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FDA phantom CT data at The Cancer Imaging Archive

 

Updated: September 6, 2017

 

Summary:  As part of a more general effort to probe the interrelated factors impacting the accuracy and precision of lung nodule size estimation, we have been conducting phantom CT studies with an anthropomorphic thoracic phantom containing a vasculature insert on which synthetic nodules were inserted or attached.  The utilization of synthetic nodules with known truth regarding size and location allows for bias and variance analysis, enabled by the acquisition of repeat CT scans.  Using a factorial approach to probe imaging parameters (acquisition and reconstruction) and nodule characteristics (size, density, shape, location), ten repeat scans have been collected for each protocol and nodule layout.  The resulting database of CT scans is incrementally becoming available to the public via The Cancer Imaging Archive (TCIA) to facilitate the assessment of lung nodule size estimation methodologies and the development of image analysis software among other possible applications. 

 

Database use:  The database is publicly available for free download thought the TCIA website (https://public.cancerimagingarchive.net/ncia/home.jsf).  The data should not be used for commercial purposes.  When using this data in scientific publications or technical reports please cite the following reference:

 

Marios A Gavrielides , Lisa M Kinnard, Kyle J Myers, Jenifer Peregoy, William F Pritchard, Rongping Zeng, Juan Esparza, John Karanian, and Nicholas Petrick, “A resource for the assessment of lung nodule size estimation methods: database of thoracic CT scans of an anthropomorphic phantom”, Optics Express , vol. 18, n.14, pp. 15244-15255, 2010.

 

Please refer to the same reference for more details regarding the development of this database and a discussion regarding its usage.

 

Database Description

The anthropomorphic thoracic phantom (Kyotokagaku Incorporated, Tokyo, Japan) employed in this study is shown in Figure 1, along with the vasculature insert on which synthetic nodules were attached before CT imaging.  The phantom does not contain lung parenchyma so the space within the vascular structure is filled with air.

 

Fig 1:   Photograph of the exterior shell of the thoracic phantom (left) and the vasculature insert (right).

 

The synthetic lung nodules used in our data CT scans were manufactured by either Kyotokagaku Incorporated (Japan) and Computerized Imaging Reference Systems (CIRS, Norfolk, VA).  They consisted of objects varying in size (5, 8, 10, 12, 20, 40 mm), shape (spherical, elliptical, lobulated, spiculated), and density (-800, -630, -10, +100 HU).  Figure 2 shows examples of the various sizes and shapes of synthetic nodules used in our CT data collection.

Eight different layouts of nodules were specified by placing them in pre-marked positions within the phantom vasculature, where they were either attached to vessels or suspended in foam (non-attached configuration).  Care was taken to maintain constant positioning of the nodules when a particular layout was scanned multiple times or with different protocols.  For that purpose, vessels on which nodules were attached were color coded.  Table 1 tabulates the nodule configuration for the nodule layouts that are currently available at https://public.cancerimagingarchive.net/ncia/home.jsf in terms of nodule positioning, size, shape, and density. All tables and figures in this document will be updated as more data is posted.

 

Figure 2:  Photographs of the different types of synthetic nodules used in this study.  Each column shows example nodules in three sizes, with lobulated , elliptical , spiculated , spherical , and irregular nodules shown from left to right.  The three sizes shown here were manufactured to have the equivalent volumes of spherical nodules with diameters of 5, 10, and 20 mm (with the exception of the irregular shapes which have nominal diameters of about 5, 10, 12 mm).  Additional nodules used in this study span the size range between 5-60mm.

 

 

Nodule layout #

Vessel attachment

Nodule placement and description

Left lung

Right lung

Nominal diameter (mm)

Shape*

 

HU

Nominal diameter (mm)

Shape

HU

1

attached

5,8,10

SPH   

-800

5,8,10

SPH

-630

2

attached

5,8,10

SPH

100

8,12,15

irregular

-300, 30,30

3

attached

5,8,10,20,40

SPH

100

5,8,10,20,40

SPH

-630

4

attached

10, 20, 10, 20,

10, 20

ELL,  ELL,  LOB, LOB, SPI, SPI

-630

10, 20, 10, 20,

10, 20

ELL ^ ,  ELL, LOB, LOB, SPI, SPI

100

6

attached

5, 8, 10, 20, 40

SPH

-10

20, 40, 20

SPH

100, 100, -630

8

non-attached

5, 8, 10

SPH

-630, 100

5, 8, 10

SPH

-800, -10

9

attached

5, 8, 10

5, 8

5, 8

ELL, ELL, ELL

LOB, LOB,

SPI, SPI

100

5, 8

5, 8

5, 8

ELL, ELL

LOB, LOB,

SPI, SPI

-630

 

