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Quality of life (qQOL), patient satisfaction and cosmesis following partial breast irradiation (PBRT) with balloon brachytherapy
Abstracts / Brachytherapy 5 (2006) 78–117 abnormal digital rectal exam (n 5 6). 56.2% of the patients had an increase in Gleason score at time of re-biopsy before re-irradiation with HDR. All patients tolerated re-irradiation without any acute- or long-term morbidity. Conclusions: Re-irradiation with temporary Ir-192 high-dose-rate prostate brachytherapy is effective, well tolerated, and safe for patients who have failed definitive external beam radiation therapy and/or prostate seed brachytherapy. OR-44 Presentation Time: 9:30 AM Temporal relationship between colorectal cancer and clinically localized prostate cancer in patients managed with permanent interstitial brachytherapy Sarah Gutman, B.S.,1 Gregory S Merrick, M.D.,1 Wayne M Butler, Ph.D.,1 Kent E Wallner, M.D.,2 Zachariah A Allen, M.S.,1 Robert W Galbreath, Ph.D.,1,3 Edward Adamovich, M.D.4 1Schiffler Cancer Center, Wheeling Hospital, Wheeling, WV; 2Puget Sound Healthcare Corporation, University of Washington, Group Health Cooperative, Seattle, WA; 3Ohio University Eastern, St. Clairsville, OH; 4Department of Pathology, Wheeling Hospital, Wheeling, WV. Purpose: To evaluate the temporal relationship between the diagnosis of colorectal cancer and clinically localized prostate cancer in patients managed with permanent interstitial brachytherapy. In addition, to identify the location of pre- and post-brachytherapy colorectal malignancies and post-brachytherapy polyps. Methods and Materials: From April 1995 through July 2004, 1,351 consecutive patients underwent brachytherapy for clinical stage T1b-T3a (2002 AJCC) prostate cancer. Six hundred sixty-nine patients (51.7%) received supplemental external beam radiation therapy and 531 (39.9%) received androgen deprivation therapy. The median followup was 4.5 years. Operative and pathology reports were reviewed for all patients with colorectal cancer, while the location of all post-brachytherapy colorectal polyps was documented. Multiple clinical, treatment and dosimetric parameters were evaluated for the development of colorectal cancer or post-brachytherapy colorectal polyps. Results: Colorectal cancer was diagnosed in 23 and 25 patients prior to and following prostate brachytherapy, respectively. No differences were discerned in the distribution of colorectal cancers either before or after treatment (3 and 4 rectal cancers in the pre- and post-brachytherapy cohorts, respectively). Thirty-seven of the 48 colorectal cancers (77%) were diagnosed either 5 years before or 5 years after treatment with a peak incidence two years following brachytherapy. One hundred ninetytwo patients developed post-brachytherapy colorectal polyps with 27 (14%) located in the rectum. One hundred fifty-eight (82%) of the colorectal polyps occurred within 4 years of brachytherapy. In multivariate Cox regression analysis, none of the evaluated parameters predicted for the diagnosis of colorectal cancer. Rectal polyps were most closely correlated with patient age and percent positive biopsies, while sigmoid and colon polyps were best predicted by patient age and supplemental XRT. Conclusions: In patients with clinically localized prostate cancer, colorectal cancer appears to occur with equal frequency prior to and following treatment with a comparable geographic distribution throughout the rectum and colon. Post-brachytherapy colorectal polyps were most likely diagnosed within 4 years of brachytherapy and the vast majority were located beyond confines of the rectum.
BREAST P-45 Mammographic surveillance after MammoSite breast brachytherapy: Analysis of architectural patterns and additional interventions Anthony E Dragun, M.D.,1 Joseph M Jenrette, M.D.,1 Thomas L Pope, M.D.,2 Susan J Ackerman, M.D.,2 Abid Irshad, M.D.2 1Radiattion Oncology, Medical University of South Carolina, Charleston, SC; 2 Radiology, Medical University of South Carolina, Charleston, SC.
