Concomitant Imaging Dose and Cancer Risk in Image Guided Thoracic Radiation Therapy
Publication Date
2015
Journal Title
Int J Radiat Oncol Biol Phys
Abstract
PURPOSE: Kilovoltage cone beam computed tomography (CT) (kVCBCT) imaging guidance improves the accuracy of radiation therapy but imposes an extra radiation dose to cancer patients. This study aimed to investigate concomitant imaging dose and associated cancer risk in image guided thoracic radiation therapy. METHODS AND MATERIALS: The planning CT images and structure sets of 72 patients were converted to CT phantoms whose chest circumferences (Cchest) were calculated retrospectively. A low-dose thorax protocol on a Varian kVCBCT scanner was simulated by a validated Monte Carlo code. Computed doses to organs and cardiac substructures (for 5 selected patients of various dimensions) were regressed as empirical functions of Cchest, and associated cancer risk was calculated using the published models. The exposures to nonthoracic organs in children were also investigated. RESULTS: The structural mean doses decreased monotonically with increasing Cchest. For all 72 patients, the median doses to the heart, spinal cord, breasts, lungs, and involved chest were 1.68, 1.33, 1.64, 1.62, and 1.58 cGy/scan, respectively. Nonthoracic organs in children received 0.6 to 2.8 cGy/scan if they were directly irradiated. The mean doses to the descending aorta (1.43 +/- 0.68 cGy), left atrium (1.55 +/- 0.75 cGy), left ventricle (1.68 +/- 0.81 cGy), and right ventricle (1.85 +/- 0.84 cGy) were significantly different (P
Volume Number
93
Issue Number
3
Pages
523-31
Document Type
Article
EPub Date
2015/10/16
Status
Faculty
Facility
School of Medicine
Primary Department
Radiation Medicine
PMID
DOI
10.1016/j.ijrobp.2015.06.034