Fluke 18-222 User Manual

Nuclear Associates 18-222 and 18-223

Tissue-Equivalent Mammography Phantom

Instruction Manual

(Blank Page)

Contents

Section 1: Introduction .................................................................................................................... 1-1

1.1 Background .................................................................................................................................................................1-1

1.2 The Development of the Standard of Reference .................................................................................1-1

1.3 The Realistically Shaped, Tissue-Equivalent Series of Breast Phantom ...................................1-1

1.4 Clinical Usefulness...................................................................................................................................................1-3

Section 2: Operation......................................................................................................................... 2-1

2.1 How to Use the Mammographic Phantom.............................................................................................2-1

2.2 References....................................................................................................................................................................2-8

i

(Blank Page)

Section 1

Introduction

1.1 Background

The American Cancer Society and American College of Radiology guidelines for the screening of asymptomatic
women have made over 50 million women candidates for mammography. In view of the staggering numbers
involved, it is critically important that simple but reliable methods be developed to assess system performance, to
assure consistent system performance, and to assure consistent production of diagnostically useful images (1, 17).

1.2 The Development of the Standard of Reference

Phantoms for use in mammography should simulate a real breast as closely as possible (2). A list of desirable features
for such a phantom can be found in Section 2, page 2-2. Note that the phantom should be able to test for both
image quality and dose if system performance is to be evaluated. The phantoms must also be easy to use and yield
images that may be unambiguously interpreted.

In developing the tissue-equivalent/realistically shaped phantom:

• Image Contrast may be measured quantitatively with standard densitometers though the use of the
embedded step wedge.

• Dose may be calculated by "TLD" or by ion chamber placed on top of the phantom and converted to average
glandular dose through conversion tables (3.6 and 3.7) in NCRP Report #985 (2). A suggested dose chart is
shown in Figure 2-1.

• Resolution - Simulated tumors and microcalcifications of known size and location are embedded in the
phantom for qualitative evaluation. The smallest microcalcifications and tumors are small enough that they
will not normally be detected.

1.3 The Realistically Shaped, Tissue-Equivalent Series of Breast
Phantoms

Shape

Standard dental modeling techniques were used to obtain molds of the compressed right breast of a volunteer
female subject. This breast is 4.5 cm thick and 18 cm in width.

Materials

Tissue-equivalent resin molding techniques were used. The system of resins used have been developed over the past
six years to permit mimicking of any body tissue at different diagnostic x-ray levels. The elemental composition of the
simulating tissue as compared to Hammerstein's analysis (11) of human tissue is shown in Table 2-1. Also shown in
Table 2-2 are comparisons of linear attenuation coefficients for actual and simulated tissue.

1-1

The basic phantom (Model 18-222) matches the composition of an average firm breast consisting of 50% adipose
tissue and 50% glandular tissue and is realistically shaped. The phantom is suitable for evaluating the mammographic
process in the laboratory as well as for monitoring system performance in the clinic. The phantom may be used for
screen-film mammography or xeromammography. Each molded breast is surrounded with a .5 cm adipose­equivalent tissue. Thus, the glandular portion of the standard phantom is 3.5 cm in thickness.

The materials used in this phantom have been formulated for optimum response in the film-screen mammographic
range of x-ray exposure (24 to 34 kVp), but will generally provide similar results at higher (xeromammographic)
exposure ranges.

The resin materials mimic the photon attenuation coefficients of a range of breast tissues. The average elemental
composition of the human breast being mimicked is based on the individual elemental compositions of adipose and
glandular tissues as reported by Hammerstein (11). See Tables 2-1 and 2-2 for comparative data.

The attenuation coefficients are calculated using the "mixture rule" and the photon mass attenuation and energy
absorption coefficients table of J.H. Hubbell (16).

Optional Size Phantoms

The Model 18-222 Phantom is 4.5 cm in compressed thickness. Other sizes available are 4 cm, 5 cm, and 6 cm
thickness.

Optional Tissue Densities

Densities ranging from 20% glandular/80% adipose to 70% glandular/30% adipose are available on request.

Details

The Standard Phantom (Model 18-222) has embedded details (Figure 2-2) consisting of:

• Seven masses that are 75% glandular and hemispherical in shape.

