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Volumetric Dose Summation Between Brachytherapy Fractions in Patients Treated for Cervical Cancer: Feasibility of Using Deformable Registration
Volume 87 Number 2S Supplement 2013 of Full and Empty Bladder at Computed Tomography Simulation as Internal Target Volume J. Chen, C. Huang, Y. Huang, S. Lu, C. Chen, S. Kuo, and J. Cheng; National Taiwan University Hospital, Taipei, Taiwan Purpose/Objective(s): In order to ensure adequate target coverage, RTOG 0418, a phase II study evaluating IMRT as postoperative adjuvant therapy for patients with gynecologic cancers, first introduced internal target volume (ITV) accounting for individualized organ motion affected by bladder volume. The aim of this analysis was to evaluate the toxicity and clinical outcomes for cervical cancer patients with intact uterus treated definitively with pelvic IMRT followed by intracavitary brachytherapy with fusion of full and empty bladder at computed tomography (CT) simulation as ITV. Materials/Methods: Between September 2010 and June 2012, twenty-six patients with FIGO stage IIA-IVA cervical cancer were treated with definitive pelvic IMRT followed by planned intracavitary brachytherapy. All patients underwent two CT simulations (full and empty bladder). The ITV was contoured by fusion the two CT scans. The study was approved by the Institutional Review Board of our institution. The treatment volumes included the cervix, uterus, parametrium, presacral space, upper vagina, and pelvic lymphatics to the superior border of L5, and were designed to deliver 45 Gy in 1.8-Gy daily fractions while minimizing dose to the bowel, bladder, and rectum. The pelvic lymph nodes were involved in 11 (42%) patients, and were simultaneously designed to deliver 50 Gy in 2.0-Gy daily fractions. Most (85%) patients received concurrent platinumbased chemotherapy. The median follow-up time was 18 months. Results: All patients completed the prescribed course of IMRT. All but two patients received intracavitary brachytherapy, and the median dose to Point A was 85 Gy. Median length of treatment was 57 days. Grade 3 acute gastrointestinal toxicity was seen in one (4%) patient. Twenty-three (88%) patients had complete response to treatment. The rates of 2-year actuarial locoregional control, distant metastasis-free survival, progression-free survival, and overall survival were 88%, 72%, 68%, and 91%, respectively. Three (12%) patients had locoregional recurrence, and all were in-field failures. Six (23%) patients had distant metastasis, and the most common site (67%) was the para-aortic lymphadenopathy. Two (8%) patients experienced late grade 3 gastrointestinal or genitourinary complications. Conclusions: Definitive IMRT with contouring ITV by full and empty bladder followed by intracavitary brachytherapy offers acceptable toxicities and favorable locoregional control in patients with locally advanced cervical cancer. Author Disclosure: J. Chen: None. C. Huang: None. Y. Huang: None. S. Lu: None. C. Chen: None. S. Kuo: None. J. Cheng: None.
