Our sample included 621 surgical interventions performed in children and adolescents from 0 to 18 years old, being 286 (54,3%) males and 241 (45,7%) females. 18 children were under 1 year old, 160 were 1-5, 110 were 6 e 10 years old, 194 were 11 to 15 and 139 were 16 to 18 years old (Fig 3). 290 of the analysed interventions were appendicular skeleton orthopaedic surgery, 158 were central line placement, 116 were axial skeleton orthopaedic surgery, 25 were cochlear implant, 11 were procedures related to the gastrointestinal tract, 10 were urological procedures, 7 were 3D fluoroscopy in the context of orthopaedic procedures and 4 were pacemaker implantation procedures (Fig 4).

DAP values were obtained for each surgical procedure, and divided into 7 intervals: [0-20[, [20-100[, [100-250[, 250-500[, [500-1000[, [1000-1500[, [1500-2000[ and [2000-2500] cGy.cm2. The values obtained are shown in table 1 and figure 5.

96,3% of the children were exposed to less than 250 cGycm2, but four were exposed to between 1000 and 1500 cGycm2 (one from the 6-10 years old interval, another one from the 11-15 and two from the 16-18 years old interval, as shown in figure 6). One of the elements of the sample received between 2000 and 2500 cGycm2 (from the 16-18 years old interval). Figure 6 shows the dispersion of the DAP values in each age group. 

The surgery types associated with higher DAP (cGy.cm²) mean values were pacemaker placement, axial skeleton orthopaedic interventions and appendicular skeleton orthopaedic interventions, as shown in table 2. 

Considering the different surgery types, and due to the non-specification of the procedure performed within each group, there is great heterogeneity in the obtained values, which is shown by the standard deviations. The non specification of each procedure in each medical specialty was due to the great variability within each group.

The mean, minimum and maximum values of DAP obtained for each age group, and for each surgery type, are summarized in table 3. 

Overall, we conclude from the obtained data that the 300Gy.cm2, or 30.000cGy.cm2 threshold for deterministic radiation effect of skin erytema was not passed, being 2087 cGy.cm2 the higher value of DAP obtained, in a 16-18 year old in an axial orthopaedic procedure. The lowest values of DAP were found in the under 1 year old group.

Nevertheless, and as Rassow et al (2000)  pointed out when they analysed the DAP in 2,114 infants and children, the highest effective doses they found in newborns compared with adolescents aged 15–21 years, corresponded to the lowest measured DAP values. This occurs because the decreased value of the conversion factors overcompensates for the increase of DAP with age. So, all the measures should be taken to lower to ALARA the radiation doses in fluoroscopic procedures.

Limitations - The lack of patient information, namely biometric, and specific information on each procedure, namely the specific surgical technique used,  as well as the lack of technical data, as number of pulses used, limits the study and the possibility of monitoring cases with higher radiation exposures.