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Volumetric Modulated Arc Therapy for Bilateral Breast Carcinoma: Dosimetric Analysis and Immediate Tolerance
S864
International Journal of Radiation Oncology Biology Physics
blocks, which could open the way to improved CTV definition and planning. Materials/Methods: An in-house, spectral domain OCT system was developed for this study. A pair of tilting galvanometer mirrors permits lateral scanning of the infrared beam resulting in a 5x5x3-mm3 image volume. Paraffin blocks (40x25x4 mm3) containing formalin-fixed mouse mammary glands with tumor were imaged. Other than removing the plastic mount, the blocks were not manipulated in any way in preparation for imaging. After each scan, the blocks were translated on a moveable stage until the entire sample was imaged. Blocks were scanned through both sides in order to image their full thickness. Individual scans were stitched together to generate a final, complete image volume. For comparison, sections at multiple depths were obtained from the blocks, stained with hematoxylin and eosin (H&E), and photographed at high magnification and resolution. Results: Complete 3D images of the tissue blocks were obtained. The scan time for a single 5x5x3-mm3 image was about 15 seconds. A lateral resolution of 16 mm and a 6-mm resolution in the depth direction permitted visualization of tissue micro-architecture that correlated with the H&E section images. Images from consecutive blocks could be stitched together, allowing reconstruction of larger specimens over multiple blocks. Because of the paraffin medium, both micro-CT and small animal MRI were unable to visualize any features within the blocks. Conclusions: Optical coherence tomography is a fast, non-invasive, highresolution imaging modality capable of volumetric reconstruction of paraffin tissue blocks. As such, it could greatly facilitate the imaging and analysis of microscopic disease needed to study and improve CTV design and treatment. Author Disclosure: L. Kim: None. R. Droz-Rosario: None. E. Hwuang: None. L. Higgins: None. M. Pierce: None.
Conclusions: Volumetric modulated arc therapy provides an optimal dosimetric solution for complex bilateral breast volumes. No severe immediate toxicity was noted in our series. Longer follow up will be required to exclude late changes. Author Disclosure: R.M. Draghici: None. C. Bourgier: None. C. Lemanski: None. A. Ducteil: None. M. Charissoux: None. J. Molinier: None. S. Thezenas: None. L. Bedos: None. N. Ailleres: None. P. Fenoglietto: None. D. Azria: None.
3661 Volumetric Modulated Arc Therapy for Bilateral Breast Carcinoma: Dosimetric Analysis and Immediate Tolerance R.M. Draghici,1 C. Bourgier,2 C. Lemanski,2 A. Ducteil,2 M. Charissoux,2 J. Molinier,2 S. Thezenas,2 L. Bedos,2 N. Ailleres,2 P. Fenoglietto,2 and D. Azria2; 1CHU Fort de France, Fort de France, France, 2Institut Regional du Cancer Montpellier, Montpellier, France Purpose/Objective(s): Large target volumes or unfavorable patient anatomy can be restrictive conditions for an optimal treatment plan, especially in case of bilateral breast carcinoma. VMAT technique could propose an ideal solution in this particular case but irradiation of a large volume of organs at risk with a low dose is still a challenging question .This study present dosimetric results and early toxicities for organs at risk include in treatment area. Materials/Methods: A continuous series of 20 patients presenting histological proven bilateral breast carcinoma stage I to IV requiring bilateral radiation therapy was analyzed. VMAT optimization and treatment delivery was applied for all 20 cases. Organ contouring was performed respecting RTOG contouring guidelines for the breast. PTV was obtained by CTV expansion of 0.7 cm for tumoral and nodal CTV with skin spearing margin of 0.5 cm. The prescribed doses were 63.2 Gy for the PTV boost, 52.2 Gy for the breast and internal mammary chain PTV and 49.3 Gy for the supraclavicular nodes PTV in 29 fractions. Organs at risk objectives were for each lung: mean dose <15 Gy, V20 gy <22 % and mean dose <12 Gy for heart .Treatment toxicity was graded using NCI CTC v3.0 toxicity criteria. Results: Mean value and SD for right lung are V30 of 8.91% (2.93) , V20 of 18.6% (4.92), V10 of 43.63% (12.55) and an V5 of 79.60 % (14.01) .For the left lung we obtained a V30 of 8.32% (3.89) ,V20 of 17.05% (6.11),V10 of 38.88 (11.38) and the V5 of 77.68 % (16.15).Mean dose to the heart was of 10.75 Gy (4.63). No grade 3 toxicity was recorded. Ten out of 20 patients presented grade 1 or 2 skin reactions and only one patient presented grade 2 esophagitis.
