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NTCP Modeling Analysis of Acute Hematologic Toxicity in Whole-Pelvic Radiation Therapy for Gynecologic Malignancies: A Dosimetric Comparison of IMRT and Spot-Scanning Proton Therapy
E254
International Journal of Radiation Oncology Biology Physics
Results: The P value was 3.480.68 Gy, it was higher than P1 (3.250.69 Gy) in the same point (P<.05). Both the P and P1 were significantly lower than the DICRU (3.710.62 Gy) and the D2cc (3.870.68 Gy). Moreover, the P value has a high relationship with the DICRU (PZ.000; correlation coefficientZ0.722), but not with D2cc (PZ.002; correlation coefficientZ0.284). Conclusion: The rectal point dose determined with the use of rectal detector in vivo has a big deviation with the same point in planning system, and it underestimated the rectal dose comparing with the DICRU and D2cc. Therefore, we did not recommend it as a perfect indicator for rectal dose evaluation for treatment planning. However, we argued that it is a good method in monitoring the real-time rectal dose for quality control and quality assurance during brachytherapy. Author Disclosure: G. Cheng: None. Z. Zhao: None. M. He: None. H. Zhao: None.
2632
2631 The Clinic Values of the Self-made “T Type” Fixing Belt on Preventing the Utrecht Interstitial Applicator Shifts in 3D CT-Based Brachytherapy of Cervical Cancer M. He,1 J. MAO,2 D. Han,1 H. Zhao,1 and Z. Zhao1; 1China-Japan Union Hospital of Jilin University, Changchun, China, 2Greensboro Day School, Greensboro, Greensboro, NC Purpose/Objective(s): To evaluate the self-made “T type” fixing belt on preventing the Utrecht interstitial applicator shifts in 3-dimensional (3D) brachytherapy of cervical cancer (CC). Materials/Methods: Twenty-five patients from 2012 and 30 patients from 2013 in our hospital who suffered from CC were treated with 3D computed tomography (CT)-based and ultrasound-guided high-dose-rate (HDR) brachytherapy using the Utrecht interstitial applicator with or without the self-made “T type” belt fixation, respectively. After the applicator was implanted, the applicator was fixed by the routine vaginal packing with cotton, and the patients in 2013 received an additional “T type” belt fixation. The “T type” belt was kept until the end of the treatment. Moreover, the Zephyr Patient Transport Sled included in Lithotomy Stirrups was also employed for all the patients in order to control the movement of body. The CT imaging was following achieved for oncologist contouring the target volume and organs at risk (OARs) delineation according to GYN GEC ESTRO recommendations. After the treatment with a 192Ir HDR brachytherapy, the CT imaging was repeated to determine applicator shifts. Two results of CT imaging were matched by pelvic structures. In both imaging results, we defined the tandem by the tip and the base as the marker point, and evaluated applicator shift, including X (left as negative and right as positive), Y (head as negative and foot as positive), and Z (anterior as negative and posterior as positive). This self-made “T type” fixing belt was invented by our department in 2012 (Patent No: 201420584782.3). The “T type” fixing belt with a “cross” type structure comprises a horizontal section and a vertical section, and the 2 ends of the horizontal section connected with an elastic binding band. There were several gaps in the vertical section and they were flexible, which allowed the various applicators to go through it conveniently. There were several bound holes in lower of the gap which could be adjusted according to the physique of the patients. This fixing band has the advantages of low cost, stable structure, excellent fixing effect, and easy operation, which was suitable for clinical application. Results: The average applicator shift was -0.18 mm to 0.21 mm for X, 3.28 mm to 5.87 mm for Y, and 2.9 mm to 3.4mm for Z in routine packing fixation. Using the self-made “T type” fixing belt could slightly prevent the applicator shifts for X (-0.18 mm to 0.14 mm) and Z (2.1 mm to 2.7 mm), and significantly for Y (1.47 mm to 2.08 mm). Conclusion: The self-made “T type” fixing belt could prevent the applicator shift especially in the head and foot position of the applicator, which has development and application value in precise brachytherapy for cervical cancer. Author Disclosure: M. He: None. J. MAO: None. D. Han: None. H. Zhao: None. Z. Zhao: None.
