Characterisation and evaluation of a PNP strip detector for synchrotron microbeam radiation therapy

Davis, Joel; Paino, Jason; Dipuglia, Andrew; Cameron, Matthew; Siegele, Rainer; Pastuović, Željko; Petasecca, Marco; Perevertaylo, Vladimir; Rosenfeld, Anatoly B.; Lerch, Michael L. F

doi:10.1088/2057-1976/aab10c

Cited by 17 publications

(14 citation statements)

References 23 publications

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“…The same applies to the use of scintillating fibers, as shown by Archer et al 20 Various groups have developed silicon strip detectors capable of quantifying parameters of the microbeam field. [21][22][23] Whilst hybrid strip detectors (with separate sensor and readout) can offer greater resistance to radiation than monolithic pixelated detectors, strip detectors do not provide detailed information about the 2D profile of the radiation field and, therefore, will be more sensitive to angular misalignment.…”

Section: B Current Verification Methodsmentioning

confidence: 99%

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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Section: B Current Verification Methodsmentioning

confidence: 99%

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

et al. 2020

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“…Metal oxide semiconductor field-effect transistors (MOSFET) have the required spatial resolution for MRT dosimetry, but lack the radiation hardness to withstand the high dose rate 13 . A number of silicon strip detectors (SSD) have been developed for MRT beam quality monitoring 14–16 . These detectors have reached an estimated resolution of 15 μ m defined by the electrical field distribution under biasing.…”

Section: Introductionmentioning

confidence: 99%

High spatial resolution scintillator dosimetry of synchrotron microbeams

Archer

Davis

et al. 2019

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Microbeam radiation therapy is a novel pre-clinical external beam therapy that uses high-brilliance synchrotron X-rays to deliver the necessary high dose rates. The unique conditions of high dose rate and high spatial fractionation demand a new class of detector to experimentally measure important beam quality parameters. Here we demonstrate the highest spatial resolution plastic scintillator fibre-optic dosimeter found in the literature to date and tested it on the Imaging and Medical Beam-Line at the Australian Synchrotron in a X-ray beam where the irradiation dose rate was 4435 Gy/s. With a one-dimensional spatial resolution of 10 μ m the detector is able to resolve the individual microbeams (53.7 ± 0.4 μ m wide), and measure the peak-to-valley dose ratio to be 55 ± 17. We also investigate the role of radioluminescence in the optical fibre used to transport the scintillation photons, and conclude that it creates a significant contribution to the total light detected.

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“…In vitro experiments, dosimetry and treatment verification. The dosimetric protocol for SBB and MRT at the IMBL is outlined in previous publications [25][26][27][28][29][30][31] . Briefly, it involves characterizing the pre-filtered SBB uniform in custom designed RMI-457 Gammex Solid Water ® phantoms (Gammex-RMI, Middleton, WI, USA) using a PinPoint ionization chamber (IC) (PTW 31014, Freiburg, Germany), calibrated to a traceable standard.…”

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Toward personalized synchrotron microbeam radiation therapy

Engels

Davis

et al. 2020

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Synchrotron facilities produce ultra-high dose rate X-rays that can be used for selective cancer treatment when combined with micron-sized beams. Synchrotron microbeam radiation therapy (MRT) has been shown to inhibit cancer growth in small animals, whilst preserving healthy tissue function. However, the underlying mechanisms that produce successful MRT outcomes are not well understood, either in vitro or in vivo. this study provides new insights into the relationships between dosimetry, radiation transport simulations, in vitro cell response, and pre-clinical brain cancer survival using intracerebral gliosarcoma (9LGS) bearing rats. As part of this groundbreaking research, a new image-guided MRT technique was implemented for accurate tumor targeting combined with a pioneering assessment of tumor dose-coverage; an essential parameter for clinical radiotherapy. Based on the results of our study, we can now (for the first time) present clear and reproducible relationships between the in vitro cell response, tumor dose-volume coverage and survival post MRT irradiation of an aggressive and radioresistant brain cancer in a rodent model. our innovative and interdisciplinary approach is illustrated by the results of the first long-term MRT pre-clinical trial in Australia. Implementing personalized synchrotron MRT for brain cancer treatment will advance this international research effort towards clinical trials.

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Characterisation and evaluation of a PNP strip detector for synchrotron microbeam radiation therapy

Cited by 17 publications

References 23 publications

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

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

High spatial resolution scintillator dosimetry of synchrotron microbeams

Toward personalized synchrotron microbeam radiation therapy

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