Tissue properties

sonosk.tissues is a database of acoustic and thermal properties of the tissues used by the anatomical phantoms. Every value carries the paper it comes from and a note on how it was measured or derived, so a simulation can always be traced back to its inputs.

from sonosk import tissues

fat = tissues.material("fat")                       # a Material
fat.c, fat.alpha0, fat.source
tissues.material("subcutaneous fat")                 # alias, labelled as given
tissues.material("fibroadenoma", echo=-6.0)          # one property changed
tissues.info("breast carcinoma")                     # (property, value, unit, ref, note)
tissues.cite("myometrium")                           # full citations
tissues.names("uterus"), tissues.groups()

How the values were chosen

The rules, in order:

1. a measurement in human tissue, in vivo if possible, published since 2009 when one exists (for example breast sound speeds from ultrasound tomography in 61 women, Li et al. 2009, and attenuation of breast fat in 24 women, Nasief et al. 2015);

2. otherwise the most specific ex vivo human measurement (myometrium, fibroid and cervix, Keshavarzi et al. 2001 and Kiss et al. 2011; skin, Moran et al. 1995);

3. otherwise a value used and cited in a recent peer-reviewed simulation study of the same organ (prostate attenuation, Suomi et al. 2018), or a reviewed compilation (ICRU Report 61 through Culjat et al. 2010);

4. otherwise the average of the IT’IS tissue property database V5.0 (2025), which pools many studies for each tissue; most densities, thermal properties and perfusions come from it;

5. where nothing fits, a modelling choice, marked * in the table and explained in its note (perfusion of fibroids and of blood in vessels, B/A of bone).

Where a paper gives two points of a power law, the exponent is fitted through them; the notes say so. Echo levels are the least certain numbers: they are relative to breast fat (the BI-RADS standard of comparison) and, apart from fat, are modelling choices that reproduce the usual B-mode appearance of each tissue.

Provenance and spread

A reference per value does not make every value equally strong. tissues.provenance(name) says how each value was obtained: measured, fitted, database average, used in a simulation study, review compilation, generic soft-tissue value, inherited from a similar tissue, reference level, or modelling choice. For the values taken from IT’IS V5.0, tissues.uncertainty(name, prop) returns the standard deviation, the minimum, the maximum and the number of samples or studies (a standard deviation of 0 with one study means a single source), and tissues.sample(name, rng) draws a material with every such value within its spread, for Monte Carlo runs.

tissues.provenance("prostate carcinoma")   # {'c': 'inherited', ..., 'perfusion': 'used in a simulation study', ...}
tissues.uncertainty("muscle", "rho")       # (55.14, 1041, 1178, 14)
m = tissues.sample("muscle", rng=1)
tissues.to_csv("tissues.csv")              # the whole table with provenance and spread

The table, with the provenance and the spread of every value, is also available as tissues.csv, generated from the code.

Properties and units

Name	Meaning	Unit
c	speed of sound	m/s
rho	density	kg/m³
alpha0, y	attenuation \(\alpha(f) = \alpha_0 f^y\)	dB/(cm MHz\(^y\))
ba	nonlinearity parameter \(B/A\)
k	thermal conductivity	W/(m K)
cp	specific heat	J/(kg K)
perfusion	blood perfusion	mL/(min kg), converted to kg/(m³ s)
echo	backscatter level relative to breast fat	dB