NTCP Modeling Analysis of Acute Hematologic Toxicity in Whole-Pelvic Radiation Therapy for Gynecologic Malignancies: A Dosimetric Comparison of IMRT and Spot-Scanning Proton Therapy T. Yoshimura,1,2 R. Kinoshita,1 S. Onodera,2,3 C. Toramatsu,4 R. Suzuki,1 Y.M. Ito,2 S. Takao,1 T. Matsuura,1 Y. Matsuzaki,5 S. Shimizu,2,6 K. Umegaki,1,6 and H. Shirato2,6; 1Hokkaido University Hospital, Sapporo, Japan, 2Hokkaido University Graduate School of Medicine, Sapporo, Japan, 3Hokkaido Cancer Center, Sapporo, Japan, 4National Institute of Radiological Sciences Research Center for Charged Particle Therapy, Chiba, Japan, 5Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan, 6Hokkaido University, Sapporo, Japan Purpose/Objective(s): Postoperative whole-pelvic radiation therapy (WPRT) is used for gynecologic malignancies. Previous studies have shown that the volume of bone marrow (BM) receiving low-dose radiation caused hematological toxicity (HT), and reduction of the irradiated volume of the BM was able to reduce the risk of grade 3 HT (HT3+). The purpose of this study is to compare the dosimetric parameters of spotscanning proton beam therapy (SSPT) and intensity modulated radiation therapy (IMRT) for WPRT and to determine if SSPT reduces the risk of HT3+ more than IMRT. Materials/Methods: IMRT and SSPT plans were created for 13 gynecologic malignancy patients who had received hysterectomy (with or without lymphadenectomy) and irradiation to the pelvic region. The clinical target volume was delineated according to the Radiation Therapy Oncology Group atlas. The rectum, bladder, BM, femoral head, and bowel bag were contoured as organs at risk (OARs). All structures were contoured using a radiation therapy planning system with IMRT plans generated using a 7-fields step and shoot technique. SSPT plans were generated using a proton beam therapy planning system with anterior-posterior field and single-field optimization. The prescribed dose was 45 Gy in 1.8 Gy per fraction with at least 95% of the planning target volume (PTV), reducing doses to OARs. IMRT and SSPT plans were compared by the homogeneity index (HI) and conformity index (CI) of the PTV and dose volume statistics of OARs. The risk of HT3+ evaluation used the Lyman-KutcherBurman normal tissue complication probability (LKB-NTCP) model. The statistical analysis used the Wilcoxon signed rank test. Results: BM and femoral head doses using SSPT were significantly lower than IMRT. NTCP modeling analysis showed that the risk of HT3+ using SSPT was significantly lower than IMRT (PZ.0002). There were no statistically significant differences in the HI and CI of IMRT and SSPT (HIZ1.240.11 for IMRT and 1.270.05 for SSPT, CIZ0.970.01 for IMRT and 0.960.02 for SSPT, PZ.3054, and .6355, respectively). In addition, no significant difference was found in dose volume statistics in other OARs. Dosimetric results for OARs of IMRT and SSPT are listed in the table. Conclusion: SSPT achieves significant reductions in the dose to BM without compromising target coverage, compared with IMRT. The results of our study indicate the advantage of WPRT using SSPT for the risk of HT3+. Poster Viewing Abstracts 2632; Table 1 IMRT Mean Bone marrow(V10Gy)[%] Bone marrow(V20Gy) [%] Femoral head(V30Gy) [%] Rectum(V40Gy) [%] Bladder(V45Gy) [%] Bowel bag(V40Gy) [%]
83.47 64.86 7.28 53.34 23.35 25.81
SSPT SD
Mean
2.30 3.18 4.53 5.79 11.01 4.19
55.14 42.63 2.09 50.68 26.16 24.61
SD
P
3.00 5.20 2.34 15.28 13.13 4.92
.0002 .0002 .0002 .2439 .2734 .2163
Author Disclosure: T. Yoshimura: None. R. Kinoshita: None. S. Onodera: None. C. Toramatsu: None. R. Suzuki: None. Y.M. Ito: None. S. Takao: None. T. Matsuura: None. Y. Matsuzaki: None. S. Shimizu: None. K. Umegaki: None. H. Shirato: Research Grant; Hitachi Ltd, Mitsubishi heavy Industries Ltd, Shimadzu Corporation.
