- Email: [email protected]
or Serosal Invasion in Cervical Cancer Patients Treated with Radiotherapy
I. J. Radiation Oncology d Biology d Physics
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Volume 75, Number 3, Supplement, 2009
mean squares. In addition, Body Mass Index (BMI), cross-sectional area at the most cranial slice of the femoral head (PA), crosssectional area at the largest slice in the abdomen (AA), and the subcutaneous adipose-tissue thickness (SAT) were determined. Results: Of the 19 patients, 21.1% were normal weight (NW) (BMI\ 25), 31.6% were overweight (OW) (BMI 25 – 29.9), 10.5% were mildly obese (MO) (BMI 30 – 34.9), and 36.8% were moderately to severely obese (SO) (BMI . 35). The mean 3D shift in mm for each group was 7 (range, 5.7 – 8.2) NW, 8.1 (range, 3.7 – 18.0) OW, 8.8 (range, 8.5 – 9.2) MO, 12.7 (range, 9.3 – 23.1) SO. A spearman rank correlation was performed. The 3D shift was positively correlated with all parameters: BMI (p = 0.001), wt (p = 0.0002), AA (p = 0.0001), PA (p = 0.0001), SAT (p = 0.023). The magnitude of the correlation for the 3D shifts change was 0.25 mm per 1 unit of BMI. Of the component shifts, the LA and V shifts had significant correlations between BMI, wt, SAT, AA, PA (all p values less than 0.03), while LO shifts did not. Of the shifts that require pt repositioning (P, RO, RL), P shifts were significantly correlated with wt, AA, and PA (all with p = 0.04). Conclusions: This study demonstrates that pt body habitus affects the likelihood of shift requirements in pelvic radiotherapy. These results may suggest that pt body habitus should be taken into consideration before setup margins are reduced. Author Disclosure: L. Hertan, None; E. Garver, None; R. Rengan, None; L. Lin, None.
2438
Japanese Patterns of Care Study of Definitive Radiotherapy for Cervical Carcinoma among Three Surveys
T. Kodaira1, T. Toita2, T. Uno3, A. Shinoda4, N. Tomita1, K. Tsujii5, T. Teshima5, M. Mitsumori6 Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Japan, 2Department of Radiology, University of the Ryukyus, Naha, Japan, 3Department of Radiation Oncology, Chiba University, Chiba, Japan, 4Department of Radiation Oncology, Shinsyu University, Matsumoto, Japan, 5Department of Medical Physics & Engineering, Osaka University, Osaka, Japan, 6Department of Radiation Oncology and Image-Applied Therapy, Kyoto, Japan 1
Purpose/Objective(s): The Patterns of Care Study of radiotherapy for cervical cancer during recent 10 years was researched by Japanese Patterns of Care Study group. Materials/Methods: The current study analyzed the data of 1200 patients with cervical cancer treated with radiotherapy including intracavitary brachytherapy for curative intent (1996–1998 PCS: 591 patients; 1999–2001 PCS: 324 patients; 2003–2005 PCS: 285 patients). Results: Patient number of three surveys has decreased slightly. The fraction of patients with Stage III disease did not show a significant difference between three surveys (1996–1998 48%, 1999–2001 38%, 2003–2005 43% p.0.05). Application of intracavitary brachytherapy (ICBT; 1996–1998 77%, 1999–2001 82%, 2003–2005 78%), median radiation dose of both external beam radiotherapy at A point (EBRT 1996–1998 32.2 Gy, 1999–2001 32.4 Gy, 2003–2005 32.4 Gy) and ICBT (1996–1998 24 Gy, 1999–2001 20.3 Gy, 2003–2005 24 Gy) did not significantly change among three surveys. As for EBRT, application of four field portals has greatly increased in three surveys (1996–1998 2%, 1999–2001 7%, 2003–2005 20.4%; p\0.0001). In addition, ratio of appropriate beam energy of EBRT with more than or equal to 10 MV (1996–1998 65%, 1999–2001 74%, 2003–2005 79%; p = 0.001) showed a significantly increase among three surveys. Analysis for ICBT, iridium source has grown rapidly in three surveys (1996–1998 25%, 1999–2001 42%, 2003–2005 82%; p\0.0001). Application of concurrent chemotherapy has dramatically increased within three analyses (1996–1998 5%, 1999–2001 17%, 2003–2005 44%; p\0.0001). Cisplatin was most common agent in concurrent chemoradiotherapy (1999–2001 68%, 2003–2005 73%). On the other hand, neoadjuvant chemotherapy has slightly decreased in recent survey (2003–2005 6%) compared to the others (1996–1998 14%, 1999–2001 16%). Conclusions: The Japanese Pattern of Care Study has monitored dramatic change in patterns of care in definitive radiotherapy of cervical cancer. Especially after announcement of NCI alert on 1999, timing of chemotherapy has intensely shifted to concurrent method in Japanese practice. Author Disclosure: T. Kodaira, None; T. Toita, None; T. Uno, None; A. Shinoda, None; N. Tomita, None; K. Tsujii, None; T. Teshima, None; M. Mitsumori, None.
