Computed tomography dosimetry with high‐resolution detectors commonly used in radiotherapy — an energy dependence study

Liebmann, M; Poppe, B; Boetticher, Heiner von

doi:10.1120/jacmp.v16i5.5302

Cited by 2 publications

(2 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Liebmann et al. reported an energy response variation of 4.5% for the Pinpoint chamber (PTW 31014) in water over the energy range of 50–125 kV 32 which this study extends upon to include 200 kV and 6 MV. Snow et al.…”

Section: Discussionmentioning

confidence: 50%

“…The difference in response is attributed to the amount of aluminum in the Farmer inner central electrode that makes it more susceptible to over-respond to low-energy photons. Liebmann et al reported an energy response variation of 4.5% for the Pinpoint chamber (PTW 31014) in water over the energy range of 50-125 kV 32 which this study extends upon to include 200 kV and 6 MV. Snow et alexamined the change in air-kerma calibration coefficients as a function of photon energy, and between 100 and 250 kV, the Farmer-type chambers in the study displayed a variation of up to 14% when used during negative charge collection but less than 5% during positive charge collection.…”

Section: Detector Energy Dependencementioning

confidence: 50%

See 1 more Smart Citation

Energy‐dependence investigation for a range of clinically used detectors from 70 kV to 6 MV

et al. 2022

View full text Add to dashboard Cite

Purpose Accurate measurement of out‐of‐field dose in radiotherapy directly impacts beam data modeling in treatment planning systems, verification of implanted electronic devices/lens/fetus dose, secondary cancer risk estimation, and organ‐at‐risk dose reporting. When performing out‐of‐field dosimetry, it is therefore imperative that the response of the detector has been well characterized. Due to the softening of the radiation beam out‐of‐field, many detectors will exhibit energy dependence. This study investigated the energy dependence of a range of clinical available detectors over typical energies experienced out‐of‐field. Methods The response of detectors to photon beams from 70 kV to 6 MV was measured. The relative change in response from 6 MV down to 70 kV highlighted the expected deviation in the response of detectors that would typically be calibrated in‐field for use out‐of‐field. Results The Pinpoint detector displayed the most energy‐independent response over the energy range investigated. The Micro‐Lion detector was the only detector to show an under‐response to all low‐energy beams relative to 6 MV. The diode‐type detectors showed the largest energy dependence. Conclusions When considering detectors for use in out‐of‐field dose measurements, it is important that the energy dependence is investigated over a low‐energy range as out‐of‐field the energy spectra comprise a larger component of photons in the 50–100‐keV range. This study highlights the variation in response of a range of clinically available detectors to low‐energy radiation beams relative to 6 MV for out‐of‐field dosimetry. The Pinpoint detector was the most energy‐independent detector with a response close to unity over the entire energy range investigated.

show abstract

Section: Discussionmentioning

confidence: 50%

Section: Detector Energy Dependencementioning

confidence: 50%

Energy‐dependence investigation for a range of clinically used detectors from 70 kV to 6 MV

et al. 2022

View full text Add to dashboard Cite

show abstract

Quantitative characterization of the X-ray beam at the Australian Synchrotron Imaging and Medical Beamline (IMBL)

et al. 2017

View full text Add to dashboard Cite

A critical early phase for any synchrotron beamline involves detailed testing, characterization and commissioning; this is especially true of a beamline as ambitious and complex as the Imaging & Medical Beamline (IMBL) at the Australian Synchrotron. IMBL staff and expert users have been performing precise experiments aimed at quantitative characterization of the primary polychromatic and monochromatic X-ray beams, with particular emphasis placed on the wiggler insertion devices (IDs), the primary-slit system and any in vacuo and ex vacuo filters. The findings from these studies will be described herein. These results will benefit IMBL and other users in the future, especially those for whom detailed knowledge of the X-ray beam spectrum (or `quality') and flux density is important. This information is critical for radiotherapy and radiobiology users, who ultimately need to know (to better than 5%) what X-ray dose or dose rate is being delivered to their samples. Various correction factors associated with ionization-chamber (IC) dosimetry have been accounted for, e.g. ion recombination, electron-loss effects. A new and innovative approach has been developed in this regard, which can provide confirmation of key parameter values such as the magnetic field in the wiggler and the effective thickness of key filters. IMBL commenced operation in December 2008 with an Advanced Photon Source (APS) wiggler as the (interim) ID. A superconducting multi-pole wiggler was installed and operational in January 2013. Results are obtained for both of these IDs and useful comparisons are made. A comprehensive model of the IMBL has been developed, embodied in a new computer program named spec.exe, which has been validated against a variety of experimental measurements. Having demonstrated the reliability and robustness of the model, it is then possible to use it in a practical and predictive manner. It is hoped that spec.exe will prove to be a useful resource for synchrotron science in general, and for hard X-ray beamlines, whether they are based on bending magnets or insertion devices, in particular. In due course, it is planned to make spec.exe freely available to other synchrotron scientists.

show abstract

Computed tomography dosimetry with high‐resolution detectors commonly used in radiotherapy — an energy dependence study

Cited by 2 publications

References 21 publications

Energy‐dependence investigation for a range of clinically used detectors from 70 kV to 6 MV

Energy‐dependence investigation for a range of clinically used detectors from 70 kV to 6 MV

Quantitative characterization of the X-ray beam at the Australian Synchrotron Imaging and Medical Beamline (IMBL)

Contact Info

Product

Resources

About