Development of novel ionization chambers for reference dosimetry in electron flash radiotherapy.
Saved in:
| Title: | Development of novel ionization chambers for reference dosimetry in electron flash radiotherapy. |
|---|---|
| Authors: | Liu, Kevin1,2 (AUTHOR), Holmes, Shannon3 (AUTHOR), Khan, Ahtesham Ullah4,5 (AUTHOR), Hooten, Brian3 (AUTHOR), DeWerd, Larry4 (AUTHOR), Schüler, Emil1,2 (AUTHOR) eschueler@mdanderson.org, Beddar, Sam1,2 (AUTHOR) abeddar@mdanderson.org |
| Source: | Medical Physics. Dec2024, Vol. 51 Issue 12, p9275-9289. 15p. |
| Subjects: | Ionization chambers, Electric fields, Medical dosimetry, Ion plating, Electrodes |
| Abstract: | Background: Reference dosimetry in ultra‐high dose rate (UHDR) beamlines is significantly hindered by limitations in conventional ionization chamber design. In particular, conventional chambers suffer from severe charge collection efficiency (CCE) degradation in high dose per pulse (DPP) beams. Purpose: The aim of this study was to optimize the design and performance of parallel plate ion chambers for use in UHDR dosimetry applications, and evaluate their potential as reference class chambers for calibration purposes. Three chamber designs were produced to determine the influence of the ion chamber response on electrode separation, field strength, and collection volume on the ion chamber response under UHDR and ultra‐high dose per pulse (UHDPP) conditions. Methods: Three chambers were designed and produced: the A11‐VAR (0.2–1.0 mm electrode gap, 20 mm diameter collector), the A11‐TPP (0.3 mm electrode gap, 20 mm diameter collector), and the A30 (0.3 mm electrode gap, 5.4 mm diameter collector). The chambers underwent full characterization using an UHDR 9 MeV electron beam with individually varied beam parameters of pulse repetition frequency (PRF, 10–120 Hz), pulse width (PW, 0.5–4 µs), and pulse amplitude (0.01–9 Gy/pulse). The response of the ion chambers was evaluated as a function of the DPP, PRF, PW, dose rate, electric field strength, and electrode gap. Results: The chamber response was found to be dependent on DPP and PW, and these dependencies were mitigated with larger electric field strengths and smaller electrode spacing. At a constant electric field strength, we measured a larger CCE as a function of DPP for ion chambers with a smaller electrode gap in the A11‐VAR. For ion chambers with identical electrode gap (A11‐TPP and A30), higher electric field strengths were found to yield better CCE at higher DPP. A PW dependence was observed at low electric field strengths (500 V/mm) for DPP values ranging from 1 to 5 Gy at PWs ranging from 0.5 to 4 µs, but at electric field strengths of 1000 V/mm and higher, these effects become negligible. Conclusion: This study confirmed that the CCE of ion chambers depends strongly on the electrode spacing and the electric field strength, and also on the DPP and the PW of the UHDR beam. A significant finding of this study is that although chamber performance does depend on PW, the effect on the CCE becomes negligible with reduced electrode spacing and increased electric field. A CCE of ≥95% was achieved for DPPs of up to 5 Gy with no observable dependence on PW using the A30 chamber, while still achieving an acceptable performance in conventional dose rate beams, opening up the possibility for this type of chamber to be used as a reference class chamber for calibration purposes of electron FLASH beamlines. [ABSTRACT FROM AUTHOR] |
| Copyright of Medical Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
|
Full text is not displayed to guests.
Login for full access.
