[Dose evaluation in mammography for Japanese breast thickness]

Accuracy control of mammography equipment involves more than just equipment management; the proportions of the mammary glands used to obtain appropriate images is also important, as is control of the glandular X-ray dose in accordance with thickness. Methods for evaluating glandular dose include the ACR, EUREF, and IAEA protocols. The aim of this study was to elucidate the differences between the various protocols and to suggest a dose evaluation method suited to Japanese breast thickness. An ionization chamber dosimeter was used for dose measurement, with a 156 phantom used as a breast phantom for the ACR and a PMMA phantom used for the EUREF and IAEA. There were no major differences in the protocols. The AGDs in the breast phantoms recommended HVLs for each protocol but were 25-30% higher in the EUREF and IAEA compared with the ACR, owing to the different breast thicknesses in each case. The IAEA should be regarded as the basic method for implementing optimum accuracy control in Japan, and a 35-mm PMMA should be used to correspond most closely to Japanese breast thickness.