Radiation doses from low-dose CT scans in SPECT/CT and PET/CT examinations: A survey in Germany.

AIM: Recently, dose reference levels (DRLs) have been defined in Germany for auxiliary low-dose CT scans in hybrid SPECT/CT and PET/CT examinations, based on data from 2016/17. Here, another survey from 2020 was evaluated and compared with the new DRLs as well as with similar surveys from foreign countries. METHODS: The survey, which had already been conducted in the Nordic countries, queried for various examinations including the following values: patient weight and height, volume CT dose index (CTDIvol), dose length product (DLP). For each examination, statistical parameters such as the third quartile (Q3) were determined from all submitted CTDIvol and DLP values. Additionally, for examinations comprising datasets from at least 10 systems, the third quartile (Q3-Med) of the respective median values of each system was calculated. Q3 and Q3-Med were compared with the newly published DRLs from Germany and values from similar studies from other countries. RESULTS: Data from 15 SPECT/CT and 13 PET/CT systems from 15 nuclear medicine departments were collected. For the following examinations datasets from more than 10 systems were submitted: SPECT lung VQ, SPECT bone, SPECT&PET cardiac, PET brain, PET oncology. Especially for examinations of the thorax and heart, the new DRLs are very strict compared to this study. The CTDIvol values for examinations of the head were lower in this study than the DRLs prescribe now. CONCLUSIONS: For certain examination types, there is a need for dose optimization at some clinics and devices in order to take into account the new DRLs in Germany in the future.

[Radiation exposure of staff during endovascular brachytherapy with Re-188 after PTA in the peripheral blood stream]. / Strahlenexposition des Personals bei der endovaskulären Brachytherapie (EVBT) mit Re-188 nach PTA im peripheren Stromgebiet.

Endovascular brachytherapy using a balloon catheter filled with Re-188 solution is a promising method for the prophylaxis of restenosis in peripheral blood circulation after percutaneous transluminal angioplasty (PTA) treatments. Thereby about 20 GBq Re-188 with a specific activity of about 5 GBq/ml are used. The high ionisation density of the beta radiation with high energy leads to selective irradiation of the blood vessel wall near the catheter, whereas the surrounding tissue remains almost unaffected. However the hospital staff has to carry out some work steps within close range to the high activity during preparation and therapy, causing a high risk of skin exposure, in particular at the hands. Estimations and measurements of the maximal local skin dose were made with thin-layered thermoluminescence dosimeters. It was assessed that the annual dose limit for skin of 500 mSv may be exceeded considerably when using conventional procedures and considering the expected number of 75 treatments per annum. By using the newly developed rhenium-188 application device "FlowMedical Application System" the exposure risk for the staff could be reduced drastically. The maximum skin dose of 76 mSv for the radiologist and of 50 mSv for the physicist was decreased to 2 mSv per treatment for both of them. Consequently, from the radiation protection point of view, the itm Rhenium-PTA is a safe method. Any exceeding of the dose limit can be prevented.

Endovascular brachytherapy in the femoropopliteal segment using 192Ir and 188Re.

This report presents a review of the literature on endovascular brachytherapy (EVBT) after percutaneous transluminal angioplasty (PTA) in the femoropopliteal segment. We summarize the pathophysiological changes induced by PTA and EVBT within the vessel wall, technical considerations regarding various radiation sources and their application, the impact of stents on the radial dose profile, recommendations for dosimetry of beta and gamma sources, results of experimental and clinical trials, and the medication required before, during, and after EVBT. We aim to help to identify patients who are eligible for EVBT, to choose an appropriate technical approach, and to initiate adequate antiplatelet and anticoagulant therapy.

Prostate lymphoscintigraphy for sentinel lymph node identification in canines: reproducibility, uptake, and biokinetics depending on different injection strategies.

At present there are neither clinical nor experimental data available on the influence of technical details on the quality and reproducibility of prostate lymphoscintigraphy. Six adult fox hounds received repeated transrectal ultrasound guided intraprostatic injections of a technetium 99m labeled nanocolloid to prove the influence of different techniques of injection (one central injection in both prostate lobes vs two peripheral injections in both lobes) on tracer accumulation in sentinel lymph nodes (SLN) and other organs. The reproducibility of the favored technique was examined and in a last step it was subject to scrutiny following a reduction of the injected volume to 1% of the prostate volume. The number of scintigraphically visualized SLN varied between four and seven. They were located in the region of the internal and external iliac vessels, presacrally, paravesically, and directly paraprostatically. In five of six cases, the localization was reproducible both with the central application of an identical volume as well as with the volume reduced central injection. Tracer accumulation of SLNs and other organs varied enormously. We expect that with the combination of both injection techniques, even with the reduced injection volume, an optimized prostate lymphoscintigraphy will be the outcome.

Prostate lymphoscintigraphy and radio-guided surgery for sentinel lymph node identification in prostate cancer. Technique and results of the first 350 cases.

INTRODUCTION: Having in mind the promising results of lymphoscintigraphy and intraoperative gamma probe application for the detection of sentinel lymph nodes (SLN) in malignant melanoma, breast and penis cancer, we tried to identify the SLN in prostate cancer by applying a comparable technique. MATERIALS AND METHOD: 350 patients with prostate cancer were examined after providing informed consent. The day before pelvic lymphadenectomy technetium-99m nanocolloid was transrectally injected into the prostate under ultrasound guidance. A single central application was done per prostate lobe in most cases. Activity attained 90- 400 MBq, and the total injected volume was about 2-3 ml. Hereafter, lymphoscintigraphy was carried out. Those lymph nodes having been identified as SLN by means of gamma probe detection and lymphoscintigraphy were removed intraoperatively. Later, most of the cases had different types of pelvic lymphadenectomy. SLN received serial sections and immunohistochemistry, non-SLN step sections. RESULTS: 335 patients showed at least 1 SLN in lymphoscintigraphy. 24.7% had lymph node metastases. In 2 patients, metastases in non-SLN were found without at least one SLN being affected (false-negative patient). CONCLUSION: Our experience suggests that the SLN identification is not only feasible in breast cancer and malignant melanoma, but also in prostate cancer with a comparable technique.