How to add sprite clicked on collision without rects?

I am new to pygame, not python and I am trying to make a alien shooter game, and i want collision between the crosshairs and the sprite. I want to collide a circle with a alien image and a shape? I don't want rects, just pure 'click on sprite and disappear'. Is there any way to do this? Here is the code:

"""Alien_ShooterDescription: a game to shoot aliens"""import pygameimport tskimport randompygame.init()WIDTH = 1018HEIGHT = 573w = pygame.display.set_mode([WIDTH, HEIGHT])c = pygame.time.Clock()shooting= FalseinvaderImage = []invader_X = []invader_Y = []invader_Xchange = []invader_Ychange = []no_of_invaders = 8turn = Falsefor num in range(no_of_invaders):    alien = pygame.image.load('SquidMan.png')    alien = pygame.transform.scale(alien, (100,100))    alien_hb = pygame.Rect(200, 500, 50, 50)    #collide = pygame.Rect.colliderect(player_rect, mouse)    invaderImage.append(alien)    invader_X.append(random.randint(64, 737))    invader_Y.append(random.randint(30, 180))    invader_Xchange.append(0)    invader_Ychange.append(1)def invader(x, y, i):    w.blit(invaderImage[i], (x, y))drawing = Truewhile drawing:    for e in pygame.event.get():        if e.type == pygame.QUIT:            drawing = False        if e.type == pygame.MOUSEBUTTONDOWN:            shooting = True        else:            shooting = False    #collide = pygame.Rect.colliderect(alien_rect, center_rect)    x, y = pygame.mouse.get_pos()    #print(x,y)    if shooting == True:        # gives the flashing effect when shooting        color = (0,0,0)    else:        color = (255,255,255)    for i in range(no_of_invaders):        invader_X[i] += invader_Xchange[i]    # movement of the invader    for i in range(no_of_invaders):        invader_Y[i] += invader_Ychange[i]        invader(invader_X[i], invader_Y[i], i)    line1 = pygame.draw.line(w, color, (x,y), (350, 700), 3)    line2 = pygame.draw.line(w, color, (x,y), (650, 700), 3)    # crosshares    center = pygame.draw.circle(w,color, (x, y), 10, 2)    pygame.draw.line(w, color, (x,y), (x+20, y), 3)    pygame.draw.line(w, color, (x,y), (x-20, y), 3)    ####################    #        |         #    #      --o--       #    #        |         #    ####################    pygame.draw.line(w, color, (x,y), (x, y+20), 3)    pygame.draw.line(w, color, (x,y), (x, y-20), 3)    pygame.display.flip()    c.tick(20)    w.fill((0,0,0))

I tried to fix this but I am not sure how to do it without rects