Conventional brachytherapy often results in less than ideal tumor dose conformity due to the non-symmetrical shape of the tumors, resulting in dose spillage to radiation sensitive healthy tissues. Intensity modulated brachytherapy (IMBT) can dynamically direct the radiation towards the tumor and away from healthy tissues by incorporating partially-shielded brachytherapy sources. The hypothesis is that IMBT can reduce the dose spillage to organs at risk in sites treated with conventional brachytherapy and thereby reduce numerous side effects. IMBrachy is a novel delivery system for IMBT which can incorporate the intermediate energy brachytherapy source 169Yb available from SPECMed. IMBrachy is standalone and can be connected to any commercial afterloader as an add-on device. Specifically, the device dynamically controls the rotation of shielded catheters. The device is compatible with both interstitial and intracavitary applicators. As in conventional brachytherapy, the afterloader is responsible for the motion of the source through the source guide and within the catheter. The device is divided in three main systems: a rotating system, a link assembly and a shield assembly. The rotation of the shield is controlled through a series of moving panels with an interlock system. Each panel is connected to a motor which handles the rotation of a subset of needles. The shielded needles are connected to the rotating mechanism through flexible locking luers that will give radiation oncologists the opportunity to implant the needles at an angle. The motors are equipped with controller sensors that control the motor position. A second set of sensors placed directly on the shield, or at the end of the link assembly, reads the actual position of the shield and provides feedback to the controller sensors. As a proof of principle, an IMBT treatment plan for a prostate cancer patient was simulated using a Monte Carlo based treatment planning system to show the potential advantages of the IMBrachy system. The Wilcoxon signed rank test was used to check for significant differences (p < 0.05) between the dose-volume histogram points. Validation of the functionality of the delivery system, the stability of the connection between the source guide and the shielded catheters, and the resistance to wear of the plastic needle during use has been completed. For the same minimum dose to the hottest 90 % of the planning target volume (PTV), the IMBT plan resulted in a statistically significant reduction in the bladder V75, rectum V75, and urethral D10 by 10 %, 8 %, and 15 %, respectively, while improving the homogeneity within the target (PTV V150 was reduced by 25 %). Delivering IMBT using the IMBrachy device has the potential to reduce radiation sensitive normal tissue toxicity and improve brachytherapy treatment outcomes.