2547 FDG PET Imaging in Cervical Cancer Patients Treated With Chemoradiation Therapy M.A. Kollmeier, A. Mojtahedi, L. Friguglietti, M. Gonen, M. Hsu, H. Pannu, K. Alektiar, and N. Pandit-Taskar; Memorial Sloan-Kettering Cancer Center, New York, NY Purpose/Objective(s): To explore predictors of response and progression free survival (PFS) on baseline and follow-up FDG PET (PET) imaging in patients treated with definitive chemoradiation for cervical cancer. Materials/Methods: We retrospectively reviewed PET imaging in 46 patients with Stage IB1-IVA cervical cancer patients who underwent definitive radiation therapy with concurrent cisplatin chemotherapy. A baseline PET scan and a post-treatment PET scan were performed in all patients. Radiation therapy (RT) consisted of external beam radiation therapy (EBRT) to the pelvic +/- para-aortic lymphatics (median dose Z 50.4 Gy) +/- intracavitary (n Z 36) or interstitial (n Z 7) brachytherapy boost (median dose Z 20 Gy (interstitial); 30 Gy (intracavitary)). Cisplatin chemotherapy was delivered concurrently with radiation
Poster Viewing Abstracts S413 therapy in all patients. Follow-up PET scans were performed at a median of 17.4 weeks following treatment (range, 11-30 weeks). PET data collected included, for both primary and nodal disease: tumor size, number of positive nodes and uptake in tumor and nodes (SUV max and SUV mean). Progression free survival (PFS) was determined from start of RT or from follow-up PET. Results: Baseline PET scans demonstrated FDG-avid cervix lesions in all patients with 67 FDG-avid nodes seen. PFS was significantly associated with baseline PET primary tumor size (HR, 1.41; 95% CI, 1.00-2.00; p Z 0.05) and number of positive lymph nodes (HR, 1.36; 95% CI, 1.01-1.85; p Z 0.04). In addition, the SUV max of the nodal disease at baseline also correlated with PFS (HR, 1.12; 95% CI, 1-1.25; p Z 0.05). In comparison with follow-up PET study, there was significant correlation between PFS and percent decrease of: primary tumor size (HR, 0.98; 95% CI, 0.97-1; p Z 0.03), primary SUV mean (HR, 0.98; 95% CI, 0.97-1; p Z 0.05), nodal size (HR, 0.99; 95% CI, 0.98-1; p Z 0.03) and nodal TLG (HR, 0.99; 95% CI, 0.98-1; p Z 0.02). Conclusions: Primary tumor size and number of positive lymph nodes on baseline PET appear to be predictors of PFS following definitive chemoradiation. Tumor response as measured by SUV mean and nodal TLG on follow-up PET, are also significant predictors of PFS. Author Disclosure: M.A. Kollmeier: None. A. Mojtahedi: None. L. Friguglietti: None. M. Gonen: None. M. Hsu: None. H. Pannu: None. K. Alektiar: None. N. Pandit-Taskar: None.
2548 Volumetric Dose Summation Between Brachytherapy Fractions in Patients Treated for Cervical Cancer: Feasibility of Using Deformable Registration l. Ding, J. Chino, J. Cai, B. Steffy, S. Meltsner, and O. Craciunescu; Duke University Medical Center, Durham, NC Purpose/Objective(s): Deformable registration techniques have potential to aid in quantifying volumetric dose delivered with multimodality therapy for cervical cancer. Due to the complexity of dose summation between external beam and HDR, we are proposing to test available deformable registration tools to add the dose for HDR treatments only, quantify the result of the registration, and compare the calculated dose with the current clinical point dose summation protocol. Materials/Methods: Five patients treated with HDR brachytherapy were used in this study. The HDR plans were generated with BrachyVision v. 10 to deliver 5.5 Gy/fx using a tandem and ring applicator. The crude HDR doses were converted to EQD2 using an a/b 10 for early and 3 for late effects. For registration purposes, two deformable registrations were investigated: 1) VelocityAI (Atlanta, GA) that uses a multi-resolution mutual information (B-Spline) algorithm, and 2) MIM Software (Cleveland, OH) that uses an intensity-based free form algorithm. For each patient, the HDR CT sets were registered using both rigid (r), based on applicator, and deformable (d) registration. Either the first or fifth fraction HDR CT was used a primary set for co-registration purposes. To quantify geometrical similarities between deformed secondary structures and original primary structures, dice coefficient (DC) was calculated. Structures investigated were HRCTV (as defined by GEC-ESTRO guidelines), bladder and rectum. Each fractional dose was resampled to the primary set and then added to generate rSUM_HDR and dSUM_HDR. To test the validity of the dose summation, D90 HRCTV and bladder and rectum D2 cc were extracted from DVHs and compared to the current clinical point dose summation protocol. Results: More than 100 dice coefficients were computed as a result of different registrations between different fractions and for the considered structures. The average DC for HDRCTV, bladder and rectum was 0.8, 0.8 and 0.6 for MIM and 0.7, 0.7 and 0.6 for Velocity. For HRCTV D90, HDR dose summation lead to differences of 7.2 7.7% and 3.9 3.3% between clinical standard and rSUM_HDR, and differences of 8 6.5% and 5.6 4.5% between clinical standard and dSUM_HDR using MIM and Velocity, respectively. Larger differences, 12-21%, were seen for D2 cc rectum and
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bladder using rigid registration, and 9-20% when using deformable registration. Conclusions: Deformable image registration allows us to track dose accumulated from multiple HDR fractions. The two algorithms tested produced similar results, with expected better DC for HRCTV and bladder then for rectum. The large differences between current standard point dose sum and the one extracted from volumetric doses for bladder and rectum warrant further investigation. Author Disclosure: L. Ding: None. J. Chino: None. J. Cai: None. B. Steffy: None. S. Meltsner: None. O. Craciunescu: None.
