IOWA CITY — Children who brave the reality of radiation therapy often are thought of as heroes. Super heroes. And a University of Iowa administrator has created a way for them to look the part.Jana Grienke, clinical department administrator of the Radiation Oncology Clinic in the Holden Comprehensive Cancer Center, about a year ago went looking for a volunteer to help recreate an initiative she’d seen in Canada to turn radiology masks into art — or disguises of sorts.She found what she was looking for in first-year medical student Weiren Liu, who signed up to decorate the masks according to patient wishes.