Quality Assessment in the USA: How the Patterns of Care Study Has Made a Difference.

Improving the quality and accessibility of radiation care in the United States has been the primary objective of the Patterns of Care Study (PCS) since its inception. While patient care has two components, technical and interpersonal, the PCS has only studied the quality of technical care. Such assessments of technical quality of radiation oncology, which are representative of the United States as a whole, virtually do not exist outside those of the PCS. The methodology used by the PCS to assess quality in radiation oncology is based on an examination of structure, process, and outcome. Structural elements identified by the PCS to be associated with inferior quality include the use of a Cobalt 60 unit with surface-to-skin distance (SSD)