how to echo image alt in wordpress attachment page

I have a piece of code for wordpress attachment page

$image_size = apply_filters( 'wporg_attachment_size', 'large' );
    echo wp_get_attachment_image( get_the_ID(), $image_size );

it woks fine and show the image with everything including Alt, but I want to show attachment ALT text below the image. what should I use? like this image:

You can display just the alt text below your image seperately by getting the alt text from the post within the DB.

<?php echo get_post_meta(get_the_ID(), '_wp_attachment_image_alt', true); ?>