title: Prediction of the location and size of the stomach using patient characteristics for retrospective radiation dose estimation following radiotherapy.
abstract: Following cancer radiotherapy, reconstruction of doses to organs, other than the target organ, is of interest for retrospective health risk studies. Reliable estimation of doses to organs that may be partially within or fully outside the treatment field requires reliable knowledge of the location and size of the organs, e.g., the stomach, which is at risk from abdominal irradiation. The stomach location and size are known to be highly variable between individuals, but have been little studied. Moreover, for treatments conducted years ago, medical images of patients are usually not available in medical records to locate the stomach. In light of the poor information available to locate the stomach in historical dose reconstructions, the purpose of this work was to investigate the variability of stomach location and size among adult male patients and to develop prediction models for the stomach location and size using predictor variables generally available in medical records of radiotherapy patients treated in the past. To collect data on stomach size and position, we segmented the contours of the stomach and of the skeleton on contemporary computed tomography (CT) images for 30 male patients in supine position. The location and size of the stomach was found to depend on body mass index (BMI), ponderal index (PI), and age. For example, the anteroposterior dimension of the stomach was found to increase with increasing BMI (≈0.25 cm kg(-1) m(2)) whereas its craniocaudal dimension decreased with increasing PI (≈-3.3 cm kg(-1) m(3)) and its transverse dimension increased with increasing PI (≈2.5 cm kg(-1) m(3)). Using the prediction models, we generated three-dimensional computational stomach models from a deformable hybrid phantom for three patients of different BMI. Based on a typical radiotherapy treatment, we simulated radiotherapy treatments on the predicted stomach models and on the CT images of the corresponding patients. Those dose calculations demonstrated good agreement between predicted and actual stomachs compared with doses derived from a reference model of the body that might be used in the absence of individual CT scan data.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Lamart
authors.forename: Rebecca
authors.initials: R
authors.lastname: Imran
authors.forename: Steven L
authors.initials: SL
authors.lastname: Simon
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Doi
authors.forename: Lindsay M
authors.initials: LM
authors.lastname: Morton
authors.forename: Rochelle E
authors.initials: RE
authors.lastname: Curtis
authors.forename: Choonik
authors.initials: C
authors.lastname: Lee
authors.forename: Vladimir
authors.initials: V
authors.lastname: Drozdovitch
authors.forename: Roberto
authors.initials: R
authors.lastname: Maass-Moreno
authors.forename: Clara C
authors.initials: CC
authors.lastname: Chen
authors.forename: Millie
authors.initials: M
authors.lastname: Whatley
authors.forename: Donald L
authors.initials: DL
authors.lastname: Miller
authors.forename: Karel
authors.initials: K
authors.lastname: Pacak
authors.forename: Choonsik
authors.initials: C
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D058958:Organs at Risk / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000528:radiation effects*; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012189:Retrospective Studies; D013270:Stomach / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000528:radiation effects*; D014057:Tomography, X-Ray Computed; D055815:Young Adult