Estimation of oesophageal surface dose in breast cancer patients undergoing supraclavicular irradiation by thermoluminescent dosimeter (TLD) and treatment planning system (TPS)

Background: the purpose of this study was to measure the surface dose in breast cancer patients undergoing supraclavicular irradiation using a thermoluminescent dosimeter (tld) and compare the measurements to calculated doses determined by the treatment planning system (tps). the results of in vivo patients’ measurements were verified using a phantom. materials and methods: the oesophageal surface dose of 30 breast cancer patients undergoing supraclavicular lymph node irradiation was measured by tld and tps. for each patient, two tlds were positioned on the oesophageal surface. the tld and tps results were verified using a phantom that covered from the oesophagus to the supraclavicular area. the tld was positioned within or outside the treatment field on the phantom depending on the patient. results: the average oesophagus surface dose was 9.04 ± 5.07 gy and 8.06 ± 6.17 gy for tld and tps, respectively (p=0.09). oesophagus surface doses were greater for the left than for the right side. the calculated and measured dose values at the surface for the phantom were 0.78 gy and 0.96 gy, respectively, with the tld placed inside the radiation field (p=0.02). the calculated and measured dose values at the surface for the phantom were 0.024 gy and 0.10 gy, respectively, with the tld placed outside the radiation field (p=0.01). conclusion: the results showed a good agreement between tld measurements and tps calculations, except when the tld was placed outside the radiation field. therefore, dose calculations in peripheral regions should be used with caution.