144 / 1542
3-D / 4-D IGRT
• Preferred for tumours close to organs at risk
• Mobile tumours (4
th
dimension is time) e.g. lung, lower
oesophagus, liver
• Valuable for target volumes prone to changes in size and shape
e.g. bladder, prostate, lung
• Essential for soft tissue tumours surrounded by soft tissue e.g.
pancreas
• Essential for extra-cranial stereotactic XRT
• May enable reduction in planning margins which may improve
treatment outcome and prognosis.