Two-dimensional solid-state array detectors: A technique for in vivo dose verification in a variable effective area.

Purpose: We introduce a technique that employs a 2D detector in transmission mode (TM) to verify dose maps at a depth of d in Solid Water. TM measurements, when taken at a different surface-to-detector distance (SDD), allow for the area at d (in which the dose map is calculated) to be adjusted.

Methods: We considered the detector prototype "MP512" (an array of 512 diode-sensitive volumes, 2 mm spatial resolution).

CyberKnife fixed cone and Iris™ defined small radiation fields: Assessment with a high-resolution solid-state detector array.

Purpose: The challenges of accurate dosimetry for stereotactic radiotherapy (SRT) with small unflattened radiation fields have been widely reported in the literature. In this case, suitable dosimeters would have to offer a submillimeter spatial resolution. The CyberKnife (Accuray Inc.

Real-time high spatial resolution dose verification in stereotactic motion adaptive arc radiotherapy.

Purpose: Radiation treatments delivered with real-time multileaf collimator (MLC) tracking currently lack fast pretreatment or real-time quality assurance. The purpose of this study is to test a 2D silicon detector, MagicPlate-512 (MP512), in a complex clinical environment involving real-time reconfiguration of the MLC leaves during target tracking.

Methods: MP512 was placed in the center of a solid water phantom and mounted on a motion platform used to simulate three different patient motions.

The relative biological effectiveness for carbon, nitrogen, and oxygen ion beams using passive and scanning techniques evaluated with fully 3D silicon microdosimeters.

Background: The aim of this study was to measure the microdosimetric distributions of a carbon pencil beam scanning (PBS) and passive scattering system as well as to evaluate the relative biological effectiveness (RBE) of different ions, namely C, N, and O, using a silicon-on-insulator (SOI) microdosimeter with well-defined 3D-sensitive volumes (SV). Geant4 simulations were performed with the same experimental setup and results were compared to the experimental results for benchmarking.

Method: Two different silicon microdosimeters with rectangular parallelepiped and cylindrical shaped SVs, both 10 μm in thickness were used in this study.

Impact of a monolithic silicon detector operating in transmission mode on clinical photon beams.

Purpose: To investigate the effect on surface dose, as a function of different field sizes and distances from the solid water phantom to transmission detector (D), of using the monolithic silicon detector MP512T in transmission mode.

Methods: The influence of operating the MP512T in transmission mode on the surface dose of a phantom for SSD 100cm was evaluated by using a Markus IC. The MP512T was fixed to an adjustable stand holder and was positioned at different D, ranging from 0.

Microdosimetric measurements of a clinical proton beam with micrometer-sized solid-state detector.

Purpose: Microdosimetry is a vital tool for assessing the microscopic patterns of energy deposition by radiation, which ultimately govern biological effect. Solid-state, silicon-on-insulator microdosimeters offer an approach for making microdosimetric measurements with high spatial resolution (on the order of tens of micrometers). These high-resolution, solid-state microdosimeters may therefore play a useful role in characterizing proton radiotherapy fields, particularly for making highly resolved measurements within the Bragg peak region.

Characterization of proton pencil beam scanning and passive beam using a high spatial resolution solid-state microdosimeter.

Purpose: This work aims to characterize a proton pencil beam scanning (PBS) and passive double scattering (DS) systems as well as to measure parameters relevant to the relative biological effectiveness (RBE) of the beam using a silicon on insulator (SOI) microdosimeter with well-defined 3D sensitive volumes (SV). The dose equivalent downstream and laterally outside of a clinical PBS treatment field was assessed and compared to that of a DS beam.

Methods: A novel silicon microdosimeter with well-defined 3D SVs was used in this study.

Development of a silicon diode detector for skin dosimetry in radiotherapy.

Purpose: The aim of in vivo skin dosimetry was to measure the absorbed dose to the skin during radiotherapy, when treatment planning calculations cannot be relied on. It is of particularly importance in hypo-fractionated stereotactic modalities, where excessive dose can lead to severe skin toxicity. Currently, commercial diodes for such applications are with water equivalent depths ranging from 0.

Technical Note: Angular dependence of a 2D monolithic silicon diode array for small field dosimetry.

Purpose: This study aims to investigate the 2D monolithic silicon diode array size of 52 × 52 mm (MP512) angular response. An angular correction method has been developed that improves the accuracy of dose measurement in a small field.

Methods: The MP512 was placed at the center of a cylindrical phantom, irradiated using 6 MV and 10 MV photons and incrementing the incidence of the beam angle in 15° steps from 0° to 180°, and then in 1° steps between 85° and 95°.

A 2D silicon detector array for quality assurance in small field dosimetry: DUO.

Purpose: Nowadays, there are many different applications that use small fields in radiotherapy treatments. The dosimetry of small radiation fields is not trivial due to the problems associated with lateral disequilibrium and source occlusion and requires reliable quality assurance (QA). Ideally such a QA tool should provide high spatial resolution, minimal beam perturbation and real time fast measurements.

A comparison of entrance skin dose delivered by clinical angiographic c-arms using the real-time dosimeter: the MOSkin.

Coronary angiography is a procedure used in the diagnosis and intervention of coronary heart disease. The procedure is often considered one of the highest dose diagnostic procedures in clinical use. Despite this, there is minimal use of dosimeters within angiographic catheterisation laboratories due to challenges resulting from their implementation.

Development of a large-area silicon α-particle detector.

Circular ion-implanted silicon detector of α-particles with a large, 5-cm(2), sensitive area has been developed. An advantage of the detector is that the detector surface is easily cleanable with chemicals. The hardened surface of the detector shows no signs of deterioration of the spectroscopic and electrical characteristics upon repeated cleaning.

In vivo real-time rectal wall dosimetry for prostate radiotherapy.

Rectal balloons are used in external beam prostate radiotherapy to provide reproducible anatomy and rectal dose reductions. This is an investigation into the combination of a MOSFET radiation detector with a rectal balloon for realtime in vivo rectal wall dosimetry. The MOSFET used in the study is a radiation detector that provides a water equivalent depth of measurement of 70 microm.