Radiation dose-volume effects on growth hormone secretion

摘要: Abstract Purpose: Growth hormone (GH) deficiency is a known consequence of central nervous system irradiation. The relationship between the dose to hypothalamus and time onset clinically significant GH unknown. Conformal radiotherapy (CRT) techniques allow for more accurate determination hypothalamic dosimetry. We correlated dosimetry peak value after CRT in children with localized primary brain tumors. Methods materials: arginine tolerance/l-dopa test was performed before (baseline) repeated 6 12 months 25 (median age 4.8 years) ependymoma ( n = 15) or low-grade 8) high-grade 2) astrocytoma. None had evidence (arginine level >10 ng/mL [10 μg/L]) at baseline. Peak levels were modeled as function volume receiving within specified intervals 0–20 Gy, 20–40 40–60 Gy. model used predict change over (0–12 months) fit under assumption that integral effect irradiation linear sum products particular impact dose. Results: declined during 0–12 p Gy +0.00106V +0.00156V )×t], where bGH baseline level, V , percent-volume irradiated from 0 20 40 60 respectively, t When included model, rate decline response also influenced by hydrocephalus tumor location. Conclusion: depends on dose-volume effects may be predicted basis sums entire distribution optimize minimize treat deficiency.