Loading...
Please wait, while we are loading the content...
Similar Documents
Ion recombination correction factor in scanned light-ion beams for absolute dose measurement using plane-parallel ionisation chambers
| Content Provider | Scilit |
|---|---|
| Author | Rossomme, S. Horn, J. Brons, S. Jäkel, O. Mairani, A. Ciocca, M. Floquet, V. Romano, Francesco Garcia, D. Rodriguez Vynckier, S. Palmans, Hugo |
| Copyright Year | 2017 |
| Description | Journal: Physics in Medicine & Biology Based on international reference dosimetry protocols for light-ion beams, a correction factor (k$ _{s}$) has to be applied to the response of a plane-parallel ionisation chamber, to account for recombination of negative and positive charges in its air cavity before these charges can be collected on the electrodes. In this work, k$ _{s}$ for IBA PPC40 Roos-type chambers is investigated in four scanned light-ion beams (proton, helium, carbon and oxygen). To take into account the high dose-rates used with scanned beams and LET-values, experimental results are compared to a model combining two theories. One theory, developed by Jaffé, describes the variation of k$ _{s}$ with the ionization density within the ion track (initial recombination) and the other theory, developed by Boag, describes the variation of k$ _{s}$ with the dose rate (volume recombination). Excellent agreement is found between experimental and theoretical k$ _{s}$-values. All results confirm that k$ _{s}$ cannot be neglected. The solution to minimise k$ _{s}$ is to use the ionisation chamber at high voltage. However, one must be aware that charge multiplication may complicate the interpretation of the measurement. For the chamber tested, it was found that a voltage of 300 V can be used without further complication. As the initial recombination has a logarithmic variation as a function of 1/V, the two-voltage method is not applicable to these scanned beams. |
| Related Links | http://iopscience.iop.org/article/10.1088/1361-6560/aa730f/pdf |
| Ending Page | 5382 |
| Page Count | 18 |
| Starting Page | 5365 |
| ISSN | 00319155 |
| e-ISSN | 13616560 |
| DOI | 10.1088/1361-6560/aa730f |
| Journal | Physics in Medicine & Biology |
| Issue Number | 13 |
| Volume Number | 62 |
| Language | English |
| Publisher | IOP Publishing |
| Publisher Date | 2017-06-12 |
| Access Restriction | Open |
| Subject Keyword | Journal: Physics in Medicine & Biology Ionisation Chamber |
| Content Type | Text |
| Resource Type | Article |
| Subject | Radiology, Nuclear Medicine and Imaging Radiological and Ultrasound Technology |
