Aspects of Green Hospital Approaches with a Focus on Developing ...

X-ray beam and hence decreases anterior organ dose, it also attenuates X-rays coming
from the posterior direction that have already contributed to organ dose and contain important
image information [35 - 37]. Additionally, the dose reduction provided by these
shields can be readily achieved by decreasing X-ray tube current <strong>with</strong>out introducing
noise or increasing beam-hardening artifacts, as explained in the following paragraph.
Hence, it has to be well considered to use such shields in developing countries.
B.2 System Control – Optimization <strong>of</strong> Scanning Parameters and Scanning Protocol
Lowering tube current or voltage or increasing the helical beam pitch is the most direct
way <strong>of</strong> achieving radiation dose reduction. This paragraph will analyze these possibilities
to improve the examination conditions in developing nation.
a) Tube Current Modulation
By adjusting the tube current for each patient individually, radiation dose can be reduced
because patient size varies greatly, especially between developed and developing
countries. For smaller patients, less tube current and therefore less dose is sufficient to
obtain the desired image quality (Figure 7A). For larger patients, to ensure adequate
image quality, the radiation dose must be increased (Figure 7B). Hence, application <strong>of</strong> a
single protocol is inherently inefficient. Especially the failure <strong>of</strong> transfer scanning protocols
from developed nation where the average patient is much more corpulent than in
developing nations has to be avoided. Otherwise the mainly small patients in Cameroon
and other developing nations will have redundant exposure to radiation. Therefore,
scanning parameters must be adjusted according to body size, weight and cross-sectional
body dimensions (Figure 7A, B) [29, 38].
Figure 7: Tube current modulation: longitudinal (z-axis) and angularly (x- and y-axis) [26]
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