title: A computerized framework for monitoring four-dimensional dose distributions during stereotactic body radiation therapy using a portal dose image-based 2D/3D registration approach.
abstract: A computerized framework for monitoring four-dimensional (4D) dose distributions during stereotactic body radiation therapy based on a portal dose image (PDI)-based 2D/3D registration approach has been proposed in this study. Using the PDI-based registration approach, simulated 4D "treatment" CT images were derived from the deformation of 3D planning CT images so that a 2D planning PDI could be similar to a 2D dynamic clinical PDI at a breathing phase. The planning PDI was calculated by applying a dose calculation algorithm (a pencil beam convolution algorithm) to the geometry of the planning CT image and a virtual water equivalent phantom. The dynamic clinical PDIs were estimated from electronic portal imaging device (EPID) dynamic images including breathing phase data obtained during a treatment. The parameters of the affine transformation matrix were optimized based on an objective function and a gamma pass rate using a Levenberg-Marquardt (LM) algorithm. The proposed framework was applied to the EPID dynamic images of ten lung cancer patients, which included 183 frames (mean: 18.3 per patient). The 4D dose distributions during the treatment time were successfully obtained by applying the dose calculation algorithm to the simulated 4D "treatment" CT images. The mean±standard deviation (SD) of the percentage errors between the prescribed dose and the estimated dose at an isocenter for all cases was 3.25±4.43%. The maximum error for the ten cases was 14.67% (prescribed dose: 1.50Gy, estimated dose: 1.72Gy), and the minimum error was 0.00%. The proposed framework could be feasible for monitoring the 4D dose distribution and dose errors within a patient's body during treatment.
authors.affiliation: Division of Medical Quantum Science, Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nakamoto
authors.affiliation: Division of Medical Quantum Science, Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: arimurah@med.kyushu-u.ac.jp.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Arimura
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Saga Heavy Ion Medical Accelerator in Tosu, Saga, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Shioyama
authors.affiliation: Kurume University Hospital, Fukuoka, Japan.
authors.forename: Asumi
authors.initials: A
authors.lastname: Mizoguchi
authors.affiliation: Kyushu University Hospital, Fukuoka, Japan.
authors.forename: Taka-Aki
authors.initials: TA
authors.lastname: Hirose
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
authors.affiliation: Kyushu University Hospital, Fukuoka, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Umezu
authors.affiliation: Kyushu University Hospital, Fukuoka, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: Division of Medical Quantum Science, Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Hirata
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D056973:Four-Dimensional Computed Tomography / Q000379:methods*; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods; D014915:Whole-Body Counting / Q000379:methods
keywords: 2D/3D registration; Four-dimensional dose distribution; Optimization; Stereotactic body radiation therapy