In addition there are special problems in assuring the safety of individual patients participating in each study, in maximizing their likelihood of exposure to optimal treatment, and in general, ensuring that the interests of patient participants are not subsidiary to those of the scientific investigation. The continual assessment of the progress of studies necessary to achieve these ends is referred to in this document as study monitoring. A related need is for verification of the accuracy of data submitted from individual investigators to the Group. Each Group is therefore required to establish a system of periodic on-site audits of each performance site, with CTEP oversight of the audit program. This dual responsibility of the Groups and the DCTD is referred to as the on-site audit program.
Generalization concerning optimal quality control is impossible.
Cost and benefit are obviously important factors in this assessment. Minimal standards for acceptability of equipment may be required. The RPC in Houston, TX also supplies each Group's radiation therapy quality control office with the physics data necessary to conduct its case-level review. Chemotherapy quality control is usually carried out through retrospective review of submitted flow sheets, with determination of protocol compliance in dose administration and dosage modification. The criteria vary considerably from study to study and from Group to Group and depend heavily on the specific research questions addressed.