The comparison of isodose plans: radiotherapy techniques in the treatment of thyroid ophtalmopathy.
Thyroid ophthalmopathy is listed among benign disorders as the fourth indication for radiotherapy. Radiation reduces symptoms and signs of the disease in 46-93% of patients. Except for the lenses, the orbital content is resistant to the usual radiation dose of 20 Gy in 10 fractions. A number of radiotherapeutic techniques which avoid the lenses have been suggested. The testing of different techniques was performed on the same patient by using a computerized simulation of lateral alternating and crossed photon beams from a 6 MV and 18 MV linear accelerator or cobalt device. The radiation from a 6 MV linear accelerator using lateral beams angled at 5 degrees posteriori gave the best results. By this technique both lenses receive below 10% of the prescribed dose with a safety zone of 20% of the field size. Isodose distribution in clinical target volume is within the range of 10%. The described technique is recommended as it enables a successful avoidance of both lenses with a satisfactory homogeneity of dose distribution in the clinical target volume.
Department of Radiation Therapy, Clinic for Tumors, Zagreb, Croatia.
M
M
Samija
M
M
Solarić
A
A
Purisić
N
N
Stiglmayer
D000328:Adult; D005260:Female; D006111:Graves Disease / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D010315:Particle Accelerators; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D011882:Radiotherapy, High-Energy