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Purpose: To report the post-treatment mamographic findings of patients who received MammoSite brachytherapy at the Medical University of South Carolina (MUSC). Methods and Materials: Since May 2002, 100 patients with Stage 0, I, or II breast adenocarcinoma have completed lumpectomy and adjuvant MammoSite breast brachytherapy at MUSC. A total of 128 mammograms from a cohort of 38 patients who underwent post-treatment mammographic followup exclusively at MUSC are the subject of this analysis. Surveillance mammography commenced at a median time of 6 months after completion of brachytherapy and was repeated every 6 to 12 months thereafter, depending on Breast Imaging Reporting and Data System (BI-RADS) classification and further testing recommendations. Patients were assessed at least every 3 months by their radiation, surgical and/or medical oncologist, and all available data were retrospectively reviewed for documentation of mammographic findings and subsequent interventions. All patients had a minimal followup of 6 months; the median followup was 28 months. Results: All 38 patients were complaint with mammographic surveillance and additional interventions as recommended. Of the 128 mammograms analyzed, 14 (11%) were classified as BI-RADS category 2, 92 (73%) as category 3, 9 (7%) as category 4, and 1 (0.8%) as category 5. Further details of the 92 BI-RADS 3 studies included descriptions of 60 (65%) as surgical changes, 30 (32%) as seromas, and 2 (2%) as calcifications. Additional interventions were performed following 10 (11%) of the BIRADS 3 studies (8 ultrasound-guided needle aspirations and 2 breast MRIs), all of which revealed benign findings. All ten BUI-RADS 4 or 5 studies led to needle aspiration (2) or breast biopsy (8). Two biopsies were positive for malignancy, and both were classified as elsewhere breast failures. The elsewhere breast failure rate in this cohort was 5.3%; the rate in our entire treated population was 2.2%. Conclusions: Mammographic architectural patterns observed after partial breast irradiation, and potential differences with respect to those traditionally seen following whole breast radiotherapy, have yet to be well characterized. Our experience may be of clinical utility in the counseling of patients who have undergone MammoSiteÔ breast brachytherapy until comparison data from randomized clinical trials become available. P-46 Quality of life (qQOL), patient satisfaction and cosmesis following partial breast irradiation (PBRT) with balloon brachytherapy Kevin Albuquerque, M.D., F.R.C.S., Linda Janusek, Ph.D., Herbert Mathews, Ph.D., Linda Millbrandt, R.N., Sheryl Gabram, M.D.Cardinal Bernadin Cancer Center, Loyola University Medical Center, Maywood, IL. Purpose: Breast radiation is a physical stressor and impacts QOL though scant data are available for PBRT. A phase IV study of PBRT with MammositeÒ Brachytherapy analyzing QOL, cosmesis and patient satisfaction was initiated. Herein the results for the first 30 women on the study are reported. Methods and Materials: WomenO45 years of age with low-grade DCIS or non-lobular invasive T1N0 tumors and resection margins O2 mm were eligible. PBRT was delivered with a MammositeR balloon applicator and HDR brachytherapy to a total dose of 34 Gy prescribed 1 cm from surface balloon in 10 fractions /5 days. Cosmesis and patient satisfaction were assessed prospectively at three-month intervals during the followup period. In addition, a QOL survey was done with the Functional Assessment of Cancer Therapy-Breast (FACT-B) scale prior to the therapy and three months after completion. Results: Of the enrolled patients who had catheter placed; 5 did not have brachytherapy due to suboptimal skin thickness. Of the remaining, 20 completed QOL and Cosmesis scores. Median followup was 1.5 years. All except 3 patients (one had grade 3 fibrosis of lumpectomy bed, a second had a chronic cellulites, a third had persistent erythema) reported good to excellent cosmetic results which was confirmed by physician evaluation. The remaining toxicities noted were grade 1–2 fibrosis in the scar. All women (except 3 above) reported complete satisfaction with procedure and would recommend it to other women with breast cancer. They were unanimous in preferring lumpectomy to mastectomy. QOL assessment indicated that mean scores were high and remained stable at 3 months suggesting no detriment in QOL with PBRT.
