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Radiological Protection of Patients |
Computed tomography (CT) is extremely useful tool in medical practice, and in many cases a life saving resource when rapid decisions are needed in emergency room. The frequency on CT examination is increasing the world over. Also the pattern of use is changing, from discrete slice by slice scanning with inter-slice gap in conventional systems, it is now volume scanning in helical/ spiral CT scanning and moving to multislice CT. The speed and ease with which imaging procedure can be performed has resulted in over-stretching the use of this modality to have whole body screening rather than confining the imaging study to small part of the body. As per UNSCEAR 2000, CT contributes over 34% of collective dose from diagnostic X ray examinations in the world. This figure is much larger than this for developed countries, approaching as much as 50% to 70% even though the frequency of CT examinations in these countries is of the order of 5 to 12%. As compared with the previous UNSCEAR report six years earlier, the collective dose has grown to a factor of about 2.5. The individual patient doses have also been increasing despite technological advances, primarily because of varying patterns of use. There is growing realisation that image quality in CT often exceeds the level needed for confident diagnosis and that patient doses are higher than necessary. This is so as increasing exposure factors do not result in blackening of images, rather better quality images are obtained.
Radiation dose in CT is of particular importance for children. It is very well known that children are more sensitive and likely to get radiation induced cancer than adults. A study in 2001 in US indicated that exposure factors in CT examination used for children are similar to adults. The situation in developing countries can very well be understood. There is definite need to attend to patient doses in paediatric procedures, certainly for high dose procedures.
| Phase | IAEA’s Inputs | Action by Member State |
| I. Survey of practice |
1. Literature and proforma for making survey 2. Technical assistance through expert and IAEA Technical Officer |
1. Select few CT facilities 2. Survey of exposure parameters used for children and adults 3. Estimate frequency of CT examinations on children and difference in exposure factors |
| II. Patient dose |
1. Methodology for CTDI 2. Technical documents 3. Fellowship/Scientific visit 4. Technical assistance |
1. Availability of Medical Physicist 2. CTDI and DLP estimation 3. Comparison with DRL 4. Report and publish results |
Additional requirements of Member State, if any.