Shielding disk position in intra-operative electron radiotherapy (IOERT): A Monte Carlo study

Alhamada, Husein; Simon, Stéphane; Philippson, C.; Vandekerkhove, C.; Jourani, Y.; Pauly, Nicolas; Dubus, Alain; Reynaert, N.

doi:10.1016/j.ejmp.2018.05.023

Cited by 12 publications

(7 citation statements)

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“…Using special applicator or beam shaper device are not possible with IORT TPS [28][29][30][31]. Alhamada et al and Kamomae et al have proposed new shielding disks and tungsten paper for organ at risk protection [32,33]. 3D Dosimetry impact verification of using these new materials is possible only with our methodology whereas a limited materials list is available in IOERT TPS.…”

Section: Discussionmentioning

confidence: 99%

3D Monte Carlo dosimetry of intraoperative electron radiation therapy (IOERT)

et al. 2019

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This paper studies the feasibility of using Monte Carlo (MC) for treatment planning of intraoperative electron radiation therapy (IOERT) procedure to get 3D dose by using patient's CT images. Methods: The IOERT treatment planning was performed using the following successive steps:I) The Mobetron 1000® machine was modelled with the EGSnrc MC codes. II) The MC model was validated with measurements of percentage depth doses and profiles for three energies (12, 9, 6) MeV. III) CT images were imported as DICOM files. IV) Contouring of the planning target volume (PTV) and the organs at risk was done by the radiation oncologist. V) The medical physicist with the radiation oncologist, had chosen the same parameters of IOERT procedures like energy, applicator (type, size) and using or not bolus. VI) Finally, dose calculation and analysis of 3D maps was carried out. Results: The tuning process of the MC model provides good results, as the maximum value of the root mean square deviation (RMSD) was less than 3% between the MC simulated PDDs and the measured PDDs. The contouring and dose analysis review were easy to conduct for the classical treatment planning system. The radiation oncologist had many tools for dose analysis such as DVH and color wash for all the slides. Summation of the 3D dose of IOERT with other radiotherapy plans is possible and helpful for total dose estimation. Archiving and documentation is as good as treatment planning system (TPS). Conclusions: The method displayed in this paper provides a step forward for IOERT Dosimetry and allows to obtain accurate dosimetry of treated volumes.

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Section: Discussionmentioning

confidence: 99%

3D Monte Carlo dosimetry of intraoperative electron radiation therapy (IOERT)

et al. 2019

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“…Besides, as provided in Table 1, the first disk layer is always constructed from a low atomic number element or composition with a light physical density to ensure minimizing the electron backscattering effect from the upper disk surface. This backscatter dose component can considerably affect the dose distribution uniformity inside the target volume, as established by some studies 14–16,20,28–30 …”

Section: Methodsmentioning

confidence: 97%

“…15 These radioprotection disks are the most widespread ones which are clinically used during breast intraoperative electron radiotherapy to minimize both the received dose by the healthy underlying tissues and the electron backscattered dose originating from the upper disk surface. 20,28 As demonstrated in Table 1, the thickness of these disks does not exceed 1 cm, because higher disk thicknesses may not allow the surgeon to prepare an appropriate flap (remaining the tumor bed after the surgery) upon the disk surface.…”

Section: Employed Ioert Shielding Disksmentioning

confidence: 99%

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Evaluating the induced photon contamination by different breast IOERT shields using Monte Carlo simulation

Baghani

Robatjazi

2023

J Applied Clin Med Phys

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Background and ObjectiveAvoiding the underlying healthy tissue over‐exposure during breast intraoperative electron radiotherapy (IOERT) is owing to the use of some dedicated radioprotection disks during patient irradiation. The originated contaminant photons from some widely used double‐layered shielding disks including PMMA+Cu, PTFE+steel, and Al+Pb configurations during the breast IOERT have been evaluated through a Monte Carlo (MC) simulation approach.MethodsProduced electron beam with energies of 6, 8, 10, and 12 MeV by a validated MC model of Liac12 dedicated IOERT accelerator was used for disk irradiations. Each of above‐mentioned radioprotection disks was simulated inside a water phantom, so that the upper disk surface was positioned at R90 depth of each considered electron energy. Simulations were performed by MCNPX (version 2.6.0) MC code. Then, the energy spectra of the contaminant photons at different disk surfaces (upper, middle, and lower one) and relevant contaminant dose beneath the studied disks were determined and compared.ResultsNone of studied shielding disks show significant photon contamination up to 10 MeV electron energy, so that the induced photon dose by the contaminant X‐rays was lower than those observed in the disk absence under the same conditions. In return, the induced photon dose at a close distance to the lower disk surface exceeded from calculated values in the disk absence at 12 MeV electron energy. The best performance in contaminant dose reduction at the energy range of 6–10 MeV belonged to the Al+Pb disk, while the PMMA+Cu configuration showed the best performance in this regard at 12 MeV energy.ConclusionFinally, it can be concluded that all studied shielding disks not only don't produce considerable photon contamination but also absorb the originated X‐rays from electron interactions with water at the electron energy range of 6–10 MeV. The only concern is related to 12 MeV energy where the induced photon dose exceeds the dose values in the disk absence. Nevertheless, the administered dose by contaminant photons to underlying healthy tissues remains beneath the tolerance dose level by these organs at the entire range of studied electron energies.

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“…The position of the shielding disk during the operation can be checked by a surgeon with a needle or with in vivo measurements, see section 4.1.3.2 for more detail. Based on MC calculations, the shielding plate should consist of materials that can attenuate the beam almost completely for used energies and reduce the backscatter radiation (Martignano et al 2007, Alhamada et al 2018.…”

Section: Clinical Applications Of Iortmentioning

confidence: 99%

In vivo dosimetry in cancer patients undergoing intraoperative radiation therapy

Petoukhova,

Snijder,

Vissers

et al. 2023

Phys. Med. Biol.

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In vivo dosimetry (IVD) is an important tool in external beam radiotherapy (EBRT) to detect major errors by assessing differences between expected and delivered dose and to record the received dose by individual patients. Also, in intraoperative radiation therapy (IORT), IVD is highly relevant to register the delivered dose. This is especially relevant in low-risk breast cancer patients since a high dose of IORT is delivered in a single fraction. In contrast to EBRT, online treatment planning based on intraoperative imaging is only under development for IORT. Up to date, two commercial treatment planning systems proposed intraoperative ultrasound or in-room cone-beam CT for real-time IORT planning. This makes IVD even more important because of the possibility for real-time treatment adaptation. Here, we summarize recent developments and applications of IVD methods for IORT in clinical practice, highlighting important contributions and identifying specific challenges such as a treatment planning system for IORT. HDR brachytherapy as a delivery technique was not considered. We add IVD for ultrahigh dose rate (FLASH) radiotherapy that promises to improve the treatment efficacy, when compared to conventional radiotherapy by limiting the rate of toxicity while maintaining similar tumour control probabilities. To date, FLASH IORT is not yet in clinical use.

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Shielding disk position in intra-operative electron radiotherapy (IOERT): A Monte Carlo study

Cited by 12 publications

References 11 publications

3D Monte Carlo dosimetry of intraoperative electron radiation therapy (IOERT)

3D Monte Carlo dosimetry of intraoperative electron radiation therapy (IOERT)

Evaluating the induced photon contamination by different breast IOERT shields using Monte Carlo simulation

In vivo dosimetry in cancer patients undergoing intraoperative radiation therapy

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