The table

Shared

Tissue	c [m/s]	rho [kg/m3]	alpha0 [dB/(cm MHz^y)]	y	B/A	k [W/(m K)]	cp [J/(kg K)]	perfusion [mL/(min kg)]	echo [dB]
fat	1422 [9]	911 [3]	0.73 [13]	1 [13]	11 [8]	0.211 [3]	2348 [3]	32.7 [3]	0 [13]
muscle	1588.4 [3]	1090.4 [3]	0.617 [3]	1.08 [3]	7 [8]	0.495 [3]	3421 [3]	36.7 [3]	-6 [1]
water	1523.7 [10]	993.3 [5]	0.0022 [3]	2 [14]	4.96 [3]	0.605 [3]	4178 [3]	0 [3]	anechoic [1]
blood	1578.2 [3]	1049.8 [3]	0.206 [3]	1.05 [3]	6.11 [3]	0.517 [3]	3617 [3]	0 *	-30 [1]
bone	3515 [3]	1908 [3]	4.74 [3]	1 [3]	7 *	0.32 [3]	1313 [3]	10 [3]	20 [1]

Skin

Tissue	c [m/s]	rho [kg/m3]	alpha0 [dB/(cm MHz^y)]	y	B/A	k [W/(m K)]	cp [J/(kg K)]	perfusion [mL/(min kg)]	echo [dB]
epidermis	1645 [11]	1109 [3]	0.44 [11]	1.55 [11]	7 [8]	0.372 [3]	3391 [3]	0 *	15 [1]
dermis	1595 [11]	1109 [3]	0.264 [11]	1.69 [11]	7 [8]	0.372 [3]	3391 [3]	106.4 [3]	10 [1]
smas	1595 [11]	1109 [3]	0.264 [11]	1.69 [11]	7 [8]	0.372 [3]	3391 [3]	106.4 [3]	8 [1]

Breast

Tissue	c [m/s]	rho [kg/m3]	alpha0 [dB/(cm MHz^y)]	y	B/A	k [W/(m K)]	cp [J/(kg K)]	perfusion [mL/(min kg)]	echo [dB]
fibroglandular tissue	1487 [9]	1020 [2]	0.75 [2]	1 [2]	7 [8]	0.335 [3]	2960 [3]	150 [3]	10 [1]
cooper ligament	1595 [11]	1109 [3]	0.264 [11]	1.69 [11]	7 [8]	0.372 [3]	3391 [3]	106.4 [3]	14 [1]
breast cyst	1523.7 [10]	993.3 [5]	0.0022 [3]	2 [14]	4.96 [3]	0.605 [3]	4178 [3]	0 [3]	anechoic [1]
fibroadenoma	1513 [9]	1040.5 [3]	0.94 [12]	1 [12]	7 [8]	0.335 [3]	2960 [3]	150 [3]	-3 [1]
breast carcinoma	1548 [9]	1040.5 [3]	1.16 [12]	1 [12]	7 [8]	0.415 [16]	3750 [17]	150 [3]	-6 [1]

Prostate

Tissue	c [m/s]	rho [kg/m3]	alpha0 [dB/(cm MHz^y)]	y	B/A	k [W/(m K)]	cp [J/(kg K)]	perfusion [mL/(min kg)]	echo [dB]
prostate	1561 [15]	1045 [15]	0.78 [15]	1.1 [15]	7.5 [15]	0.51 [15]	3400 [15]	394.1 [3]	-6 [1]
prostate transition zone	1561 [15]	1045 [15]	0.78 [15]	1.1 [15]	7.5 [15]	0.51 [15]	3400 [15]	394.1 [3]	-9 [1]
prostate carcinoma	1561 [15]	1045 [15]	0.78 [15]	1.1 [15]	7.5 [15]	0.51 [15]	3400 [15]	93 [15]	-14 [1]
calcification	2184 [15]	1466 [15]	2.64 [15]	1.1 [15]	7.5 [15]	3.85 [15]	858 [15]	0 [15]	25 [1]
rectal wall	1588.4 [3]	1090.4 [3]	0.617 [3]	1.08 [3]	7 [8]	0.495 [3]	3421 [3]	36.7 [3]	-4 [1]