• A wax insert with embedded nylon fibers.

• The Model 18-222 has an optical density reference zone. This allows OD measurements, which are position

dependent, to be taken from the same area each time. This helps factor out OD variances.

• The Model 18-222 has two edges of beam targets. This enables precise localization of the x-ray beam's edge - for

example, is the machine penetrating the chest wall, or is it not close enough to the chest wall such that
something may be missed in a clinical setting?

• One line pair test target with line pair tests between 5 and 20 line pair/mm.

The Physicist Research Model

• Three tissue equivalent phantoms with removable outer fat layer and with embedded details similar to Model
18-222

- 4 cm - 50/50 (dense)

- 5 cm – 30/70 (normal) (or 4.5 cm - 50/50)

- 6 cm - 20/80 (fatty)

• Three tissue equivalent slab combinations of plates ranging from .5 cm thickness to 2 cm. This permits test
imaging in .5 cm increments from a thickness of .5 cm to 7 cm.

- 30% glandular/70% adipose

- 50% glandular/50% adipose

- 70% glandular/30% adipose

(Model 18-223) includes:

1-2

• Each set has one removable detail plate (50% glandular) containing:

- Step Wedge

- Simulated tumors (100% glandular)

- Microcalcifications (CaCO

- Tabular alumina specs (AL

3

)

2O3

)

- Fibril (8.7 micron) plus cladding

- Line pair test target (20 LP/mm)

1.4 Clinical Usefulness

The phantom approaches the desirable features see Section 2, page 2-2. The phantom is realistically shaped and has
the tissue equivalency of an average, firm breast. Breast detail components closely mimic the radiographic properties
and shapes of normal and pathological breast structures. The shape and configuration of the phantom makes it easy
to use by both technologists and physicists. Since the phantom is both realistically shaped and tissue equivalent, it
can be reliably used to test for radiation dose as well as image quality. A recently completed field study confirms this
assumption (6). Finally, the phantom provides valuable image quality information. The subjective assessment of detail
visibility is easy to use for routine clinical assessment while densitometric analysis provides necessary accuracy for
laboratory work. Hence the phantoms may be used to assess the mammographic process as well as assuring
consistent image performance.

Table 2-3 provides a comparison of composite attenuation for various mammographic phantoms currently
commercially available. Also shown are similar calculations for breast tissue using Hammerstein's methodology (11).

1-3

(Blank page)

Section 2

Operation

2.1 How To Use the Mammographic Phantom

What To Do First

• Select the technique you would use on a normal 4.5 cm compressed breast of average glandular composition.

• Take one photo-timed image at the technique normally used for the average breast patient.

• With standard densitometer, read central background density in the center of the phantom image. This

background density should be 1.0 to 1.2 optical density.

• If first film does not give OD of 1.0, then adjust technique to obtain a background OD of 1.0.

• Record technique and retain image. This now becomes your image control film.

Quantitative Procedures (at least once a week)

• Count the number of microcalcification groups visible and record the number.

• Count the number of simulated tumors and record the number.

• With optical densitometer, read fat and gland steps of the step wedge. Record the values, and the difference

(i.e., contrast). The fat/gland (steps 1 vs. step 5) should be .28 or greater.

• With a magnification lens, identify the number of line pair/mm, which are discernible.

• Record values on the record sheet (Figure 2-3).

Long Term Comparisons

• Once a quarter, take one of the weekly test films and compare visually to the initial film. You should see
identical images. If not, then corrective actions should be initiated.

Records To Keep

• Daily record of processor function (temperature and OD of step 10 or 11). This requirement is well understood
and not discussed further herein.

• Weekly record of step wedge contrast and detail visibility.

• Retained films of weekly phantom checks.

• Keep the QA record sheets (see Figure 2-3) in a file. These records of system performance are valuable to you

as a management tool and as proof of good "QA" should your system performance ever be challenged.

Care And Handling

These phantoms are manufactured from high quality materials but, like anatomy they represent, they can be broken.
Please

handle with care.

If you will treat these phantoms as you would any fragile piece of technical equipment, they will serve you well for
many years.

