One of the most common issues with radiation therapy is finding ways to destroy cancerous cells while preserving healthy cells. Using this beam-shaping technique, radiation doesn't pass through as much healthy tissue to reach the cancerous areas. Hospitals advertised their new accelerators as being able to treat previously untreatable cancers because of the precision of the beam-shaping method. Using older machinery, cancers that were too close to important bodily structures were considered too dangerous to treat with radiation due to the imprecision of the equipment.