Fig. 1

a Quasar phantom with (b) cedar lung insert encapsulating an offset polystyrene target 3.0 cm diameter. c Shows an identical cedar insert with imbedded 3.0 cm target bored out to fit a 0.125 cc ion chamber at isocenter
a Quasar phantom with (b) cedar lung insert encapsulating an offset polystyrene target 3.0 cm diameter. c Shows an identical cedar insert with imbedded 3.0 cm target bored out to fit a 0.125 cc ion chamber at isocenter