X-RAY EMISSION SPECTRUM

X-RAY PRODUCTION

BREMSTRAHLUNG RADIATION

CHARACTERISTIC RADIATION

BREMS

BREMS EMISSION-CONTINUOUS

Characteristic Radiation

                                                

  

CHARACTERISTIC EMISSION-LESS POLYENERGETIC

X-RAY EMISSION SPECTRUM

BREMSINTENSITY

X-RAY ENERGY

X-RAY EMISSION SPECTRUM

BREMSINTENSITY

X-RAY ENERGY

K-CHARACTERISTIC

L-CHARACTERISTIC

X-RAY EMISSION SPECTRUM

CHARACTERISTIC

BREMS

MAXIMUM ENERGY OF AN X-RAY IN THE BEAM

= kVp OF OPERATION= kVp OF OPERATION

kVkVpeakpeak

GREATEST # OF PHOTONS IS EMITTED WITH ENERGY:

APPROX. 1/3 OF MAX PHOTON ENERGY

FOUR PRINCIPAL FACTORS INFLUENCING THE SHAPE OF AN X-RAY EMISSION

SPECTRUM:ELCTRONS TRAVELING FROM CATHODE TO ANODE HAVE DIFFERENT ENERGIES– NOT JUST PEAK ENERGY

THE TARGET IS RELATIVELY THICK– CAUSING MULTIPLE INTERACTIONS.

LOW ENERGY X-RAYS ARE MORE LIKELY ABSORBED IN THE TARGET

EXTERNAL FILTRATION REMOVES LOW ENERGY PHOTONS

MINIMUM VAVELENGTH

MAX. X-RAY ENERGY

MIN. = 12.4 * 10 –10

kVpm

nm DIVIDE BY 10 –9

FACTORS AFFECTING THE X-RAY EMISSION SPECTRUM

TUBE CURRENT

TUBE VOLTAGE

ADDED FILTRATION

TARGET MATERIAL

VOLTAGE WAVEFORM

TUBE CURRENT CHANGE

CURRENT CHANGE

CURRENTINTENSITY

ENERGY – NO CHANGE

2 * mA = 2 * number of photons4 * mA = 4 * number of photons

Tube voltage

Tube voltage (kVp) CHANGE

kVp

INTENSITY

ENERGY –

15% INCREASE OF KVP = 2 * mAs

FILTRATION CHANGE

2.5 mm

4 mm

FILTRATION CHANGE

FILTRATION

INTENSITY

ENERGY –

TARGET MATERIAL CHANGE

TUNGSTEN

MOLYBDENUM

70

74 W 57981.77(14) 59318.847(50)

75 Re 59718.57(43) 61141.00(89)

76 Os 61487.27(90) 63001.07(95)

77 Ir 63287.29(96) 64896.2(10)

78 Pt 65123.3(20) 66832.9(21)

79 Au 66990.73(22) 68804.50(18)

80 Hg 68895.1(17) 70819.5(18)

81 Tl 70832.5(12) 72872.5(13)

82 Pb 72805.42(24) 74970.11(17)

83 Bi-209 74816.21(92) 77109.2(22)

K-CHARACTERISTICENERGY FOR

DIFFERENT TARGETS

TARGET CHANGE

TARGET MATERIAL

Z #

INTENSITY

ENERGY

CHARACTERISTIC RADIATION

CHANGECHANGE

VOLTAGE-WAVEFORM CHANGE

3-PHASE

1-PHASE

VOLTAGE WAVEFORM CHANGE

VOLTAGE WAVEFORM

INTENSITY

ENERGY

OPERATION ON 3-PHASE EQUIPMENT = 12% * SINGLE PHASE

PATIENT DOSE

SINGLE PHASE THREE PHASE>>