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Fig. 1. Composition of tissue mimicking ner field phntom.

The filments re mde from stinless steel with dimeter of 0.1 mm.

the phntom. Fig. 2. Evlution of imge uniformity.

2 Fig. 1. Composition of tissue mimicking ner field phntom. A commercilly ville tissue mimicking phntom composed with filments nd msses. The filments re mde from stinless steel with dimeter of 0.1 mm. There re lso two known volumes, 10 mm nechoic mss nd nechoic focl lesions emedded within the phntom. Fig. 2. Evlution of imge uniformity. () The imge demonstrtes uniform texture similr to tht of liver prenchym. () There is horizontl nd (rrows) t the depth from 3 cm nd 4 cm. (c) After chnging focl zones, hypoechoic nd disppered. c 114

Fig. 4. Evlution of distnce ccurcy. The filments re positioned 1 cm prt down the center of the phntom in verticl plne. The test imge shows verticl trgets with 1cm of verticl distnce. Fig. 3.

() The sctters nd filments re visile t 7 cm in depth. () 5 mm sized nechoic spheres re visile etween 5 cm nd 6 cm. The depth of penetrtion is 6 cm.

3 Fig. 4. Evlution of distnce ccurcy. The filments re positioned 1 cm prt down the center of the phntom in verticl plne. The test imge shows verticl trgets with 1cm of verticl distnce. Fig. 3. Evlution of depth of penetrtion. The imges re cquired t the setting of deepest focl zone, mximl gin, TGC t full gin, nd field of view t mximum depth of penetrtion. () The sctters nd filments re visile t 7 cm in depth. () 5 mm sized nechoic spheres re visile etween 5 cm nd 6 cm. The depth of penetrtion is 6 cm. (c) 3 mm sized nechoic spheres re visile t 5 cm. But the imge shows some spheres (lck rrows) which demonstrte fill-in effect, jgged mrgin, incresed internl echogenicity nd loss of posterior coustic enhncement. The depth of penetrtion is less thn 5 cm. c 115

c d Fig. 5. Evlution of xil nd lterl resolution. The xil resolution trget ( nd ) consists of six pirs of prllel, 0.1 mm dimeter filments horizontlly spced 6 mm prt from center to center.

5 mm from center to center. The zoomed imge of xil resolution trget shows clerly distinguished the lst pir of trget (rrow). The xil resolution of this equipment is less thn 0.5 mm. The lterl resolution (c nd d) trget consists of six prllel filments horizontlly spced t distnces of 5, 4, 3, 2, nd 1 mm from center to center.

4 c d Fig. 5. Evlution of xil nd lterl resolution. The xil resolution trget ( nd ) consists of six pirs of prllel, 0.1 mm dimeter filments horizontlly spced 6 mm prt from center to center. The lower wire in ech pir is horizontlly offset from the upper wire y 1 mm to further reduce ny coustic shdowing effects. The verticl distnce etween ech pir of wires is 5, 4, 3, 2, 1, nd 0.5 mm from center to center. The zoomed imge of xil resolution trget shows clerly distinguished the lst pir of trget (rrow). The xil resolution of this equipment is less thn 0.5 mm. The lterl resolution (c nd d) trget consists of six prllel filments horizontlly spced t distnces of 5, 4, 3, 2, nd 1 mm from center to center. The zoomed imge shows clerly seprted filments, so the lterl resolution is less thn 1 mm. 116

Fig. 6. Evlution of nechoic oject imging. A 1 cm sized nechoic mss nd 3 mm nd 5 mm sized nechoic spheres cn e used for nechoic oject imging test in this phntom.

The trget of ded zone () consists of prllel, 0.1 mm dimeter filment horizontlly spced 6 mm prt from center to center.

5 Fig. 6. Evlution of nechoic oject imging. A 1 cm sized nechoic mss nd 3 mm nd 5 mm sized nechoic spheres cn e used for nechoic oject imging test in this phntom. The imge demonstrtes nechoic mss with round shpe nd circumscried mrgin. The difference etween width nd height is 3.6 mm, less thn 15%. Fig. 7. Evlution of ded zone. The trget of ded zone () consists of prllel, 0.1 mm dimeter filment horizontlly spced 6 mm prt from center to center. Verticl distnce from the center of ech filment to the top edge of the scnning surfce rges from 5 mm down to 1 mm in 1 mm increments. The imge () shows cler visulized t 1 mm depth from surfce. The ded zone distnce is less thn 1 mm. 117

6 1. Goodsitt MM, Witt S, Hykes DL, Koflwer JM. Rel-time B-mode ultrsound qulity control test procedures. Report of AAPM ultrsound tsk group. Med Phys 1998;25: AIUM, Methods for mesuring performnce of pulse-echo ultrsound equipment-prt II: Digitl methods (stge 1), edited y H. Lopez et l. (Americ Institute of Ultrsound In Medicine, Lurel, MD, 1995) Ultrsound In Medicine, Lurel, MD, 1995) 3. AIUM, Qulity Assurnce mnul for gry scle ultrsound scnners (stge 2), edited y E. Mdsen et l. (Americn Institute of 4. Berg WA, Blume JD, Cormck JB, Mendelson EB, Medsen EL. Lesion detection nd chrcteriztion in rest US phntom: Results of the ACRIN 6666 investigtors. Rdiology 2006;239:

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±èÇ¥³â 533 Fig. 1. Dead zone. Nine echoes are positioned 2-10 mm below the scan surface with 1 mm distance. All nine echoes are clearly visualized. 534 Fig. 2. Vertical and horizontal measurement. 10 cm distance