A system for maintaining a registration of a subject space to an image space, comprising: a dynamic reference frame (58; 200; 300; 400) having a first tracking device and a mounting portion configured to be fixed to a subject, wherein the first tracking device is configured to be placed in a first configuration relative to the mounting portion and a second configuration relative to the mounting portion, wherein the first configuration is a first physical location and the second configuration is a second physical location relative to the mounting portion; a probe configured to contact the first tracking device in the first configuration and the second configuration, wherein the probe is configured to be tracked when the probe is contacting the first tracking device in the first configuration or the second configuration; and a processor system configured to: register the subject space to the image space with the first tracking device of the dynamic reference frame in the first configuration; determine a difference between the first configuration and the second configuration based on the tracked position of the probe when the probe is contacting the first tracking device; determine an adjustment factor based on the determined difference between the first configuration and the second configuration; and apply the adjustment factor to the registration of the subject space to the image space to maintain the registration. a dynamic reference frame (58; 200; 300; 400) having a first tracking device and a mounting portion configured to be fixed to a subject, wherein the first tracking device is configured to be placed in a first configuration relative to the mounting portion and a second configuration relative to the mounting portion, wherein the first configuration is a first physical location and the second configuration is a second physical location relative to the mounting portion; a probe configured to contact the first tracking device in the first configuration and the second configuration, wherein the probe is configured to be tracked when the probe is contacting the first tracking device in the first configuration or the second configuration; and a processor system configured to: register the subject space to the image space with the first tracking device of the dynamic reference frame in the first configuration; determine a difference between the first configuration and the second configuration based on the tracked position of the probe when the probe is contacting the first tracking device; determine an adjustment factor based on the determined difference between the first configuration and the second configuration; and apply the adjustment factor to the registration of the subject space to the image space to maintain the registration. register the subject space to the image space with the first tracking device of the dynamic reference frame in the first configuration; determine a difference between the first configuration and the second configuration based on the tracked position of the probe when the probe is contacting the first tracking device; determine an adjustment factor based on the determined difference between the first configuration and the second configuration; and apply the adjustment factor to the registration of the subject space to the image space to maintain the registration.