Ryuta Hirai1, Tomoaki Tamaki2,3, Mitsunobu Igari2, Y U Kumazaki2, Shin-Ei Noda2, Shingo Kato2. 1. Department of Radiation Oncology, Saitama Medical University International Medical Center, Saitama, Japan rhirai@saitama-med.ac.jp. 2. Department of Radiation Oncology, Saitama Medical University International Medical Center, Saitama, Japan. 3. Department of Radiation Oncology, Fukushima Medical University, Fukushima, Japan.
Abstract
AIM: To establish a method of plan optimization in pelvic volumetric-modulated arc therapy (VMAT) for cervical cancer using the central-shielding (CS) principle. PATIENTS AND METHODS: We created external beam VMAT plans for eight cases with non-bulky stage I-IIb using the CS principle based on the Japanese standard guideline. Clinical target volumes (CTVs) for whole-pelvis (WP) irradiation were created using published guidelines, and CTVs for CS irradiation were created by subtracting the uterus corpus and 4 cm-wide regions centered at the cervix and vagina from the CTVs for WP irradiation. For plan optimization of CS irradiation, a 4-cm diameter cylindrical volume centered in the cervix and vagina was created as the volume receiving a high dose in brachytherapy, and the volume overlapping with the rectum was defined as the Ant-Rectum. Dose-volume histogram (DVH) parameters of two CS VMAT plans with and without (VMATOPT/VMATNO) dose optimization to the Ant-Rectum were compared. RESULTS: VMATOPT plans resulted in significantly lower DVH parameters of the Ant-Rectum and rectum compared to VMATNO plans. These were comparable to the DVH parameters of three-dimensional conformal radiotherapy (3DCRT) plans. Both VMAT plans resulted in significantly better coverage of planning target volumes than did the 3DCRT plans. CONCLUSION: In the implementation of IMRT/VMAT as the standard treatment for cervical cancer in Japan, our optimization method may be an essential step toward fully benefitting from the CS principle. Copyright
AIM: To establish a method of plan optimization in pelvic volumetric-modulated arc therapy (VMAT) for cervical cancer using the central-shielding (CS) principle. PATIENTS AND METHODS: We created external beam VMAT plans for eight cases with non-bulky stage I-IIb using the CS principle based on the Japanese standard guideline. Clinical target volumes (CTVs) for whole-pelvis (WP) irradiation were created using published guidelines, and CTVs for CS irradiation were created by subtracting the uterus corpus and 4 cm-wide regions centered at the cervix and vagina from the CTVs for WP irradiation. For plan optimization of CS irradiation, a 4-cm diameter cylindrical volume centered in the cervix and vagina was created as the volume receiving a high dose in brachytherapy, and the volume overlapping with the rectum was defined as the Ant-Rectum. Dose-volume histogram (DVH) parameters of two CS VMAT plans with and without (VMATOPT/VMATNO) dose optimization to the Ant-Rectum were compared. RESULTS: VMATOPT plans resulted in significantly lower DVH parameters of the Ant-Rectum and rectum compared to VMATNO plans. These were comparable to the DVH parameters of three-dimensional conformal radiotherapy (3DCRT) plans. Both VMAT plans resulted in significantly better coverage of planning target volumes than did the 3DCRT plans. CONCLUSION: In the implementation of IMRT/VMAT as the standard treatment for cervical cancer in Japan, our optimization method may be an essential step toward fully benefitting from the CS principle. Copyright
Authors: Petra Georg; Richard Pötter; Dietmar Georg; Stefan Lang; Johannes C A Dimopoulos; Alina E Sturdza; Daniel Berger; Christian Kirisits; Wolfgang Dörr Journal: Int J Radiat Oncol Biol Phys Date: 2011-02-23 Impact factor: 7.038
Authors: Elizabeth A Kidd; Barry A Siegel; Farrokh Dehdashti; Janet S Rader; Sasa Mutic; David G Mutch; Matthew A Powell; Perry W Grigsby Journal: Int J Radiat Oncol Biol Phys Date: 2009-10-31 Impact factor: 7.038