2439
Prognostic Significance of MRI-detected Bladder Muscle and/or Serosal Invasion in Cervical Cancer Patients Treated with Radiotherapy
H. Nam, S. Huh, J. Lee Samsung Medical Center, Seoul, Republic of Korea Purpose/Objective(s): In patients with cancer of the uterine cervix, the prognostic significance of posterior bladder wall invasion on MRI without pathological evidence of mucosal invasion is not well known. Materials/Methods: From 454 consecutive patients with cervical cancer who were treated with radiation therapy with or without chemotherapy at Samsung Medical Center, we reviewed images and analyzed the outcome of 97 patients. These patients were all diagnosed with FIGO Stage IIIB–IVA cervical cancer, and had received pretreatment pelvic MRI. After exclusion of four patients without follow-up data and one who was treated with adjuvant hysterectomy after radiotherapy, the current study included 92 patients. We analyzed the patients in three groups, the normal, wall (muscle and/or serosal) invasion, and mucosal invasion groups, according to the depth of posterior bladder wall invasion on the MRI. Results: MRI detected abnormalities in the posterior bladder wall in 42 patients (45.6%): wall invasion in 24, and mucosal invasion in 18. Five of 18 patients, suspected on MRI to have mucosal invasion, showed no pathological evidence of mucosal invasion. During the follow-up (median 34 months), seven patients died of causes other than cervical cancer. Three-year cause-specific survival (CSS) in the normal vs. the wall invasion group was 76.2 % vs. 71.4 % (p = 0.48). Three-year CSS for the wall invasion vs. the mucosal invasion group was 71.4 % vs. 54.3 % (p = 0.04). Pathological evidence of mucosal invasion did not correlate with survival in any group. Mucosal invasion on MRI (p = 0.03, H.R 5.15, 95% C.I 1.21 – 21.92) and concurrent chemoradiotherapy (p = 0.01, H.R 0.26, 95% C.I 0.09 – 0.69) were significant factors for CSS. Conclusions: The prognosis of cervical cancer patients with evidence of muscle and/or serosal invasion of the bladder on MRI may not differ from that of patients without muscle and/or serosal abnormality on MRI. In patients with the MRI finding of bladder
Proceedings of the 51st Annual ASTRO Meeting mucosal invasion, further studies should be conducted regarding the role of staging cystoscopy to determine the need for pathologic confirmation of the mucosal lesion. Author Disclosure: H. Nam, None; S. Huh, None; J. Lee, None.
2440
Pretreatment FDG-PET is Helpful in Subgrouping the Prognosis of Cervical Cancer Patients with Enlarged Pelvic Lymph Nodes on MRI
J. C. S. Tsai1,2, J. Hong3, C. Lai4, T. Chang4 Departments of Radiation Oncology, Keelung, Chang Gung Memorial Hospital, Keelung, Taiwan, 2Department of Medical Imaging and Radiological Science, Chang Gung University, School of Medicine, Taoyuan, Taiwan, 3Departments of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan, 4Departments of Obstetrics and Gynecology, CGMH, Linkou, Taiwan 1
Purpose/Objective(s): This study is to evaluate the benefits of pre-treatment FDG-PET in determining the nature of MRI-detected pelvic lymph nodes and as a prognostic predictor for cervical cancer treated with chemoradiation. Materials/Methods: From January 2002 to April 2006, consecutively 139 patients with enlarged pelvic node (.=1 cm) on MRI image and without extrapelvic lesion were referred to our department for curative chemoradiation. Among these, 71 cases had an additional FDG-PET exam before treatment. Results: According to the PET findings, whole patients were categorized into 4 groups: negative for both pelvic and para-aortic nodes (Group A, n = 23), positive for pelvic node and without extrapelvic lesion (Group B, n = 41), positive finding for PA node or extrapelvic lesion (Group C, =7), and control group for those who did not have FDG-PET exam (n = 68). Until the end of October 2008, only one patient in Group A had disease recurrence (lung metastasis). The corresponding 4-year disease-free survival rate was 96% versus 77% for the control group. Conclusions: Cervical cancer with morphologically enlarged pelvic node does not inevitably represent locally advanced disease. Our analysis indicates there are heterogeneous populations and diverse outcomes for these patients. Pre-treatment FDG-PET can serve as tool of metabolic biopsy for enlarged pelvic node and accurately predict the disease outcome. Author Disclosure: J.C.S. Tsai, None; J. Hong, None; C. Lai, None; T. Chang, None.
