A system for generating a radiation therapy treatment plan by using ultrasound images, the system comprising: an ultrasound device configured to generate a first set of image data representing a first image of an anatomical region, wherein the anatomical region includes a treatment applicator inserted into the anatomical region; a tracking device configured to generate tracking information indicating a position of the treatment applicator as represented in the first set of image data; and a processor configured to: obtain the first set of image data from the ultrasound device; receive the tracking information from the tracking device; obtain, from an imaging device, a second set of image data representing a second image of the anatomical region, wherein the imaging device is one of a computed tomography device, a magnetic resonant imaging device, or an X-ray device; combine at least a portion of the first set of image data with the second set of image data by aligning: a graphical representation of the treatment applicator projected to the first set of image data based on the position of the treatment applicator with respect to the first set of image data, and a graphical representation of the treatment applicator projected to the second set of image data based on a location of the treatment applicator in the second set of image data, determined based on an identification of the treatment applicator in the second set of image data, wherein the combined image data is used to identify a target tissue portion in the anatomical region; and generate, based on the combined image data, treatment plan information for treating the target tissue portion in the anatomical region. an ultrasound device configured to generate a first set of image data representing a first image of an anatomical region, wherein the anatomical region includes a treatment applicator inserted into the anatomical region; a tracking device configured to generate tracking information indicating a position of the treatment applicator as represented in the first set of image data; and a processor configured to: obtain the first set of image data from the ultrasound device; receive the tracking information from the tracking device; obtain, from an imaging device, a second set of image data representing a second image of the anatomical region, wherein the imaging device is one of a computed tomography device, a magnetic resonant imaging device, or an X-ray device; combine at least a portion of the first set of image data with the second set of image data by aligning: a graphical representation of the treatment applicator projected to the first set of image data based on the position of the treatment applicator with respect to the first set of image data, and a graphical representation of the treatment applicator projected to the second set of image data based on a location of the treatment applicator in the second set of image data, determined based on an identification of the treatment applicator in the second set of image data, wherein the combined image data is used to identify a target tissue portion in the anatomical region; and generate, based on the combined image data, treatment plan information for treating the target tissue portion in the anatomical region. obtain the first set of image data from the ultrasound device; receive the tracking information from the tracking device; obtain, from an imaging device, a second set of image data representing a second image of the anatomical region, wherein the imaging device is one of a computed tomography device, a magnetic resonant imaging device, or an X-ray device; combine at least a portion of the first set of image data with the second set of image data by aligning: a graphical representation of the treatment applicator projected to the first set of image data based on the position of the treatment applicator with respect to the first set of image data, and a graphical representation of the treatment applicator projected to the second set of image data based on a location of the treatment applicator in the second set of image data, determined based on an identification of the treatment applicator in the second set of image data, wherein the combined image data is used to identify a target tissue portion in the anatomical region; and generate, based on the combined image data, treatment plan information for treating the target tissue portion in the anatomical region. a graphical representation of the treatment applicator projected to the first set of image data based on the position of the treatment applicator with respect to the first set of image data, and a graphical representation of the treatment applicator projected to the second set of image data based on a location of the treatment applicator in the second set of image data, determined based on an identification of the treatment applicator in the second set of image data, wherein the combined image data is used to identify a target tissue portion in the anatomical region; and generate, based on the combined image data, treatment plan information for treating the target tissue portion in the anatomical region.