dorsal/arxiv
View SchemaDevelopment and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance
| Authors | J. Pardo, L. Franco, F. Gomez, A. Iglesias, A. Pazos, J. Pena, R. Lobato, J. Mosquera, M. Pombar, J. Sendon |
|---|---|
| Categories | |
| ArXiv ID | physics/0412003 |
| URL | https://arxiv.org/abs/physics/0412003 |
| DOI | 10.1088/0031-9155/50/8/006 |
Abstract
A liquid isooctane (C$_{8}$H$_{18}$) filled ionization linear array for radiotherapy quality assurance has been designed, built and tested. The detector consists of 128 pixels, each of them with an area of 1.7 mm $\times$ 1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for high gradient beam profiles like those present in Intensity Modulated Radiation Therapy (IMRT) and radiosurgery. As read-out electronics we use the X-Ray Data Acquisition System (XDAS) with the Xchip developed by the CCLRC. Studies concerning the collection efficiency dependence on the polarization voltage and on the dose rate have been made in order to optimize the device operation. In the first tests we have studied dose rate and energy dependences, and signal reproducibility. Dose rate dependence was found lower than 2.5 % up to 5 Gy min$^{-1}$, and energy dependence lower than 2.1 % up to 20 cm depth in solid water. Output factors and penumbras for several rectangular fields have been measured with the linear array and were compared with the results obtained with a 0.125 cm$^{3}$ air ionization chamber and radiographic film, respectively. Finally, we have acquired profiles for an IMRT field and for a virtual wedge. These profiles have also been compared with radiographic film measurements. All the comparisons show a good correspondence. Signal reproducibility was within a 2% during the test period (around three months). The device has proved its capability to verify on-line therapy beams with good spatial resolution and signal to noise ratio.
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"abstract": "A liquid isooctane (C$_{8}$H$_{18}$) filled ionization linear array for\nradiotherapy quality assurance has been designed, built and tested. The\ndetector consists of 128 pixels, each of them with an area of 1.7 mm $\\times$\n1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for\nhigh gradient beam profiles like those present in Intensity Modulated Radiation\nTherapy (IMRT) and radiosurgery. As read-out electronics we use the X-Ray Data\nAcquisition System (XDAS) with the Xchip developed by the CCLRC.\n Studies concerning the collection efficiency dependence on the polarization\nvoltage and on the dose rate have been made in order to optimize the device\noperation.\n In the first tests we have studied dose rate and energy dependences, and\nsignal reproducibility. Dose rate dependence was found lower than 2.5 % up to 5\nGy min$^{-1}$, and energy dependence lower than 2.1 % up to 20 cm depth in\nsolid water. Output factors and penumbras for several rectangular fields have\nbeen measured with the linear array and were compared with the results obtained\nwith a 0.125 cm$^{3}$ air ionization chamber and radiographic film,\nrespectively. Finally, we have acquired profiles for an IMRT field and for a\nvirtual wedge. These profiles have also been compared with radiographic film\nmeasurements. All the comparisons show a good correspondence. Signal\nreproducibility was within a 2% during the test period (around three months).\n The device has proved its capability to verify on-line therapy beams with\ngood spatial resolution and signal to noise ratio.",
"arxiv_id": "physics/0412003",
"authors": [
"J. Pardo",
"L. Franco",
"F. Gomez",
"A. Iglesias",
"A. Pazos",
"J. Pena",
"R. Lobato",
"J. Mosquera",
"M. Pombar",
"J. Sendon"
],
"categories": [
"physics.med-ph",
"physics.ins-det"
],
"doi": "10.1088/0031-9155/50/8/006",
"title": "Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance",
"url": "https://arxiv.org/abs/physics/0412003"
},
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