Medical Physics

Teacher: Shengqin Feng
Professor of Physics

Tel 6392698 13972540759
：

email: fengsq@ctgu.edu.cn

Chapter 1
Introduction and
Background to Medical
Physics

Part I Introduction to physics
The concepts ( 概 念 ) of physics, the relations between physics and medical science, the significance of learning
Medical physics
Part II Introduction to Fundamental mathematical background
This part is also important as physical ideas are expressed by mathematical formulas. Generally speaking, if you would like to be good at physics, you have to be good at mathematics.

1.1 An introduction to physics
1.1.1 What is physics?
(1). Physics is a branch of science. The main goal
(目标）of physics is to seek out (找出) and to understand the basic Laws of nature upon which all physical phenomena depend.

(2). Physics is based on mathematics and experiments. Classical physics traditionally includes mechanics (力学), optics (光学), electricity and magnetism, acoustics (声学) and heat.
Modern physics, based on quantum theory, includes atomic physics, semiconductor physics, nuclear physics, laser physics (激光
物 理 ), superconductive physics, particle physics and solid-state physics.

Northern lights

cruise missiles, fighters, weapons, radars, sonar system, nuclear fuel, antimissile system, torpedo and so on

(3). Medical Physics is the cross subject between the medical science and modern physics. Our textbook is so called Medical physics, but it is not matched to the definition world-wide. According to the contents in our textbook, it should be called “Fundamental physics and its applications to medical science”. Medical Fibrescopes

Videolaryngoscopy with a flexible fiberscope Gamma rays, x-rays, laser and so on

1.1.2 The methods of studying physics
Observations and measurements
Models
Theories, Laws and Principles

Measurements to test theories

NO
Yes

Good?

•

Models:

When scientists are trying to understand a particular set of phenomena, they often make use of a model which is a kind of mental image of the phenomena in term of something we are familiar with.

tropic of
Capricorn

tropic of cancer Baseball model

Wave model of light

Laws and principles

Theories and Models

Planetary model of atoms

1.1.3 Physics and its relations to other fields
Physics has been applied to many other fields and a lot of new subjects based on physics are formed such as chemical physics, physical chemistry, biophysics (生物物理学）, astrophysics （天体物理学）, geophysics
（地球物理学）, medical physics （医学物理
学）and so on.

Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus, Neptune (8_plenets)

Ultraviolet radiation of the Sun
About a million K temperature

Space_shuttle

Hydrogen Bomb

MedicalPhysics
The application of physics to the medical science is the main branch of physics applications to other fields.
The physical application to medical science are such that

ultrasound （超声波）, X-rays （X－射线）, optical microscope (光学显微镜), electronic microscope,
NMR-CT (Nuclear Magnetic ResonanceComputerized Tomography 核磁共振-计算机
化X射线层面摄影术)， Low temperature technology (低温技术)，microwave (微波)，
Laser (激光), CT－Scanner (an X-ray machine which can produce stereographic image, 能够产生立体摄影图像的X光机)

1.2 Physical Backgrounds
1.2.1 Physical concepts
Physical quantities and units;
Precision and significant figures;
Scientific notation.
1.2.2 Mathematical backgrounds
Vectors 矢量 (addition, components, products); Calculus 微积分

1.2.1 Physical concepts (物理概念)
(a) Quantities
Any number or set of numbers used for a quantitative description of a physical phenomenon is called “physical quantity (物理量) ”.
Fundamental
physical quantities used in International System of Units (SI) (Système
International) are Time (s), Length (m), Mass (kg),
Electric current (Ampere, A), Temperature (Kelvin,
K), Amount of substance (mole, mol.),