Suitability of laser stimulated TLD arrays as patient dose monitors in high dose x-ray imaging

R. A. Geise, B. A. Schueler, W. Lien, S. C. Jones

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Skin entrance doses of patients undergoing interventional x-ray procedures are capable of causing skin damage and should be monitored routinely. Single TLD chips am not suitable because the location of maximum skin exposure cannot be predicted. Most photographic films are too sensitive at diagnostic x-ray energies for dosimetry, exhibit temporal changes in response, and require special packaging by the user. We have investigated the suitability of laser heated MgB4O7 TLDs in a polyimide binder in the range of 0.2-20 Gy. These are available in radioluscent arrays up to 30 x 30 cm for direct measurement of patient skin dose. Dose response was compared with a calibrated ion chamber dosimeter. Exposures were made at 60, 90, and 120 kVp, at low (fluoroscopy) and high (DSA) dose rates, and at different beam incidence angles. Longitudinal reproducibility and response to temperature changes during exposure were also checked. The dose response is linear below approximately 6 Gy where the slope starts to increase 2% per Gy. Errors were less than ±2% over a 0-80 degree range of beam incidence angles; less than ±3% for both dose rate variations and kVp differences between 70 and 120 kVp. The response was unaffected by temperature changes between 20 and 37 °C. Reproducibility is currently ±7%. MgB4O7 TLD arrays are suitable for patient dosimetry in high dose fluoroscopy procedures if appropriate calibrations are used. Uncertainty in skin dose measurement is less than 10%, which is substantially better than film dosimetry.

Original languageEnglish (US)
Pages (from-to)1643-1646
Number of pages4
JournalMedical physics
Volume24
Issue number10
DOIs
StatePublished - Oct 1997

Keywords

  • Angiography
  • Dosimetry
  • Interventional radiology
  • Skin dose
  • Thermoluminescence

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

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