7. IMRT – new standards in treatment planning

Abstract

Technological advances in medical imaging have prompted accelerator manufactures to produce more and more advanced treatment delivery systems capable to precise shape the dole distribution.

For several years radiation beams have been modulated by mechanical and dynamic wedges, compensators, individual shields and unequal beam weights. Nowadays three dimensional conformal treatment and intensity modulated radiation therapy techniques (IMRT) provide very precise conformation of the dose to the target volume while sparing adjacent healthy tissues. On the other hand conformal radiotherapy requires very precise definition of anatomical structures, improved patient repositioning systems. New challenge represents quality control program and treatment verification.

IMRT was introduced in clinical practice in Center of Oncology, Glivvice in year 2000. Such treatment is delivered by Clinac 2300 with dynamic MLC option, on the base of dose distributions calculated by CadPlan-Helios treatment planning system, and sent via Varis to accelerator.

The aim of this paper is to present our experience with IMRT technique with particular regard to IMRT treatment plan (definition of PTV and calculation factors like Termination Tolerance, Priority Factor, Scatter Factor).