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SU‐FF‐T‐456: A Comparison of Cysto‐Conray II to Readi‐Cat 2 Contrast Material for Use in Rectal Balloons During Proton Therapy
Author(s) -
Tasson A,
Fitzek M,
Shahnazi K,
Simmons J,
Simoneaux V,
Speights D,
SullivanDickey M,
Thornton A,
Wallace D
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3181938
Subject(s) - nuclear medicine , medicine , barium sulfate , contrast (vision) , iohexol , radiology , materials science , optics , physics , renal function , metallurgy
Purpose: In our clinic, a rectal balloon filled with contrast is used to fixate and localize the prostate during proton treatments. We have traditionally used a 70%/30% mixture of water/Cysto‐Conray II, which is iodine‐based. After having a small leak in a rectal balloon, an alternative solution was investigated, namely Readi‐Cat 2 (a barium sulfate suspension), due to iodine related allergies, as well as increasing cost of the contrast, and dilution requirements. Method and Materials: The likelihood of an allergic reaction, as well as cost, was evaluated for the Cysto‐Conray and Readi‐Cat. The electron densities were compared by importing a CT scan of the contrast agents into a treatment planning work station. A depth scan was taken in a water tank after the proton beam passed through the contrast agents allowing the attenuation of the proton beam to be measured. X‐rays were taken of patients where rectal balloons containing both types of contrast were used and evaluated. The amount of preparation required for the Cysto‐Conray and Readi‐Cat was also considered. Results: The Readi‐Cat 2 has a lower risk of an allergic reaction and is six times less expensive than the Cysto‐Conray. The electron densities were found to be 1.18 and 1.28 for the Readi‐Cat and Cysto‐Conray respectively. Both contrast agents have comparable proton range attenuation and visibility on x‐rays. The Cysto‐Conray requires being diluted with water, whereas the Readi‐Cat has no dilution requirements. Conclusions: It has been determined that the Readi‐Cat 2 is a contrast agent that can be used instead of the Cysto‐Conray II solution. The Readi‐Cat is cheaper than the Cysto‐Conray, has a minimal risk of allergy, has a comparable attenuation of the proton beam, can be easily seen with the imaging equipment in the treatment room, and requires no dilution before using.