Clinical-dosimetric relationship between lacrimal gland dose and ocular toxicity after intensity-modulated radiotherapy for nasopharyngeal carcinoma
Purpose/Objective
To evaluate the relationship between lacrimal gland dose and ocular toxicity among those patients.
Material/Methods
Between September 2020 and May 2022, we selected 20 patients treated for NPC by IMRT technique to a curative dose of 70Gy at Salah Azaeiz Institute. The lacrimal gland was contoured on the axial slice as Organ at risk (OAR). The following dosimetric parameters were evaluated: mean dose and maximum dose. A Tear Break-up Time (TBUT) test was conducted to assess dry eye syndrome.
Results
The median follow-up time was 9 months (5 - 22 months). Based on the dose-volume histogram analysis, averages of mean and maximum doses to the ipsilateral lacrimal gland were 11.4 Gy (range, 3.7-29.9 Gy) and 30.3 Gy, (range, 14.4-46.9 Gy) respectively. The median time of the TBUT test was 7 seconds. The incidence of late Grade 3+ toxicities was 15%. We reported a severe dry eye syndrome in two patients and the mean dose to their lacrimal gland were superior to 25 Gy.
Conclusion
High-grade ocular toxicity is a potential complication that detrimentally affect the quality of life in patients treated by IMRT for NPC. The incidence of these complications has been shown to increase with higher doses to the lacrimal gland. To reduce the toxicity and prevent dry eye syndrome lacrimal gland should be contoured as OAR and dose constraints should be given.
