Abstract
Purpose: To present a dosimetric study of a large‐area 2D diode matrix QA device recently introduced for the validation of planar dose distributions resulting from patient IMRT plans used for treating prostate and head and neck (H&N) cancers.Method and Materials: MapCHECK 2™ Model 1177 (Sun Nuclear Corporation, Melbourne, FL) is a new 2D diode array consisting of 1527 n‐diodes distributed over a 26×32 cm2 octagonal space with a uniform diode spacing of 7.07 mm. Its predecessor (MapCHECK model 1175) contained 445 n‐diodes arranged over a 22×22 cm2 area. Spatial resolution over the 10×10 cm2 central portion was 7.07mm and increased to 14.14 mm outside this area. TG‐51 dose calibrations and diode sensitivity measurements were performed on both diode arrays before their clinical application. From a pool of IMRT patients, 5 prostate and 5 H&N treatment plans were selected for plan validation using both devices. Dose plan verification was accomplished by superimposing measured isodose distribution, at 10‐cm depth, for each IMRT field on the companion distribution calculated using the Pinnacle3treatment planning system (8.0m). Results: (1) As expected, both diode arrays faithfully reproduce the calculated isodose distributions for all prostate treatment plans, because the same inner high‐resolution (7 mm) area is used. (2) For H&N plans, the isodose distribution measured with MapCHECK 2, owing to its uniform 7 mm diode spacing, gives superior agreement with the Pinnacle isodose distributions. (3) Similar results are obtained with the older MapCHECK by utilizing the inner high‐resolution area at the expense of making multiple exposures for each field following translational and rotational shifts. Conclusions: We have successfully implemented the new MapCHECK 2 and demonstrated that it is more efficient for H&N IMRT QA than its predecessor. It is better suited for measuring planar dose distributions of larger IMRT fields encountered in H&N IMRT treatments.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
