Parotid gland as a risk organ in whole brain radiotherapy.

Background And Purpose: Since the introduction of CT-based simulation for use in whole brain radiotherapy (WBRT), we have observed that a large volume of the parotid glands is included in the radiation fields. The purpose of this study is to analyze the dose-volume statistics of the parotid glands in patients undergoing WBRT.

Materials And Methods: Thirty-two patients received WBRT using CT-based simulation with bilateral two-field arrangement. Daily fraction was 3 Gy with total dose of 30 Gy in 2 weeks. We analyzed the radiation dose from WBRT to the parotid glands.

Results: Average of the mean parotid dose was 17.5 Gy (range, 10.5-26.2) for both glands. Mean parotid doses ≥20 and ≥25 Gy were observed in 22 (34.4%) and 4 (6.3%) of 64 individual glands. The numbers of patients with a mean parotid dose of both glands ≥20Gy and ≥25 Gy were 12 (37.5%) and 1 (3.1%), respectively.

Conclusions: Mean parotid dose was variable in patients with WBRT. According to the parotid dose and combined potential risk factors, parotid glands can be regarded as a risk organ in WBRT for improvement of patient quality of life.