Pelvis

Tissue	c [m/s]	rho [kg/m3]	alpha0 [dB/(cm MHz^y)]	y	B/A	k [W/(m K)]	cp [J/(kg K)]	perfusion [mL/(min kg)]	echo [dB]
bladder wall	1588.4 [3]	1090.4 [3]	0.617 [3]	1.08 [3]	7 [8]	0.495 [3]	3421 [3]	36.7 [3]	2 [1]
urine	1523.7 [10]	993.3 [5]	0.0022 [3]	2 [14]	4.96 [3]	0.605 [3]	4178 [3]	0 [3]	anechoic [1]

Uterus

Tissue	c [m/s]	rho [kg/m3]	alpha0 [dB/(cm MHz^y)]	y	B/A	k [W/(m K)]	cp [J/(kg K)]	perfusion [mL/(min kg)]	echo [dB]
myometrium	1613 [6]	1104.5 [3]	0.316 [7]	1.6 [7]	7 [8]	0.527 [3]	3676 [3]	457.5 [3]	-4 [1]
fibroid	1613 [6]	1104.5 [3]	0.357 [7]	1.65 [7]	7 [8]	0.527 [3]	3676 [3]	100 *	-8 [1]
cervix	1629 [3]	1104.5 [3]	0.218 [7]	2.09 [7]	7 [8]	0.527 [3]	3676 [3]	700 [3]	-2 [1]
endometrium	1613 [6]	1104.5 [3]	0.316 [7]	1.6 [7]	7 [8]	0.527 [3]	3676 [3]	457.5 [3]	6 [1]

References of the table

[1] Echo level chosen to reproduce the usual B-mode appearance of the tissue (ACR BI-RADS ultrasound lexicon; for breast masses see also Nam et al. 2013). A modelling choice, not a measurement.

[2] Culjat M.O., Goldenberg D., Tewari P., Singh R.S. A review of tissue substitutes for ultrasound imaging. Ultrasound Med. Biol. 36(6):861-873, 2010. doi:10.1016/j.ultrasmedbio.2010.02.012 (Table 1, values from ICRU Report 61, 1998)

[3] IT’IS Foundation. Tissue Properties Database V5.0, 21 August 2025. doi:10.13099/VIP21000-05-0 (average values; attenuation converted from Np/(m MHz^y) with 1 Np = 8.686 dB)

[4] Katz-Hanani I., Rothstein T., Gaitini D., Gallimidi Z., Azhari H. Age-related ultrasonic properties of breast tissue in vivo. Ultrasound Med. Biol. 40(9):2265-2271, 2014. doi:10.1016/j.ultrasmedbio.2014.03.034

[5] Kell G.S. Density, thermal expansivity, and compressibility of liquid water from 0 to 150 C. J. Chem. Eng. Data 20(1):97-105, 1975. doi:10.1021/je60064a005

[6] Keshavarzi A., Vaezy S., Kaczkowski P.J., et al. Attenuation coefficient and sound speed in human myometrium and uterine fibroid tumors. J. Ultrasound Med. 20(5):473-480, 2001. doi:10.7863/jum.2001.20.5.473

[7] Kiss M.Z., Varghese T., Kliewer M.A. Ex vivo ultrasound attenuation coefficient for human cervical and uterine tissue from 5 to 10 MHz. Ultrasonics 51(4):467-471, 2011. doi:10.1016/j.ultras.2010.11.012

[8] Law W.K., Frizzell L.A., Dunn F. Determination of the nonlinearity parameter B/A of biological media. Ultrasound Med. Biol. 11(2):307-318, 1985. doi:10.1016/0301-5629(85)90130-9

[9] Li C., Duric N., Littrup P., Huang L. In vivo breast sound-speed imaging with ultrasound tomography. Ultrasound Med. Biol. 35(10):1615-1628, 2009. doi:10.1016/j.ultrasmedbio.2009.05.011

[10] Marczak W. Water as a standard in the measurements of speed of sound in liquids. J. Acoust. Soc. Am. 102(5):2776-2779, 1997. doi:10.1121/1.420332

