Purpose: Encryption of patient information has become an important issue in medical ultrasound instrumentation to secure information when images are accessed off-site. The proposed algorithm is used to encrypt private medical images and transfer the encrypted images to improve the encryption capability and elapsed time.

Materials and methods: We generate a public key using three prime numbers, including a fixed Mersenne prime number, in the modified Rivest-Shamir-Adelman (RSA) algorithm to compare the encryption capability. We calculated and compared the elapsed time using the modified RSA algorithm with a breast phantom in the medical ultrasound imaging instrumentation.

Results: The encryption capability is improved because the elapsed time when using three prime numbers is longer (1.2337 s) than that when using two prime numbers (1.0712 s). However, the elapsed time using fixed Mersenne prime numbers (0.8360 s) is a similar to that using two prime numbers (0.8389 s).

Conclusions: Our proposed cryptographic algorithm provides improved encryption in medical ultrasound imaging compared to algorithms that use two prime numbers that are not Mersenne prime numbers, while transmitting images with adequate elapsed times.

目的：在非现场访问图像时，对患者信息进行加密已成为医疗超声仪器中保护信息安全的重要问题。所提出的算法用于加密私人医学图像并传输加密后的图像，以提高加密能力和经过时间。

资料和方法：我们使用改良的Rivest-Shamir-Adelman（RSA）算法中的三个素数（包括固定的Mersenne素数）生成一个公钥，以比较加密能力。我们在医学超声成像仪器中使用改良的RSA算法与乳腺体模计算并比较了经过时间。

结果：由于使用三个质数的时间比使用两个质数的时间（1.0712 s）更长（1.2337 s），因此提高了加密能力。但是，使用固定的梅森质数（0.8360 s）所花费的时间与使用两个质数（0.8389 s）所经历的时间相似。

结论：与使用两个不是Mersenne素数的素数，同时以足够的经过时间传输图像的算法相比，我们提出的密码算法在医学超声成像中提供了改进的加密。