On the Actual State of Industrial Quality Assurance Procedures with Regard to 106Ru Ophthalmic Plaques

Abstract

Legislation has to make sure that the use of radioactive material on humans be, among other things, permitted as a matter of principle only, if the dose rate calibration can be traced to standards of a federal authority of measurement procedures. Furthermore, special leakage tests for radiation sources which come into direct contact with body fluids should be established. A historical retrospect reveals that the greatest changes have taken place in the indication of the dose rates of (125)I sources. Since the beginning of the use of (125)I sources in brachytherapy in the late 1960s, the dose rate indications, so far, have had to be reduced in small steps over a period of about 35 years by nearly a factor of 2. As regards the (106)Ru ophthalmic plaques, the NIST 2001 calibration has resulted in a comparable reduction of the dose rate indications of up to a factor of 2 within the period of about several months. Thus, in the previous history of radiotherapy this case must be regarded as unique, because for the first time ever, an urgently needed recalibration has been protracted for such an unduly long period of time.

Calculation of dose distributions for 12 106Ru/106Rh ophthalmic applicator models with the PENELOPE Monte Carlo code

“…6). However, the difference in the relative dose compared to the findings of Kaulich et al 24 is up to 3.5%. The measurements conducted by the manufacturer prior to 2001 show a relative dose that is up to 6% lower than the PENELOPE calculations and up to 9% lower than the measurements conducted using small-volume scintillators.…”

“…The only available reference containing dose data for the CGD applicator is the work of Kaulich et al, 24 who analyzed the quality assurance procedures followed by the manufacturer in producing the applicators. One criticism of the mea applicator measured with the manufacturer's improved measurement system.…”

Does the Imaging Method Have an Influence on the Measured Tumor Height in Ruthenium Plaque Therapy of Uveal Melanoma?

“…This seems tolerable considering the fact that the dose rate of the currently used ruthenium applicators can only be measured to an accuracy of ± 25% (95% CI) [6].…”

Irradiation for Conjunctival Granulocytic Sarcoma

“…In the case of more focal tumor growth the use of beta emitting eye applicators may be an alternative. However, grave therapyrelevant shortcomings of the industrial quality assurance of ophthalmic plaques as shown by Kaulich et al [10] have to be taken into consideration. Another alternative treatment of more superficial focal tumor manifestations could be the use of soft X-ray irradiation units as shown by Willner et al [31] for the treatment of recurrent pterygia.…”