Future directions of in vivo dosimetry for external beam radiotherapy and brachytherapy

Verhaegen, Frank; Fonseca, Gabriel Paiva; Johansen, Jacob; Beaulieu, Luc; Beddar, Sam; Greer, Peter; Jornet, N.; Kertzscher, Gustavo; McCurdy, Boyd; Smith, R. L.; Mijnheer, Ben J.; Olaciregui-Ruiz, Ígor; Tanderup, Kari

doi:10.1016/j.phro.2020.09.001

Cited by 10 publications

(11 citation statements)

References 8 publications

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“…A comprehensive characterization of the detector is therefore necessary before broader clinical implementation can be achieved and the results of the first in vivo measurements can be interpreted. Thorough characterization of the detectors was also recommended by an ESTRO task group that investigated how to advance the use of in IVD in BT 26,27 …”

Section: Introductionmentioning

confidence: 99%

A high‐Z inorganic scintillator–based detector for time‐resolved in vivo dosimetry during brachytherapy

et al. 2021

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Purpose High‐dose rate (HDR) and pulsed‐dose rate (PDR) brachytherapy would benefit from an independent treatment verification system to monitor treatment delivery and to detect errors in real time. This paper characterizes and provides an uncertainty budget for a detector based on a fiber‐coupled high‐Z inorganic scintillator capable of performing time‐resolved in vivo dosimetry during HDR and PDR brachytherapy. Method The detector was composed of a detector probe and an optical reader. The detector probe consisted of either a 0.5 × 0.4 × 0.4 mm3 (HDR) or a 1.0 × 0.4 × 0.4 mm3 (PDR) cuboid ZnSe:O crystal glued onto an optical‐fiber cable. The outer diameter of the detector probes was 1 mm, and fit inside standard brachytherapy catheters. The signal from the detector probe was read out at 20 Hz by a photodiode and a data acquisition device inside the optical reader. In order to construct an uncertainty budget for the detector, six characteristics were determined: (1) temperature dependence of the detector probe, (2) energy dependence as a function of the probe‐to‐source position in 2D (determined with 2 mm resolution using a robotic arm), (3) the signal‐to‐noise ratio (SNR), (4) short‐term stability over 8 h, and (5) long‐term stability of three optical readers and four probes used for in vivo monitoring in HDR and PDR treatments over 21 months (196 treatments and 189 detector calibrations, and (6) dose‐rate dependence. Results The total uncertainty of the detector at a 20 mm probe‐to‐source distance was < 5.1% and < 5.8% for the HDR and PDR versions, respectively. Regarding the above characteristics, (1) the sensitivity of the detector decreased by an average of 1.4%/°C for detector probe temperatures varying from 22 to 37°C; (2) the energy dependence of the detector was nonlinear and depended on both probe‐to‐source distance and the angle between the probe and the brachytherapy source; (3) the median SNRs were 187 and 34 at a 20 mm probe‐to‐source distance for the HDR and PDR versions, respectively (corresponding median source activities of 4.8 and 0.56 Ci, respectively); (4) the detector response varied by 0.6% in 11 identical irradiations over 8 h; (5) the sensitivity of the four detector probes decreased systematically by 0–1.2%/100 Gy of dose delivered to the probes, and random fluctuations of 4.8% in the sensitivity were observed for the three probes used in PDR and 1.9% for the probe used in HDR; and (6) the detector response was linear with dose rate. Conclusion ZnSe:O detectors can be used effectively for in vivo dosimetry and with high accuracy for HDR and PDR brachytherapy applications.

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Section: Introductionmentioning

confidence: 99%

A high‐Z inorganic scintillator–based detector for time‐resolved in vivo dosimetry during brachytherapy

et al. 2021

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“…This ex situ measurement approach serves a twofold purpose: (1) determination of the actual radiation dose delivered to the intended treatment location in vivo through dose reconstruction and (2) assurance that healthy tissues have indeed been spared from unintended radiation exposure. Placement of gel nanosensors away from the treatment site is also intended to (1) minimize disruption to the existing treatment workflow and (2) minimize perturbations to the dose delivered to the patient while simultaneously facilitating in vivo dose measurements …”

