However, they are reported more in secondary hyperparathyroidism. Brown tumors occur more with primary hyperparathyroidism than secondary. Tumors are due to the direct effect of the parathyroid hormone. In ribs, clavicle, long bones and pelvis and are uncommon in other facial bones except mandible.
Because of that, Microbeam radiation therapy of muzzle tumors in pet animals is unlikely to cause sizeable damage to normal teeth, bone and soft tissues, if a single array as used here delivers a limited entrance dose of 200 Gy and a valley dose of ≤14 Gy.īackground: Brown tumours are expansile osteolytic lesions of bone, occurring in Hyperparathyroidism. A single, unidirectional array of microbeams with a peak entrance dose ≤200 Gy (valley dose14 Gy) did not damage normal bone, teeth and soft tissues of the muzzle of normal rabbits longer than one year after irradiation. Conversely, normal incisor teeth exposed to peak entrance doses of 330 Gy or 500 Gy developed marked caries-like damage, whereas the incisors of the two rabbits exposed to 200 Gy remained unscathed. There was no radionecrosis of facial bones in any rabbit. The boundaries of the radiation field were identified histologically by microbeam tracks in cartilage and other tissues. The muzzles were examined 431 days postirradiation by computed microtomographic imaging (micro-CT) ex vivo, and extensive histopathology. To this end, the muzzle of six young adult New Zealand rabbits was irradiated by a lateral array of microplanar beamlets with peak entrance doses of 200, 330 or 500 Gy. This will require data on the largely unknown radiation toxicity of microbeam arrays for bones and teeth.
Microbeam radiation therapy, an alternative radiosurgical treatment under preclinical investigation, aims to safely treat muzzle tumors in pet animals.
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