Frequently Asked Questions: Radiation Therapy Products

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1. How can I reduce shrinkage of thermoplastic masks?

To minimize shrinkage, it is important to allow masks to completely cool before removing from the patient.  We recommend leaving a mask on for at least 10 minutes. Moist towels can speed the cooling, but this will increase shrinkage. As water evaporates from the surface of a mask, it removes heat from the mask, which increases the shrinkage. Masks made in an oven will shrink less, because there is no water evaporation.  


2. What is the best water temperature for heating Klarity masks and cushions?

In both water baths and ovens, an ideal temperature should be maintained between 165-170°F (73-77°C) . Lower temperatures can cause uneven molding and inadequate working time. Higher temperatures can cause tackiness, excessive stretching and difficult handling.


3. How long should I heat a Klarity mask?

Total heating time varies according to the thickness of the mask, heating method, ambient room temperature and the perforation pattern.  Usual times are 3 to 4 minutes in a water bath, or 4 to 5 minutes in an oven.   Be sure that the mask is thoroughly heated at the recommended temperature before removing from the oven or water bath. Masks will become translucent when heated, but an heating for an additional 30 seconds to a minute will insure complete and even heating. Masks can be left in the oven or water bath for up to 15 minutes at the recommended temperatures.


 4. How long should I heat a Klarity AccuCushion?

Total heating time varies according to the size of the cushion, ambient room temperature and the heating method.  A typical medium AccuCushion will be ready after 5 minutes in an oven or 7-10 minutes in a water bath at the recommended temperature.  Larger cushions will take more time.   Manipulate the cushion by hand to be sure that it is completely heated and easily moldable.   Cushions can be left in an oven for up to an hour or more at the recommended temperature.  They can also be allowed to cool and then be reheated.


5. What is the purpose of the reinforced perforation patterns?

Klarity AccuPerf™ and reinforced masks are designed for the higher stability requirements of IMRT.  Reinforcing strips hold firmly while the more open perforation areas allow for comfortable breathing and patient visibility.


6. What if the masks are too tight?

Shims can be used if necessary to relieve excessive shrinkage. However, with Klarity thermoplastic shims are usually not needed, as long as the following steps are taken:

Use proper water temperature (165° to 170°F)
Allow mask to cool completely before removing from patient.
Mold gently and somewhat loosely around the face, to allow for the minimal shrinkage that will occur.


7. How long should the mask cool before removing it from the patient?

We recommend leaving the mask on the patient for at least 10 minutes.   This minimizes shrinkage and insures an accurate fit for subsequent treatments.


8. How do I choose the right thickness of Klarity masks?

Thicker (3.2mm) masks will provide the highest stability.   However, thinner masks (2.4mm or 1.6mm) may have less attenuation and are sometimes preferred.


9. Will Klarity thermoplastic cause any skin reaction?

Klarity® thermoplastic contains no latex and is not known to cause any allergic or skin sensitive reactions. 


10. Can Klarity masks be used more than once?

A Klarity mask has memory. If reheated, it will return to its original flat shape. It can then be reheated and formed again.  However, multiple uses are not recommended. Masks are not easily disinfected, and body fluids can be unwittingly transferred between patients. Multiple heatings will also weaken the thermoplastic and may cause instability.


11. Can Klarity AccuCushions be used more than once?

A Klarity AccuCushion can be reheated and formed again.  This includes spot heating for adjustments.   However, AccuCushions are recommended for single patient use only.  AccuCushions are not easily cleaned or disinfected, and body fluids can be unwittingly transferred between patients.


12. How do I dispose of a Klarity mask or AccuCushion?

Klarity masks and AccuCushions contain no toxic chemicals or components.  They can be safely disposed of with normal hospital or household waste.