Effective energy assessment during breast cancer intraoperative radiotherapy by low-energy X-rays: A Monte Carlo study

Shamsabadi, Reza; Baghani, Hamid Reza; Mowlavi, Ali Asghar; Azadegan, B.

doi:10.1007/s00411-020-00887-2

Cited by 4 publications

(6 citation statements)

References 19 publications

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“…In treatment plans consisting of entirely steep gradients (brachytherapy, stereotactic radiosurgery, IORT), the use of similar tolerance in dose and distance is misleading, since most points will fail on distance not dose (magnitude). Therefore, asymmetric tolerances of 7% in dose difference and 0.5 mm in distance‐to‐agreement were chosen to compute the gamma for the steep gradient of INTRABEAM dose distributions 3,11,28,43 . A solution would be accepted if at least 95% of the voxels pass the gamma evaluation with respect to the reference dose, with a threshold set at 5% of the maximum dose D max 33 …”

Section: Methodsmentioning

confidence: 99%

“…Therefore, asymmetric tolerances of 7% in dose difference and 0.5 mm in distance-to-agreement were chosen to compute the gamma for the steep gradient of INTRABEAM dose distributions. 3,11,28,43 A solution would be accepted if at least 95% of the voxels pass the gamma evaluation with respect to the reference dose, with a threshold set at 5% of the maximum dose D max . 33…”

Section: F I G U R Ementioning

confidence: 99%

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XIORT‐MC: A real‐time MC‐based dose computation tool for low‐ energy X‐rays intraoperative radiation therapy

et al. 2021

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Purpose: The INTRABEAM system is a miniature accelerator for low-energy X-ray Intra-Operative Radiation Therapy (IORT), and it could benefit from a fast and accurate dose computation tool. With regards to accuracy, dose computed with Monte Carlo (MC) simulations are the gold standard, however, they require a large computational effort and consequently they are not suitable for realtime dose planning. This work presents a comparison of the implementation on Graphics Processing Unit (GPU) of two different dose calculation algorithms based on MC phase-space (PHSP) information to compute dose distributions for the INTRABEAM device within seconds and with the accuracy of realistic MC simulations. Methods: The MC-based algorithms we present incorporate photoelectric, Compton and Rayleigh effects for the interaction of low-energy X-rays. XIORT-MC (X-ray Intra-Operative Radiation Therapy Monte Carlo) includes two dose calculation algorithms; a Woodcock-based MC algorithm (WC-MC) and a Hybrid MC algorithm (HMC), and it is implemented in CPU and in GPU. Detailed MC simulations have been generated to validate our tool in homogeneous and heterogeneous conditions with all INTRABEAM applicators, including three clinically realistic CT-based simulations. A performance study has been done to determine the acceleration reached with the code, in both CPU and GPU implementations. Results: Dose distributions were obtained with the HMC and the WC-MC and compared to standard reference MC simulations with more than 95% voxels fulfilling a 7%-0.5 mm gamma evaluation in all the cases considered. The CPU-HMC is 100 times more efficient than the reference MC, and the CPU-WC-MC is about 50 times more efficient. With the GPU implementation, the particle tracking of the WC-MC is faster than the HMC, with the extraction of the particle's information from the PHSP file taking a major part of the time. However, thanks to the variance reduction techniques implemented in the HMC, up to 400 times less particles are needed in the HMC to reach the same level of noise than the WC-MC. Therefore, in our implementation for INTRABEAM energies, the HMC is about 1.3 times more efficient than the WC-MC in an NVIDIA GeForce GTX 1080 Ti card and about 5.5 times more efficient in an NVIDIA GeForce RTX 3090. Dose with noise below 5% has been obtained in realistic situations in less than 5 s with the WC-MC and in less than 0.5 s with the HMC. Conclusions:The XIORT-MC is a dose computation tool designed to take full advantage of modern GPUs, making possible to obtain MC-grade accurate dose distributions within seconds. Its high speed allows a real-time dose calculation that includes the realistic effects of the beam in voxelized geometries

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Section: Methodsmentioning

confidence: 99%

Section: F I G U R Ementioning

confidence: 99%

XIORT‐MC: A real‐time MC‐based dose computation tool for low‐ energy X‐rays intraoperative radiation therapy

et al. 2021

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“…A more objective means of defining and reporting breast density is likely a critical component of any attempt to accurately relate these metrics. Additionally, given the ability of breast tissue composition to effect RBE values of low-energy x-rays during TARGIT-IORT, more objective breast density calculations may also allow for correction of variations in prescribed dose for patients with differing breast densities who undergo TARGIT-IORT ( 21 ). In summary, a better understanding of breast density as a tenet of risk stratification for patients undergoing TARGIT-IORT is an area that warrants further investigation.…”

