A military judge will rule today whether an officer in today's volunteer Army can stop serving once he decides the government has broken his contract.

"This is a difficult time and a different place in the military" with "a different soldier," said the civilian lawyer for Army Capt. Leon T. Davis, a doctor who stopped practicing on the ground the Army had breached his contract for services.

"Military status," countered the prosecution, "is like a marriage" which "takes legal action to terminate, not something you do unilaterally."

Davis, if convicted of all the crimes with which he is charged, could be sentenced to up to 3 1/2 years at hard labor. But, under a deal the defense and prosecution made with Maj. Gen. Kenneth E. Dohlemann, commander of the Military District of Washington who ordered Davis court martialed, the doctor's sentence would be kept to a minimum of six months.

Davis' lawyers spent most of yesterday trying to document the alleged breaches in the doctor's contract with the Army, including the failure to provide modern medical equipment as promised by recruitments and in Army advertising for volunteers.

Four radiologists from Walter Reed Army Hospital Center, where the 30-year-old Davis practiced as a resident radiologist before staging his sit-down strike, testified that some of Welter Reed's equipment is so old it poses a danger to patients.

Capt. Kathleen Dunne Eggli said the angiogram equipment at Walter Reed used for X-raying blood vessels is so poor that doctors often cannot see the pictures of what they are doing as they try to feed tiny tubes into a patient's blood vessels.

Then so-called "back room" in Walter Reed's radiological department is in "almost a continuous state of disarray." Eggli said in her sworn testimony. The equipment there is "extremely antiquated."

Because the X-ray pictures come out so murky, she continued, "you can't see the edge of the catcheter," the thin tube inserted into blood vessels as part of the diagnostic process.

Yet, she continued, a slip of the tube can provoke a stroke and, at the minimum, the faulty equipment exposes the patient to an inordinate dose at X-rays as procedures are slowed down.

The out-of-date radiology equipment at Walter Reed, she said, "certainly does increase the danger to the patient."

Eggli said Davis supervised her and other residents in radiology and displayed and extraordianry concern for the patients. He instituted policies to improve patient care, she said, including orders to read all the X-rays taken on a given day before quitting work rather than let the pictures pile up as had been the practice previously.

Maj. Stewart P. Axelbaum testified that Walter Reed was four years behind Georgetown University Hospital in getting advanced X-Ray machine called a CAT (computerized axial tomography) scan.

Stephen D. Keefe, Davis' civilian attorney, said that the government promised to provide doctors who joined the Army modern medical equipment and yet did not have it in its model hospital, Walter Reed. This was one of several breaches of Davis' countract Keefe argued.

A spokesman for Walter Reed said the hospital is in the process of moving into a new facilities and that the radiological department is one that has not yet been moved and modernized.

Army Surgeon General Charles C. Pixley, who was called as a witness by the defense yesterday, conceded the sevice's radiological equipment needs modernizing, calling this a "front burner" concern. He added that the Army has only about half the radiologists on duty that it needs.

Lt. Col. John W. Hanft, the military judge who heard the case after Davis waived his right to be tried by a military jury, said he will announce his verdict at 9:30 a.m. today. Davis is charged with desertion, going absent without leave, refusing to obey orders and missing his deployment to Korea.