The aim of the investigation was to assess the conversion factor (F) for derivation of effective dose from measured dose-area product (DAP) during radiological examination of congenital heart diseases. Two anthropomorphic phantoms corresponding to a 1-year-old and a 5-year-old child were irradiated at several projections to imitate irradiation conditions at heart examinations. Organ doses were measured using thermoluminescent dosimeters for calculation of mean organ doses and effective dose according to ICRP. DAP values were measured simultaneously. The conversion factor (F) was calculated from the ratio of effective dose (mSv) to DAP value (Gy cm2). The conversion factor (F) correlated strongly to the size of the phantom but less to the irradiation projection. However, at major beam angulation and at lateral projection F deviated note-worthily from that obtained at true or slightly angulated frontal views. Effective dose can therefore be estimated from the DAP values at heart investigation using two different F values. The following values are recommended for PA and lateral view respectively: for children weighing 7-11 kg, 1.8 and 1.4; for children weighing 15-26 kg 0.9 and 0.7.

No abstract

Paediatric double-contrast barium enema examinations are usually performed at high tube voltage, 102-105 kV. The aim of this study was to investigate how much the effective dose to the child could be reduced by increasing the X-ray energy further by adding copper filter in the beam, and if this dose reduction could be achieved without endangering image quality. Organ doses to an anthropomorphic phantom simulating a 1-year-old child was measured using thermoluminescence dosimetry for assessment of the effective dose and this value was compared with the energy imparted which was obtained from kerma-area product measurements. To verify that the image quality achieved with this added filtration was still diagnostically acceptable, the study included 15 patient examinations. Since the increased X-ray energy will most probably affect low-contrast objects, image quality was also evaluated with two different phantoms containing low-contrast objects. Effective dose for a complete examination can be decreased 44 % and energy imparted 77 % when a 0.3-mm copper filter is inserted in the beam at tube voltage 102 kV. The patient study did not show any significant deterioration of image quality, whereas phantom measurements of contrast-detail resolution and signal-to-noise ratio was marginally impaired by the added copper filtration. This technique is now in clinical practice for paediatric colon examinations.

The use of BaSO4 or air in reduction of intussusception requires the proper combination with CER and AEC, respectively, to minimize the radiation load to the patient; the lowest radiation load is obtained by using air and AEC.

The energy imparted to the children in diagnosing and hydrostatic reduction of intussusception was measured in 45 children by means of an area-dose measurement device and the mean absorbed dose was estimated. The device was provided with data on tube kVp, mAs and shutter positions and the results were presented as dGy x cm'. The device had been calibrated against a 30 cm3 ionisation chamber at the relevant kVp range. The median energy imparted and mean absorbed dose were 10.8 mJ and 0.94 mGy, respectively. 70% of the total dose was delivered during fluoroscopy. The complex irradiation situation with varying field collimation, tube voltage and amount of photon absorbing barium sulphate in the intestines renders organ dose and hazards estimations less reliable. However, even leaving the radiation shielding effect of the barium sulphate out, the radiation load is justifiable for a combined diagnostic and interventional procedure. children.The energy imparted to the patients is a suitable measure for risk estimates and optimization of radiological diagnostic and interventional procedures (2). It has been applied in studies on irradiation to adults (3, 5, 12) while investigations including children are sparse. However, irradiation to children is a matter of major interest because of their greater susceptibility to radiation hazards, their greater life expectancy involving higher risk of carcinogenic effects and their greater probability of transmitting genetic injuries (6, 7).The radiation load to the children in diagnosing and at hydrostatic reduction of intussusception emanates from a complex irradiation situation involving alternate film exposures and intervals of fluoroscopy using varying field size, projections and tube voltage. To the best of our knowledge no investigation on the radiation load during such procedures has been presented previously. Material and MethodsThe clinical material comprised 45 children with intussusception. Their age range was 0.2 to 5.3 years, median 1.5 years.Hydrostatic reduction was employed in all patients and was successfully completed in 42. Our routines at the radiographic examination included the following sequence: 1) Abdominal survey of frontal and of lateral decubitus view. The radiation contribution from these films was not measured. 2) Barium enema to establish the diagnosis. This was made under fluoroscopy and, in addition, films were taken.3) The reduction procedure included fluoroscopy and film exposures. If necessary, several reduction trials were made.The procedure was carried out with the child in prone or apron position or in slight rotation. All radiation exposure during 2 and 3 was measured.The examinations were made with an undercoache tube (Philips Diagnost 65) fitted with an area-dose measurement device (Philips Area Dose Display), which uses data from tube kVp, mAs and shutter positions to give a readout in dGy x cm2. The area-dose device and a transmission chamber (Diamentor) were calibrated simultaneously from 60 to 117 kVp against a 30 cm3 cylindric ionisati...