2441
Relevance of Repeating the Planning CT for HDR Vaginal Cylinder Treatments: A Comparison of Intra Patient Variability and Inter User Contouring Variability
O. I. Craciunescu, J. M. Pepek, B. A. Steffey, J. Zhang, E. L. Jones Duke University Medical Center, Durham, NC Purpose/Objective(s): To address the relevance of generating CT-based plans for each fraction versus first fraction CT-based plan applied to subsequent insertions, while accounting for user variability in contouring bladder and rectum for vaginal cuff HDR brachytherapy (BT) . Materials/Methods: Forty individual intracavitary implants from 10 patients were retrospectively analyzed. Patients have either been previously treated with 45 Gy external beam radiation therapy (n = 2) followed by 5 x 4 Gy of HDR BT, or had BT alone (n = 8), 3 x 7 Gy. For each insertion, CT-based image-guided treatment planning was performed using templates generated in BrachyVision for 3 and 3.5 cm diameter stump cylinders. The dose was prescribed to 0.5 cm from the cylinder surface for treatment lengths ranging from 4 to 6 cm. Bladder and rectum were contoured for each treatment (User A), and also retrospectively by a different user (User B). The D2cc, D1cc, D0.1cc were extracted for both bladder and rectum from dose volume histograms and normalized to an equivalent dose of 2 Gy/fx (EQD2). The metrics were summed for the 3(5) planned fractions, and also by multiplying the number of fractions with the first insertion metrics, then the difference between the two was calculated (DIFF_SUM). To establish intra patient variability with summation method and inter user variability with contouring, coefficients of variation were calculated (sCV, uCV). To quantify the difference between intra patient/inter user variability, the log of the ratio between each sCV and uCV was calculated (logRCV). A Wilcoxon two-paired sample test was performed to establish the variability in contouring. Results: The following reflect the results obtained for the D2cc metric converted to EQD2. The mean DIFF_SUM for bladder and rectum were -0.54 ± 1.41 Gy, 0.6 ± 4.14 Gy for User A, and -1.53 ± 2.1 Gy, -4.62 ± 5.62 Gy for User B. The intra patients CV were much smaller then the inter user CV. For bladder, sCV = 0.031 ± 0.015/0.048 ± 0.043, for User A/B, with the uCV = 0.313 ± 0.623. For rectum, sCV = 0.07 ± 0.047/0.088 ± 0.088 for User A/B, with the uCV = 3.66 ± 8.8. Nearly all logRCVs were . 0. The twopaired Wilcoxon sample test resulted in a p = 0.160 for bladder, and p = 0.0039 for rectum. For this set, the differences between the two summation methods and between the 2 users were larger for rectum than bladder. Conclusions: Using the first fraction CT set to estimate overall bladder and rectum metrics for HDR vaginal cuff treatments might be feasible based on the CV calculated from one user, albeit a large standard deviation. However, the large inter user variation should be considered. MRIs will be acquired for this procedure to test the possibility of reducing the inter user contouring variability with the goal of one imaging procedure per treatment course. Author Disclosure: O.I. Craciunescu, None; J.M. Pepek, None; B.A. Steffey, None; J. Zhang, None; E.L. Jones, None.
