11% of the sample studies had significant quality defects that potentially led to missed pathology or inappropriate therapy. They included studies where the selected field-of-view made it impossible for the clinician to fully appreciate the presence or extent of disease. Ultrasound studies were performed with the wrong transducer. Prostate ultrasound was performed without an endorectal coil. Obsolete equipment produced spinal images so poor that the edge of the spinal facets could not be seen. Brain CT produced artifacts that mimicked brain tumors.