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Abstracts / Brachytherapy 5 (2006) 78–117
When comparing this with FACT- B scores of another cohort of women (age O45 years and tested at the same time periods) receiving Whole Breast Radiation (WBRT) there was a statistically significant (p!0.03) improvement for the Emotional Well-Being and Physical Well-Being subscales in the PBRT group in comparison to the other group of women. The FACT-G and Functional Well-Being subscales were also better for PBRT and tended towards significance (p 5 0.06). Conclusions: Our experience suggests that PBRT with balloon brachytherapy results in patient satisfaction and good to excellent cosmetic results with minimum disruption of QOL in the majority of women. There was a significantly greater Emotional and Physical WellBeing on QOL assessment with PBRT compared to WBRT. P-47 A quantitative analysis of dose reductions due to a radiopaque iodine-based contrast solution in Ir-192 HDR MammoSite balloon: Monte Carlo calculations, TLD, MOSFET and ion-chamber measurements E Ishmael Parsai, Zhengdong Zhang. Radiation Oncology, Medical University of Ohio, Toledo, OH. Purpose: Current MammoSite radiation system (RTS) often neglects the effect of inhomogeneity beyond a source, leading to potential inaccuracies in dose distributions. We investigated the dose perturbation caused by radiographic iodine-based contrast solution inside the MammoSite breast brachytherapy applicator. Methods and Materials: The impact of the concentration of the radiopaque solution on the physical dosimetry of this brachytherapy procedure is investigated using MCNP Monte Carlo simulations in coupled photon/ electron transport. The source geometry was that of the new VariSource wire model VS2000. Concentration of the iodine-based solution was varied from 5% to 25% by volume, a range recommended by the balloon’s manufacturer. Balloon diameters of 4, 5, and 6 cm were simulated. Measurements using TLD, MOSFET and ion-chamber were done in water, using a water equivalent jig for precision positioning of balloon and instruments. Dose rates at the typical prescription line of 1 cm away from the balloon surface were determined in different polar angles. Results: According to the computations, the dose rate reduction throughout the entire region of interest ranged from 20.33% for the smallest balloon diameter and contrast concentration to a maximum of 26.29% for the largest balloon diameter and contrast concentration, relative to a waterfilled balloon, whereas measurements showed a good agreement with the simulations within the errors (0.9%~2.8%). Conclusions: We defined attenuation-corrected radial dose and anisotropy functions and incorporate them into a treatment planning system in a form parallel to the AAPM TG-43 formalism. This will bring on the inaccuracies in dose distributions as small as possible. P-48 MammoSite catheter HDR brachytherapy for patients who refuse mastectomy for localized breast cancer after prior radiation Amrita G Sawhney, M.D., Mary Katherine Hayes, M.D., Alexander Swistel, M.D., Syed Hoda, M.D., Dattatreyudu Nori, M.D. 1Radiation Oncology, New York Presbyterian Hospital, New York, NY; 2Surgery, New York Presbyterian Hospital, New York, NY; 3Pathology, New York Presbyterian Hospital, New York, NY. Purpose: There are a growing number of US women who prefer breast conservation surgery for a localized breast cancer in a previously conservatively treated breast despite a clear understanding that mastectomy is the treatment of choice for their condition. To address this population of women, we evaluated the conservative retreatment of women who have previously received lumpectomy followed by external beam radiation therapy with HDR brachytherapy using the MammoSite catheter device. Methods and Materials: Between May 2003 and November 2005 seven women received HDR MammoSite partial breast brachytherapy following a second breast conserving surgery. The median age was 61 (44–79). Median time to new cancer, 10 years (5–14). 6/7 patients had documented