When not in use, the phantom should be stored in a safe location. Store at normal room temperature. If subjected to
temperatures above 110° for any extended period of time, return the phantom to Cardinal Health, Radiation
Management Service for re-certification.

2-1

Cleaning may be accomplished by using mild

p

cause the surface of the to become tacky. We use "Armor-All" vinyl protectant and experience no difficulty with tacky
surfaces.

Avoid contact with corrosive substances and with radiographic contrast media. Wash thoroughly if such contact
occurs.

soap and water solution. It has been reported that some detergents

Desirable Features of A Breast Phantom

1. Structural characteristics of the phantom:

a. Phantom should be realistically shaped.

b. Phantom should be tissue equivalent.

c. Phantom should have a realistic background

d. Phantom components should mimic features of breast disease (calcifications, tumors.).

2. Phantom should be easy to use.

3. Phantom should test relevant parameters including absorbed dose and image quality.

4. Phantom images should be easy to interpret and provide an accurate, unambiguous measure of image
quality.

Suggested Dose Curve for

Tissue-Equivalent Phantom with

CGR-500 Unit

(HVL = .344 @ 30 kVp)

Dg

(RADS)

Average Glandular Dose (2)

kV

Figure 2-1. Suggested Dose Chart

(1) ½ RAD is considered the maximum acceptable dose for 1 view mammogram of the average patient per the National

Council on Radiation Protection and Measurements (NCRP-80).

(2) NCRP-85; Pages 40 – 56.

(3) Measurements were taken at exposure settings that produced background photographic density of 1.0 using Ortho-M

Film, Min-R screen, Grid, and General Purpose film processor.

2-2

Table 2-1. Actual vs. Simulated Tissue (Weight Fractions)

Tissue C O H N Ca P Al G1

Specific

Gravity

30% Glandular

Actual Tissue 48.850 46.400 10.700 2.150 .200 .930
Simulated 75.510 9.960 11.730 1.230 .350 1.180 .930

50% Glandular

Actual Tissue 40.150 46.400 10.700 2.450 .300 .982
Simulated 75.070 10.160 11.670 1.230 .670 1.170 .982

70% Glandular

Actual Tissue 31.150 54.920 2.750 .380 1.004
Simulated 74.650 10.350 11.620 1.230 .970 1.170 1.004

100% Glandular

Actual Tissue 18.400 67.700 10.200 3.200 .5000 1.040
Simulated 70.210 12.510 10.930 1.150 .610 3.460 1.100 1.040

100% Adipose

Actual Tissue 61.900 25.100 11.200 1.700 .100 .930

Simulated 75.950 9.820 11.760 1.230 1.170 .924

2-3

Table 2-2. Actual vs. Simulated Linear Attenuation Coefficients (u)

30% Glandular 100% Glandular

keV Actual Simulated keV Actual Simulated

10.0 3.400820 3.262850 10.0 4.919490 4.685870

15.0 1.112980 1.098010 15.0 1.560170 1.535910

20.0 0.574784 0.574784 20.0 0.768012 0.768012

30.0 0.302201 0.304501 30.0 0.368387 0.371520

40.0 0.232988 0.234800 40.0 0.268827 0.270928

50.0 0.205005 0.206445 50.0 0.229969 0.231386

60.0 0.189907 0.191118 60.0 0.209919 0.210931

80.0 0.172653 0.173673 80.0 0.188308 0.189033

100.0 0.161710 0.162638 100.0 0.175442 0.176050

50% Glandular 100% Adipose

keV Actual Simulated keV Actual Simulated

10.0 3.812000 3.622000 10.0 2.975010 2.837940

15.0 1.234110 1.213450 15.0 0.995056 0.960624

20.0 0.627163 0.627163 20.0 0.530186 0.511345

30.0 0.320188 0.323307 30.0 0.294058 0.280331

40.0 0.242758 0.245163 40.0 0.233268 0.220533

50.0 0.211829 0.213702 50.0 0.208080 0.195861

60.0 0.195389 0.196938 60.0 0.194093 0.182268

80.0 0.176952 0.178232 80.0 0.177546 0.166402

100.0 0.165485 0.166639 100.0 0.166690 0.156112

70% Glandular

keV Actual Simulated

10.0 4.231200 3.984430

15.0 1.357150 1.329930

20.0 0.679992 0.679992

30.0 0.337905 0.342249

40.0 0.252103 0.255583

50.0 0.218186 0.220987

60.0 0.200393 0.202773

80.0 0.180781 0.182797

100.0 0.168807 0.170643

NOTE

Our simulated materials are formulated to maximize
simulation properties at 20 keV for the mammographic
energy range and 70 keV for the diagnostic energy range.

