Table 4.

Sample comments and responses from external validation of the MLA (Medical Linear Accelerators and MLC) TQC guideline. Test acronyms are defined in parentheses

Comment from External Validation Center	Response from Expert Reviewers
Test DL7 (Room radiation monitoring system): We believe that this system adds no benefit to security, nor quality, bearing in mind economic considerations, and should not be encouraged by the TQC guidelines. We suggest removing the test from TQC guideline. Similar comment received from a second institution during external validation.	Action taken: Review of federal regulations show no requirement for an in independent radiation room monitoring system for linear accelerators. The test has been removed from the TQC guideline.
Citing an example procedure may clarify the implementation of certain tests. For example, it was not exactly clear from the description how Test AL14 (Coincidence of axes of rotation) and Test AL15 (Coincidence of radiation and mechanical isocentre) differ. The names may be mismatched from the description and the technical details of implementation could be clarified.	Action taken: Test descriptions changed to clarify that AL14 (Coincidence of radiation and mechanical isocentres) refers to the independent congruence of the radiation and mechanical isocentres for collimator, gantry and couch rotation, whereas Test AL15 (Coincidence of axes of rotation) refers to the diameter of the sphere that encompasses the mechanical axes of rotation of the collimator, gantry and couch.
Test AL1 (Profile reproducibility): The test description note does not specify the depth of measurement for electron beams, while it does for photon beams. We suggest specifying for both or remove it for photons.	Action taken: Specification of depths removed.