A tandem applicator assembly for brachytherapy that includes a tandem and a camera system. The tandem has a tubular main body with a trail end and a lead end. A transparent cap is affixed to the lead end. The camera system is removably received by the tandem through the trail end of the tubular main body. The camera system is disposed inside of the transparent cap. The camera system includes at least one digital camera configured to acquire color images from a patient through the transparent cap. The tandem applicator assembly may be used with a treatment planning system and method for customizing a treatment plan for a patient undergoing brachytherapy.