Breast screening. Woman undergoing breast screening by X-ray mammography, a technique which reveals the fine details of internal breast tissues. The breast is compressed into a flat plane between a plastic sheet and a metal X-ray plate (lower centre). Breast tissue is then exposed to low-dose X-rays to obtain a mammogram image. Mammography is used to routinely screen women in order to detect breast tumours at an early stage. If a tumour is located on a mammogram, other techniques are employed to identify it. A biopsy (tissue sampling) of the tumour will confirm whether it is cancerous (malignant).