Computed Tomography (CT) has nowadays an important role in clinical practice,
having been observed an increasing number of available CT equipment and a growing trend to use CT as a complementary diagnostic modality in the past few years [1,
2].
In Portugal,
specifically,
the number of CT equipment in hospital context has increased,
particularly between 2008 and 2015,
and the number of CT studies also presents a growing trend (Figure 1)[3,4].
According to data from 2008,
CT studies represents about 12% of all diagnostic imaging procedures [1].
Despite that,
CT procedures had a large contribution to collective effective dose [2].
Head CT studies have an important role in clinical practice.
This study is the most commonly performed CT procedure,
the seventh most commonly imaging procedure and represents an exposure on eyes lens,
a radiosensitive organ [1,
5,
7,
8].
This clinical practice importance and associated radiation risk had lead to an increasing interest in head CT protocol optimization [5].
Head CT protocol optimization involves the development and use of different strategies,
such as,
the use of local exterior shielding of the eyes lens,
gantry tilt optimization,
organ-based current tube modulation,
correct patient positioning in the isocenter and when available to use iterative reconstruction techniques [5-6,
9-11].
Gantry tilt optimization had a special focus to eyes lens exposure reduction,
were reductions of 75% were achieved when eyes lens where not exposed [5].
European guidelines propose a gantry tilt of 10 to 12 degrees above orbitomeatal line,
which represents a supraorbitomeatal line orientation when patient positioning is orbitomeatal [12].
In practice,
how are head studies performed relative to axial acquisition? In what way does gantry tilt and/or scan acquisition orientation angle influence total dose exposure in patients exposed to Head CT studies in a local hospital?
In order to answer those questions the main objective of our study was to analyse the role of the radiographer in dose exposure for patients submitted to Head CT regarding protocol,
patient positioning and scan angle optimization.