[11] Moran C.M., Bush N.L., Bamber J.C. Ultrasonic propagation properties of excised human skin. Ultrasound Med. Biol. 21(9):1177-1190, 1995. doi:10.1016/0301-5629(95)00049-6

[12] Nam K., Zagzebski J.A., Hall T.J. Quantitative assessment of in vivo breast masses using ultrasound attenuation and backscatter. Ultrason. Imaging 35(2):146-161, 2013. doi:10.1177/0161734613480281

[13] Nasief H.G., Rosado-Mendez I.M., Zagzebski J.A., Hall T.J. Acoustic properties of breast fat. J. Ultrasound Med. 34(11):2007-2016, 2015. doi:10.7863/ultra.14.07039

[14] Pinkerton J.M.M. The absorption of ultrasonic waves in liquids and its relation to molecular constitution. Proc. Phys. Soc. B 62(2):129-141, 1949. doi:10.1088/0370-1301/62/2/307

[15] Suomi V., Treeby B., Jaros J., et al. Transurethral ultrasound therapy of the prostate in the presence of calcifications: a simulation study. Med. Phys. 45(11):4793-4805, 2018. doi:10.1002/mp.13183

[16] Valvano J.W., Cochran J.R., Diller K.R. Thermal conductivity and diffusivity of biomaterials measured with self-heated thermistors. Int. J. Thermophys. 6(3):301-311, 1985; values as tabulated by Rossmann C., Haemmerich D. Crit. Rev. Biomed. Eng. 42(6):467-492, 2014. doi:10.1615/critrevbiomedeng.2015012486

[17] Vaupel P., Piazena H. Strong correlation between specific heat capacity and water content in human tissues suggests preferred heat deposition in malignant tumors upon electromagnetic irradiation. Int. J. Hyperthermia 39(1):987-997, 2022. doi:10.1080/02656736.2022.2067596

* modelling choice where no measurement fits; the notes below give the reason.

Notes on each value

fat: c: breast fat in vivo, ultrasound tomography, 61 women; used for all adipose layers; rho: fat, 23 samples; alpha0: breast fat in vivo, slope at 7 MHz, 24 women; y: linear frequency dependence assumed for the slope; ba: fat: B/A around 11; k: fat; cp: fat; perfusion: fat; echo: reference level; breast fat is the BI-RADS standard of comparison.

muscle: c: skeletal muscle, mean of 24 values; rho: skeletal muscle, 14 samples; alpha0: 7.11 Np/(m MHz^y); ba: muscle: B/A close to 7; perfusion: resting muscle; echo: muscle is hypoechoic to fat.

water: c: water at 37 C; rho: water at 37 C; alpha0: 0.0253 Np/(m MHz) at 1 MHz; y: viscous absorption grows with f^2; IT’IS lists a linear law, which understates the loss above 1 MHz; ba: room temperature; echo: anechoic.

blood: rho: 584 samples; alpha0: 2.37 Np/(m MHz^y); perfusion: flowing blood in a vessel; heat carried by flow is not a Pennes term; echo: nearly anechoic at clinical frequencies.

epidermis: c: excised skin, 20-30 MHz, 24 C; rho: skin; alpha0: fit alpha1 f^n over 20-30 MHz; y: fit over 20-30 MHz; ba: soft tissue value; k: skin; cp: skin; perfusion: the epidermis has no blood vessels; echo: bright entry echo.

dermis: c: excised skin, 20-30 MHz, 24 C; rho: skin; alpha0: fit alpha1 f^n over 20-30 MHz; y: fit over 20-30 MHz; ba: soft tissue value; k: skin; cp: skin; perfusion: skin; echo: dermis is hyperechoic to subcutaneous fat.

