranging from 6 to 9 (median 7). The median PSA was 11.56 (range 3.41 to 90.40). 39 malignant nodes were identified. Metastases were situated in the following locations or vascular segments: obturator fossa (7); internal lilac (3); external lilac (11); common lilac (5); aortic/aortocaval (3); pararectal (6); and sacral (4). Conclusion: Nodal metastases appeared to be primarily localized in proximity to the major pelvic vessels. However, radial expansion around the major pelvic vessels to define a radiotherapy target volume for IMRT may not encompass all of the nodes at risk of harboring disease. Specific knowledge of the distribution of nodal metastases in prostate cancer as well as a better understanding of the pathways of pelvic lymphatic drainage will help in the delineation of nodal target volumes. 94 Stereotactic Fractionated Radiotherapy for the T r e a t m e n t of Benign M e n i n g i o m a s - C u r r e n t Results and Future Perspectives C. Candish, M. McKenzie, B. Clark, E. Vol/ans, R. Ma, R. Lee, E. Gete, M. Martin British Columbia Cancer Agency, Vancouver, British Columbia Background and Purpose: Stereotactic fractionated radiotherapy (SRT) is used for the treatment of benign meningiomas. This study reviewed the feasibility, efficacy and toxicity of SRT using static conformat fields, and investigated the possible therapeutic gain of dynamic arc or intensity modulated SRT. M e t h o d s and :Materials: A retrospective review and dosimetric analysis of 38 patients undergoing SRT was performed (1999-2004). Following this, 20 cases of base of skull meningioma were re-planned with dynamic arc and intensity modulated SRT. Comparison for conformality, homogeneity and dose to normal tissues was undertaken. Results: Of 34 patients (36 tumours) assessed, the median age was 53 years. The indication was primary treatment in 26 cases (no histology) and post-operative in 10 cases. The most common sites were cavernous sinus (17), optic nerve (6), and cerebellopontine angle (5). The median gross target volume and planning target volume were 8.9 cc and 18.9 cc respectively. Stereotactic treatment was delivered with static conformal fields (median number 6 with custom made blocks, 9 patients and micro-multileaf collimator, 25 patients). The