prohibit appropriate placement of ovoid applicators to provide equivalent Point A doses. Author Disclosure: E.C. Fields: None. D.A. Thornton: None. D.C. Westerly: None. S. Day: None. T.E. Schefter: None. C.M. Fisher: None.
2549 Dosimetric Comparison of Tandem and Ovoids Versus Tandem Alone Intracavitary Applicators for Treatment of Locally-Advanced Cervical Cancer E.C. Fields, D.A. Thornton, D.C. Westerly, S. Day, T.E. Schefter, and C.M. Fisher; University of Colorado Denver, Aurora, CO Purpose/Objective(s): Standard therapy for locally advanced cervical cancer includes intracavitary brachytherapy. Tandem and ovoids (TO) are traditionally used in the US, but when the vaginal fornices are obliterated by tumor, ovoid placement is difficult. Practice patterns surveys in Canada reveal 9% of practitioners there use tandem only. This study compares the dosimetry of TO versus tandem (T) alone insertions with respect to the dose to ICRU points A, B, bladder and rectum, volumetric dose to bladder and rectum and volume of tissue receiving various dose gradients. Materials/Methods: One hundred eight brachytherapy cases from 27 women with stage II-IV cervical cancer were treated consecutively for cervical cancer with HDR brachytherapy with 4 applicator insertions. The prescribed dose of each insertion was 7 Gy to ICRU point A with additional goals of minimizing bladder and rectal doses. Patients were treated with either TO or T alone at physician discretion based on the clinical evaluation of the vaginal fornices at the time of the procedure. Parameters compared were ICRU point A and B doses, volume receiving 95%, 85%, 50%, and 20% of the prescription dose, ICRU bladder and rectal point doses, and maximal dose to 2 cc of bladder and rectum (D2 cc). The Mann-Whitney U test was used to compare these parameters. Results: The mean dose to ICRU point A was not significantly different between the TO and T applicators, 681 cGy vs 670 cGy (p Z 0.09). The mean dose to ICRU point B was significantly higher with the TO applicator than T alone, 200 Gy vs 177 cGy (p Z 10-7). Dose distribution was different between the two applicators, with significantly increased volume receiving 95%, 85%, 50%, and 20% of the prescription dose using the TO applicator. The mean V95 was 109.5 cc for TO vs 96.4 cc for T (p Z 0.001) and the mean V20 was 1041.7 cc for TO vs 923.9 cc for T (p Z 0.009). There was no significant difference in ICRU rectal point doses between the applicators, 361.8 cGy TO vs 375.1 cGy T (p Z 0.7). However, there were significantly increased doses to the ICRU bladder point, and D2 cc of the rectum and bladder with the T alone. The bladder point dose was 294.9 cGy TO vs 360.6 cGy T (p Z 0.02), bladder D2 cc 403.7 cGy TO vs 632.7 cGy T (p Z 0.001) and rectal D2 cc 289.7 cGy TO vs 224.8 cGy T (p Z 0.01). Conclusions: TO and T applicator insertions for cervix brachytherapy provide equivalent doses to the ICRU point A, however, the volumetric distribution is significantly different between the 3 channel applicator and single channel tandem. The TO applicator provides increased volumetric dose within the patient, but allows better sparing of the rectum and bladder. In trained providers, T may be considered when the vaginal fornices