second primaries (new location, in situ disease, long interval). 3/7 patients received chemotherapy at the time of their original diagnosis. The catheters were placed intraoperatively for all patients. 34 Gy was prescribed to 1 cm from the balloon surface. Ten equal fractions of 3.4 Gy was delivered BID, 6 hours apart. Radiation was delivered using an Irridium-192 source. A minimum skin distance of 5 mm from the balloon surface to the skin was maintained. All margins were negative. All patients received antibiotic prophylaxis. Results: All the patients tolerated the treatment well. The followup ranged from 1–24 months with a median of 5 months. Grade 1 skin toxicity was noted in one patient (14.3%) on treatment. After the fifth treatment for this patient, the dose per fraction was reduced from 3.4 to 3.06 Gy. At 4week followup, there was no erythema. The rate of infection for this group was 0%. All patients are noted to have excellent cosmesis with minimal induration noted in 4/7 patients. Within this short followup, there were no recurrences at the treated sites and no significant toxicity. Conclusions: Our experience showed that conservative management of a localized breast cancer in an already irradiated breast is a feasible alternative to mastectomy for this group of patients. The treatment is well tolerated and there is no compromise in cosmesis after retreatment. We believe that the encouraging results to date in this small set of patients merits further evaluation of conservative retreatment as an alternative to mastectomy in a highly motivated and selected group of patients. P-49 Three-dimensional dosimetry and Q/A in multi-catheter APBI Imran Zoberi, M.D.,1 Jacqueline Esthappan, Ph.D.,1 Zuofeng Li, D.Sc.2 1 Radiation Oncology, Washington University, St. Louis, MO; 2Radiaton Oncology, University of Florida, Gainesville, FL. Purpose: We report the dosimetric parameters in our institutional experience with multi-catheter APBI. Dosimetric parameters play a role in quality assurance. Methods and Materials: From 7/2003 through 12/2005, 135 consecutive early stage breast cancers have been treated with multi-catheter APBI using 3-D treatment planning. Multi-plane implants were initially performed with an open cavity and later via ultrasound guidance. The CTV was defined in all cases as the partial mastectomy cavity plus two cm of surrounding breast tissue excluding pectoral muscles, chest wall, axilla, and limited to >5 mm from the skin. Dosimetric parameters of the implant, target volume coverage, and homogeneity were prospectively recorded. Radiotherapy was delivered via HDR, 34 Gy in 10 fractions. Dosimetric planning goals included coverage of at least 95% of the CTV with the prescription dose, V150 <50 mL, V200 <20 mL, and homogeneity (12V150/V100) >0.70. Additional catheters were occasionally added to meet the coverage goal. Results: The surgical cavity was covered by the prescription dose in all cases. Mean followup is 10.1 mo. Forty-three patients had catheters placed via an open cavity. Means and standard deviation for the recorded parameters were: number of catheters inserted 21.9 G 4.9, partial mastectomy cavity 21.8 G 23.1 mL, CTV Volume 162 G 78.6 mL, percentage of CTV covered 95.6 G 2.4%, V100 234.1 G 109.0 mL, V150 49.9 G 26.8 mL, V200 17.3 G 7.6 mL, and homogeneity 0.79 G 0.06. The number of catheters implanted decreased (r2 5 0.12) while homogeneity increased (r2 5 0.30) over time of the study. Number of catheters was lower in the ultrasound-guided group (21 vs 23.7 catheters, p 5 0.002). Coverage did not change over time. Four patients in the open cavity group and one patient in the ultrasound-guided group required additional catheters to meet dosimetric goals (p 5 0.04). Actual milligram Radium equivalent hours (mgRaEqhr) were calculated using treatment time and source activity. Data from the Patterson-Parker volume implant tables, corrected for Iridium-192, were used to calculate the expected mgRaEqhr. The two values were highly correlated (r 5 0.978) and typically within 8% of each other. Conclusions: Excellent CTV coverage was achieved throughout our APBI experience. Increasing operator experience led to expected improvements in catheter efficiency and implant homogeneity. Actual and expected mgRaEqhr are easily calculated. A hand calculation of expected mgRaEqhr functions as an integral quality assurance check of the treatment plan. These dosimetric parameters add to the growing body of
BREAST P-45 Mammographic surveillance after MammoSite breast brachytherapy: Analysis of architectural patterns and additional interventions Anthony E Dragun, M.D.,1 Joseph M Jenrette, M.D.,1 Thomas L Pope, M.D.,2 Susan J Ackerman, M.D.,2 Abid Irshad, M.D.2 1Radiattion Oncology, Medical University of South Carolina, Charleston, SC; 2 Radiology, Medical University of South Carolina, Charleston, SC.
