title: [Cone-beam computed tomography-derived adaptive radiotherapy].
abstract: The purpose of this study was to evaluate the reliability of cone-beam computed tomography (CBCT)-derived adaptive radiotherapy. We evaluate planning computed tomography (pCT) and CBCT in 50 patients who had undergone image guided radiotherapy (IGRT) with CBCT. Irradiated sites included head, neck, chest, abdomen, and pelvis; there were 10 patients in each group. Treatment plans including 153 beam data were recalculated based on CBCT. To compare between pCT and CBCT, we estimated CT values of normal tissues, body contour, effective depth, and monitor units (MU) calculation. The maximum difference in CT values was observed in lung estimation. The 5 mm or more differences in depth were observed in 2 beams of 2 pelvic cases, but CBCT also demonstrated a shift of abdominal wall due to intestinal motility. There were downward trends for the effective depth and MU based on CBCT, especially in lung cases. However, the differences in prescribed dose due to MU calculation were less than 5% because all patients were treated with a multifield irradiation plan. CBCT provides not only precise daily setup but also accurate anatomical information on body contour. In addition, CBCT may be considered as a useful tool for dose calculation.
authors.affiliation: Department of Radiological Technology, Kumamoto University Hospital.
authors.forename: Masato
authors.initials: M
authors.lastname: Maruyama
authors.forename: Ryuji
authors.initials: R
authors.lastname: Murakami
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakaguchi
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Kakei
authors.forename: Eriko
authors.initials: E
authors.lastname: Takenaga
authors.forename: Naoko
authors.initials: N
authors.lastname: Tsujita
authors.forename: Yuki
authors.initials: Y
authors.lastname: Omura
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Kodabashi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Yokoo
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Saito
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Matsuyama
mesh_terms: D054893:Cone-Beam Computed Tomography; D006257:Head / Q000000981:diagnostic imaging; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D009333:Neck / Q000000981:diagnostic imaging; D010388:Pelvis / Q000000981:diagnostic imaging; D011860:Radiography, Abdominal; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*