抄録
The use of three-dimensional conformal radiotherapy (3DCRT) has now become common practice in radiation oncology departments around the world. Using beam's eye viewing of volumes defined on a treatment planning CT scan, beam directions and beam shapes can be selected to conform to the shape of the projected target and minimize dose to critical normal structures. Intensity modulated radiotherapy (IMRT) can yield dose distributions which conform closely to the three-dimensional shape of the target volume while still minimizing dose to normal structures by allowing the beam intensity to vary across those shaped fields. These IMRT dose distributions can be generated using a number of different delivery methods including static “step and shoot” segmental (SMLC-IMRT) or dynamic sliding window (DMLC-IMRT) approaches using conventional multileaf collimators (MLC) or serial tomotherapy using a special add-on MLC. Results of dose comparisons indicate that IMRT can yield significantly better dose distributions in some situations at the expense of additional time and resources. New technologies are being developed which should significantly reduce the time needed to plan, implement and verify these treatments. Current research should help define the future role of IMRT in clinical practice.
