DOI:10.2214/AJR.05.1804
AJR 2006; 187:972-974
© American Roentgen Ray Society
Low-Cost Phantom for Stereotactic Breast Biopsy Training
Matthew Larrison1,
Alex DiBona1 and
David E. Hogg1
1 All authors: Radiology Department, University of Alabama Hospital, 619 19th
Street South, Birmingham, AL 35249.
Received October 13, 2005;
accepted after revision February 14, 2006.
Address correspondence to M. Larrison
(mlarrison{at}uabmc.edu).
Abstract
OBJECTIVE. This article reports on the construction of a low-cost
phantom to be used for training technologists, residents, and radiologists to
perform stereotactic breast biopsy. The model is adaptable to a variety of
biopsy devices and realistically simulates the aspects of stereotactic breast
biopsy.
CONCLUSION. We believe our model provides an excellent alternative
to more expensive commercial products.
Keywords: biopsy • breast • breast cancer • phantom • stereotactic breast biopsy
Materials and Methods
In our study, an eggplant served as a model for the breast. Similar models
have used turkey breasts [1]
and modeling clay [2], which
are more difficult to work with for many reasons, including concerns about
contamination and excessive preparation time. The radiographic appearance of
the fibrous eggplant tissue closely resembles that of actual breast tissue.
The eggplant fit easily into our biopsy device and could be repositioned
without difficulty.
Except for the eggplant, all materials needed for preparation of the model
were available in our department, including 10-mL syringe, 18-gauge spinal
needle, barium sulfate tablet, water-soluble sonography transmission gel, and
scissors. The entire procedure was accomplished in less than 15 minutes and
required no special skill. We estimate our phantom can be produced for less
than $20.
The preparation requires five steps. First, remove the plunger from the
10-mL syringe and add 3 mL of sonography gel. Second, using scissors, cut the
barium tablet into particles small enough to pass through an 18-gauge needle;
allow the particles to fall into the syringe. Third, mix the barium particles
with the gel. Fourth, attach the 18-gauge spinal needle to the syringe,
replace the plunger, and express the excess air. Fifth, make several passes
through the eggplant, perpendicular to its long axis, while injecting the
mixture.
The introduction of the gel mixture into the egg-plant provides multiple
targets for biopsy training. The barium particles serve as an appropriate
substitute for microcalcifications. The use of sonography gel reduces the
amount of air introduced into the phantom. We used the MammoTest Select
(Ethicon Endo-Surgery) with MammoVision Electronic Stereotaxy System (Fisher
Imaging). The phantom was placed in the compression paddle with the track of
barium oriented parallel to the image receptor
(Fig. 1). A scout image was
then obtained to ensure that an adequate sample was appropriately positioned.
Parallax views were obtained next, and a specific lesion was targeted
(Fig. 2). The biopsy needle was
then positioned according to the coordinates provided by the MammoVision
System, and images were obtained to confirm positioning
(Fig. 3). Multiple samples were
obtained using an 11-gauge Mammotome ST stereotactic probe (Ethicon
Endo-Surgery). A mammogram of the specimen was used to confirm that the lesion
was successfully biopsied (Fig.
4). Both localization and specimen imaging were performed using
preexisting protocols (26 kV, 120 mA and 22 kV, 15 mA, respectively). Imaging
results were adequate without manipulation of technique (kVp, mA), reflecting
the favorable imaging characteristics of the phantom.
Discussion
Using the eggplant model, the practical aspects of performing stereotactic
breast biopsy are achieved—visualization and localization of the target,
retrieval, and confirmation of lesion sampling. The use of barium particles in
the eggplant allowed for the adequate visualization and localization required
for biopsy. The varied shapes and clusters of particles allowed for targeting
of a specific group. With each targeted lesion, we were able to obtain several
core samples of tissue. We were able to confirm the presence of the lesion
(barium particles) by obtaining a mammographic image of the sample.
Our study had some limitations. We were only able to retrieve three to five
cores from each biopsy site. As a result, if a lesion was not sampled in the
first three to five cores, a new lesion would have to be targeted. Inaccurate
initial sampling of the lesion and subsequent retargeting of a new lesion
could, therefore, add time to the training process. The cores we obtained were
smaller than those retrieved with actual breast tissue. After several passes,
the eggplant tissue fragmented and only small pieces of tissue could be
obtained from a single site; however, confirmation by radiography was still
achieved. Complications that may be encountered during the actual procedure
and some aspects of the procedure, such as anesthesia, were not simulated.
At our institution, radiologists actively participate in all aspects of the
biopsy, including patient positioning and targeting of the lesion. Although we
did not directly compare the biopsy success rates between residents who
trained with the phantom and those who did not train with the phantom,
previous studies have shown that success rates improve after completing
several procedures [3].
Therefore, one would expect that performing multiple procedures with the
phantom would allow operators to improve their accuracy and increase patient
safety.
In summary, our eggplant model proved to be ideal for training residents in
the performance of stereotactic breast biopsy. The availability and low cost
of the model, combined with the ease of preparation and reproducibility, made
the training process efficient and highly effective. The excellent imaging
characteristics of the eggplant added to the realistic nature of the process.
The advantages of using the eggplant as a model include the ability to perform
several biopsies on the same phantom, the ability to place lesions at multiple
depths, and the fact that the eggplant leaves very little residue on the
biopsy needle. The ability to confirm lesion sampling is a distinct advantage
of using the barium sulfate particles. The biopsy specimens closely simulated
actual core biopsy specimens and provided instant feedback on the success of
the procedure. We believe this training model provides an outstanding method
of quickly and efficiently exposing trainees to the process of performing a
stereotactic biopsy and substantially increases confidence and skill for
performing this procedure on patients.
Acknowledgments
We thank Barbara Ann Berry and Mark Lockhart for their invaluable help.
References
- Harvey JA, Morgan RE, Hamer MM, DeAngelis GA, Omary RA. Evaluation
of a turkey-breast phantom for teaching freehand, US-guided core-needle breast
biopsy. Acad Radiol 1997;8
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- Quinn AD, Smiddy PF, Duggan M, Murphy J, Molloy M. Technical
report: A training phantom for stereotactic breast biopsies. Clin
Radiol 1997; 52:149
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- Liberman L, Benton C, Dershaw DD, Abramson AF, LaTrenta LR, Morris
EA. Learning curve for stereotactic breast biopsy: how many cases are enough?
AJR 2001; 176:721
-777[Abstract/Free Full Text]
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Abstract
Materials and Methods
