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Intraoperative TRUS-fluoroscopy fusion improves prostate brachytherapy quality
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Abstracts / Brachytherapy 6 (2007) 77e118
Methods and Materials: This non-randomized study compares 20 patients who underwent brachytherapy with loose seeds (September 2002dJuly 2003) and 9 patients (ongoing) with stranded seeds. Preplanning was based on transrectal ultrasound images using I-125 seeds from Draximage for the loose seed cohort and IsoAid for the strands. PTV definition and planning parameters were similar in both cohorts. Post-implant dosimetry used CT-MRI fusion done on day 0, 7 and 30 for both cohorts. Factors evaluated were V100, V150, V200 and D90. Increase or decrease in prostate volumes and dosimetric factors were calculated as percentage difference from the pre-plan values and compared using unpaired Student’s t test with unequal variance. Results: For loose vs. stranded seeds the baseline prostate volume was 35.4 vs. 40.9 cc, the preplan V150 was 60.7 vs. 58.7%, V200 was 16.5 vs. 13.2% and D90 was 179.2 vs. 178.3 Gy, respectively. At each time point (day 0, 7 and 30), prostate edema was greater for the loose seed cohort; 33.9%, 23.3% and 7.8%, respectively, compared to stranded seeds 25.7%, 13% and 1%, respectively, (day 7 difference p 5 0.02). The day 0 V100 was higher for loose than stranded seeds (93.2 vs. 90.1%; p 5 0.04). By day 7 and 30 this difference had resolved (day 7: 93.2 vs. 92.7%; day 30: 94.9 vs. 95.4%). The mean percentage decrease of D90 at day 0 compared to the preplan was greater for stranded seeds (18.2%) in comparison to loose seeds (14.1%) (p 5 0.07), but by day 7 and 30 the values were similar; 14.8 vs. 12.6% at day 7 and 5.8 vs. 8.6% at day 30. Similarly, the mean percentage decrease of V150 at day 0 was greater for stranded seeds (35.1 vs. 25.4% for loose seeds; p 5 0.03). V150 at day 7 and 30 and V200 at all time points were similar. Even though the decrease in V100, V150 and D90 at day 0 was higher for stranded seeds, the day 0 absolute values were clinically acceptable; 90.1%, 38.1% and 145.7 Gy, respectively, and the day 30 values were 95.4%, 59.1% and 165.7 Gy, respectively. Conclusions: Despite greater prostate edema with loose seeds, V100, V150 and D90 at day 0 were significantly better when compared to stranded seeds. This may be due to the inherent ability of loose seeds to move with the expanding prostate volume post implant procedure. By day 7, all these parameters became similar for both cohorts. OR-29 Presentation Time: 2:50 PM Intraoperative TRUS-fluoroscopy fusion improves prostate brachytherapy quality Peter F. Orio, III, D.O.1,2,3 Ismail Tudor, Ph.D.2,3 Sreeram Narayanan, Ph.D.2,3 Paul Cho, Ph.D.2 Yongmin Kim, Ph.D.2 Gregory S. Merrick, M.D.4 Kent E. Wallner, M.D.3 1Radiation Oncology, Brooke Army Medical Center, FT Sam Houston, TX; 2Radiation Oncology, Univ. of Washington Medical Center, Seattle, WA; 3Radiation Oncology, Puget Sound VA, Seattle, WA; 4Radiation Oncology, Schiffler Cancer Center, Wheeling, WV. Purpose: We have instituted intraoperative TRUS-fluoroscopy fusion dosimetry in our clinical practice. After the seed implant is executed based on a preplan, we visualize the dose delivered to the prostate while the patient is still on the operating table. We refer to our method as intraoperative post-implant dosimetry. This method allows us to make corrections to maximize dosimetric parameters achieved by the implant. Methods and Materials: Twenty-five patients with clinical stage T1ceT2 prostate cancer were treated with Pd-103 implantation and intraoperative post-implant dosimetry. After the seeds were implanted, a set of ‘‘rotational images’’ and ‘‘axial images’’ were acquired with a TRUS probe in reference to the same coordinate system. Three fluoroscopic images were acquired. After 3D locations of all the implanted seeds were reconstructed, investigators identified implanted seeds in the rotational images. The registration algorithm used the seeds as fiducial markers and determined the locations of the implanted seeds in relation to the axial TRUS images. Both the axial TRUS images and registered 3D seed coordinates were input to VariSeed 7.1 software for dose visualization. V100 and D90 were computed, and isodose lines were overlaid on axial TRUS images. Additional seeds were placed if the V100 !80%, the D90 !90%, or adverse isodose patterns were identified. If additional seeds were placed, intra-op dosimetry was repeated. Day 0 CT-based dosimetry was compared to final intraoperative dosimetry. Detailed time logs were maintained. Results: In 16 patients, 4 1.8 additional seeds were added. The initial intraoperative V100 and D90 values were 86 8% and 94 18%,
