I tried to get image for invoice email template. I used below code. Just i'm getting magento placeholder image in email template. 


```
<td>
        <?php 
        $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
        $product_id = $_item->getOrderItem()->getProduct();
        $product = $objectManager->get('Magento\Catalog\Model\Product')->load($product_id);

        $_imagehelper = $objectManager->get('Magento\Catalog\Helper\Image');
        $image_url = $_imagehelper->init($product, 'cart_page_product_thumbnail')->getUrl();

        ?>
          <img src="<?php echo $image_url; ?>" alt="<?php echo $product->getName(); ?>" />
    </td>
```

Please help to solve this solution.

Thank you.