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Purpose: To report the post-treatment mamographic findings of patients who received MammoSite brachytherapy at the Medical University of South Carolina (MUSC). Methods and Materials: Since May 2002, 100 patients with Stage 0, I, or II breast adenocarcinoma have completed lumpectomy and adjuvant MammoSite breast brachytherapy at MUSC. A total of 128 mammograms from a cohort of 38 patients who underwent post-treatment mammographic followup exclusively at MUSC are the subject of this analysis. Surveillance mammography commenced at a median time of 6 months after completion of brachytherapy and was repeated every 6 to 12 months thereafter, depending on Breast Imaging Reporting and Data System (BI-RADS) classification and further testing recommendations. Patients were assessed at least every 3 months by their radiation, surgical and/or medical oncologist, and all available data were retrospectively reviewed for documentation of mammographic findings and subsequent interventions. All patients had a minimal followup of 6 months; the median followup was 28 months. Results: All 38 patients were complaint with mammographic surveillance and additional interventions as recommended. Of the 128 mammograms analyzed, 14 (11%) were classified as BI-RADS category 2, 92 (73%) as category 3, 9 (7%) as category 4, and 1 (0.8%) as category 5. Further details of the 92 BI-RADS 3 studies included descriptions of 60 (65%) as surgical changes, 30 (32%) as seromas, and 2 (2%) as calcifications. Additional interventions were performed following 10 (11%) of the BIRADS 3 studies (8 ultrasound-guided needle aspirations and 2 breast MRIs), all of which revealed benign findings. All ten BUI-RADS 4 or 5 studies led to needle aspiration (2) or breast biopsy (8). Two biopsies were positive for malignancy, and both were classified as elsewhere breast failures. The elsewhere breast failure rate in this cohort was 5.3%; the rate in our entire treated population was 2.2%. Conclusions: Mammographic architectural patterns observed after partial breast irradiation, and potential differences with respect to those traditionally seen following whole breast radiotherapy, have yet to be well characterized. Our experience may be of clinical utility in the counseling of patients who have undergone MammoSiteÔ breast brachytherapy until comparison data from randomized clinical trials become available. P-46 Quality of life (qQOL), patient satisfaction and cosmesis following partial breast irradiation (PBRT) with balloon brachytherapy Kevin Albuquerque, M.D., F.R.C.S., Linda Janusek, Ph.D., Herbert Mathews, Ph.D., Linda Millbrandt, R.N., Sheryl Gabram, M.D.Cardinal Bernadin Cancer Center, Loyola University Medical Center, Maywood, IL. Purpose: Breast radiation is a physical stressor and impacts QOL though scant data are available for PBRT. A phase IV study of PBRT with MammositeÒ Brachytherapy analyzing QOL, cosmesis and patient satisfaction was initiated. Herein the results for the first 30 women on the study are reported. Methods and Materials: WomenO45 years of age with low-grade DCIS or non-lobular invasive T1N0 tumors and resection margins O2 mm were eligible. PBRT was delivered with a MammositeR balloon applicator and HDR brachytherapy to a total dose of 34 Gy prescribed 1 cm from surface balloon in 10 fractions /5 days. Cosmesis and patient satisfaction were assessed prospectively at three-month intervals during the followup period. In addition, a QOL survey was done with the Functional Assessment of Cancer Therapy-Breast (FACT-B) scale prior to the therapy and three months after completion. Results: Of the enrolled patients who had catheter placed; 5 did not have brachytherapy due to suboptimal skin thickness. Of the remaining, 20 completed QOL and Cosmesis scores. Median followup was 1.5 years. All except 3 patients (one had grade 3 fibrosis of lumpectomy bed, a second had a chronic cellulites, a third had persistent erythema) reported good to excellent cosmetic results which was confirmed by physician evaluation. The remaining toxicities noted were grade 1–2 fibrosis in the scar. All women (except 3 above) reported complete satisfaction with procedure and would recommend it to other women with breast cancer. They were unanimous in preferring lumpectomy to mastectomy. QOL assessment indicated that mean scores were high and remained stable at 3 months suggesting no detriment in QOL with PBRT.
