IVIS
®
Lumina XRMS Series III Hardware Manual
Chapter 5 | X-ray Safety and Radiation Hazards
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filter. When the filter is engaged and intersects the X-ray beam, the range of transmitted radiation is
from 5 to 40 keV with average intensity of approximately 25 keV and radiation from bremsstrahlung
attenuated. When the filter has been moved out of the beam path, the range of energy remains from
5 to 40 keV, but with very strong bremsstrahlung intensity at the10 keV energy level. The practical
affect of having these two energy settings is to provide a reduced dose when animal imaging (filter
in), but increased contrast when imaging tissue samples (filter out).
Lumina XRMS Series III X-ray Source Tube
The X-ray generating tube is located beneath the imaging chamber in a separate enclosure. The tube
is neither accessible nor serviceable by the user. The separate enclosure, called an electronics tray,
has a safety interlock switch design to make the X-ray tube inoperable if the tray is opened. The tube
and its integrated high voltage power supply are manufactured to PerkinElmer's specifications. The
tube is rated at 40kV high voltage potential with a maximum beam current of 0.10milliAmps. Total
power is 4.0 watts. The X-ray window is 0.127mm thick Beryllium and the X-ray target is tungsten.
X-ray tube control such as ON/OFF, and beam power settings are carried out by Living Image
®
software commands acting through an electronic X-ray controller. The controller is mounted on the
back of the IVIS Lumina XRMS Series III. Living Image also controls the IN-OUT status of the
aluminum X-ray filter.
5.3 Biological Effects of Radiation
Ionization Process and the Cell
X-rays are a form of electromagnetic radiation that has enough penetrating energy to ionize atoms
with in cell. Ionization occurs when an X-ray photon interacts with an orbital electron and transfers
energy to it, causing the electron to be ejected from the atom. Such ionizations may disrupt cellular
molecules such as DNA. A DNA molecule may be broken by the radiation and the cell may be
severely damaged, resulting in cell death. With enough cell death, tissue and organs may be damaged.
Injury to a living organism can also occur in indirect ways such as the creation of free radicals or
other ions. The deleterious effects of radiation exposure are classified into two categories:
deterministic effects and stochastic effects.
Deterministic Effects
Deterministic effects are effects in which a clear causal connection can be made between the
exposure to radiation and the effect. Deterministic effects are the result of cell killing and tissue
damage. This effect is dose related, and a certain threshold of radiation dose needs to occur so that a
large enough number of cell deaths occur for the tissue to be damaged. After the dose threshold is
exceeded, the severity of the effect is increased by the amount of the dose. Skin reddening is one
example of a deterministic effect resulting from radiation exposure. Overexposure of skin to X-rays
can result in changes to pigmentation, blistering and ulceration. Other examples of a deterministic
effect are the formation of cataracts and fetal abnormalities.
The deterministic effects of radiation can be classified as either acute or delayed. An acute effect such
as skin reddening results soon after the overexposure to radiation. A delayed effect such as cataracts
may take some time, even years, to develop. Other delayed effects are cancer, genetic defects,
shortened life span, and metal retardation in children exposed in utero.
Deterministic effects have clear connection between the individual exposure to radiation and the
biological effect. The biological effect requires a minimum threshold dose and the severity of the
effect increases with increased dose.