respectively, while the final intraoperative V100 and D90 were 93 4% and 109 12%, respectively. The average improvement in the V100 and D90 was 7.0% (p 5 0.005) and 15% (p 5 0.011), respectively. The increase in both V200 and V300 was 2% (NS). The final TRUS-fluoroscopy fusion-based V100 and D90 values were 95 4% and 120 24%, respectively. Day 0 CT-based dosimetry computed the same parameters as 95 4% and 122 24%, respectively. Intraoperative dosimetry required 11.5 4.9 minutes. Conclusions: TRUS-fluoroscopy fusion allows calculation of standard dosimetric parameters, facilitates more accurate cold spot detection, and provides visual guidance for the physicians to implant the extra seeds to their optimum locations. The value of this technology in improving implant quality is evidenced by the higher V100 and D90 achieved, with minimal increase in high dose regions. PHYSICS PAPER SESSION Tuesday May 1, 2007 9:00 AMe10:00 AM OR-30 Presentation Time: 9:00 AM 3D-image-based treatment planning for gynecological interstitial brachytherapy (IB) with GEC-ESTRO Working Group recommended dose volume parameters: Initial experience Alexander Chi, M.D., Mingcheng Gao, Ph.D., Kevin Albuquerque, M.D. Radiation Oncology, Loyola University Medical Center, Maywood, IL. Purpose: To describe and evaluate the feasibility of pre-implant 3D-imagebased treatment planning for interstitial brachytherapy to treat gynecological malignancies based on recommendations of the GECESTRO Working Group. Methods and Materials: Based on the GEC-ESTRO guidelines of volumebased dosimetry for intracavitary brachytherapy of cervical tumors, we devised a system to evaluate treatment plans for gyncecological IB. Initially, pretreatment CT is performed with the Syed apparatus in place and areas of clinically palpable/imaged disease defined. After CTV and OAR (rectum, sigmoid, bladder, and bowel) delineation, a preliminary treatment plan is generated based on the prescription dose and GECESTRO-defined dose constraints to critical structures. After the actual implant is performed, a diagnostic pelvic-CT was obtained and fused with our pre-implant scan/initial treatment plan. Modifications in actual Flexineedle positioning and change of treatment plan were easily made if required and dose volume coverage is adjusted based on anatomical variations. DVH parameters evaluated include doses to the CTV and OAR. Dose values were normalized to equivalent doses in 2 Gy fractions (LQED2) derived from the linear-quadratic model. Results: Pre-implant 3D-image-based planning resulted in consistent approximation of dose coverage after the actual procedure with our experience. D90 to CTV from brachytherapy was 87.76 4.10% of the prescribed dose (82.03e89.2% of prescribed dose) based on tumor DVH values. DVH of organs at risk were evaluated by combined (EBRT + IB) D2 cc. D2 cc (LQED2) for the bladder, rectum, sigmoid, and small bowel were the following: 64.44 7.25 Gy; 64.29 10.6 Gy; 49.73 4.85 Gy; 52.12 5.60 Gy; which were within the range of the GEC-ESTRO recommended doses. Conclusions: This study confirms the feasibility of GEC-ESTRO recommended dose volume parameters in 3D-image-based treatment planning for gynecological interstitial brachytherapy. 2-D dose parameters used in treatment planning is misleading as no provision of dose constraints was available based on 3-D dimensional anatomy. 3-D dosimetry more accurately presents dose coverage of target volumes, and doses to organs at risk. Pre-implant CT-based planning also leads to very consistent approximation of the actual needle geometry and dose coverage confirmed by postimplant imaging. OR-31 Presentation Time: 9:10 AM Cesium-131 permanent prostate brachytherapy: The dosimetric analysis of a multi-institutional Phase II trial William S. Bice, Ph.D.1,2 Bradley R. Prestidge, M.D.2,3 1Southwest Cancer Foundation, San Antonio, TX; 2Radiological Sciences,
