Real-time in vivo dosimetry in high dose rate prostate brachytherapy

Mason, J.; Mamo, Arielle; Al-Qaisieh, B.; Henry, Ann; Bownes, Peter

doi:10.1016/j.radonc.2016.05.008

Cited by 31 publications

(22 citation statements)

References 22 publications

(28 reference statements)

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“…Interestingly, the distance dependence appeared to be due to the response of the detector, given the consistency of absorbed dose estimations by Monte Carlo methods, by the planning system, and by the radiochromic film measurements, whereas the detector response varied, which can be attributed to the energy dependence of the detector. Mason et al measured the relative response normalized to a distance of 1.5 cm from the detector and showed a linear fit with R 2 value of 0.457 vs. our finding of 0.785, with a slope value of 0.026 cm −1 vs. our result of (0.014 ± 0.001) cm −1 . Mason et al described a value of 0.975 for the ordinate origin, highly similar to the value of 0.975 in our study.…”

Section: Discussionsupporting

confidence: 78%

“…In relation to the response dependence on the source‐detector distance, we found a variation of (5.76 ± 0.03)% (k = 1) between distances of 1 and 5 cm, lower than the variation of 10.4% reported by Mason et al for these distances, which led them to propose a correction of 2.6% cm −1 in the detector reading. Interestingly, the distance dependence appeared to be due to the response of the detector, given the consistency of absorbed dose estimations by Monte Carlo methods, by the planning system, and by the radiochromic film measurements, whereas the detector response varied, which can be attributed to the energy dependence of the detector.…”

Section: Discussioncontrasting

confidence: 77%

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Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir

et al. 2020

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Purpose: The objective of this study was to characterize the Best Medical Canada microMOSFET detectors for their application in in vivo dosimetry for high-dose-rate brachytherapy (HDRBT) with 192 Ir. We also developed a mathematical model to correct dependencies under the measurement conditions of these detectors. Methods: We analyzed the linearity, reproducibility, and interdetector variability and studied the microMOSFET response dependence on temperature, source-detector distance, and angular orientation of the receptor with respect to the source. The correction model was applied to 19 measurements corresponding to five simulated treatments in a custom phantom specifically designed for this purpose. Results: The detectors (high bias applied in all measurements) showed excellent linearity up to 160 Gy. The response dependence on source-detector distance varied by (8.65 AE 0.06)% (k = 1) for distances between 1 and 7 cm, and the variation with temperature was (2.24 AE 0.05)% (k = 1) between 294 and 310 K. The response difference due to angular dependence can reach (10.3 AE 1.3)% (k = 1). For the set of measurements analyzed, regarding angular dependences, the mean difference between administered and measured doses was À4.17% (standard deviation of 3.4%); after application of the proposed correction model, the mean difference was À0.1% (standard deviation of 2.2%). For the treatments analyzed, the average difference between calculations and measures was 4.7% when only the calibration coefficient was used, but it is reduced to 0.9% when the correction model is applied. Conclusion: Important response dependencies of microMOSFET detectors used for in vivo dosimetry in HDRBT treatments, especially the angular dependence, can be adequately characterized by a correction model that increases the accuracy of this system in clinical applications.

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Section: Discussionsupporting

confidence: 78%

Section: Discussioncontrasting

confidence: 77%

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir

et al. 2020

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“…For this setup, the standard error of the mean is equal to 50% of the standard deviation. This dose difference is in the range of published uncertainties for in vivo dosimetry in HDR brachytherapy (Mason et al 2016;Belley et al 2018). Finally, all ten fractions of the clinical HDR plan were consecutively delivered, amounting to a dose of at least 300 Gy to the surface of the applicator, and the applicator was monitored for structural damage.…”

Section: Testing and Validationmentioning

confidence: 99%

A Design Process for a 3D Printed Patient-Specific Applicator for HDR Brachytherapy of the Orbit

