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Pediatr Radiol. 2014 Mar;44(3):313-21. doi: 10.1007/s00247-013-2824-9. Epub 2013 Nov 27.

Guidelines for anti-scatter grid use in pediatric digital radiography.

Author information

1
Department of Imaging Physics, The University of Texas, M. D. Anderson Cancer Center, 1400 Pressler St., Houston, TX, 77030, USA, shannon.fritz@gmail.com.

Abstract

BACKGROUND:

Pediatric radiography presents unique challenges in balancing image quality and patient dose. Removing the anti-scatter grid reduces patient dose but also reduces image contrast. The benefit of using an anti-scatter grid decreases with decreasing patient size.

OBJECTIVE:

To determine patient thickness thresholds for anti-scatter grid use by comparing scatter-to-primary ratio for progressively thinner patients without a grid to the scatter-to-primary ratio for a standard adult patient with a grid.

MATERIALS AND METHODS:

We used Solid Water™ phantoms ranging in thickness from 7 cm to 16 cm to simulate pediatric abdomens. The scatter-to-primary ratio without a grid was measured for each thickness at 60 kVp, 70 kVp and 80 kVp for X-ray fields of view (FOV) of 378 cm(2), 690 cm(2) and 1,175 cm(2) using indirect digital radiography (iDR) and computed radiography (CR). We determined thresholds for anti-scatter grid use by comparing the intersection of a fit of scatter-to-primary ratio versus patient thickness with a standard adult scatter-to-primary ratio measured for a 23-cm phantom thickness at 80 kVp with an anti-scatter grid. Dose area product (DAP) was also calculated.

RESULTS:

The scatter-to-primary ratio depended strongly on FOV and weakly on kVp; however DAP increased with decreasing kVp. Threshold thicknesses for grid use varied from 5 cm for a 14 × 17-cm FOV using iDR to 12 cm for an 8 × 10-cm FOV using computed radiography.

CONCLUSIONS:

Removing the anti-scatter grid for small patients reduces patient dose without a substantial increase in scatter-to-primary ratio when the FOV is restricted appropriately. Radiologic technologists should base anti-scatter grid use on patient thickness and FOV rather than age.

PMID:
24281685
DOI:
10.1007/s00247-013-2824-9
[Indexed for MEDLINE]

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