Towards using a Monolithic Active Pixel Sensor for in vivo beam monitoring of Intensity Modulated Radiotherapy

Page, Ryan; Abbott, Natalie L.; Davies, J.; Dyke, Emma; Randles, Heather J.; Velthuis, J. J.; Fletcher, Sally; Gregory, Stephen; Hall, Christopher D.; John, Anne-Marie; Lawrence, Henry; Stevens, P.; Hugtenburg, Richard P.; Tunbridge, Victoria

doi:10.1016/j.nima.2013.05.144

Cited by 6 publications

(5 citation statements)

References 3 publications

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“…An upstream monitoring device must be radiation hard enough to operate long enough in a clinical setting, have an attenuation less than 1% to avoid beam hardening, a MLC leaf precision better than 300 μm to keep total dose errors below 2% [ 14 ] and be large enough to monitor full treatment fields, which at most measure 40 × 40 cm 2 at the isocentre. As demonstrated before, a Monolithic Active Pixel Sensor (MAPS)-based device can fulfill all requirements, except the size; see for example [ 2 , 15 , 16 , 17 , 18 , 19 ]. The concept was patented in [ 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

Performance of a Full-Scale Upstream MAPS-Based Verification Device for Radiotherapy

Velthuis

Pritchard

et al. 2023

Sensors

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Intensity-modulated radiotherapy is a widely used technique for accurately targeting cancerous tumours in difficult locations using dynamically shaped beams. This is ideally accompanied by real-time independent verification. Monolithic active pixel sensors are a viable candidate for providing upstream beam monitoring during treatment. We have already demonstrated that a Monolithic Active Pixel Sensor (MAPS)-based system can fulfill all clinical requirements except for the minimum required size. Here, we report the performance of a large-scale demonstrator system consisting of a matrix of 2 × 2 sensors, which is large enough to cover almost all radiotherapy treatment fields when affixed to the shadow tray of the LINAC head. When building a matrix structure, a small dead area is inevitable. Here, we report that with a newly developed position algorithm, leaf positions can be reconstructed over the entire range with a position resolution of below ∼200 μm in the centre of the sensor, which worsens to just below 300 μm in the middle of the gap between two sensors. A leaf position resolution below 300 μm results in a dose error below 2%, which is good enough for clinical deployment.

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Section: Introductionmentioning

confidence: 99%

Performance of a Full-Scale Upstream MAPS-Based Verification Device for Radiotherapy

Velthuis

Pritchard

et al. 2023

Sensors

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“…Another important advantage is that, depending on the detector, this methodology can be used for in vivo evaluation. (15,16,17,18) One of the most recent publications in this field presents a multiwire or multistrip transmission ionization chamber. In this methodology, the wires are placed between two polycarbonate windows with a total thickness of 1.4 cm and subjected to a potential difference of 400 V. During irradiation, different lengths and pairs of wires are exposed and the produced ions are collected by an electrometer.…”

Section: Introductionmentioning

confidence: 99%

“…In this methodology, the wires are placed between two polycarbonate windows with a total thickness of 1.4 cm and subjected to a potential difference of 400 V. During irradiation, different lengths and pairs of wires are exposed and the produced ions are collected by an electrometer. (13) With a similar system, Page et al (16) also conducted tests to evaluate in vivo dosimetry, demonstrating that it can be achieved by placing an ionization chamber system using a thin monolithic active pixel sensor (MAPS). With the same goal, Amaral and colleagues (19) conducted a study inserting RCF segments at the head of a linac to assess exposures in stereotactic radiotherapy.…”

Section: Introductionmentioning

confidence: 99%

A new transmission methodology for quality assurance in radiotherapy based on radiochromic film measurements

Amaral

Oliveira

Pavoni

et al. 2015

J Applied Clin Med Phys

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Despite individual quality assurance (QA) being recommended for complex techniques in radiotherapy (RT) treatment, the possibility of errors in dose delivery during therapeutic application has been verified. Therefore, it is fundamentally important to conduct in vivo QA during treatment. This work presents an in vivo transmission quality control methodology, using radiochromic film (RCF) coupled to the linear accelerator (linac) accessory holder. This QA methodology compares the dose distribution measured by the film in the linac accessory holder with the dose distribution expected by the treatment planning software. The calculated dose distribution is obtained in the coronal and central plane of a phantom with the same dimensions of the acrylic support used for positioning the film but in a source‐to‐detector distance (SDD) of 100 cm, as a result of transferring the IMRT plan in question with all the fields positioned with the gantry vertically, that is, perpendicular to the phantom. To validate this procedure, first of all a Monte Carlo simulation using PENELOPE code was done to evaluate the differences between the dose distributions measured by the film in a SDD of 56.8 cm and 100 cm. After that, several simple dose distribution tests were evaluated using the proposed methodology, and finally a study using IMRT treatments was done. In the Monte Carlo simulation, the mean percentage of points approved in the gamma function comparing the dose distribution acquired in the two SDDs were 99.92%±0.14%. In the simple dose distribution tests, the mean percentage of points approved in the gamma function were 99.85%±0.26% and the mean percentage differences in the normalization point doses were −1.41%. The transmission methodology was approved in 24 of 25 IMRT test irradiations. Based on these results, it can be concluded that the proposed methodology using RCFs can be applied for in vivo QA in RT treatments.PACS number: 87.55.Qr, 87.55.km, 87.55.N‐

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“…A principal vantagem de acoplar o dispositivo no cabeçote do acelerador linear é que o feixe fica sempre perpendicular a seu volume sensível e, desta forma, não apresenta variações na resposta em função do deslocamento angular do gantry. Outra vantagem importante é que, dependendo do detector, esta metodologia pode ser utilizada para avaliações in vivo (MYERS et al, 2013) (PAGE et al, 2013) (ISLAM et al, 2009) (VENKATARAMAN et al, 2009.…”

Section: Introductionunclassified

“…Durante a irradiação, diferentes comprimentos e pares de fios são expostos e os íons são coletados por um eletrômetro (ALMEIDA, 2012). Com um sistema semelhante, Page e colaboradores (PAGE et al, 2013) também realizaram testes para a avaliação in vivo, demostrando que a mesma pode ser conseguida através da colocação de um sistema de câmara usando um ultrafino Monolitic Active Pixel Sensor (MAPS). Com este objetivo, Amaral e colaboradores realizaram um trabalho inserindo segmentos de filme no cabeçote do acelerador linear a fim de avaliar exposições em tratamentos de radioterapia estereotáxica.…”

Section: Introductionunclassified

Desenvolvimento de uma metodologia de avaliação dosimétrica de transmissão, usando filmes radiocrômicos em tratamentos radioterápicos

Amaral¹

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Towards using a Monolithic Active Pixel Sensor for in vivo beam monitoring of Intensity Modulated Radiotherapy

Cited by 6 publications

References 3 publications

Performance of a Full-Scale Upstream MAPS-Based Verification Device for Radiotherapy

Performance of a Full-Scale Upstream MAPS-Based Verification Device for Radiotherapy

A new transmission methodology for quality assurance in radiotherapy based on radiochromic film measurements

Desenvolvimento de uma metodologia de avaliação dosimétrica de transmissão, usando filmes radiocrômicos em tratamentos radioterápicos

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