The perfect image quality is dependent on some assumptions of the propagation of ultrasound waves in tissues after generating in an imaging system. These assumptions are important for the developing of optimal ultrasound imaging systems.
A lot of steps can be taken to prevent artifacts and to improve image quality, for example beamforming is used to focus the ultrasound beam, and contrast agents decrease the reflectivity of the undesired interfaces or increase the backscattered echoes from the desired regions.

See also Coded Excitation, Validation and Refraction Artifact, Q-Value, Ultrasound Phantom, Dead Zone, Narrow Bandwidth.

Ultrasound technology has evolved significantly, providing sonographers with a wide range of ultrasound machines. As technology has advanced, portable ultrasound equipment, including handheld ultrasound systems, have emerged in the field of medical imaging. However, these devices may have limited imaging capabilities and reduced image quality compared to larger systems.
Types of ultrasound systems compiled according to their portability:

In summary, pros and cons of portable ultrasound machines:

See also Ultrasound Accessories and Supplies, Environmental Protection, Sonographer, Ultrasound Technology and Equipment Preparation.

From ALOKA Co., Ltd.;
'Unsurpassed Image Quality and Performance The SSD-1400 offers the highest image quality and performance among our line of gray-scale imaging units.'

From ALOKA Co., Ltd.;
'Innovative Image Quality in a Compact Size.
Featuring design concepts inherited from our higher end systems along with Aloka's latest proprietary electronic technologies, the compact SSD-900 delivers superb images.
Traditionally, portable units suffer from hardware and software limitations that affect image quality. Aloka's SSD-900 sets new standards for what's possible in a portable unit. Incorporating over 50 years of experience and unique micro-chip technologies, the SSD-900 generates incredibly high-resolution images.
The SSD-900 offers a full range of measurement functions for professional ultrasonic examination. And unlike conventional portable systems, the SSD-900 includes annotation labeling and 15-channel preset functions as standard features.
The system also use Super High Density transducers (found our high-end systems) to enhance imaging resolution. These multi-frequency transducers provide a broad range of imaging frequencies to optimize scan frequency for depth of view.'

From ALOKA Co., Ltd.;
'Innovative Image Quality in a Compact Size
Featuring design concepts inherited from our higher end systems along with Aloka's latest proprietary electronic technologies, the compact SSD-900V delivers superb images.
Traditionally, portable units suffer from hardware and software limitations that affect image quality. Aloka's SSD-900V sets new standards for what's possible in a portable unit. Incorporating over 50 years of experience and unique micro-chip technologies, the SSD-900V generates incredibly high-resolution images.
The SSD-900V offers a full range of measurement functions for professional ultrasonic examination. And unlike conventional portable systems, the SSD-900V includes annotation labeling and 15-channel preset functions as standard features.
The system also use Super High Density transducers (found our high-end systems) to enhance imaging resolution. These multi-frequency transducers provide a broad range of imaging frequencies to optimize scan frequency for depth of view.'