FLYING HOME after a two-week break, a happy chance to introduce 2-year-old Annie to old friends, I find myself breathing a quiet sigh of relief. My slightly irrational, but nonetheless persistent fear that I might have a brain tumor has begun to lift. In the duty-free shop, I suddenly realized that my memory is working again. I had actually recalled the name of a perfume for a friend -- one last mentioned three years ago.

I am relieved, but a bit chagrined: Maybe the memory loss I've been worrying about for almost a year is really no more than fatigue and overwork.

In December I saw a doctor, who told me working too hard was the problem. But like most of us, I craved more tangible reassurance, and debated the costs and benefits of a CAT scan of the brain -- $300 and some radiation risk versus better information.

If it were only a small tumor, I'd argued with myself, I might actually survive with surgery. I'd like to be around to see my daughter lose her baby teeth, climb a tree, throw her first softball.

"Look, you really don't need any tests," the doctor reassured me. "But if you must have a scan, you don't need to be exposed to the radiation -- we can do magnetic resonance imaging, and there's no known danger," It's the latest technology, and it costs $700 a shot.

I was comforted by the reassurance -- he's a very careful, very good doctor -- but not entirely convinced. On good days, I'd ignore the nagging worry; on bad ones, I got as far as the phone, but never quite scheduled the test. Then vacation intervened. After two weeks away, I'm almost convinced I avoided an unnecessary medical expense.

But if it's this hard for a physician to cope with the anxiety that accompanies a worrisome change, and to resist the potential comfort offered by technology, how can we expect others to?

Technology is immensely seductive. As someone who'd be twice dead if it weren't for the surgical and anesthetic developments that permit removal of a perforated appendix and Caesarean delivery of a baby unable to emerge on its own, I'm grateful and enamored of it.

I feel terrific that half the children who get acute leukemia are surviving it now -- it wasn't much more than 20 years ago that nine out of 10 succumbed to the disease. And ventilators and cardiac-support equipment developed during that same period are keeping kids alive after they accidentally swallow poisons, helping them survive until their systems are rid of toxins that can paralyze muscles and nerves. And I'm glad that our well-equipped hospital was close enough to provide rapid and effective support when the president was shot.

But I know that the same machines which preserve lives we value immensely can serve to support the dying remains of other unfortunate souls at tremendous cost.

And I know, too, that we cannot afford to maintain so many hospitals that there will be one no more than 15 minutes from anyone with any life-threatening injury.

I know if we want to cut health care costs significantly, some of those hospitals and some of those machines will have to go. How many? Which ones? Who should decide? I'm not sure we, as doctors, ought to be the ones we count on for a plan. It's often hard enough for us to figure out how to deal effectively with the technology we have now. Sometimes the technology of medicine seems so complicated I'd rather throw up my hands and depend upon intuition. Last week, for instance, a young woman came to the emergency room, frightened by intermittent pains in the back of her chest when she took deep breaths. She'd lain in bed almost a week, dizzy and weak with heavy bleeding from the uterus. Three days earlier, after pills had failed to stop the bleeding, she'd been given a hormone shot.

Because she was using birth control pills, which increase the risk of blood clots that could lodge in the lungs, cutting off oxygen to parts of the body, we put our technology to work. We tested the oxygen content of her blood. It was found to be so low the first time that the doctors didn't trust the test result. It was repeated twice, with improvements each time, but never became normal.

So a radioactive isotope lung scan was ordered. It carries little risk. The radiologist interpreted her scan as low in probability for a lung clot, but not entirely normal.

The emergency-room doctors called me to admit the woman to my service. They wanted to schedule an arteriogram of her lungs -- a more invasive test which has a risk of bleeding, injury to blood vessels or a reaction to the dye used -- to determine definitively if there was a clot.

A lung clot can be fatal. But we still won't choose to treat unless the diagnosis is proven, because anticoagulant medicine itself carries a risk of bleeding -- worrisome in a woman with that problem already -- and requires a 10-day hospital stay.

The woman -- a pleasant, sensible person with two children -- was actually more upset that one of the doctors she'd seen the previous week had told her she had been overreacting. She was less frightened by the pain than she was upset by the nausea, dizziness and palpitations following on the heavy bleeding and the hormones. She told me she'd only been short of breath when she tried to walk around, and she described pain that was much more like the back strain you might expect after a week in bed than like the pain of a lung clot.