Section: Results and Discussionmentioning

confidence: 99%

“…Placement of gel nanosensors away from the treatment site is also intended to (1) minimize disruption to the existing treatment workflow and (2) minimize perturbations to the dose delivered to the patient while simultaneously facilitating in vivo dose measurements. 34 Linear (1D) gel nanosensor devices were fabricated by mixing all four precursor components within needles of comparable dimensions to those used during interstitial brachytherapy (Figure 2B); considering that the length of the needles is significantly greater than their diameter, we approximate these as 1D devices. Needles containing the precursor gel nanosensor components are exposed to increasing levels of ionizing radiation by an external radiation source (RS-2000 X-ray biological irradiator; 160 keV), which was used as a mimic of radioactive material ( 192 Ir; 380 keV) as indicated in previous studies.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Versatile Detection and Monitoring of Ionizing Radiation Treatment Using Radiation-Responsive Gel Nanosensors

Pushpavanam

Dutta

Inamdar

et al. 2022

ACS Appl. Mater. Interfaces

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Modern radiation therapy workflow involves complex processes intended to maximize the radiation dose delivered to tumors while simultaneously minimizing excess radiation to normal tissues. Safe and accurate delivery of radiation doses is critical to the successful execution of these treatment plans and effective treatment outcomes. Given extensive differences in existing dosimeters, the choice of devices and technologies for detecting biologically relevant doses of radiation has to be made judiciously, taking into account anatomical considerations and modality of treatment (invasive, e.g., interstitial brachytherapy vs noninvasive, e.g., external-beam therapy radiotherapy). Rapid advances in versatile radiation delivery technologies necessitate new detection platforms and devices that are readily adaptable into a multitude of form factors in order to ensure precision and safety in dose delivery. Here, we demonstrate the adaptability of radiation-responsive gel nanosensors as a platform technology for detecting ionizing radiation using three different form factors with an eye toward versatile use in the clinic. In this approach, ionizing radiation results in the reduction of monovalent gold salts leading to the formation of gold nanoparticles within gels formulated in different morphologies including one-dimensional (1D) needles for interstitial brachytherapy, two-dimensional (2D) area inserts for skin brachytherapy, and three-dimensional (3D) volumetric dose distribution in tissue phantoms. The formation of gold nanoparticles can be detected using distinct but complementary modes of readout including optical (visual) and photothermal detection, which further enhances the versatility of this approach. A linear response in the readout was seen as a function of radiation dose, which enabled straightforward calibration of each of these devices for predicting unknown doses of therapeutic relevance. Taken together, these results indicate that the gel nanosensor technology can be used to detect ionizing radiation in different morphologies and using different detection methods for application in treatment planning, delivery, and verification in radiotherapy and in trauma care.

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“…Combined with information on MLC leaf movement as recorded for example in trajectory log files, it can be possible to separate delivery and patient related contributions. In addition to this, volumetric image guidance can determine the patient anatomy close to the time of delivery and as such complement EPID dosimetry to provide a powerful tool to verify dose delivery in vivo 81–83 …”

Section: Treatment Delivery: Technology and Techniquesmentioning

confidence: 99%

“…In addition to this, volumetric image guidance can determine the patient anatomy close to the time of delivery and as such complement EPID dosimetry to provide a powerful tool to verify dose delivery in vivo. [81][82][83]…”

Section: In Vivo Dosimetrymentioning

confidence: 99%

Quality management in radiotherapy treatment delivery

et al. 2022

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Radiation Oncology continues to rely on accurate delivery of radiation, in particular where patients can benefit from more modulated and hypofractioned treatments that can deliver higher dose to the target while optimising dose to normal structures. These deliveries are more complex, and the treatment units are more computerised, leading to a re-evaluation of quality assurance (QA) to test a larger range of options with more stringent criteria without becoming too time and resource consuming. This review explores how modern approaches of risk management and automation can be used to develop and maintain an effective and efficient QA programme. It considers various tools to control and guide radiation delivery including image guidance and motion management. Links with typical maintenance and repair activities are discussed, as well as patient-specific quality control activities. It is demonstrated that a quality management programme applied to treatment delivery can have an impact on individual patients but also on the quality of treatment techniques and future planning. Developing and customising a QA programme for treatment delivery is an important part of radiotherapy. Using modern multidisciplinary approaches can make this also a useful tool for department management.

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Future directions of in vivo dosimetry for external beam radiotherapy and brachytherapy

Cited by 10 publications

References 8 publications

A high‐Z inorganic scintillator–based detector for time‐resolved in vivo dosimetry during brachytherapy

A high‐Z inorganic scintillator–based detector for time‐resolved in vivo dosimetry during brachytherapy

Versatile Detection and Monitoring of Ionizing Radiation Treatment Using Radiation-Responsive Gel Nanosensors

Quality management in radiotherapy treatment delivery

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