Abstracts / Brachytherapy 6 (2007) 77e118
Methods and Materials: This non-randomized study compares 20 patients who underwent brachytherapy with loose seeds (September 2002dJuly 2003) and 9 patients (ongoing) with stranded seeds. Preplanning was based on transrectal ultrasound images using I-125 seeds from Draximage for the loose seed cohort and IsoAid for the strands. PTV definition and planning parameters were similar in both cohorts. Post-implant dosimetry used CT-MRI fusion done on day 0, 7 and 30 for both cohorts. Factors evaluated were V100, V150, V200 and D90. Increase or decrease in prostate volumes and dosimetric factors were calculated as percentage difference from the pre-plan values and compared using unpaired Student’s t test with unequal variance. Results: For loose vs. stranded seeds the baseline prostate volume was 35.4 vs. 40.9 cc, the preplan V150 was 60.7 vs. 58.7%, V200 was 16.5 vs. 13.2% and D90 was 179.2 vs. 178.3 Gy, respectively. At each time point (day 0, 7 and 30), prostate edema was greater for the loose seed cohort; 33.9%, 23.3% and 7.8%, respectively, compared to stranded seeds 25.7%, 13% and 1%, respectively, (day 7 difference p 5 0.02). The day 0 V100 was higher for loose than stranded seeds (93.2 vs. 90.1%; p 5 0.04). By day 7 and 30 this difference had resolved (day 7: 93.2 vs. 92.7%; day 30: 94.9 vs. 95.4%). The mean percentage decrease of D90 at day 0 compared to the preplan was greater for stranded seeds (18.2%) in comparison to loose seeds (14.1%) (p 5 0.07), but by day 7 and 30 the values were similar; 14.8 vs. 12.6% at day 7 and 5.8 vs. 8.6% at day 30. Similarly, the mean percentage decrease of V150 at day 0 was greater for stranded seeds (35.1 vs. 25.4% for loose seeds; p 5 0.03). V150 at day 7 and 30 and V200 at all time points were similar. Even though the decrease in V100, V150 and D90 at day 0 was higher for stranded seeds, the day 0 absolute values were clinically acceptable; 90.1%, 38.1% and 145.7 Gy, respectively, and the day 30 values were 95.4%, 59.1% and 165.7 Gy, respectively. Conclusions: Despite greater prostate edema with loose seeds, V100, V150 and D90 at day 0 were significantly better when compared to stranded seeds. This may be due to the inherent ability of loose seeds to move with the expanding prostate volume post implant procedure. By day 7, all these parameters became similar for both cohorts. OR-29 Presentation Time: 2:50 PM Intraoperative TRUS-fluoroscopy fusion improves prostate brachytherapy quality Peter F. Orio, III, D.O.1,2,3 Ismail Tudor, Ph.D.2,3 Sreeram Narayanan, Ph.D.2,3 Paul Cho, Ph.D.2 Yongmin Kim, Ph.D.2 Gregory S. Merrick, M.D.4 Kent E. Wallner, M.D.3 1Radiation Oncology, Brooke Army Medical Center, FT Sam Houston, TX; 2Radiation Oncology, Univ. of Washington Medical Center, Seattle, WA; 3Radiation Oncology, Puget Sound VA, Seattle, WA; 4Radiation Oncology, Schiffler Cancer Center, Wheeling, WV. Purpose: We have instituted intraoperative TRUS-fluoroscopy fusion dosimetry in our clinical practice. After the seed implant is executed based on a preplan, we visualize the dose delivered to the prostate while the patient is still on the operating table. We refer to our method as intraoperative post-implant dosimetry. This method allows us to make corrections to maximize dosimetric parameters achieved by the implant. Methods and Materials: Twenty-five patients with clinical stage T1ceT2 prostate cancer were treated with Pd-103 implantation and intraoperative post-implant dosimetry. After the seeds were implanted, a set of ‘‘rotational images’’ and ‘‘axial images’’ were acquired with a TRUS probe in reference to the same coordinate system. Three fluoroscopic images were acquired. After 3D locations of all the implanted seeds were reconstructed, investigators identified implanted seeds in the rotational images. The registration algorithm used the seeds as fiducial markers and determined the locations of the implanted seeds in relation to the axial TRUS images. Both the axial TRUS images and registered 3D seed coordinates were input to VariSeed 7.1 software for dose visualization. V100 and D90 were computed, and isodose lines were overlaid on axial TRUS images. Additional seeds were placed if the V100 !80%, the D90 !90%, or adverse isodose patterns were identified. If additional seeds were placed, intra-op dosimetry was repeated. Day 0 CT-based dosimetry was compared to final intraoperative dosimetry. Detailed time logs were maintained. Results: In 16 patients, 4 1.8 additional seeds were added. The initial intraoperative V100 and D90 values were 86 8% and 94 18%,
