"Before the new machine was installed in February, if the one machine we had broke down, patients were sent home until the technician arrived from Auckland," she said.
"A large percentage of our population are from the Mid and Far North. Some of these women travel large distances to their appointment, and if it was cancelled they would have to come back, which could delay their diagnosis."
Radiologist Kim Shepherd said having the additional ultrasound had been especially helpful during their Thursday assessment clinics.
"Patients often need longer ultrasound appointments than anticipated. Before, we were conscious that patients were sitting in the waiting room and often stressed. Now we can spend the extra time assessing, knowing the other radiologist can get on with other appointments using the second machine," she said.
The new ultrasound also provided more functionality and better picture quality, which Shepherd said was important for large-breasted women, and vital in Northland.
Miller said the clinic was "exceptionally grateful" for the foundation's donation.
"Women comment on how well cared for they feel coming through the assessment clinic and what a difference it makes, so this has made it even better," she said.
More than 160 Northlanders were diagnosed with breast cancer every year, and around 25 died of the disease.