3662 Dose Analysis of MRI-Based Planning Techniques Using Volumetric Modulated Arc Therapy in Brain Tumors S.P. Nirunsiriphol, D. Kannarunimit, P. Alisanant, K. Saksornchai, C. Khorprasert, C. Lertbusayanukul, C. Chakkabat, S. Suriyapee, and S. Oonsiri; King Chulalongkorn Memorial Hospital, Bangkok, Thailand Purpose/Objective(s): To evaluate whether the characteristics of dose distribution from the bulk density assigned MRI-based treatment planning are different from CT-based treatment planning in brain tumors using VMAT technique. Materials/Methods: Fifteen patients with brain tumors who had their brain scans with CT and MRI simulation were included. CT and MR datasets were employed for VMAT plans. The ICRU bulk density values of skull bone, air, and soft tissue of 1.51 gm/cm3, 0 gm/cm3, 1 gm/cm3, respectively, were assigned on an MR dataset after the structures delineation. Subsequently, we generated four plans for each patient as follows ; 1) Optimization and calculation on CT dataset (CTop/CTcal) as standard arm, 2) Optimization on CT dataset and calculation on MR dataset (CTop/MRcal), 3) Optimization and calculation on MR dataset (MRop/ MRcal), 4) Optimization on MR dataset and calculation on CT dataset (MRop/CTcal). VMAT technique and optimization constraints were identical for all those treatment plans. Dose comparisons of three experimental arms with the standard arm were analyzed including PTV D50%, PTV D95%, target coverage, conformity index, heterogeneity index, gradient index, and D1ml of brain stem. In statistics, Intraclass Correlation Coefficiency (ICC) was used for the correlation analysis. Results: All plans were achieved target dose constraints. The characteristics of dose distributions were shown in Table 1. Dose parameters comparing MR-related plans to CTop/CTcal plan (standard arm) revealed a trivial difference of ICC value within a range of 0.95-0.99. Conclusions: The ICRU bulk density assigned MRI-based treatment planning is feasible for brain tumors using VMAT technique. Dose distributions were not significantly different. MR-based treatment planning can reduce systematic error from CT-MR image registration with the advantage of better target delineation. The future challenging of treatment verification with MR image is needed to be warranted. Author Disclosure: S.P. Nirunsiriphol: None. D. Kannarunimit: None. P. Alisanant: None. K. Saksornchai: None. C. Khorprasert: None. C. Lertbusayanukul: None. C. Chakkabat: None. S. Suriyapee: None. S. Oonsiri: None.