respectively, while the final intraoperative V100 and D90 were 93 4% and 109 12%, respectively. The average improvement in the V100 and D90 was 7.0% (p 5 0.005) and 15% (p 5 0.011), respectively. The increase in both V200 and V300 was 2% (NS). The final TRUS-fluoroscopy fusion-based V100 and D90 values were 95 4% and 120 24%, respectively. Day 0 CT-based dosimetry computed the same parameters as 95 4% and 122 24%, respectively. Intraoperative dosimetry required 11.5 4.9 minutes. Conclusions: TRUS-fluoroscopy fusion allows calculation of standard dosimetric parameters, facilitates more accurate cold spot detection, and provides visual guidance for the physicians to implant the extra seeds to their optimum locations. The value of this technology in improving implant quality is evidenced by the higher V100 and D90 achieved, with minimal increase in high dose regions. PHYSICS PAPER SESSION Tuesday May 1, 2007 9:00 AMe10:00 AM OR-30 Presentation Time: 9:00 AM 3D-image-based treatment planning for gynecological interstitial brachytherapy (IB) with GEC-ESTRO Working Group recommended dose volume parameters: Initial experience Alexander Chi, M.D., Mingcheng Gao, Ph.D., Kevin Albuquerque, M.D. Radiation Oncology, Loyola University Medical Center, Maywood, IL. Purpose: To describe and evaluate the feasibility of pre-implant 3D-imagebased treatment planning for interstitial brachytherapy to treat gynecological malignancies based on recommendations of the GECESTRO Working Group. Methods and Materials: Based on the GEC-ESTRO guidelines of volumebased dosimetry for intracavitary brachytherapy of cervical tumors, we devised a system to evaluate treatment plans for gyncecological IB. Initially, pretreatment CT is performed with the Syed apparatus in place and areas of clinically palpable/imaged disease defined. After CTV and OAR (rectum, sigmoid, bladder, and bowel) delineation, a preliminary treatment plan is generated based on the prescription dose and GECESTRO-defined dose constraints to critical structures. After the actual implant is performed, a diagnostic pelvic-CT was obtained and fused with our pre-implant scan/initial treatment plan. Modifications in actual Flexineedle positioning and change of treatment plan were easily made if required and dose volume coverage is adjusted based on anatomical variations. DVH parameters evaluated include doses to the CTV and OAR. Dose values were normalized to equivalent doses in 2 Gy fractions (LQED2) derived from the linear-quadratic model. Results: Pre-implant 3D-image-based planning resulted in consistent approximation of dose coverage after the actual procedure with our experience. D90 to CTV from brachytherapy was 87.76 4.10% of the prescribed dose (82.03e89.2% of prescribed dose) based on tumor DVH values. DVH of organs at risk were evaluated by combined (EBRT + IB) D2 cc. D2 cc (LQED2) for the bladder, rectum, sigmoid, and small bowel were the following: 64.44 7.25 Gy; 64.29 10.6 Gy; 49.73 4.85 Gy; 52.12 5.60 Gy; which were within the range of the GEC-ESTRO recommended doses. Conclusions: This study confirms the feasibility of GEC-ESTRO recommended dose volume parameters in 3D-image-based treatment planning for gynecological interstitial brachytherapy. 2-D dose parameters used in treatment planning is misleading as no provision of dose constraints was available based on 3-D dimensional anatomy. 3-D dosimetry more accurately presents dose coverage of target volumes, and doses to organs at risk. Pre-implant CT-based planning also leads to very consistent approximation of the actual needle geometry and dose coverage confirmed by postimplant imaging. OR-31 Presentation Time: 9:10 AM Cesium-131 permanent prostate brachytherapy: The dosimetric analysis of a multi-institutional Phase II trial William S. Bice, Ph.D.1,2 Bradley R. Prestidge, M.D.2,3 1Southwest Cancer Foundation, San Antonio, TX; 2Radiological Sciences,