Bruker D2 PHASER - Tissue Sensitivity; Prompt and Delayed Effects; Delayed Effects of Radiation Exposure; General Physical Principles

User Manual D2 PHASER
DOC-M88-EXX141 V5 – 01.2015 26
Tissue Sensitivity
In general, the radiation sensitivity of a tissue is:
 proportional to the rate of proliferation of its cells
 inversely proportional to the degree of cell differentiation
For example, the following tissues and organs are listed from most radiosensitive to least
radiosensitive:
Most Sensitive:
 Blood-forming organs
 Reproductive organs
 Skin
 Bone and teeth
 Muscle
Least sensitive:
 Nervous system
This also means that a developing embryo is most sensitive to radiation during the early stages of
differentiation, and an embryo/fetus is more sensitive to radiation exposure in the first trimester than
in later trimesters.
Prompt and Delayed Effects
Radiation effects can be categorized by when they appear.
 Prompt effects: effects, including radiation sickness and radiation burns, seen immediately after
large doses of radiation delivered over short periods of time.
 Delayed effects: effects such as cancer induction that may appear months or years after a
radiation exposure
Delayed Effects of Radiation Exposure
Cancer
Studies of people exposed to high doses of radiation have shown that there is a risk of cancer
induction associated with high doses.
 The specific types of cancers associated with radiation exposure include leukemia, multiple
myeloma,
 breast cancer, lung cancer, and skin cancer.
 Radiation-induced cancers may take 10 - 15 years or more to appear.
 There may be a risk of cancer at low doses as well.
General Physical Principles
Production of X-rays
X-rays are photons that are emitted when electrons strike a metal target and interact with the electrons
orbiting the nuclei of the metal atoms. The electromagnetic waves in the λ-range 0.1 - 2 Å are emitted
in all directions.
In X-ray tubes, electrons are emitted by a heated cathode, accelerated, and strike an anode material.
The cathode consists of a tungsten filament. For the generation of X-rays, high voltages of 20-60 Kv
are required. Much of the energy supplied to the tube is transferred to heat, while less than 1% of it is