Appendix 5 of v3.7 of the generic Radiotherapy Dataset Manual describes the
OPCS 4.4 Codes.
I think that the description of X631 is wrong - it currently says "Vol.
Definition For Radiotherapy With Imaging/Dosimetry".
I think it should say
"Volume definition for radiotherapy with imaging and intensity-modulated
radiation therapy dosimetry"
Also - It would be nice if the manual also indicated that X633 should not be
used in the RTDS (because it refers to multiple phases, but using the
definitions we now have, each phase is a prescription and therefore should
have its own planning code).