2550 Institutional Outcomes for Para-aortic Node-Positive Cervical Cancer Patients Treated With a Novel Dynamic Field-Matching Technique C.J. Baden, A. Whitley, J. Lo´pez-Araujo, R.A. Popple, J. Duan, and R.Y. Kim; University of Alabama Medical Center, Birmingham, AL Purpose/Objective(s): PET staging of cervical cancer has increased identification of patients with para-aortic lymph node (PALN) metastasis. IMRT enables dose escalation in this area, but matching IMRT fields with traditional whole pelvis (WP) fields presents a challenge. We report institutional outcomes for PALN positive cervical cancer (CC) patients treated with a novel dynamic-field matching technique (DMT), which was developed to minimize dose inhomogeneities at the WP and IMRT field junction. Materials/Methods: From 2003 to 2012, 20 patients with CC and PALN metastasis were treated utilizing the DMT. As opposed to single-isocenter half-beam junction techniques, the DMT employs wedge-shaped dose junctions for the abutment of WP and IMRT fields. During treatment, leaves which define the superior border of the WP move continuously from a position 1.5 cm above to 1.5 cm below the superior border of the field, creating a wedge-shaped dose distribution. Para-aortic IMRT fields are then optimized to create a complementary wedge, accounting for dose contribution from WP fields. We reviewed the records of all patients who completed treatment with DMT and abstracted treatment, toxicity, and disease-related outcome data for analysis. Overall survival (OS) and disease-free survival (DFS) estimates were determined by the Kaplan-Meier method. Results: All patients were treated with concurrent platinum-based chemotherapy and 8 underwent a prior staging or debulking operation. Median prescribed dose to the WP field was 45 Gy (range, 45-49.6 Gy) and para-aortic IMRT field 50.4 Gy (range, 45-55.5 Gy). Median parametrial boost dose was 5.4 Gy. All but 3 patients underwent HDR (13 pts) or LDR (4 pts) brachytherapy, the majority receiving 8 Gy x 3 fractions. All patients developed lower GI toxicity; 10 grade 1, 9 grade 2, and 1 grade 4 (enterovaginal fistula). The fistula was diagnosed 6 months after completion of radiation therapy with 45 Gy WP, 45 Gy to PALN PTV, and LDR Syed needle brachytherapy. It developed within WP fields but well away from any dose contribution by IMRT fields. Median follow-up was 15.9 months (range, 4.4-114.7 months). Median DFS was 18.7 months (95% CI, 8.4-29.0) with 1 and 2-year DFS 62.7% and 40.2%, respectively. One-year OS was 82.8% and 2-year OS 63.1%; median OS has not yet been reached. Of the 9 patients who developed recurrence, first site of recurrence was within the WP field for 1 patient, within the field and distant for 1 patient, and distant in 7 patients. There were no failures at the dynamic junction between IMRT and WP fields. Conclusions: DMT provides a means for joining WP and para-aortic IMRT fields that substantially reduces dose deviations at the junction due to field mismatch. Treatment with DMT is simple, effective, and tolerated with no apparent increase in toxicity. Author Disclosure: C.J. Baden: None. A. Whitley: None. J. Lo´pez-Araujo: None. R.A. Popple: None. J. Duan: None. R.Y. Kim: None.
