In vivo dosimetry with extruded lithium fluoride rods

In external radiation-beam therapy it is difficult to calculate the dose to a point when the treatment beam passes through air-containing tissue. Of two approaches used to correct for the effects of tissue heterogeneity, one determines the water-equivalent thickness that the x-ray beam passes through; the other measures the dose to particular points in a patient directly. The dose delivered to the esophagus during radiation therapy of the upper chest was measured by inserting a catheter containing LiF rods into the esophagus, and the measured dose agreed with the dose calculated using the determined water-equivalent thickness of the patient.