Section: Discussionmentioning

confidence: 99%

Targeted Intraoperative Radiotherapy (TARGIT-IORT) for Early-Stage Invasive Breast Cancer: A Single Institution Experience

et al. 2022

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Purpose/ObjectiveWe present our single-institution experience in the management of invasive breast cancer with targeted intraoperative radiotherapy (TARGIT-IORT), focusing on patient suitability for IORT determined by the American Society for Radiation Oncology (ASTRO) Accelerated Partial Breast Irradiation (APBI) consensus guidelines.Materials/MethodsWe identified 237 patients treated for biopsy-proven early-stage invasive breast cancer using low energy x-ray TARGIT-IORT at the time of lumpectomy between September 2013 and April 2020 who were prospectively enrolled in an institutional review board (IRB) approved database. We retrospectively reviewed preoperative and postoperative clinicopathologic factors to determine each patient’s ASTRO APBI suitability (suitable, cautionary or unsuitable) according to the 2017 consensus guidelines (CG). Change in suitability group was determined based on final pathology. Kaplan-Meier methods were used to estimate the survival probability and recurrence probability across time.Results237 patients were included in this analysis, based on preoperative clinicopathologic characteristics, 191 (80.6%) patients were suitable, 46 (19.4%) were cautionary and none were deemed unsuitable. Suitability classification changed in 95 (40%) patients based on final pathology from lumpectomy. Increasing preoperative lesion size or a body mass index (BMI) ≥ 30 kg/m2 were significant predictors for suitability group change. Forty-one (17.3%) patients received additional adjuvant whole breast radiotherapy after TARGIT-IORT. At a median follow up of 38.2 months (range 0.4 – 74.5), five (2.1%) patients had ipsilateral breast tumor recurrences (IBTR), including two (0.8%) true local recurrences defined as a recurrence in the same quadrant as the initial lumpectomy bed with the same histology as the initial tumor. IBTR occurred in 1/103 (0.09%) patient in the post-op suitable group, 4/98 (4.08%) patients in the post-op cautionary group, and no patients in the post-op unsuitable group. At 3-years, the overall survival rate was 98.4% and the local recurrence free survival rate was 97.1%.ConclusionThere is a low rate of IBTR after TARGIT-IORT when used in appropriately selected patients. Change in suitability classification pre to postoperatively is common, highlighting a need for further investigation to optimize preoperative patient risk stratification in this setting. Patients who become cautionary or unsuitable based on final pathology should be considered for additional adjuvant therapy.

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“…The Intrabeam core system contains the PRS 500 control console and XRS 4 X-ray source. The control console supplies a low DC voltage to the X-ray source, which generates a high voltage to direct the electron beam into the probe [ 19 ]. The X-ray generator body (7 cm × 11 cm × 11 cm) attaches to a floor stand which allows for six degrees of freedom to treat various sites of a patient’s body [ 2 ].…”

Section: Methodsmentioning

confidence: 99%

“…The spherical applicators were made of a biocompatible polyetherimide thermoplastic (GE ULTEM 1000) [ 16 ], C 37 H 24 O 6 N 2 , with a density of 1.27 g/cm 3 [ 19 ]. Within the applicators was a hollow region of air; this was where the probe was inserted.…”

Section: Methodsmentioning

confidence: 99%

Dosimetric evaluation of an intraoperative radiotherapy system: a measurement-based and Monte-Carlo modelling investigation

et al. 2023

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Intraoperative radiotherapy (IORT) is a specialised subset of radiotherapy, where a high radiation dose is delivered to a surgically exposed tumour bed in order to eradicate any remaining cancer cells. The aim of this study was to examine the dose characteristics of the Zeiss Intrabeam IORT device which provides near-isotropic emission of up to 50 kV X-rays. The EGSnrc Monte Carlo (MC) code system was used to simulate the device and percentage depth dose (PDD) data measured with a soft X-ray parallel-plate ionisation chamber were used for model verification. The model provided energy spectra, isodose curves and mean photon energies. In addition, EBT3 Gafchromic film was used to verify the MC model by examining PDDs and 2D dose distributions for various applicators. The differences between MC model and ionisation chamber measurements were within 3% for most points, with a maximum deviation of ~ 9%. Most of the simulated PDD points were within 5% of the film-measured data, with a maximum deviation of ~ 10%. The mean energy of the bare probe was found to be 21.19 keV. The mean photon energy from applicators ranged from 29.00 to 30.85 keV. Results of this study may be useful for future work on creating a system for treatment planning.

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Effective energy assessment during breast cancer intraoperative radiotherapy by low-energy X-rays: A Monte Carlo study

Cited by 4 publications

References 19 publications

XIORT‐MC: A real‐time MC‐based dose computation tool for low‐ energy X‐rays intraoperative radiation therapy

XIORT‐MC: A real‐time MC‐based dose computation tool for low‐ energy X‐rays intraoperative radiation therapy

Targeted Intraoperative Radiotherapy (TARGIT-IORT) for Early-Stage Invasive Breast Cancer: A Single Institution Experience

Dosimetric evaluation of an intraoperative radiotherapy system: a measurement-based and Monte-Carlo modelling investigation

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