Scientific Abstract 3662; Table
Characteristics of dose distribution Mean (ICC)
CTop/CTcal CTop/MRcal MRop/MRcal MRop/CTcal PTV D95% (Gy) PTV D50% (Gy) Brain stem (D1ml) Target coverage Conformity index Heterogeneity index Gradient index (R50%)
59.13 61.21 52.22 0.95 1.06 1.12 4.66
58.97 (0.99) 59.29 (0.98) 59.27 (0.98) 61.12 (0.99) 61.85 (0.97) 61.76 (0.97) 53.25 (0.98) 53.36 (0.96) 55.03 (0.95) 0.94 (0.99) 0.94 (0.99) 0.93 (0.99) 1.01 (0.97) 1.04 (0.98) 1.00 (0.96) 1.12 (0.99) 1.12 (0.98) 1.13 (0.98) 4.69 (0.99) 5.08 (0.98) 5.01 (0.97)
International Journal of Radiation Oncology Biology Physics
blocks, which could open the way to improved CTV definition and planning. Materials/Methods: An in-house, spectral domain OCT system was developed for this study. A pair of tilting galvanometer mirrors permits lateral scanning of the infrared beam resulting in a 5x5x3-mm3 image volume. Paraffin blocks (40x25x4 mm3) containing formalin-fixed mouse mammary glands with tumor were imaged. Other than removing the plastic mount, the blocks were not manipulated in any way in preparation for imaging. After each scan, the blocks were translated on a moveable stage until the entire sample was imaged. Blocks were scanned through both sides in order to image their full thickness. Individual scans were stitched together to generate a final, complete image volume. For comparison, sections at multiple depths were obtained from the blocks, stained with hematoxylin and eosin (H&E), and photographed at high magnification and resolution. Results: Complete 3D images of the tissue blocks were obtained. The scan time for a single 5x5x3-mm3 image was about 15 seconds. A lateral resolution of 16 mm and a 6-mm resolution in the depth direction permitted visualization of tissue micro-architecture that correlated with the H&E section images. Images from consecutive blocks could be stitched together, allowing reconstruction of larger specimens over multiple blocks. Because of the paraffin medium, both micro-CT and small animal MRI were unable to visualize any features within the blocks. Conclusions: Optical coherence tomography is a fast, non-invasive, highresolution imaging modality capable of volumetric reconstruction of paraffin tissue blocks. As such, it could greatly facilitate the imaging and analysis of microscopic disease needed to study and improve CTV design and treatment. Author Disclosure: L. Kim: None. R. Droz-Rosario: None. E. Hwuang: None. L. Higgins: None. M. Pierce: None.
Conclusions: Volumetric modulated arc therapy provides an optimal dosimetric solution for complex bilateral breast volumes. No severe immediate toxicity was noted in our series. Longer follow up will be required to exclude late changes. Author Disclosure: R.M. Draghici: None. C. Bourgier: None. C. Lemanski: None. A. Ducteil: None. M. Charissoux: None. J. Molinier: None. S. Thezenas: None. L. Bedos: None. N. Ailleres: None. P. Fenoglietto: None. D. Azria: None.
3661 Volumetric Modulated Arc Therapy for Bilateral Breast Carcinoma: Dosimetric Analysis and Immediate Tolerance R.M. Draghici,1 C. Bourgier,2 C. Lemanski,2 A. Ducteil,2 M. Charissoux,2 J. Molinier,2 S. Thezenas,2 L. Bedos,2 N. Ailleres,2 P. Fenoglietto,2 and D. Azria2; 1CHU Fort de France, Fort de France, France, 2Institut Regional du Cancer Montpellier, Montpellier, France Purpose/Objective(s): Large target volumes or unfavorable patient anatomy can be restrictive conditions for an optimal treatment plan, especially in case of bilateral breast carcinoma. VMAT technique could propose an ideal solution in this particular case but irradiation of a large volume of organs at risk with a low dose is still a challenging question .This study present dosimetric results and early toxicities for organs at risk include in treatment area. Materials/Methods: A continuous series of 20 patients presenting histological proven bilateral breast carcinoma stage I to IV requiring bilateral radiation therapy was analyzed. VMAT optimization and treatment delivery was applied for all 20 cases. Organ contouring was performed respecting RTOG contouring guidelines for the breast. PTV was obtained by CTV expansion of 0.7 cm for tumoral and nodal CTV with skin spearing margin of 0.5 cm. The prescribed doses were 63.2 Gy for the PTV boost, 52.2 Gy for the breast and internal mammary chain PTV and 49.3 Gy for the supraclavicular nodes PTV in 29 fractions. Organs at risk objectives were for each lung: mean dose <15 Gy, V20 gy <22 % and mean dose <12 Gy for heart .Treatment toxicity was graded using NCI CTC v3.0 toxicity criteria. Results: Mean value and SD for right lung are V30 of 8.91% (2.93) , V20 of 18.6% (4.92), V10 of 43.63% (12.55) and an V5 of 79.60 % (14.01) .For the left lung we obtained a V30 of 8.32% (3.89) ,V20 of 17.05% (6.11),V10 of 38.88 (11.38) and the V5 of 77.68 % (16.15).Mean dose to the heart was of 10.75 Gy (4.63). No grade 3 toxicity was recorded. Ten out of 20 patients presented grade 1 or 2 skin reactions and only one patient presented grade 2 esophagitis.
