IMRT

Dose-volume constraints for IMRT: bone marrow  40% of total body bone marrow reserves located in pelvis:  up to 8% hematological toxicity with preop chemoRT  Mell et al (chemoRT anal cancer):  V10-20 significantly correlated with hematological toxicty  = low-dose treshold > myelosuppressive chemotherapy  Dosimetric benefit of IMRT (Mell et al, cervical cancer):  Reduction of lumbosacral BM irradiation all dose levels  Reduction of pelvic BM irradiation to high doses  Yang et al (rectal cancer):  Sacral BM: V45 < 51%  Coxal BM: V45 < 13%  Higher dose treshold (vs anal cancer)

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