Fw. Schultz et al., CALCULATION OF DOSE CONVERSION FACTORS FOR POSTERIOR-ANTERIOR CHEST RADIOGRAPHY OF ADULTS WITH A RELATIVELY HIGH-ENERGY X-RAY-SPECTRUM, British journal of radiology, 67(800), 1994, pp. 775-785
In a survey of X-ray units as applied for thorax examinations consider
able variations were observed in entrance dose among different hospita
ls in the Leyden region. For the median exposure conditions, i.e. 125
kVp, heavy filtering and large focus-to-skin distance (177.5 cm), abso
rbed dose distributions have been derived using mathematical phantoms
of a standard male or female adult. For relatively high-energy X-rays,
back scatter factors were calculated by Monte Carlo simulation. In ad
dition, conversion factors were obtained, relating organ doses to air
kerma, free in air. Effective dose equivalent and effective dose were
calculated according to ICRP-26 and ICRP-60 recommendations, respectiv
ely. The computational procedures were compared with results reported
in the literature for a similar exposure configuration but using lower
-energy X-rays. Causes of relative differences ranging from - 56% to 34% were analysed. In addition to the photon, energy spectrum and fil
tering, the exposure geometry appears to be a very important parameter
which can be optimized for the purpose of dose reduction.