2442
Dosimetric Comparison of Tomotherapy and Traditional Two-field Plans for Whole Abdominal Radiation Therapy
R. E. Vatner, K. Stook, M. Willard, R. Dowsett University of Connecticut School of Med., Farmington, CT Purpose/Objective(s): The role of radiation therapy for ovarian cancer and other cancers that metastasize to the peritoneum is unclear. Although once a promising therapeutic option, whole abdominal radiation therapy (WART) with a two-field approach
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Volume 75, Number 3, Supplement, 2009
mean squares. In addition, Body Mass Index (BMI), cross-sectional area at the most cranial slice of the femoral head (PA), crosssectional area at the largest slice in the abdomen (AA), and the subcutaneous adipose-tissue thickness (SAT) were determined. Results: Of the 19 patients, 21.1% were normal weight (NW) (BMI\ 25), 31.6% were overweight (OW) (BMI 25 – 29.9), 10.5% were mildly obese (MO) (BMI 30 – 34.9), and 36.8% were moderately to severely obese (SO) (BMI . 35). The mean 3D shift in mm for each group was 7 (range, 5.7 – 8.2) NW, 8.1 (range, 3.7 – 18.0) OW, 8.8 (range, 8.5 – 9.2) MO, 12.7 (range, 9.3 – 23.1) SO. A spearman rank correlation was performed. The 3D shift was positively correlated with all parameters: BMI (p = 0.001), wt (p = 0.0002), AA (p = 0.0001), PA (p = 0.0001), SAT (p = 0.023). The magnitude of the correlation for the 3D shifts change was 0.25 mm per 1 unit of BMI. Of the component shifts, the LA and V shifts had significant correlations between BMI, wt, SAT, AA, PA (all p values less than 0.03), while LO shifts did not. Of the shifts that require pt repositioning (P, RO, RL), P shifts were significantly correlated with wt, AA, and PA (all with p = 0.04). Conclusions: This study demonstrates that pt body habitus affects the likelihood of shift requirements in pelvic radiotherapy. These results may suggest that pt body habitus should be taken into consideration before setup margins are reduced. Author Disclosure: L. Hertan, None; E. Garver, None; R. Rengan, None; L. Lin, None.
2438
Japanese Patterns of Care Study of Definitive Radiotherapy for Cervical Carcinoma among Three Surveys
T. Kodaira1, T. Toita2, T. Uno3, A. Shinoda4, N. Tomita1, K. Tsujii5, T. Teshima5, M. Mitsumori6 Department of Radiation Oncology, Aichi Cancer Center Hospital, Nagoya, Japan, 2Department of Radiology, University of the Ryukyus, Naha, Japan, 3Department of Radiation Oncology, Chiba University, Chiba, Japan, 4Department of Radiation Oncology, Shinsyu University, Matsumoto, Japan, 5Department of Medical Physics & Engineering, Osaka University, Osaka, Japan, 6Department of Radiation Oncology and Image-Applied Therapy, Kyoto, Japan 1
Purpose/Objective(s): The Patterns of Care Study of radiotherapy for cervical cancer during recent 10 years was researched by Japanese Patterns of Care Study group. Materials/Methods: The current study analyzed the data of 1200 patients with cervical cancer treated with radiotherapy including intracavitary brachytherapy for curative intent (1996–1998 PCS: 591 patients; 1999–2001 PCS: 324 patients; 2003–2005 PCS: 285 patients). Results: Patient number of three surveys has decreased slightly. The fraction of patients with Stage III disease did not show a significant difference between three surveys (1996–1998 48%, 1999–2001 38%, 2003–2005 43% p.0.05). Application of intracavitary brachytherapy (ICBT; 1996–1998 77%, 1999–2001 82%, 2003–2005 78%), median radiation dose of both external beam radiotherapy at A point (EBRT 1996–1998 32.2 Gy, 1999–2001 32.4 Gy, 2003–2005 32.4 Gy) and ICBT (1996–1998 24 Gy, 1999–2001 20.3 Gy, 2003–2005 24 Gy) did not significantly change among three surveys. As for EBRT, application of four field portals has greatly increased in three surveys (1996–1998 2%, 1999–2001 7%, 2003–2005 20.4%; p\0.0001). In addition, ratio of appropriate beam energy of EBRT with more than or equal to 10 MV (1996–1998 65%, 1999–2001 74%, 2003–2005 79%; p = 0.001) showed a significantly increase among three surveys. Analysis for ICBT, iridium source has grown rapidly in three surveys (1996–1998 25%, 1999–2001 42%, 2003–2005 82%; p\0.0001). Application of concurrent chemotherapy has dramatically increased within three analyses (1996–1998 5%, 1999–2001 17%, 2003–2005 44%; p\0.0001). Cisplatin was most common agent in concurrent chemoradiotherapy (1999–2001 68%, 2003–2005 73%). On the other hand, neoadjuvant chemotherapy has slightly decreased in recent survey (2003–2005 6%) compared to the others (1996–1998 14%, 1999–2001 16%). Conclusions: The Japanese Pattern of Care Study has monitored dramatic change in patterns of care in definitive radiotherapy of cervical cancer. Especially after announcement of NCI alert on 1999, timing of chemotherapy has intensely shifted to concurrent method in Japanese practice. Author Disclosure: T. Kodaira, None; T. Toita, None; T. Uno, None; A. Shinoda, None; N. Tomita, None; K. Tsujii, None; T. Teshima, None; M. Mitsumori, None.
