We have analyzed the data of two years of activity starting from 1th January 2017 to 31th December 2018: the total amount is 8220 CT examinations (mean age 8y 3m,
median age 9y) and 2285 MCU (mean age 4y 10m,
median age 3y) performed on children (from 0 to 18 years of age).
The radiation dose administered to patients during MCU examinations (considered metric air kerma-area product [PKA] mGy cm2) is significantly lower (from 1/3 to 1/8) than the radiation dose indicated by the reference values of the European pediatric DRLs [1].
We do not acquire radiography or high definition fluoroscopy frames during MCU examination but only pulsed fluoroscopy series that are recorded to PACS.
The result of the analysis of the CT dose data shows that: 1) most of the dose data collected for the weight groups that underwent Thorax and/or Abdomen CT examinations (considered metric Dose Length Product [DLP] mGy*cm) are within the range of pediatric DRLs of the report 185/2018; the outlier data can be quickly evaluated and,
generally,
are due to few multiphase examinations performed for clinical reasons [2]; 2) the dose data collected for the age groups that underwent CT Head exams vary according to the use of different protocols (volumetric vs sequential acquisition).
It should be considered that the CT equipment currently in use was installed in 2006 and the exposure dose administered is affected by the lack of an iterative reconstruction software and new detectors with high sensitivity.
We have introduced in our clinical practice volumetric low dose CT Head protocols to be used in selected clinical situations (follow up of trauma,
derived ventricles assessment,
etc.).
To do this,
we evaluated over the period of 22 months two different groups:
a. CT Head investigations involving 266 patients (mean age 2,8 month old,
average weight 4,42 kg) belonging to the 0 to 3 month age group; a dose reduced protocol (3DLD _0-1aa: 100 kVp,
tube current modulation,
Quality ref.
mAs = 200) was applied on 112 examinations: DLP (mGy*cm) ranging from 206 to 356.
The data were compared with those obtained by a protocol in use (3D_1control: 120 kVp,
tube current modulation,
Quality ref.
mAs = 250) applied on 154 examinations: DLP (mGy*cm)> 320.
(Table 1)
b. In patients ranging from 1 to 6 year age group we have considered CT Head exams performed on 302 subjects (mean age 5,4 years old,
average weight 20,68 kg); a new dose reduced protocol (3DLD_3-5aa: 100 kVp,
tube current modulation,
Quality ref.
mAs = 280) was applied on 102 exams: DLP (mGy*cm) ranging from 287 to 420.
The data were compared with those obtained by a protocol in use (3D_2control: 120 kVp,
tube current modulation,
Quality ref.
mAs = 320) applied on 200 examinations: DLP (mGy*cm) > 550.
(Table 2)
In our practice we have introduced the new low dose Head CT protocol,
after a positive verification of image quality for the selected clinical indications above mentioned.
Moreover, the dose tracking software,
working in combination with the RIS,
allows to produce automatically in the radiologic report the dose data received from the patient as required by the report 185/2018 [1].
(Fig.
3)