2547 FDG PET Imaging in Cervical Cancer Patients Treated With Chemoradiation Therapy M.A. Kollmeier, A. Mojtahedi, L. Friguglietti, M. Gonen, M. Hsu, H. Pannu, K. Alektiar, and N. Pandit-Taskar; Memorial Sloan-Kettering Cancer Center, New York, NY Purpose/Objective(s): To explore predictors of response and progression free survival (PFS) on baseline and follow-up FDG PET (PET) imaging in patients treated with definitive chemoradiation for cervical cancer. Materials/Methods: We retrospectively reviewed PET imaging in 46 patients with Stage IB1-IVA cervical cancer patients who underwent definitive radiation therapy with concurrent cisplatin chemotherapy. A baseline PET scan and a post-treatment PET scan were performed in all patients. Radiation therapy (RT) consisted of external beam radiation therapy (EBRT) to the pelvic +/- para-aortic lymphatics (median dose Z 50.4 Gy) +/- intracavitary (n Z 36) or interstitial (n Z 7) brachytherapy boost (median dose Z 20 Gy (interstitial); 30 Gy (intracavitary)). Cisplatin chemotherapy was delivered concurrently with radiation
Poster Viewing Abstracts S413 therapy in all patients. Follow-up PET scans were performed at a median of 17.4 weeks following treatment (range, 11-30 weeks). PET data collected included, for both primary and nodal disease: tumor size, number of positive nodes and uptake in tumor and nodes (SUV max and SUV mean). Progression free survival (PFS) was determined from start of RT or from follow-up PET. Results: Baseline PET scans demonstrated FDG-avid cervix lesions in all patients with 67 FDG-avid nodes seen. PFS was significantly associated with baseline PET primary tumor size (HR, 1.41; 95% CI, 1.00-2.00; p Z 0.05) and number of positive lymph nodes (HR, 1.36; 95% CI, 1.01-1.85; p Z 0.04). In addition, the SUV max of the nodal disease at baseline also correlated with PFS (HR, 1.12; 95% CI, 1-1.25; p Z 0.05). In comparison with follow-up PET study, there was significant correlation between PFS and percent decrease of: primary tumor size (HR, 0.98; 95% CI, 0.97-1; p Z 0.03), primary SUV mean (HR, 0.98; 95% CI, 0.97-1; p Z 0.05), nodal size (HR, 0.99; 95% CI, 0.98-1; p Z 0.03) and nodal TLG (HR, 0.99; 95% CI, 0.98-1; p Z 0.02). Conclusions: Primary tumor size and number of positive lymph nodes on baseline PET appear to be predictors of PFS following definitive chemoradiation. Tumor response as measured by SUV mean and nodal TLG on follow-up PET, are also significant predictors of PFS. Author Disclosure: M.A. Kollmeier: None. A. Mojtahedi: None. L. Friguglietti: None. M. Gonen: None. M. Hsu: None. H. Pannu: None. K. Alektiar: None. N. Pandit-Taskar: None.
2548 Volumetric Dose Summation Between Brachytherapy Fractions in Patients Treated for Cervical Cancer: Feasibility of Using Deformable Registration l. Ding, J. Chino, J. Cai, B. Steffy, S. Meltsner, and O. Craciunescu; Duke University Medical Center, Durham, NC Purpose/Objective(s): Deformable registration techniques have potential to aid in quantifying volumetric dose delivered with multimodality therapy for cervical cancer. Due to the complexity of dose summation between external beam and HDR, we are proposing to test available deformable registration tools to add the dose for HDR treatments only, quantify the result of the registration, and compare the calculated dose with the current clinical point dose summation protocol. Materials/Methods: Five patients treated with HDR brachytherapy were used in this study. The HDR plans were generated with BrachyVision v. 10 to deliver 5.5 Gy/fx using a tandem and ring applicator. The crude HDR doses were converted to EQD2 using an a/b 10 for early and 3 for late effects. For registration purposes, two deformable registrations were investigated: 1) VelocityAI (Atlanta, GA) that uses a multi-resolution mutual information (B-Spline) algorithm, and 2) MIM Software (Cleveland, OH) that uses an intensity-based free form algorithm. For each patient, the HDR CT sets were registered using both rigid (r), based on applicator, and deformable (d) registration. Either the first or fifth fraction HDR CT was used a primary set for co-registration