2439
Prognostic Significance of MRI-detected Bladder Muscle and/or Serosal Invasion in Cervical Cancer Patients Treated with Radiotherapy
H. Nam, S. Huh, J. Lee Samsung Medical Center, Seoul, Republic of Korea Purpose/Objective(s): In patients with cancer of the uterine cervix, the prognostic significance of posterior bladder wall invasion on MRI without pathological evidence of mucosal invasion is not well known. Materials/Methods: From 454 consecutive patients with cervical cancer who were treated with radiation therapy with or without chemotherapy at Samsung Medical Center, we reviewed images and analyzed the outcome of 97 patients. These patients were all diagnosed with FIGO Stage IIIB–IVA cervical cancer, and had received pretreatment pelvic MRI. After exclusion of four patients without follow-up data and one who was treated with adjuvant hysterectomy after radiotherapy, the current study included 92 patients. We analyzed the patients in three groups, the normal, wall (muscle and/or serosal) invasion, and mucosal invasion groups, according to the depth of posterior bladder wall invasion on the MRI. Results: MRI detected abnormalities in the posterior bladder wall in 42 patients (45.6%): wall invasion in 24, and mucosal invasion in 18. Five of 18 patients, suspected on MRI to have mucosal invasion, showed no pathological evidence of mucosal invasion. During the follow-up (median 34 months), seven patients died of causes other than cervical cancer. Three-year cause-specific survival (CSS) in the normal vs. the wall invasion group was 76.2 % vs. 71.4 % (p = 0.48). Three-year CSS for the wall invasion vs. the mucosal invasion group was 71.4 % vs. 54.3 % (p = 0.04). Pathological evidence of mucosal invasion did not correlate with survival in any group. Mucosal invasion on MRI (p = 0.03, H.R 5.15, 95% C.I 1.21 – 21.92) and concurrent chemoradiotherapy (p = 0.01, H.R 0.26, 95% C.I 0.09 – 0.69) were significant factors for CSS. Conclusions: The prognosis of cervical cancer patients with evidence of muscle and/or serosal invasion of the bladder on MRI may not differ from that of patients without muscle and/or serosal abnormality on MRI. In patients with the MRI finding of bladder
Proceedings of the 51st Annual ASTRO Meeting mucosal invasion, further studies should be conducted regarding the role of staging cystoscopy to determine the need for pathologic confirmation of the mucosal lesion. Author Disclosure: H. Nam, None; S. Huh, None; J. Lee, None.
2440
Pretreatment FDG-PET is Helpful in Subgrouping the Prognosis of Cervical Cancer Patients with Enlarged Pelvic Lymph Nodes on MRI
J. C. S. Tsai1,2, J. Hong3, C. Lai4, T. Chang4 Departments of Radiation Oncology, Keelung, Chang Gung Memorial Hospital, Keelung, Taiwan, 2Department of Medical Imaging and Radiological Science, Chang Gung University, School of Medicine, Taoyuan, Taiwan, 3Departments of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan, 4Departments of Obstetrics and Gynecology, CGMH, Linkou, Taiwan 1
Purpose/Objective(s): This study is to evaluate the benefits of pre-treatment FDG-PET in determining the nature of MRI-detected pelvic lymph nodes and as a prognostic predictor for cervical cancer treated with chemoradiation. Materials/Methods: From January 2002 to April 2006, consecutively 139 patients with enlarged pelvic node (.=1 cm) on MRI image and without extrapelvic lesion were referred to our department for curative chemoradiation. Among these, 71 cases had an additional FDG-PET exam before treatment. Results: According to the PET findings, whole patients were categorized into 4 groups: negative for both pelvic and para-aortic nodes (Group A, n = 23), positive for pelvic node and without extrapelvic lesion (Group B, n = 41), positive finding for PA node or extrapelvic lesion (Group C, =7), and control group for those who did not have FDG-PET exam (n = 68). Until the end of October 2008, only one patient in Group A had disease recurrence (lung metastasis). The corresponding 4-year disease-free survival rate was 96% versus 77% for the control group. Conclusions: Cervical cancer with morphologically enlarged pelvic node does not inevitably represent locally advanced disease. Our analysis indicates there are heterogeneous populations and diverse outcomes for these patients. Pre-treatment FDG-PET can serve as tool of metabolic biopsy for enlarged pelvic node and accurately predict the disease outcome. Author Disclosure: J.C.S. Tsai, None; J. Hong, None; C. Lai, None; T. Chang, None.
