The relationship between compression force, image quality and radiation dose in mammography

Abstract

Background. Mammography aims to obtain mammograms of best possible image quality with least possible radiation dose.1 Theoretically, an increase in breast compression gives a reduction in thickness, without changing the density, resulting in improved image quality and reduced radiation dose. 
 Aim. This study aims to investigate the relationship between compression force, phantom thickness, image quality and radiation dose. The existence of a compression point beyond which increased compression gives a change in density rather than thickness is also considered.
 Method. Image quality is assessed with a contrast-detail phantom within Superflab phantom on a computed radiography (CR) mammography unit using automatic exposure control (AEC). Image quality is determined by visual inspection and image quality figure (IQF) scoring. The effect of compression and lesion depth on image quality is determined. Entrance and exit doses are calculated. The relationship between entrance dose, compression and thickness is investigated, as is the existence of a compression point beyond which a change in phantom density occurs. The average glandular dose (AGD) is calculated from the scanning average level (SAL) and logarithmic mean (LgM) according to Koen et al,2 and compared to the allowable limit. 
 Results. The geometry effect was not observed. An improvement in image quality with increased compression was found. Entrance dose did decrease with increased compression. This trend was not observed with exit dose as AEC was used and exit dose was calculated from SAL values. The “change-in-density” point of compression was determined. Both LgM and SAL could be used successfully for AGD calculation.

Compression forces used in the Norwegian Breast Cancer Screening Program

“…Regarding radiation dose, studies have reported increased radiation dose with increased compressed breast thickness. [27][28][29] Further, the compression force might influence reattendance. 5,6 However, subsequent reattendance is complex and is affected by several factors rather than simply the level of pain experienced during the screening examination.…”

Practitioner compression force variation in mammography: A 6-year study

“…This will likely achieve better consistency of breast dose and image quality [19] for clients imaged serially within the NHSBSP.…”

Breast compression across consecutive examinations among females participating in BreastScreen Norway

“…Studies have reported different effects on image quality with changes in breast compression parameters of this magnitude, [33][34][35][36][37][38] from minimal and no impact on image quality, [33][34][35][36] to considerable and significant effects on image quality. 37,38 conclusions This is the first study investigating breast compression parameters over consecutive screening examinations in BreastScreen Norway. We identified an increase in compression force, compression pressure and compressed breast thickness over time when adjusting for breast volume, fibroglandular volume, age of the females, breast centre and calendar year.…”