purposes. To quantify geometrical similarities between deformed secondary structures and original primary structures, dice coefficient (DC) was calculated. Structures investigated were HRCTV (as defined by GEC-ESTRO guidelines), bladder and rectum. Each fractional dose was resampled to the primary set and then added to generate rSUM_HDR and dSUM_HDR. To test the validity of the dose summation, D90 HRCTV and bladder and rectum D2 cc were extracted from DVHs and compared to the current clinical point dose summation protocol. Results: More than 100 dice coefficients were computed as a result of different registrations between different fractions and for the considered structures. The average DC for HDRCTV, bladder and rectum was 0.8, 0.8 and 0.6 for MIM and 0.7, 0.7 and 0.6 for Velocity. For HRCTV D90, HDR dose summation lead to differences of 7.2 7.7% and 3.9 3.3% between clinical standard and rSUM_HDR, and differences of 8 6.5% and 5.6 4.5% between clinical standard and dSUM_HDR using MIM and Velocity, respectively. Larger differences, 12-21%, were seen for D2 cc rectum and
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International Journal of Radiation Oncology Biology Physics
bladder using rigid registration, and 9-20% when using deformable registration. Conclusions: Deformable image registration allows us to track dose accumulated from multiple HDR fractions. The two algorithms tested produced similar results, with expected better DC for HRCTV and bladder then for rectum. The large differences between current standard point dose sum and the one extracted from volumetric doses for bladder and rectum warrant further investigation. Author Disclosure: L. Ding: None. J. Chino: None. J. Cai: None. B. Steffy: None. S. Meltsner: None. O. Craciunescu: None.
prohibit appropriate placement of ovoid applicators to provide equivalent Point A doses. Author Disclosure: E.C. Fields: None. D.A. Thornton: None. D.C. Westerly: None. S. Day: None. T.E. Schefter: None. C.M. Fisher: None.
2549 Dosimetric Comparison of Tandem and Ovoids Versus Tandem Alone Intracavitary Applicators for Treatment of Locally-Advanced Cervical Cancer E.C. Fields, D.A. Thornton, D.C. Westerly, S. Day, T.E. Schefter, and C.M. Fisher; University of Colorado Denver, Aurora, CO Purpose/Objective(s): Standard therapy for locally advanced cervical cancer includes intracavitary brachytherapy. Tandem and ovoids (TO) are traditionally used in the US, but when the vaginal fornices are obliterated by tumor, ovoid placement is difficult. Practice patterns surveys in Canada reveal 9% of practitioners there use tandem only. This study compares the dosimetry of TO versus tandem (T) alone insertions with respect to the dose to ICRU points A, B, bladder and rectum, volumetric dose to bladder and rectum and volume of tissue receiving various dose gradients. Materials/Methods: One hundred eight brachytherapy cases from 27 women with stage II-IV cervical cancer were treated consecutively for cervical cancer with HDR brachytherapy with 4 applicator insertions. The prescribed dose of each insertion was 7 Gy to ICRU point A with additional goals of minimizing bladder and rectal doses. Patients were treated with either TO or T alone at physician discretion based on the clinical evaluation of the vaginal fornices at the time of the procedure. Parameters compared were ICRU point A and B doses, volume receiving 95%, 85%, 50%, and 20% of the prescription dose, ICRU bladder and rectal point doses, and maximal dose to 2 cc of bladder and rectum (D2 cc). The Mann-Whitney U test was used to compare these parameters. Results: The mean dose to ICRU point A was not significantly different between the TO and T applicators, 681 cGy vs 670 cGy (p Z 0.09). The mean dose to ICRU point B was significantly higher with the TO applicator than T alone, 200 Gy vs 177 cGy (p Z 10-7). Dose distribution was different between the two applicators, with significantly increased volume receiving 95%, 85%, 50%, and 20% of the prescription dose using the TO applicator. The mean V95 was 109.5 cc for TO vs 96.4 cc for T (p Z 0.001) and the mean V20 was 1041.7 cc