Python tkinter image file

from tkinter import *

window = Tk()
window.title ("Choose what you need right now")

def myFunc():
    if var.get() == 1:
        labelImage.configure(image=photo1)
    elif var.get() == 2:
        labelImage.configure(image=photo2)
    else:
        labelImage.configure(image=photo3)

labelText=Label (window, text="Vote for required items",
                  fg="red", font=("Gungseo font", 20))

var = IntVar()
rb1 = Radiobuton (window, text="tissue", variable=var,
                  value=1)
rb2 = Radiobutton (window, text="clock", variable=var,
                  value=2)
rb3 = Radiobutton (window, text="nutrients", variable=var,
                  value=3)
buttonOk = Button(window, text="View pictures",
                  command=myFunc)

photo1 = PhotoImage(file="image/tissue.png")
photo2 = PhotoImage(file="image/clock.png")
photo3 = PhotoImage(file="image/tonic.png")

labelImage = Label(window, width=200, height=200, bg="orange",
                   image=None)

labelText.pack(padx=5, pady=5)
rb1.pack(padx=5, pady=5)
rb2.pack(padx=5, pady=5)
rb3.pack(padx=5, pady=5)
buttonOk.pack(padx=5, pady=5)
labelImage.pack(padx=5, pady=5)

window.mainloop()