2-4

Table 2-3. Attenuation Comparison (µx) for Uses in the Well Known Relationship Various

µ

Phantom Densities and Sizes

I
I

O

= e

-

x

Tissue:

Thickness:

MFGR:

Fat Layer:

keV

Acrylic Acrylic Acrylic BR-12 50/50 30/70 50/50 30/70 50/50 20/80

4.4 cm 5.0 cm 4.55 cm 4.5 cm 4.0 cm 4.5 cm 4.5 cm 5.0 cm 5.0 cm 6.0 cm
ACR MFR #1 MFR #2 NAD NAD NAD NAD NAD NAD NAD

No No No No Yes Yes Yes Yes Yes Yes

10 15.542 17.769 16.995 15.942 13.703 14.257 15.514 15.889 17.325 18.294

15 5.127 5.891 5.608 5.298 4.601 4.803 5.207 5.352 5.814 6.175
20 (28 kVp) 2.705 3.103 2.936 2.728 2.392 2.523 2.706 2.811 3.021 3.251
30 1.477 1.691 1.582 1.402 1.251 1.346 1.412 1.498 1.573 1.758
40 1.162 1.328 1.236 1.062 .956 1.042 1.078 1.159 1.201 1.371
50 1.033 1.179 1.095 .925 .836 .918 .944 1.021 1.051 1.211

This chart compares the composite attenuation for various phantom size/density compositions.

The linear attenuation coefficient (µ) for each type of material (wax/lucite/gland/fat/etc.) applied to the thickness of
the material in each phantom design permits calculation of total attenuation for each phantom design.

Actual Breast Tissue per Hammerstein

Tissue

Thickness:

MFGR:

Fat Layer:

keV

10 15.689 14.411 16.317 18.223 16.578 18.996
15 5.066 4.697 5.314 5.931 5.446 6.271
20 (28 kVp) 2.571 2.411 2.725 3.038 2.829 3.279
30 1.307 1.254 1.414 1.574 1.502 1.762
40 .989 .961 1.082 1.204 1.165 1.375
50 .862 .843 .949 1.055 1.028 1.217

70/30 50/50 50/50 50/50 30/70 20/80

4.0 cm 4.0 cm 4.5 cm 5.0 cm 5.0 cm 6.0 cm
Actual Actual Actual Actual Actual Actual

Yes Yes Yes Yes Yes Yes

2-5

Figure 2-2. Embedded Details (Model 18-222 Specifications)

• Line Pair Target • Nylon Fibers
20 lp/mm

• Ca Co

Specs

3

Diameter size (mm)

19. 1.25

Grain Size (mm) 20. 0.83

2. .130 21. 0.71

3. .165 22. 0.53

4. .196 23. 0.30

5. .230

• Hemispheric Masses

6. .275 75% Glandular/ 25%

7. .400 adipose, thickness (mm)

8. .230 24. 4.76

9. .196 25. 3.16

10. .165 26. 2.38

11. .230 27. 1.98

12. .196 28. 1.59

13. .165 29. 1.19

• Step Wedge

1 cm thick

30. 0.90

• Optical Density

14. 100% Gland 31. Reference zone

15. 70% Gland

16. 50% Gland

• Edge of Beam

17. 30% Gland 32. Localization target

18. 100% Adipose

2-6

Location: Week/Month

Quality Assurance Record

Mammography

Baseline Day/WK-1 2 3 4 5 Remarks

Film Type

kVp (with photomtimer)

Processor Temperature °F

Processor Speed
(Sensitometry – Step 10)

Processor Contrast
(Step 9 – 11)

Phantom Contrast
(Step 1 – 5)

Phantom
Central Background Density

Phantom
Calcifications

Phantom
Low Contrast Masses

Phantom
Line Pair Visible

Dose
(Mean glandular dose for a

4.5 cm 50% Glandular Breast)

For daily readings, use 1 sheet/week

For weekly readings, use 1 sheet/month

Mammo Unit: QC Phantom No.

