Comparative study of alternative Geant4 hadronic ion inelastic physics models for prediction of positron-emitting radionuclide production in carbon and oxygen ion therapy

Chacon, Andrew; Guatelli, Susanna; Rutherford, Harley; Bolst, David; Mohammadi, Akram; Ahmed, Abdella; Nitta, Munetaka; Nishikido, Fumihiko; Iwao, Yuma; Tashima, Hideaki; Yoshida, Eiji; Akamatsu, Go; Takyu, Sodai; Kitagawa, A.; Hofmann, Theresa; Pinto, Marco; Franklin, Daniel; Parodi, Katia; Yamaya, Taiga; Rosenfeld, Anatoly B.; Safavi-Naeini, Mitra

doi:10.1088/1361-6560/ab2752

“…Geant4 version 10.2.p03 is used for all simulations, since it has been previously identified as providing the best agreement with experimental fragmentation measurements in particle therapy 19 , 21 , 22 . Electromagnetic interactions were modelled using the standard Geant4 physics option 3 model (G4EmStandardPhysics_option3), while the other physics models (including hadronic interactions) used in the simulation are listed in Table 1 .…”

Section: Methodsmentioning

confidence: 99%

Detection and discrimination of neutron capture events for NCEPT dose quantification

Chacon

¹

,

Kielly

²

,

Rutherford

³

et al. 2022

Sci Rep

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Neutron Capture Enhanced Particle Therapy (NCEPT) boosts the effectiveness of particle therapy by capturing thermal neutrons produced by beam-target nuclear interactions in and around the treatment site, using tumour-specific $$^{10}$$ 10 B or $$^{157}$$ 157 Gd-based neutron capture agents. Neutron captures release high-LET secondary particles together with gamma photons with energies of 478 keV or one of several energies up to 7.94 MeV, for $$^{10}$$ 10 B and $$^{157}$$ 157 Gd, respectively. A key requirement for NCEPT’s translation is the development of in vivo dosimetry techniques which can measure both the direct ion dose and the dose due to neutron capture. In this work, we report signatures which can be used to discriminate between photons resulting from neutron capture and those originating from other processes. A Geant4 Monte Carlo simulation study into timing and energy thresholds for discrimination of prompt gamma photons resulting from thermal neutron capture during NCEPT was conducted. Three simulated $$300\times 300\times 300$$ 300 × 300 × 300 mm$$^3$$ 3 cubic PMMA targets were irradiated by $$^4$$ 4 He or $$^{12}$$ 12 C ion beams with a spread out Bragg peak (SOBP) depth range of 60 mm; one target is homogeneous while the others include $$10\times 10\times 10$$ 10 × 10 × 10 mm$$^3$$ 3 neutron capture inserts (NCIs) of pure $$^{10}$$ 10 B or $$^{157}$$ 157 Gd located at the distal edge of the SOBP. The arrival times of photons and neutrons entering a simulated $$50\times 50\times 50$$ 50 × 50 × 50 mm$$^3$$ 3 ideal detector were recorded. A temporal mask of 50–60 ns was found to be optimal for maximising the discrimination of the photons resulting from the neutron capture by boron and gadolinium. A range of candidate detector and thermal neutron shielding materials were simulated, and detections meeting the proposed acceptance criteria (i.e. falling within the target energy window and arriving 60 ns post beam-off) were classified as true or false positives, depending on their origin. The ratio of true/false positives ($$R_{TF}$$ R TF ) was calculated; for targets with $$^{10}$$ 10 B and $$^{157}$$ 157 Gd NCIs, the detector materials which resulted in the highest $$R_{TF}$$ R TF were cadmium-shielded CdTe and boron-shielded LSO, respectively. The optimal irradiation period for both carbon and helium ions was 1 µs for the $$^{10}$$ 10 B NCI and 1 ms for the $$^{157}$$ 157 Gd NCI.

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“…Geant4 version 10.2.p03 is used for all simulations, since it has been previously identified as providing the best agreement with experimental fragmentation measurements in particle therapy [18,19,20]. Electromagnetic interactions were modelled using the standard Geant4 physics option 3 model (G4EmStandardPhysics option3), while the other physics models (including hadronic interactions) used in the simulation are listed in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Prompt Gamma based Detection and Discrimination of 2 Neutron Capture Events for NCEPT Dose 3 Quantification

Chacon

¹

,

Kielly

²

,

Rutherford

³

et al. 2021

Preprint

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0

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Neutron Capture Enhanced Particle Therapy (NCEPT) boosts the effectiveness of particle therapy by capturing thermal neutrons produced by beam-target nuclear interactions in and around the treatment site, using tumour-specific 10B or 157Gd-based neutron capture agents. Neutron captures release high-LET secondary particles together with prompt gamma photons with energies of 478 keV (10B) or 7.94 MeV (157Gd). A key requirement for NCEPT’s translation is the development of in vivo dosimetry techniques which can measure both the direct ion dose and the dose due to neutron capture. In this work, we report signatures which can be used to discriminate between photons resulting from neutron capture and those originating from other processes. A Geant4 Monte Carlo simulation study into timing and energy thresholds for discrimination of prompt gamma photons resulting from thermal neutron capture during NCEPT was conducted. Three simulated 300×300×300 mm3 cubic PMMA targets were irradiated by 4He or 12C ion beams with a spread out Bragg peak (SOBP) depth range of 60 mm; one target is homogeneous while the others include 10×10×10 mm3 neutron capture inserts (NCIs) of pure 10B or 157Gd located at the distal edge of the SOBP. The arrival times of photons and neutrons entering a simulated 50×50×50 mm3 ideal detector were recorded. The majority of photons resulting from neutron capture were found to arrive at the detector at least 60 ns later than photons created by other processes. A range of candidate detector and thermal neutron shielding materials were simulated, and detections meeting the proposed acceptance criteria (i.e. falling within the target energy window and arriving 60 ns post beam-off) were classified as true or false positives, depending on their origin. The ratio of true / false positives (RTF) was calculated; for targets with 10B and 157Gd NCIs, the detector materials which resulted in the highest RTF were cadmium-shielded CdTe and boron-shielded LSO, respectively. The optimal irradiation period for both carbon and helium ions was 1 µs for the 10B NCI and 1 ms for the 157Gd NCI.