International Journal of Radiation Oncology Biology Physics
Results: The P value was 3.480.68 Gy, it was higher than P1 (3.250.69 Gy) in the same point (P<.05). Both the P and P1 were significantly lower than the DICRU (3.710.62 Gy) and the D2cc (3.870.68 Gy). Moreover, the P value has a high relationship with the DICRU (PZ.000; correlation coefficientZ0.722), but not with D2cc (PZ.002; correlation coefficientZ0.284). Conclusion: The rectal point dose determined with the use of rectal detector in vivo has a big deviation with the same point in planning system, and it underestimated the rectal dose comparing with the DICRU and D2cc. Therefore, we did not recommend it as a perfect indicator for rectal dose evaluation for treatment planning. However, we argued that it is a good method in monitoring the real-time rectal dose for quality control and quality assurance during brachytherapy. Author Disclosure: G. Cheng: None. Z. Zhao: None. M. He: None. H. Zhao: None.
2632
2631 The Clinic Values of the Self-made “T Type” Fixing Belt on Preventing the Utrecht Interstitial Applicator Shifts in 3D CT-Based Brachytherapy of Cervical Cancer M. He,1 J. MAO,2 D. Han,1 H. Zhao,1 and Z. Zhao1; 1China-Japan Union Hospital of Jilin University, Changchun, China, 2Greensboro Day School, Greensboro, Greensboro, NC Purpose/Objective(s): To evaluate the self-made “T type” fixing belt on preventing the Utrecht interstitial applicator shifts in 3-dimensional (3D) brachytherapy of cervical cancer (CC). Materials/Methods: Twenty-five patients from 2012 and 30 patients from 2013 in our hospital who suffered from CC were treated with 3D computed tomography (CT)-based and ultrasound-guided high-dose-rate (HDR) brachytherapy using the Utrecht interstitial applicator with or without the self-made “T type” belt fixation, respectively. After the applicator was implanted, the applicator was fixed by the routine vaginal packing with cotton, and the patients in 2013 received an additional “T type” belt fixation. The “T type” belt was kept until the end of the treatment. Moreover, the Zephyr Patient Transport Sled included in Lithotomy Stirrups was also employed for all the patients in order to control the movement of body. The CT imaging was following achieved for oncologist contouring the target volume and organs at risk (OARs) delineation according to GYN GEC ESTRO recommendations. After the treatment with a 192Ir HDR brachytherapy, the CT imaging was repeated to determine applicator shifts. Two results of CT imaging were matched by pelvic structures. In both imaging results, we defined the tandem by the tip and the base as the marker point, and evaluated applicator shift, including X (left as negative and right as positive), Y (head as negative and foot as positive), and Z (anterior as negative and posterior as positive). This self-made “T type” fixing belt was invented by our department in 2012 (Patent No: 201420584782.3). The “T type” fixing belt with a “cross” type structure comprises a horizontal section and a vertical section, and the 2 ends of the horizontal section connected with an elastic binding band. There were several gaps in the vertical section and they were flexible, which allowed the various applicators to go through it conveniently. There were several bound holes in lower of the gap which could be adjusted according to the physique of the patients. This fixing band has the advantages of low cost, stable structure, excellent fixing effect, and easy operation, which was suitable for clinical application. Results: The average applicator shift was -0.18 mm to 0.21 mm for X, 3.28 mm to 5.87 mm for Y, and 2.9 mm to 3.4mm for Z in routine packing fixation. Using the self-made “T type” fixing belt could slightly prevent the applicator shifts for X (-0.18 mm to 0.14 mm) and Z (2.1 mm to 2.7 mm), and significantly for Y (1.47 mm to 2.08 mm). Conclusion: The self-made “T type” fixing belt could prevent the applicator shift especially in the head and foot position of the applicator, which has development and application value in precise brachytherapy for cervical cancer. Author Disclosure: M. He: None. J. MAO: None. D. Han: None. H. Zhao: None. Z. Zhao: None.