 

Table 1.  Summary of currently available nodule layouts.  *SPH- spherical, ELL- elliptical, LOB- lobulated, SPI- spiculated.  ^Note: The 10mm, 100HU elliptical nodule in the right lung (Nodule Layout #4) has a large hole in it.  A replacement was scanned as part of Nodule 6.

The phantom was scanned using a Philips 16-row scanner (Mx8000 IDT, Philips Healthcare, Andover, MA) and a Siemens 64-row scanner (Somatom Definition 64, Siemens Medical Solutions USA, Inc., Malvern, PA).  Scans were acquired with varying combinations of effective dose, pitch, and slice collimation, and were reconstructed with varying combinations of slice thicknesses and reconstruction kernels.  Ten exposures were acquired for each imaging protocol.  The phantom position was not changed during the 10 repeat exposures; however it was repositioned between different imaging protocols or different nodule layouts.  Table 2 summarizes the imaging protocols for the nodule layout.

 

NOTE Each study in the database contains 10 repeat scans for that particular acquisition protocol, multiplied by the number of reconstructions.   The study and series descriptions contain the following information:

 

Study description :  Contains information on: the scanner vendor (currently Philips or Siemens), the exposure (in mAs), the pitch (currently either 1.2 or 0.9 according to the definition  , where Δd is the patient table travel in the horizontal direction and T is the detector width at the isocenter plane), and slice collimation (in mm).

 

Series description :  Contains information on reconstructed slice thickness (in mm), reconstructed slice increment (in mm), and reconstruction filter or kernel (currently either C for detail, or B for medium).

 

Nodule

Layout #, Scanner

Eff.dose

(mAs)

Slice collimation (mm)

Slice overlap

Pitch

Recon. Slice thickness (mm)

Recon. Kernels

# sets

1,S1

20,50,100,200

16x0.75,

(16x1.5)

50%

0.9,1.2

0.75,1.5,3 (2,3,5)

C

480

2, S1

20,100,200

16x0.75,

(16x1.5)

50%

0.9,1.2

0.75,1.5,3 (2,3,5)

C, B

720

3, S2

25, 100, 200

64x0.6

0%, 50%

0.9, 1.2

0.75, 1.5, 3.0

B40f, B60f

720

4, S1

25, 100, 200

16x0.75,

(16x1.5)

50%

0.9,1.2

0.75,1.5,3 (2,3,5)

C, B

720

6, S1

25, 100, 200

16x0.75,

(16x1.5)

50%

1.2

0.75,1.5,3 (2,3,5)

C, B

360

8, S1

25, 100, 200

16x0.75,

(16x1.5)

50%

0.9,1.2

0.75,1.5,3 (2,3,5)

C, B

720

9, S1

25, 100, 200

16x0.75,

(16x1.5)

50%

0.9,1.2

0.75,1.5,3 (2,3,5)

C, B

720

TOTAL

 

 

 

 

 

 

4440

 

Table 2.  Summary of reconstructed CT datasets: a description of the individual nodule layouts are provided in Table 3. *S1: 16-row Philips Mx8000 IDT (Philips Healthcare, Andover, MA), S2: 64-row Siemens Somatom (Siemens, Erlangen, Germany).

 

For example: there are 16 studies for Nodule Layout #1 (4 exposures x 2 slice collimations x 2 pitch settings).  Each study contains 30 series (10 repeat scans x 3 reconstructed slice thickness x 1 reconstruction kernel).

 

A key component of the CT lung phantom project is the ability to compare the estimated nodule size with the known true size or reference gold standard.  As part of our project, volume was used as a surrogate measure of size.   The true volume estimate of each synthetic nodule was derived from weight and density measures.  Both the CIRS-and Kyotokagaku nodules were accompanied by density measures.  Nodule weights were measured in our lab using a precision scale of 0.1 mg tolerance (Adventurer Pro AV 2646, Ohaus Corp, Pine Brook, NJ).  Three repeat weight measurements were made and these weights were averaged to produce a final estimated weight for each nodule.  Our estimates of the true volume of the synthetic nodules in each layout are summarized in Table 3 along with approximated xyz location (based on 0.8mm slice thickness) of nodule center in the CT scans. 

