How Theoretical Physics Helped Advance Medical Science

When you think about theoretical physics, it’s easy to say that most of us assume that there are fancy scientists dressed in lab coats conducting experiments with top-secret organizations and projects. However, physics isn’t just happening in a lab, rather, it can be applied to a variety of disciplines, including medicine. Whether it’s pharmaceuticals or testing up-coming technologies, medical and biomedical physics are in charge of many of the modern advances in medicine.

The medical physic field uses physic theories, methods, and concepts, applying them to the healthcare and medicinal field. An individual who’s a practitioner in medical physics is known as a “Medical Physicist”. Their role is focused on improving and maintaining healthcare processes and patient health. These processes are divided into eleven different areas:

1.Expert consultation

Education for healthcare professionals
Occupational and public safety
Innovation
Dosimetry measurements
Clinical Involvement
Clinical medical device management
Health technology assessment
Service quality development
Patient safety
Scientific problem solving

In experimental medicine, physics is also applied as well and is under the are of “Biomedical Physics.” In leading world-class universities around the world, there are departments under both Medical and Biomedical Physics. These departments allow for cutting-edge research to flourish.

For Medical Physics, one of the most common applications of the field is diagnostics and interventional radiology. This includes x-rays, ultrasounds, fluoroscopy, mammography, MRI, and so on. The creation and use of these applications are possible because of particle accelerators which are responsible for the functioning of PET scans and cancer radiotherapy. These accelerators are also used in hadron therapy which is a form of radiotherapy that uses beams of proton particles. These charged proton particles penetrate through body tissue, attacking malignant tissues such as tumors. By directly attacking malignant tissues, it doesn’t irradiate the entire body’s healthy tissue. This form of therapy is only used in 40 hospitals around the world due to the high costs, however, it’s effectiveness is proving to help over 60,000 patients worldwide and continues to advance through Medical Physics.

PET scans or also known as Positron Emission Tomography uses particle physics to recognize radioisotopes which deteriorate via positron emission and is used as tracers in the body. These tracers are mixed with dye, which, once in the scanning machine, are able to aid doctors by measuring blood flow, glucose metabolism, oxygen use, and other factors which aid in measuring organs and tissue function. X-rays also work in a similar manner since they use high-frequency electromagnetic waves in order to penetrate through the muscle and tissue, forming 3D images of the body. In addition, if they’re passed through an x-ray detector outside of the body, they’re able to detect abnormal shadows. X-rays are ideal for detecting abnormalities including, dental issues, calcifications, masses, and pneumonia - all issues which have been that much easier to detect through the help of X-rays. X-rays continue to increase the quality of healthcare, removing invasive procedures and methods such as probing and surgery.

Other physics-related technological advancements include the field of Nuclear Medicine where they use gamma-emitting radiotracers for single-proton emission tomography, also known as SPECT scans. SPECT scans are designed by using a gamma camera which records images through a series of angles of the patient. Then, with those recorded camera angles, they create a crossed-sectioned 3D image which shows how the organs are functioning within the body. For example, they can show blood flowing through the heart or the activity level in areas of the brain. SPECT images also use radioactive isotopes that have longer half-lives in comparison to PET scans and are more common and less costly. SPECT scans are used particularly for brain disorders, seizures, head injuries, epilepsy, and clogged blood vessels. In addition, they’re also ideal for detecting heart conditions such as clogged arteries and tumors.

Radiation therapy is another commonly used medical application of physics and is used in proton therapy, LASIK, Gamma Knife, boron neutron capture therapy, and CyberKnife. For example, Gamma Knife is used by focusing 201 beams of radiation on malignant tissue which provides treatment directly on a single area. As an individual beam, they’re too weak to affect healthy tissue, however, when they’re grouped together and focused on one point, it’s highly effective for tumors. Similar to hadron therapy, Gamma Knife only targets cancerous tissues, avoiding to harm healthy tissue in the body, thus, it makes it an accurate and effective treatment option in comparison to traditional cancer treatment.

CyberKnife also works similarly as they also focus concentrated radiation rays onto tumors with extreme precision to less than one millimeter. Proton therapy uses high-energy protons which are positively charged particles which focus and eliminate cancer cells with around 60% lower radiation than x-rays. Like hardon therapy, this form of treatment is small, however, is increasing in popularity.

LASIK also known as Laser-Assisted In-Situ Keratomileusis surgery is best known as laser vision surgery. Though many may not notice, it involved physics. This surgery uses ultraviolet excimer laser (UV laser) which uses dimers. Dimers are hyper, unstable molecules of inert gas and halogen, fluorine or argon. As Physics Central states:

"With the argon and fluorine confined in a tube capped with mirrors, one of which allows some light to escape, the result is an intense UV laser beam. Excimer lasers, unlike the familiar ones in bar-code readers, are pulsed—they pack their output into short bursts about 10 nanoseconds long (10-8 sec). This pulsing makes it ideal for eye surgery, because the intense pulses vaporize tissues without heating the rest of the eye. The UV light is absorbed in a very thin layer of tissue, decomposing that tissue into a vapor of small molecules, which fly away from the surface in a tiny plume."

Since the eye lens is coated in a fluid, minimal light can be refracted, thus LASIK is necessary to reshape the cornea and increase vision. LASIK surgery is extremely popular and is highly accurate with only 5% of patients experiencing side effects.

In conclusion, physics is continuing to push the advances in medical technology and techniques, is responsible for increasing precision and efficiency in the healthcare field. Medical Physics is increasing its focus on the field and eventually, physicists will find even more ways of applying physics in healthcare. It’s clear through modern technology that physics is continuing to push boundaries and save lives.