Tips for requesting imaging
Most hospitals have a simple form or computerised system that allows doctors and other practioners (as agreed locally) to request imaging tests. Different departments have different levels of stringency on patient details but it is better to put more than less. It is usual to have to put the patients address so that they can be identified when they reach the department. I have worked in departments where they refuse to do X-rays if the address is handwritten and need the sticker to be present and other departments where if a sticker is used the name needs to be written again by hand. Spending five minutes to familiarise yourself with the form and local procedures can save your blushes later when your consultant wants to know why the patient still hasn't had their x-ray yet (chances are the form has been rejected and is in the internal post waiting for you to correct it).
Justifying the investigation
Remember that the radiographers who you deal with are not simple technicians at your beck and call but trained practioners. For the majority of the tests (plain film AXR, CXR etc.) they are responsible for authorising the exposure of that patient to radiation following your request.
For that reason it is important that the clinical details contain enough information that they can be satisfied the exposure is justified. For example "abdominal pain, AXR" on its own is likely to be bounced back to you. This is because in this circumstance other investigations may be as useful without a radiation dose. However if there is a possibility the patient is "obstructed" then say so because a plain film AXR can be justified in those circumstance. You will tend to learn which phrases are useful for different investigations. (Never lie just to get the test - remember probity.) Sometimes you will be bleeped and your request queried, remember that the phrase "because my registrar/consultant wanted it" is not a clinical indication and may result in the awkward situation of you having to get your consultant to speak to the radiographer to finish your job off.
When do you want the test
Getting to know your radiology department can be very useful. You will know which radiographers respond only to requests as "urgent" or "routine" (and they're often the ones which will need some serious convincing to do an urgent test out of hours). Some can be more helpful and if you don't need a test instantly but perhaps by a particular time (e.g. consultant ward round) then if you go and ask then you can be amazed at how helpful they can be. If you can physically get to the radiology department it can be very helpful, and your request becomes that much more difficult to refuse. If you need anything urgently then I would advise that at the very least you ring the department.
In some departments the rate-limiting step can be the portering requirements of transporting patients to and fro. If your patient can walk then you may be able to get your x-ray quicker by sending the patient to the department with the request form rather than waiting for the porters to arrive with a chair. (Always ring the department first to ensure that they are able to accept the patient when they get there.)
Sometimes urgent tests need to be discussed with the radiologists. For these you will need to be particularly prepared so spend a moment or two reviewing the patients history before you go to the department and know exactly why you want that test and why so urgently. (My own flaw is filling in request cards on the ward round, carrying them with me and then popping to the department when I'm passing. On several occasions I've been caught out because I don't know my patients well enough.)
Interventional procedures will also generally need to be discussed, as in most hospitals there will only be a small proportion of the radiologists that do these, so discussion with somebody capable of doing the procedure is essential.