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Preoperative Accelerated Partial Breast Irradiation (APBI) versus Postoperative APBI: The Potential for Improved Cosmetic Outcomes
Proceedings of the 53rd Annual ASTRO Meeting We propose an independent system that can import DICOM CT image data and automatically determine whether the tissue-balloon conformity is within tolerance. Materials/Methods: An application to import DICOM CT image data was developed using the Python programming language. 10 patients that were treated using either MammoSite, MammoSite ML, or Contura breast brachytherapy applicators, were retrospectively analyzed to automatically calculate volumes of the balloon, PTVand trapped air / fluid pockets outside of the balloon using CT density values. These volumes were compared with the original manually generated contour volumes. For each patient, the percentage of the air / fluid volume within the PTV was calculated using both automated and manual methods. Results: The automatically generated contour volumes were found to be more accurate than the manually contoured volumes due to the reliance on CT density values. Experimental results showed that using the tool to delineate volumes was much faster than manually contouring volumes and determining the tissue-balloon conformance using a treatment planning system. Additionally, the generated contour volumes could be exported into the treatment planning system via DICOM RT for use in dose calculation. Conclusions: A tool to automatically evaluate tissue-balloon conformity in breast brachytherapy has been shown to be effective in reducing the time to determine the percentage of air / fluid within the PTV. Not only does it remove the user bias of manually contouring volumes, but also shortens the time a patient must wait after being scanned for the treatment team to determine whether to modify the balloon volume or massage the cavity to improve tissue-balloon conformance. Author Disclosure: A. Panchal: None. Y. Zhang: None.
2080
Preoperative Accelerated Partial Breast Irradiation (APBI) versus Postoperative APBI: The Potential for Improved Cosmetic Outcomes
W. F. Regine, E. M. Nichols, S. J. Feigenberg University of Maryland Medical Center, Baltimore, MD Purpose/Objective(s): We have previously reported the dosimetric benefits of pre-op APBI using 3-D conformal radiotherapy (CRT). Preop APBI demonstrated significantly decreased dose to all surrounding critical structures vs. postop APBI (1). Recent reports have suggested that the ipsilateral whole breast volume (WBV) receiving 5, 20, 50 and 80% of the prescribed ABPI dose, the mean V5/WBV and the mean planning target volume (PTV)_eval/WBV ratios, correlated with the development of poor cosmetic outcome(2). We hypothesized that preop APBI would be associated with significantly less WBV dose vs postop APBI. Materials/Methods: Forty patients with 41 previously treated early stage breast cancers (tumors \ 3 cm) were retrospectively analyzed from a prospective cohort. Imaging studies (MRI, US and mammogram) were utilized to create a spherical pre-op tumor volume using the largest reported dimension centered within the previously contoured lumpectomy cavity (LPC). Plans were created and optimized for each patient using the pre-op tumor volume and LPC (post-operative) using NSABP B-39 3D CRT guidelines and dosing. The primary end-point was to evaluate for differences in ipsilateral WBV receiving 5, 20, 50 and 80% of the prescribed ABPI dose, mean V5/WBV and mean PTV_eval/WBV ratios. Differences between the cohorts were evaluated using a t-test analysis. Results: Preop 3DCRT-APBI was associated with a statistically significant improvement in ipsilateral WBV receiving 5, 20, 50 and 80% of the prescribed dose vs. postop 3DCRT: V-5% (69%, 780cc vs. 85%, 985cc, p =\0.001); V-20% (56%, 613cc vs. 76%, 859cc, p = \0.001); V-50% (41%, 402cc vs. 63%, 692cc p = \0.001); and V-80% (29%, 264cc vs. 51%, 515cc, p = \0.001). Preop 3DCRT-APBI was also associated with a statistically significant improvement in mean V5/WBV (68% vs. 85%, p\0.001) and mean PTV_eval/WBV (12% vs. 28%, p\0.001) ratios vs. postop APBI. Conclusions: Dosimetrically, preop APBI was associated with significant decreases in WBV receiving 5, 20, 50 and 80% of the prescribed dose, mean V5/WBV and PTV-eval/WBV ratios vs. postop APBI. This finding, coupled with recent literature, would suggest that preop ABPI could reduce the rates of poor cosmetic outcomes including fibrosis which can be seen with use of postop ABPI. These results provide the basis for our ongoing prospective study of preop 3DCRT-APBI. References: 1. Nichols EM, Feigenberg SJ et al. Pre-operative therapy increases patient eligibility for accelerated partial breast irradiation (APBI) and decreases normal tissue exposure. IJROBP 2010; 78(3):S251. 2. Hepel JT, Tokita M et al. Toxicity of three-dimensional conformal radiotherapy for accelerated partial breast irradiation. IJROBP 2009; 75(5):1290-1296. Author Disclosure: W.F. Regine: None. E.M. Nichols: None. S.J. Feigenberg: None.
