Mailed Thermoluminescent Dosimeters (TLD) for Quality Assurance
Radiation Therapy Machine Output Checks
The MD Anderson Radiation Dosimetry Services (RDS) provides independent peer reviews of beam output for radiation dose delivery systems. Specifically, we provide output checks for external beam radiation therapy machines including:
- megavoltage photon (2 - 25 MV)
- electron (4 - 20 MeV)
- orthovoltage (1.9 mm Al - 3 mm Cu HVL)
- Cobalt-60
Absorbed Dose in Blood Irradiators
Thermoluminescent dosimeters (TLD) are available by mail to check the absorbed dose to the blood in irradiators used by blood banks. Packets of dosimeters are supplied; these can be placed at various locations to monitor the range of dose throughout the canister for a typical irradiation. These measurements are an independent check of the calibration of the blood irradiator as provided by the manufacturer.
Radiation Dosimetry Services also offers checks of:
- total body dosimetry
- total skin dosimetry
For information on pricing and how to order our services, please visit our Pricing and Ordering Information Page.
NOTE: We no longer offer Stereotactic Head, Single Beam or IMRT services. Please contact the MD Anderson Dosimetry Laboratory (MDADL) for these service needs. You may visit their website, call their office at 713-745-8989, fax them at 713-794-1364 or email them at mdadl@mdanderson.org.
Dosimetry Process
For all of the services provided by Radiation Dosimetry Services (RDS), thermoluminescent dosimeters (TLD) and associated apparatuses are mailed to and irradiated at requesting institutions. The irradiated TLD are mailed back to RDS where they are read and doses are calculated using a well-established protocol with an uncertainty of ≤ 1.5% (Kirby et al., 1992). Our TLD system is calibrated with TLD standards irradiated using a 60Co unit at the MD Anderson accredited dosimetry calibration laboratory. The TLD dose measurements are compared to the institution’s stated dose and a report is issued to the institution for each beam or dose point checked.
Dosimetry Data
The majority of output checks performed by RDS show good agreement between doses measured by RDS and doses reported by the institution (RDS/institution ratio); 98.6% of all beams agreed within 5% and 90.9% agreed within 3%. Histograms and summary statistics for TLD/institution ratios (for the past 20 years, 2000 - 2019) are shown for All beams, and according to beam type, i.e., MV photon, Electron, and Orthovoltage beams.
Dose Ratios for Beams 01/01/2000-12/31/2019
All Beams
MV Photon Beams
Electron Beams
Orthovoltage Beams
For any radiation therapy beam output check outside ± 5% for MV photon and electron beams, or ± 10% for orthovoltage beams, the institution's physicists are contacted via email by RDS technical staff. Repeat irradiations may be requested by the physicist, to confirm corrective actions. Often discrepancies are indicative of incorrectly calibrated beams, misinterpreting the irradiation instructions, or errors in completing the irradiation form.
Current RDS Users
The history of the RDS independent peer review services dates back more than a half-century. We ship TLD worldwide and on-demand. We currently provide services for:
- 1,460 participating institutions in the United States and
- 163 participating institutions globally
As we look to the future, the RDS is working toward further expanding our services to additional centers all over the world to enhance safety and confidence at all radiotherapy centers.
Current RDS Users
Current RDS users worldwide
Current RDS users in the United States
Current RDS users worldwide
Current RDS users in the United States