94
Abstracts / Brachytherapy 5 (2006) 78–117
When comparing this with FACT- B scores of another cohort of women (age O45 years and tested at the same time periods) receiving Whole Breast Radiation (WBRT) there was a statistically significant (p!0.03) improvement for the Emotional Well-Being and Physical Well-Being subscales in the PBRT group in comparison to the other group of women. The FACT-G and Functional Well-Being subscales were also better for PBRT and tended towards significance (p 5 0.06). Conclusions: Our experience suggests that PBRT with balloon brachytherapy results in patient satisfaction and good to excellent cosmetic results with minimum disruption of QOL in the majority of women. There was a significantly greater Emotional and Physical WellBeing on QOL assessment with PBRT compared to WBRT. P-47 A quantitative analysis of dose reductions due to a radiopaque iodine-based contrast solution in Ir-192 HDR MammoSite balloon: Monte Carlo calculations, TLD, MOSFET and ion-chamber measurements E Ishmael Parsai, Zhengdong Zhang. Radiation Oncology, Medical University of Ohio, Toledo, OH. Purpose: Current MammoSite radiation system (RTS) often neglects the effect of inhomogeneity beyond a source, leading to potential inaccuracies in dose distributions. We investigated the dose perturbation caused by radiographic iodine-based contrast solution inside the MammoSite breast brachytherapy applicator. Methods and Materials: The impact of the concentration of the radiopaque solution on the physical dosimetry of this brachytherapy procedure is investigated using MCNP Monte Carlo simulations in coupled photon/ electron transport. The source geometry was that of the new VariSource wire model VS2000. Concentration of the iodine-based solution was varied from 5% to 25% by volume, a range recommended by the balloon’s manufacturer. Balloon diameters of 4, 5, and 6 cm were simulated. Measurements using TLD, MOSFET and ion-chamber were done in water, using a water equivalent jig for precision positioning of balloon and instruments. Dose rates at the typical prescription line of 1 cm away from the balloon surface were determined in different polar angles. Results: According to the computations, the dose rate reduction throughout the entire region of interest ranged from 20.33% for the smallest balloon diameter and contrast concentration to a maximum of 26.29% for the largest balloon diameter and contrast concentration, relative to a waterfilled balloon, whereas measurements showed a good agreement with the simulations within the errors (0.9%~2.8%). Conclusions: We defined attenuation-corrected radial dose and anisotropy functions and incorporate them into a treatment planning system in a form parallel to the AAPM TG-43 formalism. This will bring on the inaccuracies in dose distributions as small as possible. P-48 MammoSite catheter HDR brachytherapy for patients who refuse mastectomy for localized breast cancer after prior radiation Amrita G Sawhney, M.D., Mary Katherine Hayes, M.D., Alexander Swistel, M.D., Syed Hoda, M.D., Dattatreyudu Nori, M.D. 1Radiation Oncology, New York Presbyterian Hospital, New York, NY; 2Surgery, New York Presbyterian Hospital, New York, NY; 3Pathology, New York Presbyterian Hospital, New York, NY. Purpose: There are a growing number of US women who prefer breast conservation surgery for a localized breast cancer in a previously conservatively treated breast despite a clear understanding that mastectomy is the treatment of choice for their condition. To address this population of women, we evaluated the conservative retreatment of women who have previously received lumpectomy followed by external beam radiation therapy with HDR brachytherapy using the MammoSite catheter device. Methods and Materials: Between May 2003 and November 2005 seven women received HDR MammoSite partial breast brachytherapy following a second breast conserving surgery. The median age was 61 (44–79). Median time to new cancer, 10 years (5–14). 6/7 patients had documented