NTCP Modeling Analysis of Acute Hematologic Toxicity in Whole-Pelvic Radiation Therapy for Gynecologic Malignancies: A Dosimetric Comparison of IMRT and Spot-Scanning Proton Therapy T. Yoshimura,1,2 R. Kinoshita,1 S. Onodera,2,3 C. Toramatsu,4 R. Suzuki,1 Y.M. Ito,2 S. Takao,1 T. Matsuura,1 Y. Matsuzaki,5 S. Shimizu,2,6 K. Umegaki,1,6 and H. Shirato2,6; 1Hokkaido University Hospital, Sapporo, Japan, 2Hokkaido University Graduate School of Medicine, Sapporo, Japan, 3Hokkaido Cancer Center, Sapporo, Japan, 4National Institute of Radiological Sciences Research Center for Charged Particle Therapy, Chiba, Japan, 5Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan, 6Hokkaido University, Sapporo, Japan Purpose/Objective(s): Postoperative whole-pelvic radiation therapy (WPRT) is used for gynecologic malignancies. Previous studies have shown that the volume of bone marrow (BM) receiving low-dose radiation caused hematological toxicity (HT), and reduction of the irradiated volume of the BM was able to reduce the risk of grade 3 HT (HT3+). The purpose of this study is to compare the dosimetric parameters of spotscanning proton beam therapy (SSPT) and intensity modulated radiation therapy (IMRT) for WPRT and to determine if SSPT reduces the risk of HT3+ more than IMRT. Materials/Methods: IMRT and SSPT plans were created for 13 gynecologic malignancy patients who had received hysterectomy (with or without lymphadenectomy) and irradiation to the pelvic region. The clinical target volume was delineated according to the Radiation Therapy Oncology Group atlas. The rectum, bladder, BM, femoral head, and bowel bag were contoured as organs at risk (OARs). All structures were contoured using a radiation therapy planning system with IMRT plans generated using a 7-fields step and shoot technique. SSPT plans were generated using a proton beam therapy planning system with anterior-posterior field and single-field optimization. The prescribed dose was 45 Gy in 1.8 Gy per fraction with at least 95% of the planning target volume (PTV), reducing doses to OARs. IMRT and SSPT plans were compared by the homogeneity index (HI) and conformity index (CI) of the PTV and dose volume statistics of OARs. The risk of HT3+ evaluation used the Lyman-KutcherBurman normal tissue complication probability (LKB-NTCP) model. The statistical analysis used the Wilcoxon signed rank test. Results: BM and femoral head doses using SSPT were significantly lower than IMRT. NTCP modeling analysis showed that the risk of HT3+ using SSPT was significantly lower than IMRT (PZ.0002). There were no statistically significant differences in the HI and CI of IMRT and SSPT (HIZ1.240.11 for IMRT and 1.270.05 for SSPT, CIZ0.970.01 for IMRT and 0.960.02 for SSPT, PZ.3054, and .6355, respectively). In addition, no significant difference was found in dose volume statistics in other OARs. Dosimetric results for OARs of IMRT and SSPT are listed in the table. Conclusion: SSPT achieves significant reductions in the dose to BM without compromising target coverage, compared with IMRT. The results of our study indicate the advantage of WPRT using SSPT for the risk of HT3+. Poster Viewing Abstracts 2632; Table 1 IMRT Mean Bone marrow(V10Gy)[%] Bone marrow(V20Gy) [%] Femoral head(V30Gy) [%] Rectum(V40Gy) [%] Bladder(V45Gy) [%] Bowel bag(V40Gy) [%]
83.47 64.86 7.28 53.34 23.35 25.81
SSPT SD
Mean
2.30 3.18 4.53 5.79 11.01 4.19
55.14 42.63 2.09 50.68 26.16 24.61
SD
P
3.00 5.20 2.34 15.28 13.13 4.92
.0002 .0002 .0002 .2439 .2734 .2163
Author Disclosure: T. Yoshimura: None. R. Kinoshita: None. S. Onodera: None. C. Toramatsu: None. R. Suzuki: None. Y.M. Ito: None. S. Takao: None. T. Matsuura: None. Y. Matsuzaki: None. S. Shimizu: None. K. Umegaki: None. H. Shirato: Research Grant; Hitachi Ltd, Mitsubishi heavy Industries Ltd, Shimadzu Corporation.