smas: superficial musculoaponeurotic system, given the acoustic and thermal properties of dermis (dense connective tissue); no direct measurement; c: excised skin, 20-30 MHz, 24 C; value of dermis; rho: skin; value of dermis; alpha0: fit alpha1 f^n over 20-30 MHz; value of dermis; y: fit over 20-30 MHz; value of dermis; ba: soft tissue value; value of dermis; k: skin; value of dermis; cp: skin; value of dermis; perfusion: skin; value of dermis; echo: fibrous layer, echogenic band in the subcutis.

fibroglandular tissue: c: breast parenchyma in vivo, ultrasound tomography; rho: breast; alpha0: breast; whole breasts in vivo range from 0.96 (over 60 years) to 1.27 (under 30) dB/(cm MHz), Katz-Hanani et al. 2014; y: slope in dB/(cm MHz); ba: soft tissue value; k: breast gland; cp: breast gland; perfusion: breast gland; echo: fibroglandular tissue is hyperechoic to fat.

cooper ligament: connective tissue band, given the properties of dermis; c: excised skin, 20-30 MHz, 24 C; value of dermis; rho: skin; value of dermis; alpha0: fit alpha1 f^n over 20-30 MHz; value of dermis; y: fit over 20-30 MHz; value of dermis; ba: soft tissue value; value of dermis; k: skin; value of dermis; cp: skin; value of dermis; perfusion: skin; value of dermis; echo: thin echogenic septa.

breast cyst: simple cyst fluid modelled as water at 37 C; c: water at 37 C; value of water; rho: water at 37 C; value of water; alpha0: 0.0253 Np/(m MHz) at 1 MHz; value of water; y: viscous absorption grows with f^2; IT’IS lists a linear law, which understates the loss above 1 MHz; value of water; ba: room temperature; value of water; k: value of water; cp: value of water; perfusion: value of water; echo: simple cyst: anechoic.

fibroadenoma: c: benign breast lesions in vivo, mean of the cohort; rho: breast gland; alpha0: 14 fibroadenomas in vivo, reference phantom method; y: slope in dB/(cm MHz); ba: soft tissue value; k: breast gland; cp: breast gland; perfusion: breast gland; echo: oval circumscribed mass, mildly hypoechoic to fat.

breast carcinoma: c: malignant breast lesions in vivo, mean of the cohort; rho: breast gland; alpha0: 10 carcinomas in vivo, reference phantom method; y: slope in dB/(cm MHz); ba: soft tissue value; k: human breast adenocarcinoma, 37 C; cp: middle of the 3.6-3.9 J/(g K) range of malignant tumours; perfusion: breast gland; echo: hypoechoic mass; most carcinomas have a lower backscatter than fibroadenomas (Nam et al. 2013).

prostate: c: from Parker et al. 1993; with rho gives 1.63 MRayl; rho: same value in IT’IS; alpha0: value used for prostate tissue in their simulations; y: exponent used with alpha0; k: IT’IS gives 0.512; cp: freshly excised prostate (Patch et al. 2011); perfusion: normal prostate; echo: peripheral zone: homogeneous, isoechoic, darker than periprostatic fat.

prostate transition zone: c: from Parker et al. 1993; with rho gives 1.63 MRayl; value of prostate; rho: same value in IT’IS; value of prostate; alpha0: value used for prostate tissue in their simulations; value of prostate; y: exponent used with alpha0; value of prostate; ba: value of prostate; k: IT’IS gives 0.512; value of prostate; cp: freshly excised prostate (Patch et al. 2011); value of prostate; perfusion: normal prostate; value of prostate; echo: transition zone: hypoechoic and heterogeneous with age.

prostate carcinoma: acoustic and thermal properties of normal prostate, with the lower perfusion measured in carcinoma; no measured in vivo acoustic values; c: from Parker et al. 1993; with rho gives 1.63 MRayl; value of prostate; rho: same value in IT’IS; value of prostate; alpha0: value used for prostate tissue in their simulations; value of prostate; y: exponent used with alpha0; value of prostate; ba: value of prostate; k: IT’IS gives 0.512; value of prostate; cp: freshly excised prostate (Patch et al. 2011); value of prostate; perfusion: 1.7 kg/(m^3 s), measured in patients with locally advanced carcinoma (van Vulpen et al. 2002); echo: classically hypoechoic in the peripheral zone.