She was breathing oxygen the emergency room had given her. When I asked if she thought she needed it, she told me not at all.

I was convinced the symptoms resulted from the back pain, the anemia and her emotions that had been jangled badly by the hormones. But how to explain the tests?

We asked to have the lung scan reread, and a more senior person told us to him it looked entirely normal. But the lung specialists could find no other potential cause for those low blood-oxygen levels, widely varied as they were. Finally, we all agreed to recheck that test, because the woman simply had not looked sick enough to have that degree of oxygen depletion.

The resident drew another blood gas sample, and we all crossed our fingers. This time, it was normal. We concurred that the earlier results might have represented a laboratory problem. No arteriogram, and the woman was able to return home.

We hope our intuitions were right and the technology was wrong. But I'm left with a nagging worry in the back of my mind: what if we were wrong? Should we have done that arteriogram? Other times, I have used the technology and regretted it. Seeing the bills mount when you have an inkling of what's wrong with someone, but cannot convince the person without expensive testing can be equally frustrating.

A woman from Salvador came to my clinic, referred by a friend. She had no insurance, and earned very little. We were happy to see her at a reduced fee -- $5 per visit. But our bills became a joke compared to the cost of what we ordered in the way of tests.

She complained of dizziness and irregular heartbeat occurring several times a week. Young and healthy, she had no similar problem in the past. Now, when her heart raced, she almost passed out.

We examined her and found no problem. We suspected the symptoms were psychosomatic -- an anxiety reaction which might have to do with the family who remained in Salvador during this terrible time for that country. But she did not believe it. We sent her out for two weeks, urging her to exercise regularly and to keep a diary of her symptoms. We hoped they'd disappear with the stress-reducing benefits of exercise and our focus on fears for her loved ones as a possible cause.

But the attacks became more frequent, and she was scared. We did an electrocardiogram, which was normal, and checked the function of her thyroid gland, also normal, because those tests might indicate the cause of palpitations in a young person. Again we discussed with her personal and family concerns, but each time she told us her only worry was her heart.

Finally we ordered an echocardiogram -- a sound-wave test that can identify a relatively benign defect in a valve of the heart that could cause such symptoms. It, too, was normal, and so were some urine tests for gland problems.

The tests did no harm. And they did reassure her. But, unfortunately, they cost money. When I phoned with the results of the last of them, about six weeks after we had met, I hit paydirt. The dizziness and palpitations had disappeared -- to be replaced by a sinking, doomed feeling about her life and those of her relatives. Finally, she was able to accept reassurance that the problem, while real, was not physical. The symptoms disappeared entirely.

The cost? About $20 for the office visits -- and more than $200 for the tests. We believed from the start that she'd had no serious physical problem. But to protect her from the possibility that we might be wrong, and to protect ourselves from worry about malpractice, which concerns us all, we ended up costing this woman money she could ill afford. Yet I could not have brought myself to simply mutter to a woman who was going through mental tortures I could not begin to understand, "Anxiety attack; take a pill." Fortunately, this kind of technological overkill probably occurs rarely, compared to the extraordinarily exciting and effective uses to which some of our new technology can be put. Take digital subtraction radiology, for example. Imagine a picture of the skull and the brain. Subtract it from a second picture which also contains a small amount of dye circulating through the blood vessels in the head. Everything but the blood circulation disappears -- and you get a clear picture of a stroke or a swollen blood vessel that might burst.

Or consider positron emission tomography -- it can not only show blood flow to organs in the body like the heart or brain, but it can show as well how effectively those organs are using the blood. It's the only technique we have that can demonstrate some of the effects of Alzheimer's disease on the brain, and it's being explored as a technique to diagnose schizophrenia as well.

Since I completed medical school, CAT scanning has changed dramatically from what seemed a miraculous, but relatively clumsy way to look inside the brain to a technology precise enough now that it can reveal everything from slipped discs to tumors as small as one-50th of an inch in diameter. If colors are assigned to the different electronic intensities perceivable by CAT scan, even more can be seen: make fatty tissue appear yellow, for instance, and benign, fatty tumors can be diagnosed entirely without surgery.

