Pixel segmented ionization chamber for therapeutical beams of photons and hadrons

Belletti, S; Cirio, R.; Cocuzza, L.; Degiorgis, P.G; Donetti, M.; Madon, E.; Marchetto, F.; Marletti, M.; Marzoli, L.; Peroni, C.; Trevisiol, Edoardo; Urgesi, A.

doi:10.1016/s0168-9002(00)01263-8

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…However, RGFs need a chemical processing and over-respond to low-energy scattered photons (Sykes et al 1999, Martens et al 2002, RCFs present response non-uniformity (Niroomand-Rad et al 1998) and calibration of EPIDs is a difficult task, which complicates high precision dosimetry with all of these devices. Segmented anode ionization chambers, such as those presented in Martens et al (2001), Belletti et al (2001) and Eberle et al (2003), and diode arrays (Jursinic and Nelms 2003) are an alternative. Although faster verification procedures are possible with these devices, none of them achieve a millimetre range spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance

et al. 2005

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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 x 1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for high gradient beam profiles such as those present in intensity modulated radiation therapy (IMRT) and radiosurgery. As the read-out electronics we use the X-ray Data Acquisition System 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. Dose rate dependence was found to be lower than 2.1% up to 5 Gy min(-1), and energy dependence lower than 2.5% 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. 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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Section: Introductionmentioning

confidence: 99%

Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance

et al. 2005

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“…The pixel ionization chambers [ 18 , 19 ] are made with anodes in the form of small blocks similar to pixel dots, and the signals are acquired and processed to yield information on the relative beam dose distribution. The Italian Institute of Nuclear Physics (INFN) [ 20 ] has installed pixel ionization chambers in the Proton Radiotherapy Unit, with pixel blocks 5 mm 2 in size.…”

Section: Introductionmentioning

confidence: 99%

Development of a Time Projection Chamber Readout with Hybrid Pixel Sensors for Beam Monitoring

Song,

Yang,

Zhang

et al. 2024

Sensors

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To monitor the position and profile of therapeutic carbon beams in real-time, in this paper, we proposed a system called HiBeam-T. The HiBeam-T is a time projection chamber (TPC) with forty Topmetal-II- CMOS pixel sensors as its readout. Each Topmetal-II- has 72 × 72 pixels with the size of 83 μm × 83 μm. The detector consists of the charge drift region and the charge collection area. The readout electronics comprise three Readout Control Modules and one Clock Synchronization Module. This Hibeam-T has a sensitive area of 20 × 20 cm and can acquire the center of the incident beams. The test with a continuous 80.55 MeV/u 12C6+ beam shows that the measurement resolution to the beam center could reach 6.45 μm for unsaturated beam projections.

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“…However, RCFs present response non-uniformity (Niroomand-Rad et al (1998) and references therein) and calibration of EPIDs is a difficult task, which complicates high precision dosimetry with all of these devices. Segmented anode ionization chambers, like those presented in Martens et al (2001), Belletti et al (2001), Eberle et al (2003), Cirio et al (2004) or Spezi et al (2005), and diode arrays (Jursinic andNelms 2003, Létourneau et al 2004) are an alternative. Some of these devices are matrices which allow us to verify a dose plane, but do not provide either a high spatial resolution due to the limitation on the number of electronic channels, or a small pixel size due to the use of low mass density ionization media (air).…”

Section: Introductionmentioning

confidence: 99%

Verification of intensity modulated profiles using a pixel segmented liquid-filled linear array

Pardo¹,

Roselló²,

Sánchez‐Doblado³

et al. 2006

Phys. Med. Biol.

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A liquid isooctane (C8H18) filled ionization chamber linear array developed for radiotherapy quality assurance, consisting of 128 pixels (each of them with a 1.7 mm pitch), has been used to acquire profiles of several intensity modulated fields. The results were compared with film measurements using the gamma test. The comparisons show a very good matching, even in high gradient dose regions. The volume-averaging effect of the pixels is negligible and the spatial resolution is enough to verify these regions. However, some mismatches between the detectors have been found in regions where low-energy scattered photons significantly contribute to the total dose. These differences are not very important (in fact, the measurements of both detectors are in agreement using the gamma test with tolerances of 3% and 3 mm in most of those regions), and may be associated with the film energy dependence. In addition, the linear array repeatability (0.27% one standard deviation) is much better than the film one ( approximately 3%). The good repeatability, small pixel size and high spatial resolution make the detector ideal for the real time profile verification of high gradient beam profiles like those present in intensity modulated radiation therapy and radiosurgery.

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Pixel segmented ionization chamber for therapeutical beams of photons and hadrons

Cited by 5 publications

References 4 publications

Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance

Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance

Development of a Time Projection Chamber Readout with Hybrid Pixel Sensors for Beam Monitoring

Verification of intensity modulated profiles using a pixel segmented liquid-filled linear array

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