Medical translation systems present an intriguing research area as language barriers can become life-threatening when health issues come into place. There is however a lack of common evaluation methodologies, making the fair comparison of such systems a difficult task. In this work the authors try to remedy this deficiency by proposing a quality model based on the ISO/IEC 9126 standard that could serve as a comparison basis among homologous systems. Their work involves the definition of the internal and external quality characteristics of the model along with the quantification of their relative importance based on the results of polling two groups of users (12 doctors and 12 potential patients) that demonstrate different needs and goals towards the system. Additionally, for the internal characteristics that reflect mainly a technical viewpoint the authors polled 6 developers. Finally, as the model contains attributes that are measurable the authors proposed metrics for each characteristic.