The above manuscript was published with missing citations for Figures 1 and 2a. The following reference should have been included:
Dimitriadis A, Palmer AL, Thomas RAS, Nisbet A, Clark CH. Adaptation and validation of a commercial head phantom for cranial radiosurgery dosimetry end-to-end audit. Br J Radiol. 2017;90(1074):1-9. doi:10.1259/bjr.20170053
The authors apologise for this error which has now been corrected.