Dosimetric Evaluation of the Mean Glandular Dose for Mammography in Korean Women: A Preliminary Report

Abstract

The purpose of this study was to evaluate the thickness of the compressed breast in mediolateral oblique (MLO) and craniocaudal (CC) mammograms, to relate these thickness and breast patterns to mean glandular dose (MGD) in Korean women, and to evaluate the suitability of using the American College of Radiology's Recommendations for Korean women from a quality assurance standpoint. The study population consisted of 92 paired MLO and CC mammograms obtained on one mammographic unit. The digital readouts of compressed breast thickness, applied compression force and tube voltage were recorded. Entrance skin exposure was measured by dosimetry. MGD was calculated by multiplying entrance skin exposure by the exposure-to-absorbed dose conversion factor. The range of breast thickness was 1.3-6.2 cm in CC mammograms with a mean breast thickness of 3.6 cm, and 1.6-6.5 cm in MLO mammograms with a mean breast thickness of 3.9 cm. MGDs in CC and MLO mammograms were 1.77 mSv and 1.88 mSv per view, respectively. Breast composition patterns were divided into 4 groups according to ACR BI-RADS; P1 (n=20), P2 (n=16), P3 (n=48) and P4 (n=8). The MGDs for these groups were: 1.82, 1.84, 1.84, and 1.91 mSv, respectively. When subjects were subdivided by breast thickness into three groups, namely, below 3 cm, 3 cm to 4.2 cm, aaa and above 4.2 cm, the corresponding MGDs were 1.83, 1.86, and 1.91 mSv. According to our initial trial, the mean breast thickness and the MGDs of Korean women are lower than recommended by the American College of Radiology, which are commonly used for quality assurance purposes.

An Analysis of Application of Mean Glandular Dose and Factors on Which It Depends to Patients of Various Age Groups

“…between the mentioned doses (according to calculated values) was caused by compressed breast thickness and it was 13,54 %. Similar results were noted in works of other authors (Gentry & De Werd, 1996;Heggie, 1996;Young, 2000;Jamal et al, 2003;Oh et al, 2003;Bouzarjomehri et al, 2006;Sookpeng & Ketted, 2006;Tsapaki et al, 2008;Kunosic et al, 2010). A sample of a significant increase of doses in MLO in regard to CC projection can be explained with the fact that pectoral muscle (Helvie et al, 1994;Young, 2000) is involved in MLO projection which causes an increase of thickness of compressed tissue and requires greater exposition for an image of a better quality.…”

“…The total dose for a complete mammographic examination was 3,58 mGy, which is much less than 4 mGy which is the ceiling for mammography. In comparison with other studies (based on a principle of a great sample) the obtained patient dose is less in regard to a study conducted in Sweden (Eklund et al, 1993) which involved a sample of 1350 patients and in regard to a study conducted on 490 patients in Australia (Heggie, 1996), and it correlates well with results of studies from Korea (Oh et al, 2003) and Greece (Tsapaki et al, 2008). A study conducted in Iran included 246 patients (Bouzarjomehri et al, 2006) and showed that an obtained MGD dose for a 141 complete mammographic examination in that country was 5,57 mGy, which is significantly more in regard to this study and which, most probably, is a consequence of a quality control system which was established late and differences in compressed breast thickness.…”

“…A similar positive correlation between MGD and CBT was noted on a much smaller sample of Bosnian patients (Kunosic et al, 2010). An influence of CBT on patient doses during mammographic diagnostic examinations was confirmed by other authors in their researches (Wall & Roberts, 1992;Gentry & De Werd, 1996;Dance et al, 2000;Kruger et al, 2001;Oh et al, 2003;Bouzarjomehri et al, 2006;Sookpeng & Ketted, 2006;Bor et al, 2008;Robinson & Kotre, 2008) and some authors used this dependency to predict patient doses through training of artificial neural networks (Ceke et al, 2009). The number of previously conducted mammographic examinations for the complete group was 1,80 (SD: 0,66) while more than 75 % of patients underwent at least 2 mammographic examinations in their lives.…”

“…In the last 20 years a set of studies has been conducted in Europe with the objective to define MGD (Wall & Roberts, 1992;Faulkner et al, 1995;Klein et al, 1997;Adlien et al, 2005;Assiamah et al, 2005;Tsapaki et al, 2008;Kunosic et al, 2010;Ciraj-Bijelac et al, 2010). Similar researches were conducted on Thailand (Sookpeng & Ketted, 2006), in Iran (Bouzarjomehri et al, 2006), in the USA (Gentry & De Werd, 1996), Malaysia (Jamal et al, 2003), Australia (Heggie, 1996), Korea (Oh et al, 2003) and many other countries all over the world. Values of MGD and compressed breast thickness (CBT) were defined for a sample of 1220 images (613 CC and 607 MLO projections).…”

“…It is extremely important to examine a relation between projections (craniocaudal and mediolateral projection) during a mammographic diagnostic, compressed breast thickness and mean glandular dose received by a patient during one exposition and during the complete examination for two different age groups (Wall & Roberts, 1992;Gentry & De Werd, 1996;Heggie, 1996;Klein et al, 1997;Young, 2000;Young & Burch, 2000;Oh et al, 2003;Jamal et al, 2003;Sookpeng & Ketted, 2006;Bouzarjomehri et al, 2006;Tsapaki et al, 2008;Ciraj-Bijelac et al, 2010;Kunosic et al, 2010). Patients are divided into a group of younger patients (40 -49) and a group of older patients (50 -64), according to the European Protocol for Dosimetry in Mammography (Perry, et al, 2006).…”