Splitting an array into individual values

I am trying to split an array with multiple values into individual values so that they can be used to render associated content.

My PHP:

// Split photos out from rota names arrays
	$sunday_rota = array();
	foreach($rota_sun as $key => $rota_sunday) {
	 $sunday_rota_photos[] = $rota_sunday['staff_photo'];
	}

//print_r($sunday_rota);

// Display photos from arrays, line ny line
$sunday_photos = implode("<br />",$sunday_rota_photos);
$sunday_photos_csv = implode(", ",$sunday_rota_photos);

echo $sunday_photos;

The data that the above displays:

30132-04.jpg
60032-01.jpg
68797-01.jpg

The entire arrayay (without selecting the staff photo) is:

Array ( [0] => Array ( [rota_id] => 66 [0] => 66 [staff_id] => 22 [1] => 0 [staff_name] => Nina [2] => Nina [3] => 22 [staff_photo] => 30132-04.jpg [4] => 30132-04.jpg [staff_createddate] => 2016-11-01 12:13:41 [5] => 2016-11-01 12:13:41 ) [1] => Array ( [rota_id] => 65 [0] => 65 [staff_id] => 52 [1] => 0 [staff_name] => Karyna [2] => Karyna [3] => 52 [staff_photo] => 60032-01.jpg [4] => 60032-01.jpg [staff_createddate] => 2017-01-04 16:35:26 [5] => 2017-01-04 16:35:26 ) [2] => Array ( [rota_id] => 57 [0] => 57 [staff_id] => 58 [1] => 0 [staff_name] => Roxy [2] => Roxy [3] => 58 [staff_photo] => 68797-01.jpg [staff_createddate] => 2017-01-24 06:50:41 [5] => 2017-01-24 06:50:41 ) )

I have tried various reiterations of the above to select only the staff photo value so that I can output it as a rendered image in HTML.

Whatever I code up results in implode/explode or array to string conversion errors.

Can anyone help me see where I might be going wrong?