The Ministry of Health is reviewing a cancer treatment offered only at Dunedin Hospital.
Radiosurgery is a form of radiotherapy used to treat brain tumours and vascular malformations, by directing an intense beam of radiation to the head.
Dunedin Hospital has been the national treatment centre since 1994.
Last week, a ministry spokeswoman confirmed Outcome Management Services, a Wellington consulting firm, would carry out the review.
Terms of reference were expected next month.
Ministry of Health cancer programme national clinical director Dr John Childs said in a statement advances in technology meant radiosurgery could be used to treat more complaints.
"The ministry has initiated a review to assess the impact of these changes for radiotherapy services in New Zealand and options for future service-delivery models."
The Otago Daily Times unsuccessfully sought clarification of how the review could affect the Dunedin service, and was advised the review process itself did not affect Dunedin.
The request for proposal document issued by the Ministry of Health states the successful tenderer will provide recommendations regarding future service-delivery models, a recommendation of the most appropriate service-delivery model for publicly funded radiosurgery, and recommendations regarding improvements to the current delivery of radiosurgery, including what it is used to treat.
Southern DHB radiation oncologist Dr Shaun Costello declined to comment until the review's terms of reference were released.
In 2009-10, Southern performed 81 radiosurgery procedures.
