A simple method for fabricating artificial kidney stones of different physical properties

Abstract

A simple method for preparing artificial kidney stones with varying physical properties is described. BegoStone was prepared with a powder to water ratio (by weight) ranging from 15:3 to 15:6. The acoustic properties of the phantoms were characterized by using an ultrasound transmission technique, from which the corresponding mechanical properties were calculated based on elastic wave theory. The measured parameters for BegoStone phantoms of different water contents are: longitudinal wave speed (3148 – 4159 m/s), transverse wave speed (1813 – 2319 m/s), density (1563 – 1995 kg/m3), longitudinal acoustic impedance (4.92 – 8.30 Kg/m2*s), transverse acoustic impedance (2.83 – 4.63 Kg/m2*s), Young’s modulus (12.9 – 27.4 GPa), bulk modulus (8.6 – 20.2 GPa), and shear modulus (5.1 – 10.7 GPa), which cover the range of corresponding properties reported in natural kidney stones. In addition, diametral compression tests were carried out to determine tensile failure strength of the stone phantoms. BegoStone phantoms with varying water content at preparation have tensile failure strength from 6.9 – 16.3 MPa when tested dry and 3.2 – 7.1 MPa when tested in water-soaked condition. Overall, it is demonstrated that this new BegoStone preparation method can be used to fabricate artificial stones with physical properties matched with those of natural kidney stones of various chemical compositions.

A heuristic model of stone comminution in shock wave lithotripsy

“…Similarly, stone composition (i.e., flaw distribution) has been identified as influencing the shape and scale parameters of the model in a manner similar to variations in Weibull parameters, though uncovering its precise role within the model requires additional experimentation. The artificial kidney stones used in this study have demonstrated clinical relevance (Esch et al, 2010), but do not necessarily mimic the Weibull parameters of all renal and ureteral stones. Determination of Weibull parameters for kidney stones and correlation with parameters of artificial stones may improve applicability of the model.…”

“…1(a) shows the ranked failure stresses of various hard and soft (5:1 and 5:2 powder to water mixing ratios, respectively) BegoStone Plus (BEGO USA, Lincoln, RI) phantoms from quasi-static diametral compression [see inset Fig. 1(b)], which has been used to determine the tensile failure strength (r f ) of renal calculi and stone phantoms (Esch et al, 2010;Simmons et al, 2010). Details of the stone preparation and diametral compression test have been described previously (Esch et al, 2010).…”

“…1(b)], which has been used to determine the tensile failure strength (r f ) of renal calculi and stone phantoms (Esch et al, 2010;Simmons et al, 2010). Details of the stone preparation and diametral compression test have been described previously (Esch et al, 2010). Using a least square parameter estimation technique (i.e., median rank regression) with (a) set to 0 MPa, hard and soft BegoStones are found to have normalization stresses (b) of 7.4 and 3.3 MPa, respectively, and Weibull moduli (c) of 9.4 and 7.5, respectively, with coefficients of determination (R 2 ) greater than or equal to 0.95.…”

Improving the lens design and performance of a contemporary electromagnetic shock wave lithotripter

“…Comparable acoustic energies (E + ≈ 40 mJ) were used for each lens during stone comminution experiments (Table 1) because it has been shown that stone comminution efficiency correlates closely with the pulse or accumulated acoustic energy in SWL (51,60,61). BegoStone phantoms used during comminution experiments were fabricated with a 5:1 powder-towater mixing ratio following a previously described protocol to mimic the physical properties of hard kidney stones such as calcium oxalate monohydrate and brushite stones (62). After SWL treatment, fragments were collected, carefully rinsed, air-dried for at least 24 h, sieved sequentially with standardized mesh sizes of 4, 2.8, and 2 mm, and weighed.…”

In Vivo Evaluation of a Reverse Thermosensitive Polymer for Ureteroscopy with Laser Lithotripsy: Porcine Model

“…8 Stone phantoms were prepared from BegoStone (BEGO USA, Lincoln, RI) at a 15:3 powder-to-water ratio to approximate the properties of calcium oxalate monohydrate. 9 Two 3-mm stone phantoms were placed retrograde into each ureter through a 13/15F, 28-cm access sheath. The 13/15F access sheath was advanced to the level of the mid to distal ureter over one of the Sensor wires under fluoroscopic guidance.…”