Skip to main content
placeholder image

Erratum: The impact of sensitive volume thickness for silicon on insulator microdosimeters in hadron therapy (Phys. Med. Biol. (2020) 65 (035004) DOI: 10.1088/1361-6560/ab623f)

Journal Article


Abstract


  • The original published paper titled ���The impact of sensitive volume (SV) thickness for silicon on insulator microdosimeters in hadron therapy��� (Bolst et al 2020), showed the effect which the SV size had on microdosimetric values by means of Monte Carlo simulations. Wehave since discovered that the electron production used in these simulation were 250 keV instead of the stated value of 250 eV in the publication. The electron production is the minimum kinetic energy that a secondary electron must have in order to be produced in the simulation, such as via ionisation. If an ionisation interaction were to occur in the simulation where the secondary electron would have a kinetic energy below the production threshold, then the electron would not be produced/tracked in the simulation. Instead, the electrons kinetic energy that it would have had, is deposited at the point where it would have been generated, instead of transporting the electron in the simulation and depositing energy at multiple positions. The main consequence of the simulation having a higher production value is when a charged particle traverses a detectors SV or its surrounding material. Many of the delta electrons which would have been produced with a kinetic energy of less than 250 keV in the SV would not have deposited all their energy in the volume, instead only a fraction of their energy. This results in the lineal energy values calculated being derived from an energy deposition which is shifted towards the energy lost value (linear energy transfer (LET)). The higher production threshold effects thinner SVs the most, since a thicker volume will have the same amount of energy being artificially deposited, causing smaller SVs to have higher values of lineal energy. In addition to thinner SVs being more strongly effected, lower LET beams (protons in this context) will be more effected due to having an LET much more closer to electrons compared to higher LET beams such as carbon ions. Wesincerely apologise for this error and any confusion that the original results may have caused with the production threshold of 250 keV instead of the stated value of 250 eV. The simulations have consequently been re-run with the more appropriate production threshold of 250 eV, with the updated results/figures provided. For the benefit of the reader, an explanation is provided for each updated figure, describing the reason for the distributions values changing from the original. Despite the updated results shifting from their original values, the general conclusion of the original paper does not change. This being that microdosimetric quantities measured with different sized SVs can greatly vary due to the effects of straggling and the track density (electron production) of the beam and care should be taken when comparing two measurements against one another. However, the specific values have shifted from their original as a result of the updated electron production threshold. Figure 3���shows the lineal energy distributions for H, He andCbeams at depths of 10 and 140mmin water for different thicknesses of SVs. The updated results change fairly subtly from the original, since the spectra mostly shows the primary beams peak, the peak itself will not be strongly changed from the energy lost versus the energy it deposits in the energy range. However, due to extra electrons being produced you can see an increase in the far left of the spectra, where delta electrons enter the SV and deposit energy. Figure 4���plots the width and position of the primary beams peak for the different thicknesses of SVs. These results again remain largely unchanged since the primary beam will deposit a significant portion of the energy in the SV compared to its delta electrons it produces in the SV.that the position of the peaks of the original spectrawere lower than those in figure 3, thiswas due to the silicon to tissue conversion factor being applied twice instead of oncewhen plotting the log binned data, shif

Publication Date


  • 2021

Citation


  • Bolst, D., Guatelli, S., Tran, L. T., & Rosenfeld, A. B. (2021). Erratum: The impact of sensitive volume thickness for silicon on insulator microdosimeters in hadron therapy (Phys. Med. Biol. (2020) 65 (035004) DOI: 10.1088/1361-6560/ab623f). Physics in Medicine and Biology, 66(5). doi:10.1088/1361-6560/abe224

Scopus Eid


  • 2-s2.0-85102023698

Volume


  • 66

Issue


  • 5

Place Of Publication


Abstract


  • The original published paper titled ���The impact of sensitive volume (SV) thickness for silicon on insulator microdosimeters in hadron therapy��� (Bolst et al 2020), showed the effect which the SV size had on microdosimetric values by means of Monte Carlo simulations. Wehave since discovered that the electron production used in these simulation were 250 keV instead of the stated value of 250 eV in the publication. The electron production is the minimum kinetic energy that a secondary electron must have in order to be produced in the simulation, such as via ionisation. If an ionisation interaction were to occur in the simulation where the secondary electron would have a kinetic energy below the production threshold, then the electron would not be produced/tracked in the simulation. Instead, the electrons kinetic energy that it would have had, is deposited at the point where it would have been generated, instead of transporting the electron in the simulation and depositing energy at multiple positions. The main consequence of the simulation having a higher production value is when a charged particle traverses a detectors SV or its surrounding material. Many of the delta electrons which would have been produced with a kinetic energy of less than 250 keV in the SV would not have deposited all their energy in the volume, instead only a fraction of their energy. This results in the lineal energy values calculated being derived from an energy deposition which is shifted towards the energy lost value (linear energy transfer (LET)). The higher production threshold effects thinner SVs the most, since a thicker volume will have the same amount of energy being artificially deposited, causing smaller SVs to have higher values of lineal energy. In addition to thinner SVs being more strongly effected, lower LET beams (protons in this context) will be more effected due to having an LET much more closer to electrons compared to higher LET beams such as carbon ions. Wesincerely apologise for this error and any confusion that the original results may have caused with the production threshold of 250 keV instead of the stated value of 250 eV. The simulations have consequently been re-run with the more appropriate production threshold of 250 eV, with the updated results/figures provided. For the benefit of the reader, an explanation is provided for each updated figure, describing the reason for the distributions values changing from the original. Despite the updated results shifting from their original values, the general conclusion of the original paper does not change. This being that microdosimetric quantities measured with different sized SVs can greatly vary due to the effects of straggling and the track density (electron production) of the beam and care should be taken when comparing two measurements against one another. However, the specific values have shifted from their original as a result of the updated electron production threshold. Figure 3���shows the lineal energy distributions for H, He andCbeams at depths of 10 and 140mmin water for different thicknesses of SVs. The updated results change fairly subtly from the original, since the spectra mostly shows the primary beams peak, the peak itself will not be strongly changed from the energy lost versus the energy it deposits in the energy range. However, due to extra electrons being produced you can see an increase in the far left of the spectra, where delta electrons enter the SV and deposit energy. Figure 4���plots the width and position of the primary beams peak for the different thicknesses of SVs. These results again remain largely unchanged since the primary beam will deposit a significant portion of the energy in the SV compared to its delta electrons it produces in the SV.that the position of the peaks of the original spectrawere lower than those in figure 3, thiswas due to the silicon to tissue conversion factor being applied twice instead of oncewhen plotting the log binned data, shif

Publication Date


  • 2021

Citation


  • Bolst, D., Guatelli, S., Tran, L. T., & Rosenfeld, A. B. (2021). Erratum: The impact of sensitive volume thickness for silicon on insulator microdosimeters in hadron therapy (Phys. Med. Biol. (2020) 65 (035004) DOI: 10.1088/1361-6560/ab623f). Physics in Medicine and Biology, 66(5). doi:10.1088/1361-6560/abe224

Scopus Eid


  • 2-s2.0-85102023698

Volume


  • 66

Issue


  • 5

Place Of Publication