second primaries (new location, in situ disease, long interval). 3/7 patients received chemotherapy at the time of their original diagnosis. The catheters were placed intraoperatively for all patients. 34 Gy was prescribed to 1 cm from the balloon surface. Ten equal fractions of 3.4 Gy was delivered BID, 6 hours apart. Radiation was delivered using an Irridium-192 source. A minimum skin distance of 5 mm from the balloon surface to the skin was maintained. All margins were negative. All patients received antibiotic prophylaxis. Results: All the patients tolerated the treatment well. The followup ranged from 1–24 months with a median of 5 months. Grade 1 skin toxicity was noted in one patient (14.3%) on treatment. After the fifth treatment for this patient, the dose per fraction was reduced from 3.4 to 3.06 Gy. At 4week followup, there was no erythema. The rate of infection for this group was 0%. All patients are noted to have excellent cosmesis with minimal induration noted in 4/7 patients. Within this short followup, there were no recurrences at the treated sites and no significant toxicity. Conclusions: Our experience showed that conservative management of a localized breast cancer in an already irradiated breast is a feasible alternative to mastectomy for this group of patients. The treatment is well tolerated and there is no compromise in cosmesis after retreatment. We believe that the encouraging results to date in this small set of patients merits further evaluation of conservative retreatment as an alternative to mastectomy in a highly motivated and selected group of patients. P-49 Three-dimensional dosimetry and Q/A in multi-catheter APBI Imran Zoberi, M.D.,1 Jacqueline Esthappan, Ph.D.,1 Zuofeng Li, D.Sc.2 1 Radiation Oncology, Washington University, St. Louis, MO; 2Radiaton Oncology, University of Florida, Gainesville, FL. Purpose: We report the dosimetric parameters in our institutional experience with multi-catheter APBI. Dosimetric parameters play a role in quality assurance. Methods and Materials: From 7/2003 through 12/2005, 135 consecutive early stage breast cancers have been treated with multi-catheter APBI using 3-D treatment planning. Multi-plane implants were initially performed with an open cavity and later via ultrasound guidance. The CTV was defined in all cases as the partial mastectomy cavity plus two cm of surrounding breast tissue excluding pectoral muscles, chest wall, axilla, and limited to >5 mm from the skin. Dosimetric parameters of the implant, target volume coverage, and homogeneity were prospectively recorded. Radiotherapy was delivered via HDR, 34 Gy in 10 fractions. Dosimetric planning goals included coverage of at least 95% of the CTV with the prescription dose, V150 <50 mL, V200 <20 mL, and homogeneity (12V150/V100) >0.70. Additional catheters were occasionally added to meet the coverage goal. Results: The surgical cavity was covered by the prescription dose in all cases. Mean followup is 10.1 mo. Forty-three patients had catheters placed via an open cavity. Means and standard deviation for the recorded parameters were: number of catheters inserted 21.9 G 4.9, partial mastectomy cavity 21.8 G 23.1 mL, CTV Volume 162 G 78.6 mL, percentage of CTV covered 95.6 G 2.4%, V100 234.1 G 109.0 mL, V150 49.9 G 26.8 mL, V200 17.3 G 7.6 mL, and homogeneity 0.79 G 0.06. The number of catheters implanted decreased (r2 5 0.12) while homogeneity increased (r2 5 0.30) over time of the study. Number of catheters was lower in the ultrasound-guided group (21 vs 23.7 catheters, p 5 0.002). Coverage did not change over time. Four patients in the open cavity group and one patient in the ultrasound-guided group required additional catheters to meet dosimetric goals (p 5 0.04). Actual milligram Radium equivalent hours (mgRaEqhr) were calculated using treatment time and source activity. Data from the Patterson-Parker volume implant tables, corrected for Iridium-192, were used to calculate the expected mgRaEqhr. The two values were highly correlated (r 5 0.978) and typically within 8% of each other. Conclusions: Excellent CTV coverage was achieved throughout our APBI experience. Increasing operator experience led to expected improvements in catheter efficiency and implant homogeneity. Actual and expected mgRaEqhr are easily calculated. A hand calculation of expected mgRaEqhr functions as an integral quality assurance check of the treatment plan. These dosimetric parameters add to the growing body of