Subashi

Jacobs

Hood

et al. 2020

Preprint

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Abstract BACKGROUND: This report describes a process for designing a 3D printed patient-specific applicator for HDR brachytherapy of the orbit. CASE PRESENTATION: A 34-year-old man with recurrent melanoma of the orbit was referred for consideration of re-irradiation. An applicator for HDR brachytherapy was designed based on the computed tomography (CT) of patient anatomy. The body contour was used to generate an applicator with a flush fit against the patient’s skin while the planning target volume (PTV) was used to devise channels that allow for access and coverage of the tumor bed. An end-to-end dosimetric test was devised to determine feasibility for clinical use. The applicator was designed to conform to the volume and contours inside the orbital cavity. Support wings placed flush with the patient skin provided stability and reproducibility, while 16 source channels of varying length were needed for sufficient access to the target. A solid sheath, printed as an outer support-wall for each channel, prevented bending or accidental puncturing of the surface of the applicator. CONCLUSIONS: Quality assurance tests demonstrated feasibility for clinical use. Our experience with available 3D printing technology used to generate an applicator for the orbit may provide guidance for how materials of suitable biomechanical and radiation properties can be used in brachytherapy.

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“…Deviations were often attributed to detector positioning uncertainties that depend on the experience of the user, verification methods, proper fixation and possible anatomical changes during the treatment. Catheter and needle reconstruction were also identified as a potential source of clinically relevant deviations [56]. One study reported that improvements in the workflow and imaging immediately prior to treatment delivery reduced maximum dose deviation from 67% to 9% [54]; indeed, deviations between measured and planned dose generally increase as the time between imaging and treatment delivery increases [47].…”

Section: Clinical Studiesmentioning

confidence: 99%

In vivo dosimetry in brachytherapy: Requirements and future directions for research, development, and clinical practice

Fonseca

Johansen

Smith

et al. 2020

Physics and Imaging in Radiation Oncology

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Brachytherapy can deliver high doses to the target while sparing healthy tissues due to its steep dose gradient leading to excellent clinical outcome. Treatment accuracy depends on several manual steps making brachytherapy susceptible to operational mistakes. Currently, treatment delivery verification is not routinely available and has led, in some cases, to systematic errors going unnoticed for years. The brachytherapy community promoted developments in in vivo dosimetry (IVD) through research groups and small companies. Although very few of the systems have been used clinically, it was demonstrated that the likelihood of detecting deviations from the treatment plan increases significantly with time-resolved methods. Time-resolved methods could interrupt a treatment avoiding gross errors which is not possible with time-integrated dosimetry. In addition, lower experimental uncertainties can be achieved by using source-tracking instead of direct dose measurements. However, the detector position in relation to the patient anatomy remains a main source of uncertainty. The next steps towards clinical implementation will require clinical trials and systematic reporting of errors and nearmisses. It is of utmost importance for each IVD system that its sensitivity to different types of errors is well understood, so that end-users can select the most suitable method for their needs. This report aims to formulate requirements for the stakeholders (clinics, vendors, and researchers) to facilitate increased clinical use of IVD in brachytherapy. The report focuses on high dose-rate IVD in brachytherapy providing an overview and outlining the need for further development and research. ☆ During the 1st ESTRO Physics Workshop celebrated in November 2017 in Glasgow, Scotland, a task group was created to stimulate the wider adoption of in vivo dosimetry for radiotherapy. The members of this task group, authors of this report, were selected on the basis of their expertise to contribute relevant input to the area of study and their long-term experience in the clinical implementation of in vivo dosimetry systems.

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Real-time in vivo dosimetry in high dose rate prostate brachytherapy

Cited by 31 publications

References 22 publications

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir

A Design Process for a 3D Printed Patient-Specific Applicator for HDR Brachytherapy of the Orbit

In vivo dosimetry in brachytherapy: Requirements and future directions for research, development, and clinical practice

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Real-time in vivo dosimetry in high dose rate prostate brachytherapy

Cited by 31 publications

References 22 publications

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with 192Ir

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with 192Ir

A Design Process for a 3D Printed Patient-Specific Applicator for HDR Brachytherapy of the Orbit

In vivo dosimetry in brachytherapy: Requirements and future directions for research, development, and clinical practice

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Product

Resources

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Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir