The frontal chest radiograph shows hyperinflated right lung. With given history of chocking on a small plastic toy, one expects to see no foreign body since plastic is radiolucent.

The child was symptomatic and was admitted under the specialist for an urgent bronchoscopy.

Radiolucent foreign bodies such as plastics and food particles are not appreciated on a chest x-ray. An indirect sign associated with this presentation is a hyperinflated lung field on the affected side, due to the ball valve mechanism. The hyperinflation becomes particularly apparent on an expiratory film.

If the child is too young to understand instructions, a decubitus chest x-ray can be taken with both sides dependent. The side of the lung which does not collapse (ie remains hyperexpanded) is the affected side.

Reference: https://emedicine.medscape.com/article/405994-overview#a2