You may do a ratio analysis survey of other hospitals who are your competitors e.g you may calculate nurse to bed ratio for OT, no of technicians per patient, etc.
You may get hold of such indices from any good book on hospital management. Accordingly prepare a questionnaire and approach other hospitals. You may take the help of trainees for this project.
Also take your budget into consideration and simultaneously do a salary survey. For this you will have to do a lot of probing around on your own.
Lastly after you get all this data in an excel sheet you may draw up a prospective organisation chart depicting report relationships just for the OT.