Radiation therapy has resumed at Waikato District Health Board, following a cyber-attack which crashed the complex computer-driven treatment on May 18.

And a director of cancer services at Waikato DHB does not believe the condition of cancer patients has worsened after the cyber-attack shut down the treatment for more than two weeks

Twenty-one patients received radiation therapy at Waikato Hospital on Monday as systems were brought back online, says Waikato DHB director of oncology services Alex Gordon.

Around 74 patients remain in private hospitals in Tauranga and Wellington, and will continue radiotherapy treatments there for the time being.

Alex expects those patients could come back to Waikato DHB by the end of next week.

'We will look at it on a case-by-case basis, to see what is best for patients, but I think we will need to do some continuous treatment this week, and we will be fully up and running here this time next week.”

Alex says he did not think any radiation patients' health conditions had worsened due to the disruption from the cyber-attack.

'We put in place appropriate clinical pathways for our most urgent patients; we had the senior medical team review every single patient.

'We don't believe any patient would have been majorly negatively impacted, certainly inconvenienced, but not with a radically different clinical outcome.”

Teams of medical staff – including radiation therapists, medical physicists, nurses and doctors – accompanied patients to both Tauranga and Wellington to continue their treatment.

Medical staff had 'gone above and beyond” in the unprecedented attack, working long hours and staying in different parts of the country to ensure patients had the best care.

The 21 patients seen on Monday were just starting rounds of treatment, says Alex.

Radiation therapy is 'one of the most complex services” in the hospital, as four machines delivering the therapy, linear accelerators, run on software which could not be used in the wake of the cyber-attack.

Each linear accelerator is a multimillion-dollar investment and two of the four had been restored.

In a statement, DHB chief executive Kevin Snee says restarting radiation therapy was 'an important milestone for many staff”.

'Being able to again provide this important service for our community here in Waikato is a great reward for all the hard work of our IT, support and clinical teams.”

Kevin says other services were expected to be back online this week, including the inpatient management system and diagnostic services involving the radiology and laboratory services.

The cyber-attack, which struck the DHB in the early hours of May 18, crippled hospital IT systems across the region.

All computers and phone lines were down, meaning medical staff had to resort to pre-electronic systems and could not access patient files.

Radiation oncology clinical director Dr Cristian Hartopeneau​ previously told the media the department was in 'complete darkness” after the cyber-attack began.

Ellen O'Dwyer/Stuff.