Processor Type:

Processor Cycle: 90 sec/2.5 min/3.0 min

Record film type and record
serial number of film box in use.
Record kVp used for phantom
test measurement. Use kVp
normally used for an average
density 4.5 cm breast.
Record processor temp at 9:00
A.M. each day.
Keep a box of film set aside ­sensitize and process. Read step
10 with optical densitometer –
record value.
Again, read steps 9 – 11 on the
sensitized film. Subtract step 9
value from step 11. Record
contrast.
On the phantom test image,
read stepwedge step 1 and
step 5. Subtract values. Record
contrast.
On phantom test image, read
background density in the
middle of phantom with optical
densitometer. Record value.
On phantom test image, count
the number of micro
calcification groupings visible.
Record value.
On the phantom test image,
count the number of low
contrast masses visible.
Records value.
On phantom test image, view
line pair test target with
microscope. Record the
number of line pairs/mm
visible.
Calculate the exposure monthly
with ion chamber and convert
to mean glandular dose or,
contact CIRS for QC kit.

Figure 2-3. Quality Assurance Record

2-7

2.2 References

1. American Cancer Society, CA32: 226-230, 1982.

2. National Council on Radiation Protection and Measurements (NCRP) Report #985. March 86.

3. Stanton L. Villafana, Day, Lightfoot. Dosage Evaluation in Mammography. RADIOLOGY 50:577-584, 1984.

4. Johns HE, Cunningham Jr. THE PHYSICS OF RADIOLOGY. 4th Edition.

5. McCrohon JL, Thompson WE, Butler PF, Goldstein HA, Phillips PR, Jane RG. Mammographic Phantom

Evaluation Project. HHS Publication. 83: 8213. 1983.

6. Fatouros PF, Skubic S. The Development and Use of Realistically-shaped, Tissue Equivalent Phantom for

Assessing the Mammographic Process, RADIOLOGY 157P:32. 1985.

7. Fatouros PF. Resolution and Noise in Xeromammography. MEDICAL PHYSICS 9:819-829

8. Fatouros PF, Goodman H, Rao G, Beachley M, Janis S, Bourland P. Absorbed Dose and Image Quality in

Xeromammography. Proceedings SPIE. Vol 419. 1983.

9. White DR, Tucker A. Test Object for Assessing Image Quality in Mammography. BJR 53:331-335. 1980.

10. Hessler C, Depeusinge C, Greceescu M, et al. Objective Assessment of Mammography Systems, part I: Method.

Radiology 156:215-219. 1985

11. Hammerstein R, Miller D, White D, et al. Absorbed Dose in Mammography. RADIOLOGY 156:215-219. 1985

12. Skubic S. An Investigation of the Relationship Between Image Quality and Breast Dose in Xeromammography.

Dissertation, Medical College of Virginia. May 1986.

13. Skubic S, Fatouros PF. The Dependence of Absorbed Breast Dose on X-Ray Modality, X-Ray Technique, and

Breast Thickness. RADIOLOGY 161:263-270. 1986.

14. Fewell, Shuping. Handbook of Mammographic Spectra. FDA Publication.

15. Skubic SE, Fatouros PP, Goodman H. The Effect of Breast Composition on Absorbed Dose and Image Contrast

in Publication.

16. Hubbell JH. INTERNATIONAL JOURNAL RADIATION ISOT Vol. 33:1269-1290. 1982.

17. American College of Radiology Guidelines on Mammographic Screening.

2-8

(Blank Page)

Radiation Management Services

All rights reserved.
Manual No. 18-222-1 Rev. 2 08 apr 04

Cardinal Health
6045 Cochran Road
Cleveland, Ohio 44139

120 Andrews Road
Hicksville, New York 11801

www.cardinal.com/rms

For additional information, please contact
Radiation Management Services business
of Cardinal Health at 440.248.9300, or

516.870.0100.

© 2004 Cardinal Health, Inc. or one of its subsidiaries