Kentaro Miki1, Shinichiro Mori2, Miho Shiomi1, Shigeru Yamada1. 1. Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan. 2. Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan. Electronic address: mori.shinichiro@qst.go.jp.
Abstract
OBJECTIVE: To assess the feasibility of treatment planning for pancreatic tumours subject to respiratory motion using field-specific target volumes (FTV) and field-specific organs at risk (FOAR) using four-dimensional computed tomography (4DCT). METHODS: Fourteen pancreatic cancer patients underwent 4DCT. Radiation oncologists contoured the gross tumour volume (GTV), clinical target volume (CTV), spinal cord, duodenum, kidneys, and stomach. The gating duty cycle was set to 30 % around exhalation. FTV and FOAR were calculated using the 4DCT dataset. Planning target volumes (PTV) and planning organs at risk volumes (PRV) were defined as equal to FTV and FOAR, respectively. A dose of 55.2Gy relative biological effectiveness (RBE) was planned to target the PTV from four beam angles. A single field uniform dose (SFUD) plan was selected. The dose distribution, including intrafractional motion changes, was generated. RESULTS: The mean volume of target receiving 95 % of the planned doses was 96.4±4.1 % to the GTV and 94.7±0.9 % to the CTV. The highest dose to 2cc of duodenal volume was 27.5Gy (RBE). The volume of the stomach receiving ⩾30Gy (RBE) was <7.0cc in all patients. All metrics for OARs satisfied dose constraints. CONCLUSION: Dose to the CTV was covered sufficiently by the 4DCT-generated FTV, and dose to OARs was reduced by 4DCT-generated FOAR. This methodology may prevent adverse reactions while preserving local tumour control.
OBJECTIVE: To assess the feasibility of treatment planning for pancreatic tumours subject to respiratory motion using field-specific target volumes (FTV) and field-specific organs at risk (FOAR) using four-dimensional computed tomography (4DCT). METHODS: Fourteen pancreatic cancerpatients underwent 4DCT. Radiation oncologists contoured the gross tumour volume (GTV), clinical target volume (CTV), spinal cord, duodenum, kidneys, and stomach. The gating duty cycle was set to 30 % around exhalation. FTV and FOAR were calculated using the 4DCT dataset. Planning target volumes (PTV) and planning organs at risk volumes (PRV) were defined as equal to FTV and FOAR, respectively. A dose of 55.2Gy relative biological effectiveness (RBE) was planned to target the PTV from four beam angles. A single field uniform dose (SFUD) plan was selected. The dose distribution, including intrafractional motion changes, was generated. RESULTS: The mean volume of target receiving 95 % of the planned doses was 96.4±4.1 % to the GTV and 94.7±0.9 % to the CTV. The highest dose to 2cc of duodenal volume was 27.5Gy (RBE). The volume of the stomach receiving ⩾30Gy (RBE) was <7.0cc in all patients. All metrics for OARs satisfied dose constraints. CONCLUSION: Dose to the CTV was covered sufficiently by the 4DCT-generated FTV, and dose to OARs was reduced by 4DCT-generated FOAR. This methodology may prevent adverse reactions while preserving local tumour control.