3662 Dose Analysis of MRI-Based Planning Techniques Using Volumetric Modulated Arc Therapy in Brain Tumors S.P. Nirunsiriphol, D. Kannarunimit, P. Alisanant, K. Saksornchai, C. Khorprasert, C. Lertbusayanukul, C. Chakkabat, S. Suriyapee, and S. Oonsiri; King Chulalongkorn Memorial Hospital, Bangkok, Thailand Purpose/Objective(s): To evaluate whether the characteristics of dose distribution from the bulk density assigned MRI-based treatment planning are different from CT-based treatment planning in brain tumors using VMAT technique. Materials/Methods: Fifteen patients with brain tumors who had their brain scans with CT and MRI simulation were included. CT and MR datasets were employed for VMAT plans. The ICRU bulk density values of skull bone, air, and soft tissue of 1.51 gm/cm3, 0 gm/cm3, 1 gm/cm3, respectively, were assigned on an MR dataset after the structures delineation. Subsequently, we generated four plans for each patient as follows ; 1) Optimization and calculation on CT dataset (CTop/CTcal) as standard arm, 2) Optimization on CT dataset and calculation on MR dataset (CTop/MRcal), 3) Optimization and calculation on MR dataset (MRop/ MRcal), 4) Optimization on MR dataset and calculation on CT dataset (MRop/CTcal). VMAT technique and optimization constraints were identical for all those treatment plans. Dose comparisons of three experimental arms with the standard arm were analyzed including PTV D50%, PTV D95%, target coverage, conformity index, heterogeneity index, gradient index, and D1ml of brain stem. In statistics, Intraclass Correlation Coefficiency (ICC) was used for the correlation analysis. Results: All plans were achieved target dose constraints. The characteristics of dose distributions were shown in Table 1. Dose parameters comparing MR-related plans to CTop/CTcal plan (standard arm) revealed a trivial difference of ICC value within a range of 0.95-0.99. Conclusions: The ICRU bulk density assigned MRI-based treatment planning is feasible for brain tumors using VMAT technique. Dose distributions were not significantly different. MR-based treatment planning can reduce systematic error from CT-MR image registration with the advantage of better target delineation. The future challenging of treatment verification with MR image is needed to be warranted. Author Disclosure: S.P. Nirunsiriphol: None. D. Kannarunimit: None. P. Alisanant: None. K. Saksornchai: None. C. Khorprasert: None. C. Lertbusayanukul: None. C. Chakkabat: None. S. Suriyapee: None. S. Oonsiri: None.
Scientific Abstract 3662; Table
Characteristics of dose distribution Mean (ICC)
CTop/CTcal CTop/MRcal MRop/MRcal MRop/CTcal PTV D95% (Gy) PTV D50% (Gy) Brain stem (D1ml) Target coverage Conformity index Heterogeneity index Gradient index (R50%)
59.13 61.21 52.22 0.95 1.06 1.12 4.66
58.97 (0.99) 59.29 (0.98) 59.27 (0.98) 61.12 (0.99) 61.85 (0.97) 61.76 (0.97) 53.25 (0.98) 53.36 (0.96) 55.03 (0.95) 0.94 (0.99) 0.94 (0.99) 0.93 (0.99) 1.01 (0.97) 1.04 (0.98) 1.00 (0.96) 1.12 (0.99) 1.12 (0.98) 1.13 (0.98) 4.69 (0.99) 5.08 (0.98) 5.01 (0.97)