Objective  To examine the effect of shielding materials (single or combined)on the backscattering of X-ray used for medical diagnosis, and to find the optimized shielding materials against backscattering of medical diagnostic X-ray.

Methods  AT1123 X-γ ray dose detector and lead collimator were used to measure 45° backscattering dose and the main beam dose on the surface of shielding materials under both 100 kV voltage exposure and same geometric condition. The 45° backscattering ratio of X-ray was calculated.

Results  The backscattering ratio of X-ray varied when different shielding materials were used under the same irradiation condition (P < 0.01); the highest scattering ratio for the barium-based fiberboard and the lowest for the lead plate. The backscattering ratio slightly decreased with the increase of tube voltage, when the lead plate and lead glass with fixed thickness were used; by contraries, the backscattering ratio increased when other shielding materials were used (P < 0.01). The backscattering ratio differed significantly when the same shielding materials with different thickness were used (P < 0.01); the backscattering ratio slightly increased with the increase of thickness for the barium-based fiberboard and barium sulfate cement board, but slightly decreased for other materials (P < 0.01). The backscattering ratio varied significantly when different combination of shielding materials were used(P < 0.01), and the backscattering ratio was related both to the surface and the undersurface materials.

Conclusion The backscattering of X-ray is related to the operated voltage and the type, thickness and combination of used shielding materials. When constructing the rooms of medical diagnostic X-ray examination, the property of different shielding materials should be considered, and combinations of various shielding materials should be selected to decrease the cost of construction and the hazard of X-ray to the human health.