Our online request an appointment tool will store your information securely until the next time you use the appointment request system. To get started, choose one of the options below which describes you best. Attention patients seeking Proton Therapy Please complete any appointment requests directly on the Texas Center for Proton Therapy website. Attention patients seeking Colon and Rectal Surgery Please complete any appointment requests directly on the Texas Colon & Rectal Specialists appointment request form.