title: [Dosimetric perturbation due to scattered rays released by a gold marker used for tumor tracking in external radiotherapy].
abstract: Image-guided radiation therapy using a gold marker-based tumor tracking technique provides precise patient setup and monitoring. However, the marker consists of high-Z material, and the resulting scattered rays tend to have adverse effects on the dose distribution of radiotherapy. The purpose of this study was to evaluate the dosimetric perturbation due to the use of a gold marker for radiotherapy in the lungs. The relative dose distributions were compared with film measurement, Monte Carlo simulation, and XiO calculation with the multi grid superposition algorithm using two types of virtual lung phantoms, which were composed of tough water phantoms, tough lung phantoms, cork boards, and a 2.0-mm-diameter gold ball. No dose increase and decrease in the vicinity of the gold ball was seen in the XiO calculations, although it was seen in the film measurements and the Monte Carlo simulation. The dose perturbation due to a gold marker cannot be evaluated using XiO calculation with the superposition algorithm when the tumor is near a gold marker (especially within 0.5 cm). To rule out the presence of such dose perturbations due to a gold marker, the distance between the gold marker and the tumor must therefore be greater than 0.5 cm.
authors.affiliation: Division of Radiology, Hiroshima Red Cross Hospital & Atomic-bomb Survivors Hospital.
authors.forename: Kosaku
authors.initials: K
authors.lastname: Habara
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Shimozato
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Aoyama
authors.forename: Naoki
authors.initials: N
authors.lastname: Hayashi
authors.forename: Keisuke
authors.initials: K
authors.lastname: Yasui
authors.forename: Kanji
authors.initials: K
authors.lastname: Matsuura
authors.forename: Takashi
authors.initials: T
authors.lastname: Furukawa
authors.forename: Ryota
authors.initials: R
authors.lastname: Kawanami
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Obata
mesh_terms: D006050:Gold Radioisotopes / Q000009:adverse effects*; D008168:Lung; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D019275:Radiopharmaceuticals / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D012542:Scattering, Radiation
chemical_list: D006050:Gold Radioisotopes; D019275:Radiopharmaceuticals