Shedding light on nuclear medicine

MANILA, Philippines - For over three decades since meeting my long-time physician, Federico B. Cruz, (a bachelor of arts graduate of Ateneo de Manila University, Doctor of Medicine, University of the Philippines, and master’s of science, University of London), I had only a vague notion of the medical subspecialty called nuclear medicine.

Recently, I took the opportunity to seek enlightenment on the subject, noting that Dr. Cruz chairs the Department of Nuclear Medicine of Medical Center Manila.

“Why,” I ask him, “did you choose nuclear medicine as a specialty and what is nuclear medicine?”

“At the time, when I finished my residency in internal medicine,” he replies, “nuclear medicine was a young specialty with very few experts in the field. I found it very convenient to train in endocrinology and nuclear medicine simultaneously under the earliest specialists in the field.”

His trainors then at the Philippine General Hospital included the Father of Nuclear Medicine in the Philippines Dr. Paulo C. Campos and pioneers like Dr. Leland Villadolid, Dr. Flora Pascasio, and Dr. Norman Gaffud.

Because nuclear medicine was a new specialty, Dr. Cruz pursued graduate studies at the University of London where he got his master’s of science degree in nuclear medicine.

“To answer your question on what nuclear medicine is,” he says, “it is a subspecialty of medicine which uses radioactive materials in the form of chemical or biochemical substances which are labeled with radioactive isotopes of certain elements. Minute amounts of these radioactive substances are used by injection into a patient’s vein or taken orally in order to study the images that represent the function of an organ of interest such as the heart or the thyroid gland.”

When a radioactive substance is concentrated on an organ of interest such as the heart, the image produced by the detection of gamma rays (using a detector instrument, usually the gamma camera) represents a functional image of the heart. A cardiac scan using 99m Technessium M1B1 or 201 Thallium can therefore demonstrate both the adequacy of blood flow and pumping ability of various areas of the heart.

Nuclear medicine, according to Dr. Cruz, offers treatment for various illnesses including goiter, thyroid cancer, and certain blood dyscrasias (when the constituents of the blood are abnormal as in leukemia).

At present, the most common nuclear imaging procedures requested are: imaging of the heart muscles for blood flow and functions, study of the kidneys’ functional anatomy; study of the function and localization of the endocrine organs, and functioning tumors (including the function of the thyroid, overactive or not, or nodules in it); examination of bones for fracture, infection, arthritis, tumor or spread of cancer; lung imaging for respiratory and blood flow problems, determining if the gallbladder is inflamed; studying the density of bone in cases prone to fractures (osteoporosis), etc.

The equipment used in nuclear medicine for imaging is the gamma camera, a steel and lead encased detector head that measures radiation and, with the help of the computer, is capable of mapping out the functional anatomy of various body organs. Most detector heads can rotate around the patient and produce three-dimensional images. Radioimmunoassays use a small machine called a gamma counter, capable of counting accurately very small amounts of radiation. Most of these machines are automated and coupled also with computers to enhance their speed and accuracy.

The advantages of nuclear medicine procedures, notes Dr. Cruz, lie in their unique information, the functional data from the imaging studies, and the very precise results, both of which provide data which can facilitate diagnosis and plan of treatment for the patient.

“Imaging gives much more benefit for diagnostic results compared to more invasive procedures. In fact, the benefit of non-invasive imaging over surgical exploration is not only in the lower cost but in practically no morbidity for the patient,” he elaborates.

“The use of these procedures for more than 50 years shows there are no adverse effects associated with the use of very low doses of radiation, at times even lower than routine x-ray procedures,” he adds.

Dr. Cruz, whose patients flock to his clinic at the Medical Center Manila from all over the country, a clinical professor at the UP College of Medicine, Manila, must know whereof he speaks.

Nuclear medicine, at last, is no longer a mystery to us.