calcification: c: renal stones (Singh and Agarwal 1989); with rho gives 3.20 MRayl; rho: renal stones; alpha0: value used for prostatic calcifications; y: exponent used with alpha0; k: calcium carbonate; cp: calcium carbonate; echo: bright echo with acoustic shadow.

rectal wall: given the properties of muscle; c: skeletal muscle, mean of 24 values; value of muscle; rho: skeletal muscle, 14 samples; value of muscle; alpha0: 7.11 Np/(m MHz^y); value of muscle; y: value of muscle; ba: muscle: B/A close to 7; value of muscle; k: value of muscle; cp: value of muscle; perfusion: resting muscle; value of muscle; echo: layered muscular wall.

bladder wall: given the properties of muscle; c: skeletal muscle, mean of 24 values; value of muscle; rho: skeletal muscle, 14 samples; value of muscle; alpha0: 7.11 Np/(m MHz^y); value of muscle; y: value of muscle; ba: muscle: B/A close to 7; value of muscle; k: value of muscle; cp: value of muscle; perfusion: resting muscle; value of muscle; echo: thin echogenic wall.

urine: modelled as water at 37 C; c: water at 37 C; value of water; rho: water at 37 C; value of water; alpha0: 0.0253 Np/(m MHz) at 1 MHz; value of water; y: viscous absorption grows with f^2; IT’IS lists a linear law, which understates the loss above 1 MHz; value of water; ba: room temperature; value of water; k: value of water; cp: value of water; perfusion: value of water; echo: anechoic.

myometrium: c: fresh ex vivo, 1-3 MHz: 1611-1616 m/s for myometrium and fibroid; rho: uterus; alpha0: power law through the 5 and 10 MHz values of the abstract (4.15 and 12.6 dB/cm); y: same fit; ba: soft tissue value; k: uterus; cp: uterus; perfusion: uterus; echo: homogeneous, intermediate echo level.

fibroid: c: fresh ex vivo, 1-3 MHz; rho: uterus; alpha0: leiomyoma: power law through 5.1 and 16.0 dB/cm at 5 and 10 MHz; y: same fit; ba: soft tissue value; k: uterus; cp: uterus; perfusion: fibroids chosen for HIFU are usually hypovascular, so a value well below that of myometrium; perfusion varies widely between fibroids; echo: usually hypoechoic whorled mass.

cervix: c: cervix; rho: cervix; alpha0: power law through 6.3 and 26.8 dB/cm at 5 and 10 MHz; y: same fit; ba: soft tissue value; k: cervix; cp: cervix; perfusion: cervix; echo: intermediate echo level.

endometrium: acoustic and thermal properties of myometrium; c: fresh ex vivo, 1-3 MHz: 1611-1616 m/s for myometrium and fibroid; value of myometrium; rho: uterus; value of myometrium; alpha0: power law through the 5 and 10 MHz values of the abstract (4.15 and 12.6 dB/cm); value of myometrium; y: same fit; value of myometrium; ba: soft tissue value; value of myometrium; k: uterus; value of myometrium; cp: uterus; value of myometrium; perfusion: uterus; value of myometrium; echo: echogenic stripe (secretory phase).

bone: fluid model: shear waves are not included; c: cortical bone, compressional wave; rho: cortical bone, 27 samples; alpha0: cortical bone, 54.6 Np/(m MHz); ba: no measurement; enters only through the nonlinear term; k: cortical bone; cp: cortical bone; perfusion: cortical bone; echo: bright surface with shadow.

Missing data you can help with

In vivo measurements would improve several entries: sound speed and attenuation of the normal prostate, perfusion of fibroids, and the thermal properties of breast lesions. They are welcome through the tissue data issue form.