3 Challenges That Stand in the Way of Accurate Target Volumes

Precise treatments depend on accurate target volumes (TVs). This is especially true for hypofractionated treatments involving higher radiation doses over fewer fractions with increased risk of toxicity. 

Naturally, you need to be confident in the accuracy of your TV before delivering a high dose of radiation. But, due to the resource and billing challenges that come with hypofractionation, you also need to be sure your TV contouring process is as efficient as possible. 

If you’re not confident that your plan is built on accurate TVs, you can’t treat your patient’s cancer as precisely and aggressively as possible. And if your process for creating accurate TVs takes too much time, you risk burning out or reducing the number of patients your clinic can treat.  

What stands in the way of efficient, accurate target volumes? Below are some common challenges I’ve seen while helping radiation oncologists create better target volumes.     

1. Not all images are accessible or usable during TV contouring. 

For various reasons, potentially useful imaging data often can’t be accessed during TV contouring in the TPS. Have you experienced any of the following situations? 

• Images from an outside institution are trapped on a CD that can’t be imported into the TPS. 
• Non-axial native acquisition planes can’t be imported into the TPS.
• The anatomy differences between prior images and the treatment planning image are too significant—arms up vs. arms down, flat vs. curved bed, weight loss, applicator vs. no applicator, etc.

Regardless of the reason images aren’t accessible, the result is the same: You have fewer images to use when contouring, and your confidence in the accuracy of TVs is lower. 

2. It’s impossible to display images in a useful way.

Even if you can overcome the previous challenge and access all relevant imaging data for a patient, you probably still struggle to view the images in the TPS. Physicians I’ve worked with often get stuck switching back and forth between different modalities and registrations because only one is displayed at a time. This limitation is especially problematic when there are multiple MRs that can’t be visualized alongside the Plan CT.

To make matters worse, the displays you can see are difficult or impossible to adjust to your purpose. If you can customize a page layout, there’s no way to save it for future use. This wastes time and effort that you could spend on other important problems that require your attention. 

3. Tumor location and size are estimated without complete confidence. 

When the anatomy or positioning on the diagnostic and planning images doesn’t align, physicians often end up relying on cognitive fusion or multiple, separate rigid registrations. Deformable image registration is not considered because of the logistical burden and lack of confidence in a useful result, even though multiple rigid registrations can be more time-consuming and less precise.

It’s even more complicated when your plan involves tumor motion. Physicians often use Max IP to create an internal target volume instead of contouring directly on the phases of a 4D CT. Even though contouring directly on phases results in more accuracy, the time and effort required to contour on every single phase is not typically sustainable.

While coping with these challenges is a daily reality, considering viable options for target volume optimization can yield significant improvements with minimal effort.

Hear how a physician overcomes TV contouring challenges.