Thousands of patients throughout the country are expected to have X-rays cancelled today as a result of strike action by radiographers.

Radiographers who are part of the Apex union will walk off the job at 7am over a lack of progress in pay talks, and again for 24 hours on Wednesday. A third radiographers' strike will take place on 14 October.

Apex sonographers, who take ultrasound images, will walk off the job from Thursday to Saturday, and the following week on 11 October Apex lab workers will too.

DHBs say the series of strikes is no coincidence, but a coordinated campaign to cause maximum disruption to patients and increase pressure on DHBs over pay.

That's rejected by the Apex national secretary Deborah Powell.

DHBs have also said they expect 9927 X-rays to be cancelled today because of the strikes.

Northland DHB chief operating officer Paul Welford says the DHB had more than 30 MITs, and 70 percent of the DHB's lab staff were part of Apex.

He says any surgery on 30 September that required X-rays would need to be cancelled and re-booked.

"We'll have a skeleton staff on and we have a facility in place called life preserving services. So if someone needs acute surgery - they've had an accident and they need surgery immediately - or some other need for surgery, then we will be able to get those imaged.

"But everyone who's got planned surgery on that day, and who also might need imaging or X-rays, we'll have to reschedule them to another day when the strike is not on."

Paul Welford says the same thing would apply regarding surgery when the lab workers went on strike.

"The impact on both sets of patients is that they will be cancelled and rebooked and that means delay to their surgery which they will obviously be wanting."

Paul says some of these patients might already have been waiting for surgery for other reasons.

"So the impact is basically on delaying care and making people wait longer."

DHBs' lead negotiator for the Apex talks Nigel Trainor says 9927 X-rays were likely to be affected by the day-long strike.

He says that productivity would be permanently lost from the system.

DHBs' national contingency planner Anne Aitcheson says those in acute or urgent need would get the procedures they needed, under life preserving services agreements that were in place for the strikes.

She says those with non-urgent needs should delay going to hospital for an X-ray, but others might also be referred for X-rays at private providers if required.