A good way to think about this is to consider how to begin your speech with something that will make your audience sit up and take note. Don't be tempted to do the normal: "Good afternoon, ladies and gentleman. This afternoon I am going to talk to you about..." As effective as this kind of opening can be in terms of introducing the subject, come up with a different way of doing it. Don't be tempted to be normal and therefore boring. Introduce your topic but in a different and novel way.
How about a story of a famous technical surgeon? Or what is it that attracts you to the job? You might want to highlight a situation or a scenario faced by a technical surgeon each day and ask your audience to put themselves in that scenario. How would they feel? How would they respond? That would be an incredibly effective and different opening. So, think about what it is that attracts you to this career. If you are able to identify some points that will help you in turn to convey your enthusiasm and excitement for the role. Good luck!
Personally, I enjoy analogies that highlight the job.
For example, "Remember the medical TV shows you'd watch and the surgeon would always say 'sponge' or '10 cc's of sedative, STAT!' or 'here, hold the retractors open here; this is going to get fiddly'. Well, these jobs belong to surgical technicians, who are always right up in the action zone. Interested?"
Or something. I dunno, just a thought.
Have fun writing!