2441
Relevance of Repeating the Planning CT for HDR Vaginal Cylinder Treatments: A Comparison of Intra Patient Variability and Inter User Contouring Variability
O. I. Craciunescu, J. M. Pepek, B. A. Steffey, J. Zhang, E. L. Jones Duke University Medical Center, Durham, NC Purpose/Objective(s): To address the relevance of generating CT-based plans for each fraction versus first fraction CT-based plan applied to subsequent insertions, while accounting for user variability in contouring bladder and rectum for vaginal cuff HDR brachytherapy (BT) . Materials/Methods: Forty individual intracavitary implants from 10 patients were retrospectively analyzed. Patients have either been previously treated with 45 Gy external beam radiation therapy (n = 2) followed by 5 x 4 Gy of HDR BT, or had BT alone (n = 8), 3 x 7 Gy. For each insertion, CT-based image-guided treatment planning was performed using templates generated in BrachyVision for 3 and 3.5 cm diameter stump cylinders. The dose was prescribed to 0.5 cm from the cylinder surface for treatment lengths ranging from 4 to 6 cm. Bladder and rectum were contoured for each treatment (User A), and also retrospectively by a different user (User B). The D2cc, D1cc, D0.1cc were extracted for both bladder and rectum from dose volume histograms and normalized to an equivalent dose of 2 Gy/fx (EQD2). The metrics were summed for the 3(5) planned fractions, and also by multiplying the number of fractions with the first insertion metrics, then the difference between the two was calculated (DIFF_SUM). To establish intra patient variability with summation method and inter user variability with contouring, coefficients of variation were calculated (sCV, uCV). To quantify the difference between intra patient/inter user variability, the log of the ratio between each sCV and uCV was calculated (logRCV). A Wilcoxon two-paired sample test was performed to establish the variability in contouring. Results: The following reflect the results obtained for the D2cc metric converted to EQD2. The mean DIFF_SUM for bladder and rectum were -0.54 ± 1.41 Gy, 0.6 ± 4.14 Gy for User A, and -1.53 ± 2.1 Gy, -4.62 ± 5.62 Gy for User B. The intra patients CV were much smaller then the inter user CV. For bladder, sCV = 0.031 ± 0.015/0.048 ± 0.043, for User A/B, with the uCV = 0.313 ± 0.623. For rectum, sCV = 0.07 ± 0.047/0.088 ± 0.088 for User A/B, with the uCV = 3.66 ± 8.8. Nearly all logRCVs were . 0. The twopaired Wilcoxon sample test resulted in a p = 0.160 for bladder, and p = 0.0039 for rectum. For this set, the differences between the two summation methods and between the 2 users were larger for rectum than bladder. Conclusions: Using the first fraction CT set to estimate overall bladder and rectum metrics for HDR vaginal cuff treatments might be feasible based on the CV calculated from one user, albeit a large standard deviation. However, the large inter user variation should be considered. MRIs will be acquired for this procedure to test the possibility of reducing the inter user contouring variability with the goal of one imaging procedure per treatment course. Author Disclosure: O.I. Craciunescu, None; J.M. Pepek, None; B.A. Steffey, None; J. Zhang, None; E.L. Jones, None.
2442
Dosimetric Comparison of Tomotherapy and Traditional Two-field Plans for Whole Abdominal Radiation Therapy
R. E. Vatner, K. Stook, M. Willard, R. Dowsett University of Connecticut School of Med., Farmington, CT Purpose/Objective(s): The role of radiation therapy for ovarian cancer and other cancers that metastasize to the peritoneum is unclear. Although once a promising therapeutic option, whole abdominal radiation therapy (WART) with a two-field approach
S379