|
|
| FullText | Links: – Type: pdflink Text: Availability: 1 |
|---|---|
| Header | DbId: egs DbLabel: Engineering Source An: 181778097 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
| IllustrationInfo | |
| Items | – Name: Title Label: Title Group: Ti Data: Development of novel ionization chambers for reference dosimetry in electron flash radiotherapy. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Liu%2C+Kevin%22">Liu, Kevin</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Holmes%2C+Shannon%22">Holmes, Shannon</searchLink><relatesTo>3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Khan%2C+Ahtesham+Ullah%22">Khan, Ahtesham Ullah</searchLink><relatesTo>4,5</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Hooten%2C+Brian%22">Hooten, Brian</searchLink><relatesTo>3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22DeWerd%2C+Larry%22">DeWerd, Larry</searchLink><relatesTo>4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Schüler%2C+Emil%22">Schüler, Emil</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<i> eschueler@mdanderson.org</i><br /><searchLink fieldCode="AR" term="%22Beddar%2C+Sam%22">Beddar, Sam</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<i> abeddar@mdanderson.org</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Medical+Physics%22">Medical Physics</searchLink>. Dec2024, Vol. 51 Issue 12, p9275-9289. 15p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Ionization+chambers%22">Ionization chambers</searchLink><br /><searchLink fieldCode="DE" term="%22Electric+fields%22">Electric fields</searchLink><br /><searchLink fieldCode="DE" term="%22Medical+dosimetry%22">Medical dosimetry</searchLink><br /><searchLink fieldCode="DE" term="%22Ion+plating%22">Ion plating</searchLink><br /><searchLink fieldCode="DE" term="%22Electrodes%22">Electrodes</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Background: Reference dosimetry in ultra‐high dose rate (UHDR) beamlines is significantly hindered by limitations in conventional ionization chamber design. In particular, conventional chambers suffer from severe charge collection efficiency (CCE) degradation in high dose per pulse (DPP) beams. Purpose: The aim of this study was to optimize the design and performance of parallel plate ion chambers for use in UHDR dosimetry applications, and evaluate their potential as reference class chambers for calibration purposes. Three chamber designs were produced to determine the influence of the ion chamber response on electrode separation, field strength, and collection volume on the ion chamber response under UHDR and ultra‐high dose per pulse (UHDPP) conditions. Methods: Three chambers were designed and produced: the A11‐VAR (0.2–1.0 mm electrode gap, 20 mm diameter collector), the A11‐TPP (0.3 mm electrode gap, 20 mm diameter collector), and the A30 (0.3 mm electrode gap, 5.4 mm diameter collector). The chambers underwent full characterization using an UHDR 9 MeV electron beam with individually varied beam parameters of pulse repetition frequency (PRF, 10–120 Hz), pulse width (PW, 0.5–4 µs), and pulse amplitude (0.01–9 Gy/pulse). The response of the ion chambers was evaluated as a function of the DPP, PRF, PW, dose rate, electric field strength, and electrode gap. Results: The chamber response was found to be dependent on DPP and PW, and these dependencies were mitigated with larger electric field strengths and smaller electrode spacing. At a constant electric field strength, we measured a larger CCE as a function of DPP for ion chambers with a smaller electrode gap in the A11‐VAR. For ion chambers with identical electrode gap (A11‐TPP and A30), higher electric field strengths were found to yield better CCE at higher DPP. A PW dependence was observed at low electric field strengths (500 V/mm) for DPP values ranging from 1 to 5 Gy at PWs ranging from 0.5 to 4 µs, but at electric field strengths of 1000 V/mm and higher, these effects become negligible. Conclusion: This study confirmed that the CCE of ion chambers depends strongly on the electrode spacing and the electric field strength, and also on the DPP and the PW of the UHDR beam. A significant finding of this study is that although chamber performance does depend on PW, the effect on the CCE becomes negligible with reduced electrode spacing and increased electric field. A CCE of ≥95% was achieved for DPPs of up to 5 Gy with no observable dependence on PW using the A30 chamber, while still achieving an acceptable performance in conventional dose rate beams, opening up the possibility for this type of chamber to be used as a reference class chamber for calibration purposes of electron FLASH beamlines. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Medical Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
| PLink | https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=egs&AN=181778097 |
| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1002/mp.17425 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 15 StartPage: 9275 Subjects: – SubjectFull: Ionization chambers Type: general – SubjectFull: Electric fields Type: general – SubjectFull: Medical dosimetry Type: general – SubjectFull: Ion plating Type: general – SubjectFull: Electrodes Type: general Titles: – TitleFull: Development of novel ionization chambers for reference dosimetry in electron flash radiotherapy. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Liu, Kevin – PersonEntity: Name: NameFull: Holmes, Shannon – PersonEntity: Name: NameFull: Khan, Ahtesham Ullah – PersonEntity: Name: NameFull: Hooten, Brian – PersonEntity: Name: NameFull: DeWerd, Larry – PersonEntity: Name: NameFull: Schüler, Emil – PersonEntity: Name: NameFull: Beddar, Sam IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 12 Text: Dec2024 Type: published Y: 2024 Identifiers: – Type: issn-print Value: 00942405 Numbering: – Type: volume Value: 51 – Type: issue Value: 12 Titles: – TitleFull: Medical Physics Type: main |
| ResultId | 1 |
