DBT (Digital Breast Tomosynthesis)
It is well documented that tomosynthesis was developed to resolve cases in which, due to a superimposition of tissues, a lesion could be hidden.
The detection of early-stage breast cancer has today received a large boost from results of recent scientific research about the 2nd generation tomosynthesis.
2nd generation Tomosynthesis. It means:
- The angles between exposures are variable (patented) and optimized.
Only the useful ones are employed.
- The x-ray doses delivered at each exposure are variable (patented).
Giving a lower overall radiation dose.
- The scanning angle is wide (40°).
For optimal Tomosyntesis (3D) viewing.
- Tomosynthesis and mammography are no longer separate, but rather combined in the same scan and reconstruction.
Two results with a single scan.
- The reconstruction algorithm is not the one conceived for CT or MRI, but rather of an iterative type. Designed for tomosynthesis.
- Despite there being a wide scanning angle, the number of exposures is low (13). Reduced, optimized dose.
- Keeps original pixel size (85 microns)
- It uses a dedicated 3rd generation amorphous selenium fast detector.
- Step & Shoot tube motion (ideal for microcalc visualization)
Why Tomosynthesis? The clinical need
Early detection using screening mammography has been shown to significantly reduce the mortality associated with breast cancer (L. Nyström, et al, “Long-Term effects of mammography screening”, The Lancet March 2002).
The introduction of full-field digital mammography in the last few years has improved image quality and has been shown to improve sensitivity in the dense breast. However, FFDM relies on 2D projection images, in which pathological structures can be hidden due a superimposition of tissues. Overlapping structures can mimic lesions, leading to false positive results. The complex projection images from conventional mammography introduces a difficult diagnostic challenge: interpreting multiple layers of overlapping tissue projected into a 2D image.
There is a clear unmet clinical need for a breast imaging modality that can provide high resolution tomosynthesis imaging while remaining within both the X-ray 'dose budget' and the financial budget of traditional mammography. This is the clinical need that digital breast tomosynthesis (DBT) addresses.
DBT is a powerful tool that can improve the early detection of breast cancer, particularly in the dense breast. It is a new and advanced technique to better support the radiologist in the daily fight against breast cancer. IMS is dedicated to providing its customer with the most advanced and innovative devices. We present here our own vision of Tomosynthesis: an optimized and original solution capable of providing spectacular clinical results.
Key Differences between Optimized IMS Tomosynthesis and Naive Tomosynthesis
Not all Tomosynthesis systems are designed in the same way and this may lead to different clinical performance between systems. IMS has developed a Tomosynthesis device, using patented solutions, with optimized geometry, dose distribution and advanced reconstruction methods. The table below summarizes key differences between approaches:
|Narrow angular range & few exposures:
fast but poor 3D resolution
|Wide angular range & many exposures:
good 3D resolution but slow
2nd generation tomosynthesis:
|Variable angles and doses|
IMS has developed the second generation DBT, the device that implements unique, patented optimizations to provide the best image quality at the lowest dose to the patient. This device is the result of ten years of research and clinical study into advanced reconstruction methods, optimal imaging geometries, variable dose distributions and novel Tomosynthesis visualization methods for efficient workflow.
Other Tomosynthesis approaches still use CT style filtered back projection (FBP) reconstruction algorithms and geometries with uniform distribution of dose and projection angles.
The IMS DBT system uses methods that are optimal for Tomosynthesis, not for CT. These methods cover, among others, reconstruction algorithms, dose distribution and spacing of images.
Touch screen technology
Variable dose & central exposure
One special implementation of IMS's optimised variable dose geometry uses sufficient dose in the central projection for that image to be a 2D mammogram. The reconstruction algorithm makes full use of the extra information provided by this high contrast central image.
The IMS Tomosynthesis solution uses the 24x30 cm 3rd Generation Amorphous Selenium detector manufactured by Anrad, Canada. It has been designed especially for DBT and has a very fast read time, the highest DQE at low dose and we have verified its reliability during 7 years of clinical use in FFDM. One of the features that make it ideal for Tomosynthesis applications is the absence of ghosting effects.
3D reconstruction algorithms
The choice of advanced iterative, non-linear reconstruction methods, rather than the more common filtered back projection (FBP) method, allows the use of IMS's optimized variable geometry and decreases noise and image artefacts. FBP is ideal for fully-sampled CT in which information is acquired from a full 360 degree scan.
When used in under-sampled Tomosynthesis, FBP is sub-optimal and generates streaking artefacts and noise. It may also filter out real structures in its efforts to suppress artefacts. IMS's advanced reconstruction methods allow superior image quality to be achieved at a lower dose to the patient.
Giotto Tomo is biopsy ready.
Using the same Detector is possible perform stereotactic biopsy
Stereotactic Biopsy, compatible
with all commercial biopsy guns.