This phantom and the associated synthetic nodules designed in our lab have been used in a number of studies examining the accuracy and precision of volumetric measurements using CT.

Nodule

Layout

Right lung nodules

Left lung nodules

 

Nom.  Diam.(mm)

Shape

HU

x y z

Vol

(µl)

Nom.  Diam.

(mm)

Shape

HU

x y z

Vol (µl)

1

5

SPH

-630

177 342 192

71

5

SPH

-800

340 325 168

62

 

8

SPH

-630

179 288 531

282

8

SPH

-800

343 274 540

245

 

10

SPH

-630

170 309 385

522

10

SPH

-800

394 260 363

496

2

8

irr

-300

184 290 525

253

5

SPH

100

335 331 157

64

 

12

irr

30

170 319 379

676

8

SPH

100

351 282 538

255

 

15

irr

30

189 347 161

263

10

SPH

100

395 276 349

506

3

5

SPH

-630

192 350 562

71

5

SPH

100

338 328 580

64

 

8

SPH

-630

185 287 208

282

8

SPH

100

355 278 212

255

 

10

SPH

-630

170 324 354

522

10

SPH

100

394 270 390

506

 

20

SPH

-630

157 251 190

4193

20

SPH

100

384 240 229

4215

 

40

SPH

-630

168 280 198

34524

40

SPH

100

373 262 156

33781

4

10

ELL

-630

176 354 178

547

10

ELL

100

341 333 162

545

 

20

ELL

-630

169 322 95

4210

20

ELL

100

401 296 122

4155

 

10

LOB

-630

159 329 347

530

10

LOB

100

395 272 329

535

 

20

LOB

-630

136 292 337

4305

20

LOB

100

349 350 268

4441

 

10

SPI

-630

167 315 520

539

10

SPI

100

357 296 530

535

 

20

SPI

-630

133 269 475

4335

20

SPI

100

386 248 503

4305

6

5

SPH

-10

175 345 190

70

20

SPH

100

404 251 475

4216

 

8

SPH

-10

176 309 505

284

40

SPH

100

379 264 164

33781

 

10

SPH

-10

148 329 352

536

20

SPH

-630

367 273 532

4220

 

20

SPH

-10

148 265 524

4266

 

 

 

 

 

 

40

SPH

-10

168 281 213

37420

 

 

 

 

 

8

5

SPH

-800

157 401 205

62

5

SPH

-630

398 356 177

71

 

8

SPH

-800

138 351 493

245

8

SPH

-630

343 403 466

282

 

10

SPH

-800

118 392 424

496

10

SPH

-630

375 378 376

522

 

5

SPH

-10

167 330 233

70

5

SPH

100

369 375 180

64

 

8

SPH

-10

189 397 547

284

8

SPH

100

310 377 614

255

 

10

SPH

-10

172 348 378

536

10

SPH

100

393 325 321

506

9

5

ELL

-630

181 430 166

70

5

ELL

100

347 399 171

71

 

8

ELL

-630

142 375 155

286

8

ELL

100

408 379 121

278

 

5

LOB

-630

162 403 362

68

10

ELL

100

356 319 208

545

 

8

LOB

-630

145 342 339

283

5

LOB

100

335 411 281

70

 

5

SPI

-630

174 385 517

73

8

LOB

100

391 276 411

275

 

8

SPI

-630

155 326 536

292

5

SPI

100

368 404 332

74

 

 

 

 

 

 

8

SPI

100

400 332 529

274

 

Table 3.  Approximate center location and estimated true volume of synthetic lung nodules in each nodule layout based on 0.75mm slice thickness, 0.4mm slice increment CT scans.  (SPH=spherical, ELL=elliptical, LOB= lobulated, SPI= spiculated, irr=irregular)

 

 

Contact info:

 

Marios Gavrielides

Division of Imaging Diagnostics and Software Reliability

Office of Science and Engineering Laboratories

Center for Devices and Radiological Health

U.S. Food and Drug Administration

10903 New Hampshire Ave.

Bldg. 62, Rm.3139

Silver Spring, MD 20993, USA

Tel. (301) 796-2545

marios.gavrielides@fda.hhs.gov