Demonstrating the use of optically stimulated luminescence dosimeters (OSLDs) for measurement of staff radiation exposure in interventional fluoroscopy and helmet output factors in radiosurgery

Using the optically stimulated luminescence technique for one- and two-dimensional dose mapping: a brief review

In respect of radiation dosimetry, several applications require dose distribution verification rather than absolute dosimetry. Most protocols use radiological and radiochromic films and ionization chambers or diode arrays for dose mapping. The films are disposable which causes the precision of the results dependent on film production variability. The measurements with arrays of ionization chambers or diodes mainly lack spatial resolution. This review aims to provide an overview of the use of optically stimulated luminescence detectors (OSLDs) for one-dimensional (1D) and two-dimensional (2D) dose mapping in different applications. It reviews the ideas, OSL materials, and applications related to the assessment of dose distribution using OSLDs in the form of film or ceramic plate (BeO). Additionally, it reviews research published in the international scientific literature from 1998 to 2021. As an outcome, a table containing the main characteristics of each relevant paper is shown. The results section was divided by the type of OSL material, and we briefly described the principal findings and the significant developments of each mentioned study such as film production and OSL reader assembly. The purpose of this study was to present an overview of the main findings of several research groups on the use of OSLD in the form of film or plate for 1D and 2D dose mapping. Finally, the potential future development of dose mapping using OSLD films was outlined.

Investigation into the Energy and Scatter Response of OSLDs at Diagnostic Energies Using a C-arm System

ABSTRACT

Optically stimulated luminescent dosimeters (OSLDs) are radiation detectors commonly used in a clinical setting to monitor the dose to patients undergoing imaging or interventional procedures, especially those involving fluoroscopy. In dose tracking using OSLDs, it is important to consider that photons at the diagnostic energy range are prone to energy spectrum shifts from scattering interactions in the medium and that OSLDs have been reported to yield a somewhat strong energy-dependent response in the diagnostic energy range. This study examines the response of OSLDs exposed to a spectrum of photons in the diagnostic energy range (60-120 kVp), both free-in-air and on the surface of a PMMA phantom, within and just outside of the exposure field. From these measurements, it was observed that the response differs substantially (as high as 30%) in OSLDs irradiated under identical exposure settings but with differences in beam quality and scattering conditions. Furthermore, this study devises a method of weighted averages to calculate the calibration factors for OSLDs exposed to both primary and scatter photons, which were approximately 2-5% less than their corresponding measured values. This study emphasizes the need to develop different calibration factors in the clinical use of OSLDs for diagnostic imaging procedures, especially for procedures in which more precise dose measurements may be necessary.

APPLICATIONS OF OPTICALLY STIMULATED LUMINESCENCE IN MEDICAL DOSIMETRY

If the first decade of the new millennium saw the establishment of a more solid foundation for the use of the Optically Stimulated Luminescence (OSL) in medical dosimetry, the second decade saw the technique take root and become more widely used in clinical studies. Recent publications report not only characterization and feasibility studies of the OSL technique for various applications in radiotherapy and radiology, but also the practical use of OSL for postal audits, estimation of staff dose, in vivo dosimetry, dose verification and dose mapping studies. This review complements previous review papers and reports on the topic, providing a panorama of the new advances and applications in the last decade. Attention is also dedicated to potential future applications, such as LET dosimetry, 2D/3D dosimetry using OSL, dosimetry in magnetic resonance imaging-guided radiotherapy (MRIgRT) and dosimetry of extremely high dose rates (FLASH therapy).

DEVELOPMENT OF OPTICALLY STIMULATED LUMINESCENCE BADGE READER SYSTEM FOR INDIVIDUAL MONITORING OF RADIATION WORKERS

A new Optically Stimulated Luminescence Badge Reader (OSBARE-1) system has been designed and developed for application in the individual monitoring dosimetry. This badge reader system utilizes the 470-nm light of a blue LED for CW-OSL readout with the help of PMT photon counting module. The developed reader system can process four element 24 OSLD cards within 25 min. These four-element OSLD card consists of the Teflon embedded indigenously developed dosimetric grade α-Al2O3:C phosphor. The minimum measurable dose (MMD) was found to be ~26 μGy for these OSLD cards with reproducibility of ~1.12%. The various operational parameters such as variation in the dark counts, OSL scattering background counts and reproducibility have been studied in detailed for this reader system. The dosimetric studies performed on this developed reader system found to have a great potential for the OSLD-based large-scale personnel monitoring program for the radiation workers.

SCATTER RADIATION IN THE FLUOROSCOPY-GUIDED INTERVENTIONAL ROOM

Radiation scattered throughout the room during fluoroscopy-guided interventional (FGI) procedures was quantified at different locations using nanoDot optically stimulated luminescence dosemeters. All the tube angulation imaging shows that the radiation spectrum resembled a single peak distribution. The left anterior oblique 90° shows the highest single peak distribution (28.65 mSv/h). The single peak distribution for standard anteroposterior, left anterior oblique 45° and right anterior oblique 45° imaging was 13.32, 22.99 and 17.40 mSv/h, respectively. All tube angulation shows that the position of the interventional radiologist experienced a higher radiation level compared to other staffs. The doses of radiation varied widely around the perimeter of the patient's table and changed in accordance to imaging angles during procedures. Knowledge pertaining to radiation exposure levels is integral in order to avoid adverse risks, particularly among staff.