In the International Journal of Clinical Oncology, Dr. Hatano and colleagues from Chiba, Japan provide an excellent overview of intensity-modulated radiation therapy (IMRT). Problems with conventional, four field radiotherapy have been ineffective dose distribution and overdoses to organs at risk (OARs), such as the bladder and rectum. The use of dose escalation from 64Gy to 81Gy improves tumor response but increases toxicity. Three-dimensional conformal radiotherapy (3D-CRT) is a technique to increase dose while conforming the beam to the target organ but still has toxicity limitations. IMRT has been introduced for dose escalation with the goal of minimizing toxicity to the bladder and rectum. In fact, IMRT is an advanced form of 3D-CRT where there is enhanced control over the 3D-CRT dose distribution through the superposition of a large number of independent segmented fields either from a number of fixed directions or from directions distributed on one or multiple arcs. IMRT therefore, requires dose specifications for both the target and the surrounding normal structures.
An explanation of image guided radiation and some of its side effects. There is a new quality marker made by the government that suggests that image guided therapy is preferred over conventional radiation.