數位乳房X光攝影系統減少壓迫降低平均乳腺劑量初步探討

Reduce Compression and Mean Glandular Dose in Full Filed Digital Mammography

洪松齡(Sung-Ling Hung)

指導教授 ： 蘇振隆

中原大學/工學院/生物醫學工程研究所/碩士(2010年)

https://doi.org/10.6840/CYCU.2010.00025

摘要

摘 要
乳房X光攝影是目前唯一可以證明用在一般健康的女性上，作為早期癌症篩檢的工具，然而婦女接受過乳房X光攝影之後，對於受檢過程中對於乳房壓迫的疼痛經驗感到恐懼，另外乳房攝影是一種高吸收劑量的檢查，平均接受完一次乳房攝影的劑量，相當等於接受了28張胸部X光攝影檢查，所以乳房攝影檢查時所接受到的壓迫以及受檢者所接受到的高劑量不容忽視，本研究的目的利用乳房攝影機數位化的優勢，探討減少壓迫磅數以及降低乳腺劑量的方法。
本次研究經過三家醫院進行大規模的調查，針對受檢者所接收到的腺劑量以及壓迫所產生的疼痛進行分析，總計提交有效問卷1010份，影像4040張進行分析，並利用各種假體(RMI-156、BR12、HIGH CONTRAST RESOLUTION)於原始壓迫以及不同的壓迫程度進行模擬攝影，並藉由直方圖對比擴展法以及去銳利化影像法來評估改善因劑量減少而造成雜訊的增加情形，以主觀視覺化(解析度)以及客觀系統數位化計算的方式(訊號雜訊比、對比雜訊比、對比度)，評估數位乳房攝影系統經本研究減少壓迫，降低平均乳腺劑量的表現，並分別應用於三位受檢者，利用減少壓迫後所產生的劑量以及模擬原壓迫所產生的劑量進行分析，評估本攝影技術於臨床的可行性。
初步結果顯示受檢者所接受到的平均壓迫磅數為35.9磅，平均乳腺劑量為2.11mGy，以40到44歲年齡層所接收到的平均乳腺劑量最高，45到49歲年齡層次之，採用本研究所建立的影像技術於受檢者上時，可以使平均壓迫磅數降為20磅，平均乳腺劑量有高達13.36%到15.43%的降幅表現，而因劑量減少而降低的SNR、CNR以及對比度，經過影像處理後，SNR值高於原始影像數值14.47%，CNR值高於原始影像數值20.53%，對比度Contrast高於原始影像數值5.6%，影像品質都有顯著的增加。
本研究建立的減少壓迫，降低平均乳腺劑量的攝影技術，可以有效的減緩受檢者於接受乳房攝影檢查時所造成的疼痛感，降低了受檢者乳房所接受到的X光劑量，並藉由影像處理程式有效提升影像品質，國民健康局預計於2010年起，下修乳房篩檢受檢年齡層從50到45歲，研究中可以發現45到49歲的年齡層的平均乳腺劑量均高於其他接受乳篩的年齡層(50到69歲)，所以本研究減少壓迫，降低平均乳腺劑量的攝影技術的初步探討，在乳房攝影臨床上，有至關重要的實質助益。

關鍵字

自動控制暴露 ； 變化係數 ； 全照野數位式乳房攝影 ； 平均像素值

並列摘要

ABSTRACT
Mammography is currently the only proven screening method able to be performed on healthy women; however, after women have undergone mammography they have developed a fear of the painful pressure involved during the process. Moreover, mammography involves absorption of high amounts of radiation; the radiation dose taken in during an average mammography is equivalent to that of 28 chest x-rays. Therefore both the experiences of the patients and the radiation dose during the test are important issues to address. This study aims to use the advantages of digital mammography to discuss methods of decreasing pressure and radiation (AGD) on the patient.
After large-scaled surveys done in three hospitals, this study analyzed the radiation dose and the pain level during mammography; a total of 1010 questionnaires, 4040 images were analyzed. Using various methods (RMI-156, BR12, HIGH CONTRAST RESOLUTION) of performing imaging, as well as various different ways of applying pressure, simulated images were taken. Unsharp-enhancement and histogram-contrast stretching were use to improve the static caused by decreased dosage; subjective visualization (resolution) and objective systematic digitalize calculations (SNR, CNR, contrast) were used to evaluate the performance of digital mammography at lessening pressure and AGD. Three patients were screened using both AGD post-depressurization and AGD with simulated pressure to evaluate the viability of this imaging skill in a clinical setting.
Preliminary results show that patients are exposed to an average pressure of 35.9lb and AGD of 2.11mGy during mammography. The average AGD is highest amongst women age 40~44 years; In those aged 45~49 years, adopting the imaging skills developed by this study can lower the average pressure by 20lb, and a reduction of as high as 13.36%~15.43% can be achieved. The reduced SNR, CNR, and contrast due to dose reduction, after digital processing, have improved significantly; SNR by 14.47%, CNR by 20.53%, and contrast by 5.6%.
The imaging skills developed by this study to lessen pressure and AGD can effectively lower the pain levels of patients during mammography and reduce the amount of radiation absorbed by the patient, as well as improve image quality through digital processing. From 2010 onwards, the department of health plans to decrease the age of screening from 50 to 45. Research studies show that the AGD is higher in the 45~49 age bracket than any other group; therefore the discussion by this study regarding imaging skills involving lessening pressure and AGD plays an important, practical role in clinical mammography.

並列關鍵字

AEC ； CV ； FFDM ； MV

參考文獻

4.王秀紅,侯明鋒,"乳癌患者延遲診斷的相關因素探討",高雄醫誌, 9(2), 103-112, 1993。

1.NF Boyd and H Guo, "Mammographic Density and the Risk and Detection of Breast Cancer ", N Engl J Med, 356: 227-36, 2007

2.CA Antonis and DP Paul, "BRCA1 and BRCA2 Cancer Risks", Journal of Clinical Oncology, 24:3312-3313, 2006

3.SH Taplin and E Montano, "Age and Participation in Mammographic Screening: A Prospective Analysis", Journal of American Board of Family Practice, 6(1), 13-23, 1993.

5.X Wu, GT Barnes, and DM Tucker, "Spectral dependence of glandular tissue dose in screen-film mammography", Radiology, 179, 143-148, 1991.