MOSFET dosimetry of an X-ray microbeam

Rosenfeld, Anatoly; Kaplan, G.; Kron, Tomas; Allen, Barry J.; Dilmanian, A.; Orion, Itzhak; Ren, Bin; Lerch, Michael L. F; Holmes-Siedle, Andrew

doi:10.1109/23.819153

Cited by 36 publications

(26 citation statements)

References 21 publications

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“…22 The MOSFET detector is well known as a dosimetric detector. [23][24][25] The particular MOSFET used in our experiments was the REM RADFET. 22 The RADFET consists of two pairs of p-channel MOSFETs with different gate oxide thicknesses ͑ϳ0.13 and ϳ1 m͒.…”

Section: Materials and Instrumentationmentioning

confidence: 99%

MOSFET dosimetry for microbeam radiation therapy at the European Synchrotron Radiation Facility

et al. 2003

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Preclinical experiments are carried out with ϳ20-30 m wide, ϳ10 mm high parallel microbeams of hard, broad-''white''-spectrum x rays ͑ϳ50-600 keV͒ to investigate microbeam radiation therapy ͑MRT͒ of brain tumors in infants for whom other kinds of radiotherapy are inadequate and/or unsafe. Novel physical microdosimetry ͑implemented with MOSFET chips in the ''edge-on'' mode͒ and Monte Carlo computer-simulated dosimetry are described here for selected points in the peak and valley regions of a microbeam-irradiated tissue-equivalent phantom. Such microbeam irradiation causes minimal damage to normal tissues, possible because of rapid repair of their microscopic lesions. Radiation damage from an array of parallel microbeams tends to correlate with the range of peak-valley dose ratios ͑PVDR͒. This paper summarizes comparisons of our dosimetric MOSFET measurements with Monte Carlo calculations. Peak doses at depths Ͻ22 mm are 18% less than Monte Carlo values, whereas those depths Ͼ22 mm and valley doses at all depths investigated ͑2 mm-62 mm͒ are within 2-13 % of the Monte Carlo values. These results lend credence to the use of MOSFET detector systems in edge-on mode for microplanar irradiation dosimetry.

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Section: Materials and Instrumentationmentioning

confidence: 99%

MOSFET dosimetry for microbeam radiation therapy at the European Synchrotron Radiation Facility

et al. 2003

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“…3 shows the change of the dose rate in arbitrary units versus the coordinate leading to a penumbra with width for a continuous radiation field. Assume that an "edge-on" MOSFET [3] is continuously moving across a penumbra with speed , followed by readout with period . Such measurements will lead to an integrated dose for each step of , i.e., .…”

Section: Scanning With An Online Mosfetmentioning

confidence: 99%

“…Because of the use of thin films in an "edge-on" mode, we can obtain detectors of width on the order of 0.1 m and thus detect the profiles of microbeams of the same order. This has potential in the fields of microbeam radiotherapy and photolithography [3], [4].…”

Section: Introductionmentioning

confidence: 99%

“…Research in this field started with the investigation of microbeams of X-rays and high-intensity synchrotron radiation, applied to the response of single, small MOSFET structures [2], [3]. In [2], the irradiation was done with a beam perpendicular to the gate oxide plane.…”

Section: Introductionmentioning

confidence: 99%

“…Here is change in threshold voltage and is ionization kerma in Gray or rad(SiO ; see e.g., [4]. The question of radical improvement in spatial resolution by the use of "edge-on" MOSFETs was proposed and tested by Rosenfeld et al [3]. In that work, a manual setup was tested with synchrotron radiation and 200-m spaced X-ray beams with widths of 30 m. It was shown that the Ukrainian n-MOSFET detector gave good resolution using beams at the National Synchrotron Light Source (NSLS), BNL.…”

Section: Introductionmentioning

confidence: 99%

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Feasibility study of online high-spatial-resolution MOSFET dosimetry in static and pulsed x-ray radiation fields

Rosenfeld

Lerch

Kron

et al. 2001

IEEE Trans. Nucl. Sci.

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Abstract-Improvements have been made in the measurement of dose profiles in several types of X-ray beams. These include 120-kVp X-ray beams from an orthovoltage X-ray machine, 6-MV Bremsstrahlung from a medical LINAC in conformal mode and the 50-200 keV energy spectrum of microbeams produced at the medical beamline station of the European Synchrotron Radiation Facility. Using a quadruple metal-oxide-semiconductor field-effect transistor (MOSFET) sensor chip in "edge on" mode together with a newly developed sensor readout system, the feasibility of online scanning of the profiles of quasi-static and pulsed radiation beams was demonstrated. Measurements of synchrotron pulsed microbeams showed that a micrometer-scale spatial resolution was achievable. The use of several MOSFETs on the same chip gave rise to the correction of misalignments of the oxide films of the sensor with respect to the microbeam, ensuring that the excellent spatial resolution of the MOSFET used in "edge-on" mode was fully utilized.

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Evaluation of a pixelated large format CMOS sensor for x‐ray microbeam radiotherapy

et al. 2020

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Purpose Current techniques and procedures for dosimetry in microbeams typically rely on radiochromic film or small volume ionization chambers for validation and quality assurance in 2D and 1D, respectively. Whilst well characterized for clinical and preclinical radiotherapy, these methods are noninstantaneous and do not provide real time profile information. The objective of this work is to determine the suitability of the newly developed vM1212 detector, a pixelated CMOS (complementary metal‐oxide‐semiconductor) imaging sensor, for in situ and in vivo verification of x‐ray microbeams. Methods Experiments were carried out on the vM1212 detector using a 220 kVp small animal radiation research platform (SARRP) at the Helmholtz Centre Munich. A 3 x 3 cm2 square piece of EBT3 film was placed on top of a marked nonfibrous card overlaying the sensitive silicon of the sensor. One centimeter of water equivalent bolus material was placed on top of the film for build‐up. The response of the detector was compared to an Epson Expression 10000XL flatbed scanner using FilmQA Pro with triple channel dosimetry. This was also compared to a separate exposure using 450 µm of silicon as a surrogate for the detector and a Zeiss Axio Imager 2 microscope using an optical microscopy method of dosimetry. Microbeam collimator slits with range of nominal widths of 25, 50, 75, and 100 µm were used to compare beam profiles and determine sensitivity of the detector and both film measurements to different microbeams. Results The detector was able to measure peak and valley profiles in real‐time, a significant reduction from the 24 hr self‐development required by the EBT3 film. Observed full width at half maximum (FWHM) values were larger than the nominal slit widths, ranging from 130 to 190 µm due to divergence. Agreement between the methods was found for peak‐to‐valley dose ratio (PVDR), peak to peak separation and FWHM, but a difference in relative intensity of the microbeams was observed between the detectors. Conclusions The investigation demonstrated that pixelated CMOS sensors could be applied to microbeam radiotherapy for real‐time dosimetry in the future, however the relatively large pixel pitch of the vM1212 detector limit the immediate application of the results.

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MOSFET dosimetry of an X-ray microbeam

Cited by 36 publications

References 21 publications

MOSFET dosimetry for microbeam radiation therapy at the European Synchrotron Radiation Facility

MOSFET dosimetry for microbeam radiation therapy at the European Synchrotron Radiation Facility

Feasibility study of online high-spatial-resolution MOSFET dosimetry in static and pulsed x-ray radiation fields

Evaluation of a pixelated large format CMOS sensor for x‐ray microbeam radiotherapy

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