for TO vs 923.9 cc for T (p Z 0.009). There was no significant difference in ICRU rectal point doses between the applicators, 361.8 cGy TO vs 375.1 cGy T (p Z 0.7). However, there were significantly increased doses to the ICRU bladder point, and D2 cc of the rectum and bladder with the T alone. The bladder point dose was 294.9 cGy TO vs 360.6 cGy T (p Z 0.02), bladder D2 cc 403.7 cGy TO vs 632.7 cGy T (p Z 0.001) and rectal D2 cc 289.7 cGy TO vs 224.8 cGy T (p Z 0.01). Conclusions: TO and T applicator insertions for cervix brachytherapy provide equivalent doses to the ICRU point A, however, the volumetric distribution is significantly different between the 3 channel applicator and single channel tandem. The TO applicator provides increased volumetric dose within the patient, but allows better sparing of the rectum and bladder. In trained providers, T may be considered when the vaginal fornices
2550 Institutional Outcomes for Para-aortic Node-Positive Cervical Cancer Patients Treated With a Novel Dynamic Field-Matching Technique C.J. Baden, A. Whitley, J. Lo´pez-Araujo, R.A. Popple, J. Duan, and R.Y. Kim; University of Alabama Medical Center, Birmingham, AL Purpose/Objective(s): PET staging of cervical cancer has increased identification of patients with para-aortic lymph node (PALN) metastasis. IMRT enables dose escalation in this area, but matching IMRT fields with traditional whole pelvis (WP) fields presents a challenge. We report institutional outcomes for PALN positive cervical cancer (CC) patients treated with a novel dynamic-field matching technique (DMT), which was developed to minimize dose inhomogeneities at the WP and IMRT field junction. Materials/Methods: From 2003 to 2012, 20 patients with CC and PALN metastasis were treated utilizing the DMT. As opposed to single-isocenter half-beam junction techniques, the DMT employs wedge-shaped dose junctions for the abutment of WP and IMRT fields. During treatment, leaves which define the superior border of the WP move continuously from a position 1.5 cm above to 1.5 cm below the superior border of the field, creating a wedge-shaped dose distribution. Para-aortic IMRT fields are then optimized to create a complementary wedge, accounting for dose contribution from WP fields. We reviewed the records of all patients who completed treatment with DMT and abstracted treatment, toxicity, and disease-related outcome data for analysis. Overall survival (OS) and disease-free survival (DFS) estimates were determined by the Kaplan-Meier method. Results: All patients were treated with concurrent platinum-based chemotherapy and 8 underwent a prior staging or debulking operation. Median prescribed dose to the WP field was 45 Gy (range, 45-49.6 Gy) and para-aortic IMRT field 50.4 Gy (range, 45-55.5 Gy). Median parametrial boost dose was 5.4 Gy. All but 3 patients underwent HDR (13 pts) or LDR (4 pts) brachytherapy, the majority receiving 8 Gy x 3 fractions. All patients developed lower GI toxicity; 10 grade 1, 9 grade 2, and 1 grade 4 (enterovaginal fistula). The fistula was diagnosed 6 months after completion of radiation therapy with 45 Gy WP, 45 Gy to PALN PTV, and LDR Syed needle brachytherapy. It developed within WP fields but well away from any dose contribution by IMRT fields. Median follow-up was 15.9 months (range, 4.4-114.7 months). Median DFS was 18.7 months (95% CI, 8.4-29.0) with 1 and 2-year DFS 62.7% and 40.2%, respectively. One-year OS was 82.8% and 2-year OS 63.1%; median OS has not yet been reached. Of the 9 patients who developed recurrence, first site of recurrence was within the WP field for 1 patient, within the field and distant for 1 patient, and distant in 7 patients. There were no failures at the dynamic junction between IMRT and WP fields. Conclusions: DMT provides a means for joining WP and para-aortic IMRT fields that substantially reduces dose deviations at the junction due to field mismatch. Treatment with DMT is simple, effective, and tolerated with no apparent increase in toxicity. Author Disclosure: C.J. Baden: None. A. Whitley: None. J. Lo´pez-Araujo: None. R.A. Popple: None. J. Duan: None. R.Y. Kim: None.