To explain how physics can be used in medicine, the Physics Colloquium lecture on medical physics was given by Professor of Medical Physics at the University of Wisconsin–Madison Ronald Wakai, Ph.D. in Youngchild Hall 115 on Wednesday, Jan. 17 at 4:30 p.m.
Medical physics is related to biophysics, health physics and biomedical engineering, but is also its own distinct category of physics, explained Wakai. Biophysics is the study of biomolecular function, while health physics works with radiation safety and biomedical engineering applies engineering to medicine by making things like pacemakers. Medical physics, however, is the “application of physics to the practice of medicine” explained Wakai. Radiation therapy and medical imaging are main applications of medical physics.
Medical imaging consists of several different types of imaging which each produce slightly different results. X-ray imaging was one of the first forms of internal imaging used in medicine. An extension of x-ray imaging is fluoroscopy, which creates real time moving images of the interior of the body, which “spawned this huge area of interventional cardiology” stated Wakai.
Imaging was revolutionized by computed tomography which captures slices of the body by having an x-ray source rotate around the body. Nuclear medicine imaging includes two other types of tomography: simple-photon emission tomography (SPECT) and positron-emission tomography (PET). PET uses coincidence imaging which gives it better spatial resolution.
“The most versatile” form of imaging, stated Wakai, is magnetic resonance imaging (MRI). Another commonly used form of imaging is ultrasound imaging. Ultrasound is used often because it has many advantages, such as being both cheap and safe.
Radiation therapy is an area that frequently uses medical physics and employs many medical physicists. Around 60 percent of cancer patients receive radiation treatment. Many also receive chemotherapy, which is an active area of research for many medical physicists. Radiation therapy has many advantages in cancer treatment, such is that it is noninvasive, can be directed at specific tumors and also has no tolerance effects. Having no tolerance effects means that radiation therapy is very effective on tumors but has little effect on normal cells. There are also relatively few side effects of radiation therapy.
Wakai also discussed the role of clinical medical physicists. Many work in radiation therapy doing things such as treatment planning and dosimetry. Diagnostic imaging is one of the other main areas clinical medical physicists go into since the imaging machines require a medical physicist to make sure that they are functioning properly.
Wakai works mostly on using biomagnetism to detect epileptic spikes and he also works with cardiac electrical signals to detect fetal arrhythmia. Since fetal arrhythmia is a very rare condition, he works mostly in trying to accurately diagnose it.
The University of Wisconsin- Madison has one of the oldest and largest medical physics programs, since it was accredited in 1988 and produces 15 to 20 percent of all medical physics Ph.Ds. Wakai spoke about this program since he also works in admitting students to the Medical Physics Ph.D. program there, and encouraged students who might be interested to apply.