Radiation Physics Flashcards
Define x ray beam intensity
Rate of energy flow per unit area perpendicular to the beam
Define quality of x ray beam
The energy of the X-ray photons eg. Ability to penetrate
What affects the intensity of xray beam
Tube voltage, tube current, exposure time, distance, beam quality
What affects the quality of beam
Exposure time, collimation,filtration
What effect would the tube current have on the intensity and the quality of the beam?
increasing the tube current will increase the number of xray photons produced, quality of the beam stays the same.
How does tube current affect exposure time
Increasing tube current decreases exposure time.
The distance of the image receptor from the anode target effects…
Radiation exposure, quality of image
Roles and responsibility’s IRR- radiation protection advisor
Risk assessments, monitoring equipment, designation of controlled areas
Roles and responsibility’s of the radiation protection supervisor
Must know what to do in an emergency and present on site, compliance to the local rules
Responsabiitys of the practitioner IRR ME
Justification of an exposure and comply with the employers procedures
Responsibility’s of operator IRR ME
Responsible for each practical aspect and must comply with employer procedures
Responsibilities of referrer IRR ME
Supply the practitioner with sufficient medical data relevant to the exposure requested
Effective dose
Used to Estimate the stochastic risk from any exposure
Absorbed dose
Concentration of energy deposited in tissue as a result of exposure to ionzing radiation
Lead equivalence
A measurement of how thick a material needs to be to provide the same amount of protection as lead
Equivalent dose
Multiplying the measured absorbed dose by a weighting factor
What are grids and their purpose
Devices that improve quality of X ray images by reducing scattered radiation
Deterministic Risk
Risk of tissue damage caused by exposure to radiation above a certain threshold dose
Compton scattering
X-ray interaction with a loosely bound or free electron, yielding inelastic scattering
Attenuation
When there are fewer photons present in a beam after it has been passed through material, then when it entered because of absorption and scatter
Photoelectric absorption
A photon absorbed by a atom that transfers its energy to an electron that is ejected from an atom
Rayleigh scattering
When the beam encounters a structure that is much smaller than the wavelength