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“…[9][10][11][12][13][14] One of the most promising methods for dose verification QA is to image the shortlived positron-emitting radionuclides created through nuclear fragmentation between the ions in the beam and nuclei in the target material. 5,[15][16][17] There has been significant research into design and development of in-beam positron emission tomography (PET) scanners which can be positioned around the patient during treatment to measure the distribution of positron annihilations which occur during the interspill period of pulsed synchrotron-based irradiation (or similar) and postirradiation. 9,[11][12]18,19 In-beam PET imaging can be challenging due to the low yield of positron-emitting radionuclides relative to the delivered dose, which limits the signal-to-noise ratio (SNR) of the acquired PET image, and hence the accuracy with which the treated volume can be visualized.…”

Section: Introductionmentioning

confidence: 99%

“…As such, there is considerable interest in accurate quality assurance (QA) techniques for heavy ion therapy which can verify that the delivered dose distribution matches the treatment plan 9–14 . One of the most promising methods for dose verification QA is to image the short‐lived positron‐emitting radionuclides created through nuclear fragmentation between the ions in the beam and nuclei in the target material 5,15–17 . There has been significant research into design and development of in‐beam positron emission tomography (PET) scanners which can be positioned around the patient during treatment to measure the distribution of positron annihilations which occur during the interspill period of pulsed synchrotron‐based irradiation (or similar) and postirradiation 9,11–12,18,19 …”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the characteristics of radioactive beams for heavy ion therapy

Chacon

¹

,

James

²

,

Tran

³

et al. 2020

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This work has two related objectives. The first is to estimate the relative biological effectiveness of two radioactive heavy ion beams based on experimental measurements, and compare these to the relative biological effectiveness of corresponding stable isotopes to determine whether they are therapeutically equivalent. The second aim is to quantitatively compare the quality of images acquired postirradiation using an in-beam whole-body positron emission tomography scanner for range verification quality assurance. Methods: The energy deposited by monoenergetic beams of 11 C at 350 MeV/u, 15 O at 250 MeV/u, 12 C at 350 MeV/u, and 16 O at 430 MeV/u was measured using a cruciform transmission ionization chamber in a water phantom at the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. Dosemean lineal energy was measured at various depths along the path of each beam in a water phantom using a silicon-on-insulator mushroom microdosimeter. Using the modified microdosimetric kinetic model, the relative biological effectiveness at 10% survival fraction of the radioactive ion beams was evaluated and compared to that of the corresponding stable ions along the path of the beam. Finally, the postirradiation distributions of positron annihilations resulting from the decay of positron-emitting nuclei were measured for each beam in a gelatin phantom using the in-beam whole-body positron emission tomography scanner at HIMAC. The depth of maximum positron-annihilation density was compared with the depth of maximum dose deposition and the signal-to-background ratios were calculated and compared for images acquired over 5 and 20 min postirradiation of the phantom. Results: In the entrance region, the RBE 10 was 1.2 AE 0.1 for both 11 C and 12 C beams, while for 15 O and 16 O it was 1.4 AE 0.1 and 1.3 AE 0.1, respectively. At the Bragg peak, the RBE 10 was 2.7 AE 0.4 for 11 C and 2.9 AE 0.4 for 12 C, while for 15 O and 16 O it was 2.7 AE 0.4 and 2.8 AE 0.4, respectively. In the tail region, RBE 10 could only be evaluated for carbon; the RBE 10 was 1.6 AE 0.2 and 1.5 AE 0.1 for 11 C and 12 C, respectively. Positron emission tomography images obtained from gelatin targets irradiated by radioactive ion beams exhibit markedly improved signal-to-background ratios compared to those obtained from targets irradiated by nonradioactive ion beams, with 5-fold and 11fold increases in the ratios calculated for the 15 O and 11 C images compared with the values obtained for 16 O and 12 C, respectively. The difference between the depth of maximum dose and the depth of maximum positron annihilation density is 2.4 AE 0.8 mm for 11 C, compared to À5.6 AE 0.8 mm for 12 C and 0.9 AE 0.8 mm for 15 O vs À6.6 AE 0.8 mm for 16 O. Conclusions: The RBE 10 values for 11 C and 15 O were found to be within the 95% confidence interval of the RBEs estimated for their corresponding stable isotopes across each of the regions in which it was evaluated. Furthermore, for a given dose, 11 C and 15 O beams produce much better quality images for range verification c...

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Comparative study of alternative Geant4 hadronic ion inelastic physics models for prediction of positron-emitting radionuclide production in carbon and oxygen ion therapy

Cited by 14 publications

References 40 publications

Detection and discrimination of neutron capture events for NCEPT dose quantification

Detection and discrimination of neutron capture events for NCEPT dose quantification

Prompt Gamma based Detection and Discrimination of 2 Neutron Capture Events for NCEPT Dose 3 Quantification

Experimental investigation of the characteristics of radioactive beams for heavy ion therapy

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