Medical physics (also called biomedical physics, medical biophysics or applied physics in medicine) is, generally speaking, the application of physics concepts, theories and methods to medicine or healthcare. Medical physics departments may be found in hospitals or universities.
In the case of hospital work, the term medical physicist is the title of a specific healthcare profession, usually working within a hospital. Medical physicists are often found in the following healthcare specialties: diagnostic and interventional radiology (also known as medical imaging), nuclear medicine, radiation protection and radiation oncology.
University departments are of two types. The first type are mainly concerned with preparing students for a career as a hospital medical physicist and research focuses on improving the practice of the profession. A second type (increasingly called 'biomedical physics') has a much wider scope and may include research in any applications of physics to medicine from the study of biomolecular structure to microscopy and nanomedicine. For example, physicist Richard Feynman theorized about the future of nanomedicine. He wrote about the idea of a medical use for biological machines (see nanobiotechnology). Feynman and Albert Hibbs suggested that certain repair machines might one day be reduced in size to the point that it would be possible to (as Feynman put it) "swallow the doctor". The idea was discussed in Feynman's 1959 essay There's Plenty of Room at the Bottom.
"Medical Physicists will contribute to maintaining and improving the quality, safety and cost-effectiveness of healthcare services through patient-oriented activities requiring expert action, involvement or advice regarding the specification, selection, acceptance testing, commissioning, quality assurance/control and optimised clinical use of medical devices and regarding patient risks and protection from associated physical agents (e.g., x-rays, electromagnetic fields, laser light, radionuclides) including the prevention of unintended or accidental exposures; all activities will be based on current best evidence or own scientific research when the available evidence is not sufficient. The scope includes risks to volunteers in biomedical research, carers and comforters. The scope often includes risks to workers and public particularly when these impact patient risk"
The term "physical agents" refers to ionising and non-ionising electromagnetic radiations, static electric and magnetic fields, ultrasound, laser light and any other Physical Agent associated with medical e.g., x-rays in computerised tomography (CT), gamma rays/radionuclides in nuclear medicine, magnetic fields and radio-frequencies in magnetic resonance imaging (MRI), ultrasound in ultrasound imaging and Doppler measurements.
This mission includes the following 11 key activities:
Some education institutions house departments or programs bearing the title "medical biophysics" or "biomedical physics" or "applied physics in medicine". Generally, these fall into one of two categories: interdisciplinary departments that house biophysics, radiobiology, and medical physics under a single umbrella; and undergraduate programs that prepare students for further study in medical physics, biophysics, or medicine.
Medical imaging physics is also known as diagnostic and interventional radiology physics. Clinical (both "in-house" and "consulting") physicists typically deal with areas of testing, optimization, and quality assurance of diagnostic radiology physics areas such as radiographic X-rays, fluoroscopy, mammography, angiography, and computed tomography, as well as non-ionizing radiation modalities such as ultrasound, and MRI. They may also be engaged with radiation protection issues such as dosimetry (for staff and patients). In addition, many imaging physicists are often also involved with nuclear medicine systems, including single photon emission computed tomography (SPECT) and positron emission tomography (PET). Sometimes, imaging physicists may be engaged in clinical areas, but for research and teaching purposes, such as quantifying intravascular ultrasound as a possible method of imaging a particular vascular object.
Radiation therapeutic physics is also known as radiotherapy physics or radiation oncology physics. The majority of medical physicists currently working in the US, Canada, and some western countries are of this group. A radiation therapy physicist typically deals with linear accelerator (Linac) systems and kilovoltage x-ray treatment units on a daily basis, as well as other modalities such as TomoTherapy, gamma knife, cyberknife, proton therapy, and brachytherapy. The academic and research side of therapeutic physics may encompass fields such as boron neutron capture therapy, sealed source radiotherapy, terahertz radiation, high-intensity focused ultrasound (including lithotripsy), optical radiation lasers, ultraviolet etc. including photodynamic therapy, as well as nuclear medicine including unsealed source radiotherapy, and photomedicine, which is the use of light to treat and diagnose disease.
Nuclear medicine is a branch of medicine that uses radiation to provide information about the functioning of a person's specific organs or to treat disease. The thyroid, bones, heart, liver and many other organs can be easily imaged, and disorders in their function revealed. In some cases radiation sources can be used to treat diseased organs, or tumours. Five Nobel laureates have been intimately involved with the use of radioactive tracers in medicine. Over 10,000 hospitals worldwide use radioisotopes in medicine, and about 90% of the procedures are for diagnosis. The most common radioisotope used in diagnosis is technetium-99m, with some 30 million procedures per year, accounting for 80% of all nuclear medicine procedures worldwide.
Health physics is also known as radiation safety or radiation protection. Health physics is the applied physics of radiation protection for health and health care purposes. It is the science concerned with the recognition, evaluation, and control of health hazards to permit the safe use and application of ionizing radiation. Health physics professionals promote excellence in the science and practice of radiation protection and safety.
Some aspects of non-ionising radiation physics may be considered under radiation protection or diagnostic imaging physics. Imaging modalities include MRI, optical imaging and ultrasound. Safety considerations include these areas and lasers
Physiological measurements have also been used to monitor and measure various physiological parameters. Many physiological measurement techniques are non-invasive and can be used in conjunction with, or as an alternative to, other invasive methods. Measurement methods include electrocardiography Many of these areas may be covered by other specialities, for example medical engineering or vascular science.
Non-clinical physicists may or may not focus on the above areas from an academic and research point of view, but their scope of specialization may also encompass lasers and ultraviolet systems (such as photodynamic therapy), fMRI and other methods for functional imaging as well as molecular imaging, electrical impedance tomography, diffuse optical imaging, optical coherence tomography, and dual energy X-ray absorptiometry.