# A Novel and Stable Benchmark for Breast Measurement
## 4 Discussion
Therefore, for women with a higher BMI, fat is primarily concentrated in the soft tissues around the breasts and chest, rather than directly over the sternum. Our analysis also demonstrated that the breast volume calculations based on the terrestrial coordinate system tend to be underestimated, with larger errors compared to the actual volume. While the breast volume calculated using the new breast measurement coordinate system is also slightly underestimated, it is much closer to the actual volume. As the true diameter of the hemisphere increases, the volume calculation error using the breast measurement coordinate system remains almost constant at approximately 12.5%. This suggests that the traditional breast volume calculation method based on the terrestrial coordinate system has larger errors. When obtaining or converting anthropometric data, the human coordinate system is often employed; however, the inclined skeletal planes of the body are typically treated as vertical planes, which simplifies the spatial dimensions and affects the measurement accuracy [32]. Thus, using a breast measurement coordinate system based on anatomical features provides a more accurate calculation of the breast dimensions. To address the physiological and psychological changes in breast shape during adolescence, this study developed a novel breast measurement tool based on the new breast measurement coordinate system, which has been granted a Chinese invention patent (Patent No. ZL 2022 1 0831873.1). The new wearable breast measurement tool uses the breast measurement reference points as a starting framework. It allows for self-measurement and fitting after locating the origin of the new breast measurement coordinate system at the jugular notch. The tool measures the breast circumference (underbust circumference), length (vertical distance of the upper cup, arc distance of the lower cup), width (arc distance of the front cup, arc distance of the side cup), and height (breast height) to obtain the dimensional parameters of various breast features. These parameters are used to calculate the breast volume and assess the breast asymmetry, with standard operating procedures provided to ensure the measurement accuracy. The strength of this study lies in using the developmental stages as the basis for understanding the dynamic changes in female breast morphology. The challenge that 90% of women face in finding a suitable bra that fits, coupled with the significant risk posed to breast health by wearing improperly fitting bras, remains an unresolved issue in both academic and industrial settings. The core problem lies in the lack of reasonable, accurate, and ergonomically compliant measurement standards for breast morphology, making it difficult to accurately measure the changing female breast shape and lacking a stable framework for recording measurements. This study challenges the century-old traditional breast measurement methods used in the industry by defining appropriate measurement standards, developing new measurement methods and tools, establishing standard operating procedures, and proposing new measurement theories and technical systems. This provides robust methods and tools for data collection and product development in the lingerie industry. Although this study has made significant progress, certain limitations in terms of the study design must be acknowledged. Given that puberty marks the onset of dynamic changes in the female breast morphology, this study focused on a specific age group. Although it has been shown that the size of the sternum stabilizes after adolescence, certain special populations with different sternum shapes and sizes will need to be considered in future studies to make the new breast measurement standard more universally applicable. Additionally, due to the irregular shape of the breast, its true volume is difficult to determine and its boundaries are hard to define. The most accurate current method for measuring the breast volume is the specimen displacement method [33].