2081
Frequency and Clinical Significance of Previously Undetected Incidental Findings Detected on CT Simulation Scans for Breast Cancer Patients
N. Nakamura1, H. Tsunoda2, M. Kikuchi2, S. Honda2, N. Shikama3, K. Akahane1, S. Hatanaka1, K. Sekiguchi1 1 Department of Radiation Oncology, St. Luke’s International Hospital, Tokyo, Japan, 2Department of Radiology, St. Luke’s International Hospital, Tokyo, Japan, 3Department of Radiology, Saku Central Hospital, Saku, Japan
Purpose/Objective(s): In most institutions, CT simulation images are not routinely interpreted by diagnostic radiologists, which might cause incidental but important radiological findings to be missed. At our institution, however, all CT simulation images are prospectively interpreted by diagnostic radiologists. Our study investigated the frequency and clinical significance of previously undetected incidental findings found on CT simulation images for breast cancer patients. Materials/Methods: The official reports of CT simulation images for 881 consecutive postoperative breast cancer patients between 2009 and 2010 were retrospectively reviewed. Medically important incidental findings (MIIFs) were defined as any previously undetected benign or cancer-related findings requiring further medical follow-up or investigation. For all patients in whom an MIIF was detected, we reviewed the clinical records to determine the clinical significance of the MIIF.
S251
2080
Preoperative Accelerated Partial Breast Irradiation (APBI) versus Postoperative APBI: The Potential for Improved Cosmetic Outcomes
W. F. Regine, E. M. Nichols, S. J. Feigenberg University of Maryland Medical Center, Baltimore, MD Purpose/Objective(s): We have previously reported the dosimetric benefits of pre-op APBI using 3-D conformal radiotherapy (CRT). Preop APBI demonstrated significantly decreased dose to all surrounding critical structures vs. postop APBI (1). Recent reports have suggested that the ipsilateral whole breast volume (WBV) receiving 5, 20, 50 and 80% of the prescribed ABPI dose, the mean V5/WBV and the mean planning target volume (PTV)_eval/WBV ratios, correlated with the development of poor cosmetic outcome(2). We hypothesized that preop APBI would be associated with significantly less WBV dose vs postop APBI. Materials/Methods: Forty patients with 41 previously treated early stage breast cancers (tumors \ 3 cm) were retrospectively analyzed from a prospective cohort. Imaging studies (MRI, US and mammogram) were utilized to create a spherical pre-op tumor volume using the largest reported dimension centered within the previously contoured lumpectomy cavity (LPC). Plans were created and optimized for each patient using the pre-op tumor volume and LPC (post-operative) using NSABP B-39 3D CRT guidelines and dosing. The primary end-point was to evaluate for differences in ipsilateral WBV receiving 5, 20, 50 and 80% of the prescribed ABPI dose, mean V5/WBV and mean PTV_eval/WBV ratios. Differences between the cohorts were evaluated using a t-test analysis. Results: Preop 3DCRT-APBI was associated with a statistically significant improvement in ipsilateral WBV receiving 5, 20, 50 and 80% of the prescribed dose vs. postop 3DCRT: V-5% (69%, 780cc vs. 85%, 985cc, p =\0.001); V-20% (56%, 613cc vs. 76%, 859cc, p = \0.001); V-50% (41%, 402cc vs. 63%, 692cc p = \0.001); and V-80% (29%, 264cc vs. 51%, 515cc, p = \0.001). Preop 3DCRT-APBI was also associated with a statistically significant improvement in mean V5/WBV (68% vs. 85%, p\0.001) and mean PTV_eval/WBV (12% vs. 28%, p\0.001) ratios vs. postop APBI. Conclusions: Dosimetrically, preop APBI was associated with significant decreases in WBV receiving 5, 20, 50 and 80% of the prescribed dose, mean V5/WBV and PTV-eval/WBV ratios vs. postop APBI. This finding, coupled with recent literature, would suggest that preop ABPI could reduce the rates of poor cosmetic outcomes including fibrosis which can be seen with use of postop ABPI. These results provide the basis for our ongoing prospective study of preop 3DCRT-APBI. References: 1. Nichols EM, Feigenberg SJ et al. Pre-operative therapy increases patient eligibility for accelerated partial breast irradiation (APBI) and decreases normal tissue exposure. IJROBP 2010; 78(3):S251. 2. Hepel JT, Tokita M et al. Toxicity of three-dimensional conformal radiotherapy for accelerated partial breast irradiation. IJROBP 2009; 75(5):1290-1296. Author Disclosure: W.F. Regine: None. E.M. Nichols: None. S.J. Feigenberg: None.
2081
Frequency and Clinical Significance of Previously Undetected Incidental Findings Detected on CT Simulation Scans for Breast Cancer Patients
N. Nakamura1, H. Tsunoda2, M. Kikuchi2, S. Honda2, N. Shikama3, K. Akahane1, S. Hatanaka1, K. Sekiguchi1 1 Department of Radiation Oncology, St. Luke’s International Hospital, Tokyo, Japan, 2Department of Radiology, St. Luke’s International Hospital, Tokyo, Japan, 3Department of Radiology, Saku Central Hospital, Saku, Japan
Purpose/Objective(s): In most institutions, CT simulation images are not routinely interpreted by diagnostic radiologists, which might cause incidental but important radiological findings to be missed. At our institution, however, all CT simulation images are prospectively interpreted by diagnostic radiologists. Our study investigated the frequency and clinical significance of previously undetected incidental findings found on CT simulation images for breast cancer patients. Materials/Methods: The official reports of CT simulation images for 881 consecutive postoperative breast cancer patients between 2009 and 2010 were retrospectively reviewed. Medically important incidental findings (MIIFs) were defined as any previously undetected benign or cancer-related findings requiring further medical follow-up or investigation. For all patients in whom an MIIF was detected, we reviewed the clinical records to determine the clinical significance of the MIIF.
S251