Direct measurement of dose at depth in breast cancer using lithium fluoride.

In 23 cases of breast cancer treated conservatively using external beam and interstitial radiotherapy, lithium fluoride thermoluminescent dosimetry has been used to measure the radiation dose received by the breast tissue at depth. Thirty-six investigations were made using a number of lithium fluoride micro-rods for each investigation. Three results could not be analysed because of measurement problems in two and insufficient information in one. Twenty-eight results were obtained at a depth in tissue greater than the build-up zone, 23 of the 28 falling within +/- 5% and 27 of the 28 falling within +/- 10% of the computer-calculated prescribed dose. Of five results obtained within the build-up zone, two fell within +/- 5% and four within +/- 10% of the prescribed dose.