Thilmann C, Adamietz I A, Ramm U, Rahn R, Mose S, Saran F, Böttcher H D
Department of Radiotherapy and Oncology, J.W. Goethe-Universität, Frankfurt, Germany.
Med Dosim. 1996 Fall;21(3):149-54. doi: 10.1016/0958-3947(96)00025-8.
During irradiation of the mouth cavity, dental metallic materials emit secondary electrons and thus increase the applied radiation dose in their vicinity. Therefore, local destruction of the mucous membrane contacting metallic dental crowns and fillings may be observed. Available data on this dose increase are based on measurements with beam arrangements perpendicular to the metallic surface. Since the dose modification depends on the beam direction in relation to specimen surface, a reliable prediction of dose modification in the close vicinity of dental caps on fillings under complex beam arrangements, as applied in the irradiation of head and neck region from the published data is not possible. Therefore, we measured dose increase in the immediate surrounding of metallic dental material using thermoluminescence dosimetry on the phantom and during routinely applied 60Co gamma ray therapy. Phantom measurements were carried out using several oblique irradiation angles and rotational therapy. In vivo measurements were carried out at alloy specimens containing gold, palladium, and amalgam in six patients and at permanently fixed golden teeth in five patients. In vivo, the following relative dose increase values according to a simultaneously measured reference value were obtained at the surface of different dental materials: 61% for fixed golden caps. 68% for the specimen containing gold, 33% for the specimen of palladium and 61% for the specimen of amalgam. The measured dose increases due to metallic dental material during routinely applied external 60Co beam irradiation are lower compared with those of perpendicular beam arrangements. Although, the extent of dose modification is less than expected, we still advocate protection of the oral mucosa to prevent painful lesion spots.
在口腔照射过程中，牙科金属材料会发射二次电子，从而增加其附近区域的辐射剂量。因此，可观察到与金属牙冠和填充物接触的黏膜出现局部损伤。关于这种剂量增加的现有数据是基于垂直于金属表面的射束装置测量得出的。由于剂量修正取决于射束方向与样本表面的关系，因此根据已发表的数据，无法可靠预测在复杂射束装置下（如在头颈部区域照射中应用的）牙冠和填充物附近的剂量修正情况。因此，我们使用热释光剂量测定法在体模上以及在常规应用的钴 - 60伽马射线治疗期间，测量了牙科金属材料周围的剂量增加情况。体模测量使用了多个倾斜照射角度和旋转治疗。在六名患者中，对含有金、钯和汞合金的合金样本进行了体内测量，在五名患者中对永久固定的金牙进行了体内测量。在体内，根据同时测量的参考值，在不同牙科材料表面获得了以下相对剂量增加值：固定金冠为61%，含金样本为68%，钯样本为33%，汞合金样本为61%。与垂直射束装置相比，在常规应用的外部钴 - 60射束照射期间，牙科金属材料导致的测量剂量增加较低。尽管剂量修正程度低于预期，但我们仍主张保护口腔黏膜以防止出现疼痛性损伤部位。
