Ing Juergen Heckel, VP, Medical Business Sales and Marketing, EIZO Corporation, elaborates on how breast cancer can be cured with quality medical grade monitors
Breast cancer is the leading cancer in women worldwide. In 2012, 1.7 million people were newly diagnosed with breast cancer. The earlier a breast cancer can be detected and treated, the higher the chance of the patient surviving and receiving benefit from medical treatments. The World Health Organization states that in countries with advanced medical care, the five-year survival rate of early stage breast cancers is 80 – 90 per cent, however, for cancer diagnosed at advanced stages, the survival rate drops to 24 per cent. Because of this, on-time breast screening is the most common and effective way to diagnose breast cancer in many countries. A lot of education and information is required for women to reduce the fear of breast screening for their own benefit.
Breast screening is a series of procedures that run a mammography scan of the patient. The screening procedure takes a few seconds and is meant to detect the existence of breast cancer. If a cancer is found, more thorough testing is required to determine the characteristics of such cancer. However, detecting some breast cancers early enough is a challenge that we have to overcome. Sometimes a screening cannot show all the needed information so other modalities need to be used to go into the depth of the breast tissue.
Breast tissue can be divided into four types: mostly fatty, scattered density, consistent density and extremely dense. Mammograms discern between these four types of breast tissue through varying shades of grey; fattier material being dark and dense material being bright. Cancers are able to show up as varying shades of grey; small bright and dark dots or small abnormal breast shapes that only trained eyes can recognise as risky. However, sometimes such cancerous spots can blend in with the surrounding breast tissue. This makes it very difficult for doctors to distinguish cancers from breast tissue. In fact approximately one in five existing breast cancers are not discovered in screening. Such a case is called a false-negative diagnosis.
Nonetheless there are ways to minimise the likelihood of a false-negative diagnosis. One of these is to invest in a high-quality medical-grade monitor with specifications designed for mammography. Printed scans and commercial monitors cannot be compared to the reliability and accuracy of medical grade monitors. Only medical grade monitors are able to display DICOM defined greyscale changes. Using DICOM GSDF (DICOM Part 14) means that doctors are able to see breast cancers that may be invisible on printed scans or commercial monitors which only display in greyscales that are not appropriate for diagnosis. The human eye (HVS) distinguishes grey levels in various steps (called JND = Just Noticeable Difference) and the importance in linear grey levels is herewith underlined. Medical grade monitors certified with FDA 510(k) clearance for mammography are a minimum requirement to follow. Without a medical-grade monitor, cancers may not be diagnosed early enough, leading to delayed treatments and lowering the survival rates for patients.
The most important feature that a medical grade monitor to be used for mammograms requires is a perceptually linear greyscale according to DICOM GSDF (DICOM Part 14) that can be calibrated to remain stable over the usage time. Further, it allows doctors to consult patient cases independent from their location as both will see the same information displayed. A perceptually linear greyscale allows one to see even minimal changes in the shades of breast tissue, allowing doctors to see tiny details more accurately. In breast screening, the process goes fast and doctors have limited time analysing scans, so any difference in greyscale needs to be recognised as fast as possible. Medical grade monitors following DICOM GSDF (DICOM Part 14) standards are proven to have a linear greyscale already pre-calibrated at the factory. But as mentioned above, according to the ambient light conditions in the reading room, the medical grade monitor may require an adjustment and re-calibration before the first usage. This is called Acceptance Testing. After such an Acceptance Test the medical grade monitor requires a periodical test method that includes luminance, greyscale and uniformity control to maintain optimal conditions. This is so called Constancy Testing.
In addition to an appropriate greyscale, a maximum brightness above 350cd/m2and a contrast ratio above 1000:1 are also required. The human eye (HVS) is better at distinguishing changes in contrast with increased luminance, therefore by increasing the overall brightness of the monitor such differences in shading can be more easily noticed – even in dark areas. The American College of Radiology (ACR) recommends diagnostic monitors to have luminance levels of 350cd/m2 for general diagnostic purpose and 420cd/m² for digital mammography.
Another best way to ensure you’re viewing images as best as possible is through controlling the reading room environment. Human eyes (HVS) are sensitive to contrast changes, so it’s important to have an ideal environment where the doctor can see details on the screen without being affected by their surroundings. Furthermore, fatigue and eye strain increase with brighter ambient lighting, making interpretations less accurate and dark areas may be too bright. The ACR suggests that ambient light has to be low and consistent, and equal to the average luminance of a clinical image being displayed (generally from 20 to 45lx).
Global regulations like EN (European Standard) and ISO (International Standard) recommend an ambient environment have no more than 50lx for mammography and general diagnostic usage with 100lx as the maximum allowed. Furthermore glare and reflections have to be minimised using medical grade monitors. This can be achieved by special antiglare coatings mounted on the medical grade monitor.
Another point to consider when purchasing a monitor for breast cancer diagnosis is whether to buy a colour or monochrome monitor. 2D mammograms and 3D rendered breast images are the most common breast cancer-detecting methods, and are inherently monochrome. However, other breast cancer-detecting tests, like ultrasound, MRI and pathology use colour to highlight artefacts. Doctors frequently use these tests in conjunction with each other in order to understand as much as possible about each patient’s case. These images can either be displayed separately on both a monochrome and colour monitor, however, many doctors find this expensive and not efficient as they lose information with such fragmented viewing. The most preferred option is to use colour medical grade monitors, which allow both image types to be shown at the same time. Currently some medical grade monitor technologies are available to switch between DICOM Greyscale images and coloured Gamma 2.2 values to show both accurately. This supports an efficient and best workflow for the radiologist.
Breast cancer is one of the most prevalent and difficult to treat cancers in the world, and early diagnosis is essential for patient survival. To ensure early detection, several factors need to be considered: a combination of well-educated doctors, the correctly adjusted ambient environment, recent technology and a medical grade monitor with the recommended technical parameters. It is mandatory to have a Quality Control (QC) solution in place to be sure that the devices will maintain quality constantly and accurately. This is the best way to ensure breast cancer patients are receiving the best possible chance of survival. Only by following all these important aspects are doctors able to find cancers early.
References:
1. World Cancer Research Fund International (WCRF)
2. American Cancer Society; www.carcer.org
3. American College of Radiation
4. World Health Organization
5. DICOM Part 14 GSDF http://dicom.nema.org/dicom/2004/04_14pu.pdf
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