Radiation dose measurements for personnel performing 90Y-ibritumomab tiuxetan administration: a comparison between two injection methods for dose reduction

177Lu-Dotatate administration using an infusion pump or a peristaltic pump: comparison of two methods

OBJECTIVES

177Lu-oxodotreotide (Lutathera) is an intravenous peptide receptor radionuclide therapy to treat unresectable metastatic digestive neuroendocrine tumours. The recommended method for Lutathera administration is gravity infusion; however, other appropriate and safe techniques are possible. This work compares two infusion methods from a medico-economic, radiation protection, efficiency and practicality point of view.

METHODS

Two infusion methods were studied, either involving a volumetric infusion pump (method 1) or a peristaltic pump (method 2). For each method, the mean residual activity per vial and the mean injection time were compared. Occupational radiation exposure was measured. The cost of initial equipment and consumables for one administration was determined. Feedback from operators and past incidents during injections were collected through a survey.

RESULTS

Three operators performed 219 Lutathera injections over 70 months: 60.7% (133) with method 1 and 39.3% (86) with method 2. After infusion, the mean residual activity in vial was 124.3±16.9 MBq with method 1 and 80.9±19.3 MBq with method 2 (34.9% decrease). The average administration time was 41±7.2 min with method 1 and 39±8.5 min with method 2. Occupational exposures obtained with both methods were very low and quite similar. Method 1 required an initial investment of 1165.8 US$ plus 4.0 US$ of supplies for each administration. Initial investment for method 2 was comparable (1261.4 US$) but supplies cost per administration was higher (12.5 US$). Two major incidents were recorded with method 1 and none with method 2. From operators' experience, method 2 felt safer and more suitable.

CONCLUSIONS

Method 2 appeared to be convenient and secure, despite a higher cost per injection. It could also be applied to new radioligand therapies such as 177Lu-PSMA or 225Ac-Dotatate.

Review of extremity dosimetry in nuclear medicine

The exposure of the fingers is one of the major radiation protection concerns in nuclear medicine (NM). The purpose of this paper is to provide an overview of the exposure, dosimetry and protection of the extremities in NM. A wide range of reported finger doses were found in the literature. Historically, the highest finger doses are found at the fingertip in the preparation and dispensing of¹⁸F for diagnostic procedures and⁹⁰Y for therapeutic procedures. Doses can be significantly reduced by following recommendations on source shielding, increasing distance and training. Additionally, important trends contributing to a lower dose to the fingers are the use of automated procedures (especially for positron emission tomography (PET)) and the use of prefilled syringes. On the other hand, the workload of PET procedures has substantially increased during the last ten years. In many cases, the accuracy of dose assessment is limited by the location of the dosimeter at the base of the finger and the maximum dose at the fingertip is underestimated (typical dose ratios between 1.4 and 7). It should also be noted that not all dosimeters are sensitive to low-energy beta particles and there is a risk for underestimation of the finger dose when the detector or its filter is too thick. While substantial information has been published on the most common procedures (using^99mTc,¹⁸F and⁹⁰Y), less information is available for more recent applications, such as the use of⁶⁸Ga for PET imaging. Also, there is a need for continuous awareness with respect to contamination of the fingers, as this factor can contribute substantially to the finger dose.

Dosimetry perspectives in radiation synovectomy

Rheumatoid arthritis (RA) is a chronic inflammatory disease that can potentially damage the synovial joints. One of the effective treatment modality for RA is radiation synovectomy (RSV) where properly selected radionuclide is injected into the joint space, enabling controlled destruction of diseased synovial membrane via radiation exposure. Radiation dosimetry in RSV appears challenging due to the heterogeneous nature of synovial membrane, nonuniform distribution and leakage of radionuclide from the synovial cavity. This article reviews the dosimetric perspective pertaining to RSV. Specifically, characteristics of radionuclide for RSV and radiation dose to target and non-target (i.e., articular cartilage, bone, bloodstream, gonads, etc.) tissues of patient have been discussed. The personal dose H_p(0.07) to the hands of medical staff (i.e., radiochemist, therapist physician, nurse) may be considerably high due to handling of high specific activities (∼500 MBq/ml for Y-90); such doses are typically measured using thermoluminescence dosimeters (TLD) ring dosimeters and ranges from 1 to 21.5, 0.1 to 40 and 0.1 to 5 µSv/MBq for the radiochemist, therapist physician and the nurse, respectively. Methods to minimize radiation doses to the patient, medical staff and public are elaborated. Contamination risks and precautionary measures are also reported.