| Autor: |
Flavio Marchetto, M. Donetti, Roberto Cirio, U. Nastasi, I. Gomola, C. Brusasco, Simona Giordanengo, Michele Stasi, Cristiana Peroni, S. Iliescu |
| Rok vydání: |
2006 |
| Předmět: |
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| Zdroj: |
Medical Physics. 33:2127-2128 |
| ISSN: |
0094-2405 |
| DOI: |
10.1118/1.2241275 |
| Popis: |
Purpose: To attest the accuracy of the penumbra measurement with the use of a 2D pixel ionization chamber.Method and Materials: Penumbra measurements were carried out for several clinical cases, treated with Intensity Modulated Radiation Therapy, with a pixel ionization chamber and with radiographicfilm as reference. The pixel chamber consists of a matrix 1020 detectors, each 4.5 mm diameter and 5 mm height at a pitch of 7.62 mm. Each of the 1020 ionization chambers was read out independently with no dead time. Standard radiographicfilms have been used, scanned with a pitch of 0.16 mm and 0.40 mm. Both detectors were irradiated with 6 MV photon beams, using a linac equipped with a 120‐leaves multileaf collimator. Measured dose profiles were fitted with a “Fermi‐like” function: f(x) = 1 1 + e a(x−x 0 ) with x 0 and a as free parameters; the value for the penumbra could then be derived from the fit. The two sets of data were compared. Results: The data for the penumbra measured with the pixel chamber and the film for several IMRT fields show a strong linear correlation. This made it possible to correct the penumbra values obtained with the pixel ionization chamber to obtain a precise measurement even in a range well below the pixel dimensions. Conclusion: The 2D pixel ionization chamber has been shown to be able to measure the penumbra down to ∼ 2mm with an accuracy of ± 0.6 mm. This device can then efficiently replace radiographicfilm in some QA procedures with a significative gain in time as it gives results in real‐time and data are immediately available. Conflict of Interest: Research sponsored by MAESTRO, European project on Methods and Advanced Equipment for Simulation and Treatment in Radiation Oncology. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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