Magnetic resonance imaging, however, probably has people more excited than any other diagnostic technique at this time. It, too, shows cross-sections of the inside of the body, but it provides, as well, a chemical analysis of what it images. It can identify multiple sclerosis -- which cannot be seen with any other diagnostic tool in this definitive way -- and it can even pick out fatty deposits of arteriosclerosis on the walls of arteries. It can show the effects of a heart attack as it is happening.

Even more fantastic -- more difficult for me to imagine -- is the development of the genetic technology that may alter every medical discipline. Monoclonal antibodies are being created which will search out and destroy cancer cells; these immunologic products can be labeled with radioactive isotopes, and injected into the body of a person with a cancer against which those antibodies are active. As the antibodies locate and attack cancer cells, nuclear medicine scans can track the spread of the disease.

It's easy to understand why a doctor less than five years out of training might feel over the hill, in light of the amazingly rapid pace of these technologic changes.

And it becomes clear why medicine is ripe for computer programming. Dr. Jack Meyers of the University of Pittsburgh says master chess players can only memorize 55,000 moves, while our medical students are supposed to cope with the 180,000 to which we expose them. We internists supposedly have 300,000 at our fingertips.

But the physicians with whom I work are reassuring. They recognize, and so do I, that while computers may help us out with identifying and evaluating the information we need to do our jobs, we're still the experts at helping people cope with the complex and confusing medical system they traverse when they become sick. And we're the ones who have to deal with people's emotional and psychological reactions to their physical problems. I don't think any machine will be able to do that in my lifetime, at least.

All this technology is exciting, and it raises wonderful possibilities. But it costs money. In fact, if you ask doctors why medical care is so expensive, technology is the first answer you'll get.

Sometimes the need for it arises from a desperate situation. Expensive research programs had to be geared up, for instance, to identify the cause of, and produce a vaccine against, AIDS, which is universally fatal and may -- if we do not intervene -- threaten millions of us.

To me, that kind of research expenditure obviously makes sense. And I'm sure most of us would support spending for research to find cures for cancer, or ways to help ease pain. But research does eat up dollars, just as does applying the technology we have found to be useful.

For doctors, that's where the dilemma begins. Unless we're willing to limit the availability of technology, and to close down some of the hospitals where it is used, we cannot cut our national medical costs very significantly. But if we do want to do that, how do we approach it? Do we want to refuse dialysis for the elderly? Do we want to give artificial hearts or liver transplants only to those with cash-in-hand? Shall we raffle them off in a lottery? There was an early attempt in many cities to limit the number of CAT scanners in order to contain the proliferation of what was then considered expensive new technology. In the 1970s, the Veterans' Administration Hospital here in Washington, for instance, had no scanner.

Getting a scan done meant red tape and delays of as much as 24 hours at that time -- when at the university hospital, it could be done in an hour. That probably saved money, but it didn't save veterans.

When I interned at the VA, a man was transferred to my service who I had been told was stable. Yet I found him barely conscious and leaing heavily to one side in the wheelchair. It did not take much examination to conclude from the bruises on his head and hip that he'd fallen, and I was suspicious that he'd suffered internal bleeding in the brain. After unsuccessfully attempting to arrange an emergency trip elsewhere to get a CAT scan, I rather outrageously took matters into my own hands.

With two medical students, I actually rolled the man out of the VA, across the parking lot and into the radiology department of the hospital next door, where a very good and a very nice radiologist willingly did an emergency scan for us, free.

It confirmed our suspicion; he'd had a massive bleed in his brain. Eventually, it killed him. Meanwhile, I got roundly and well-deservedly chewed out for risking adding to his injury by taking him on that wild ride outside the hospital. But it's dreadfully hard to watch a person die when you know the technology exists to diagnose the cause, and in some cases, permit surgical intervention that might save him.

Do we really want to cut costs that much?

People have to understand that substantial decreases in what we spend for medical care means that people like themselves will be affected. If not, we may be shortchanged -- not so much in dollars as in fairness, caring and concern for one another.

It makes perfectly good sense to me to attempt to improve the efficiency of our system and to reduce the waste in it. But makes even more sense, I think, to create some kind of national forum in which our country's health-care options can be explored, so that the choices we make are reached after some thought to what they'll mean to all of us. It seems easier to live with what you choose than with that which is imposed finally by chance or by thoughtless circumstance.