A method for defining a volume of interest, VOI, in an ultrasound imaging space, comprising: defining (102, 202) an initial volume of the VOI in the ultrasound imaging space; selecting (104, 204) at least one initial I reference point at an arbitrary location in the ultrasound imaging space; creating at least one curved surface based on at least one element of the initial volume, the at least one initial reference point, and based on using a method for generating a curved surface; the least one element of the initial volume is a point or line segment of the initial volume; selecting at least one reference plane in the ultrasound imaging space, wherein each of the at least one reference plane is a section view of the initial volume; selecting at least one proxy reference point at an arbitrary location in the at least one reference plane; obtaining at least one new reference point to be a calculated reversed projection point of each of the at least one proxy reference point, wherein the at least one reversed projection point is obtained by projecting the at least one proxy reference point according to a reversed projection relationship which is the reverse of a projection relationship according to which the at least one initial reference point is projected onto the at least one reference plane; adjusting the at least one curved surface based on at least one element of the initial volume, the at least one new reference point, and based on using a method for generating a curved surface; the at least one element of the initial volume for adjusting the at least one curved surface is a point or line segment of the initial volume; and creating (108, 214) the VOI based on the adjusted curved surface in the ultrasound imaging space. defining (102, 202) an initial volume of the VOI in the ultrasound imaging space; selecting (104, 204) at least one initial I reference point at an arbitrary location in the ultrasound imaging space; creating at least one curved surface based on at least one element of the initial volume, the at least one initial reference point, and based on using a method for generating a curved surface; the least one element of the initial volume is a point or line segment of the initial volume; selecting at least one reference plane in the ultrasound imaging space, wherein each of the at least one reference plane is a section view of the initial volume; selecting at least one proxy reference point at an arbitrary location in the at least one reference plane; obtaining at least one new reference point to be a calculated reversed projection point of each of the at least one proxy reference point, wherein the at least one reversed projection point is obtained by projecting the at least one proxy reference point according to a reversed projection relationship which is the reverse of a projection relationship according to which the at least one initial reference point is projected onto the at least one reference plane; adjusting the at least one curved surface based on at least one element of the initial volume, the at least one new reference point, and based on using a method for generating a curved surface; the at least one element of the initial volume for adjusting the at least one curved surface is a point or line segment of the initial volume; and creating (108, 214) the VOI based on the adjusted curved surface in the ultrasound imaging space.