Radiation dose reduction during venous access port implantation: the importance of upgrading equipment and radiation-protection training.

BACKGROUND: Implantable central venous port systems are widely used in oncology. We upgraded our fluoroscopy machines, and all anesthetists completed two training courses focusing on the risks of ionizing radiation for patients and health workers. AIMS: This study aimed to evaluate the impact of upgrading the machines and the radiation-protection training on ionizing radiation exposure during venous port system implantation. METHODS: We retrospectively analyzed consecutive venous port implantations between 2019 and 2022. The older fluoroscopy machines were replaced by two new machines. A first training session about health worker radioprotection was organized. The medical staff completed a second training course focused on protecting patients from ionizing radiation. We defined four distinct time intervals (TI): venous port implantations performed with the old equipment, the new fluoroscopy machines, after the first training course, and after the second training course. The air kerma-area product (KAP) was compared between these four TI and fluoroscopy times and the number of exposures only with the new machines. RESULTS: We analyzed 2587 procedures. A 93% decrease in the median KAP between the first and last TI was noted (median KAP = 323.0 mGy.cm2 vs. 24.0 mGy.cm2, p < 0.0001). A decrease in the KAP was observed for each of the 11 anesthetists. We also noted a significant decrease in the time of fluoroscopy and the number of exposures. CONCLUSIONS: Upgrading the fluoroscopy equipment and completing two dedicated training courses allowed for a drastic decrease patient exposure to ionizing radiation during venous access port implantation by non-radiologist practitioners.

Brainstem toxicity after proton or photon therapy in children and young adults with localized intracranial ependymoma: A French retrospective study.

BACKGROUND AND PURPOSE: Ependymoma is the third most frequent childhood braintumor. Standard treatment is surgery followed by radiation therapy including proton therapy (PBT). Retrospective studies have reported higher rates of brainstem injury after PBT than after photon therapy (XRT). We report a national multicenter study of the incidence of brainstem injury after XRT versus PBT, and their correlations with dosimetric data. MATERIAL AND METHODS: We included all patients aged < 25 years who were treated with PBT or XRT for intracranial ependymoma at five French pediatric oncology reference centers between 2007 and 2020. We reviewed pre-irradiation MRI, follow-up MRIs over the 12 months post-treatment and clinical data. RESULTS: Of the 83 patients, 42 were treated with PBT, 37 with XRT, and 4 with both (median dose: 59.4 Gy, range: 53­60). No new or progressive symptomatic brainstem injury was found. Four patients presented asymptomatic radiographic changes (punctiform brainstem enhancement and FLAIR hypersignal), with median onset at 3.5 months (range: 3.0­9.4) after radiation therapy, and median offset at 7.6 months (range: 3.7­7.9). Two had been treated with PBT, one with XRT, and one with mixed XRT-PBT. Prescribed doses were 59.4, 55.8, 59.4 and 54 Gy. CONCLUSION: Asymptomatic radiographic changes occurred in 4.8% of patients with ependymoma in a large national series. There was no correlation with dose or technique. No symptomatic brainstem injury was identified.

Mutation analysis in individual circulating tumor cells depicts intratumor heterogeneity in melanoma.

Circulating tumor DNA (ctDNA) is the cornerstone of liquid biopsy diagnostics, revealing clinically relevant genomic aberrations from blood of cancer patients. Genomic analysis of single circulating tumor cells (CTCs) could provide additional insights into intra-patient heterogeneity, but it requires whole-genome amplification (WGA) of DNA, which might introduce bias. Here, we describe a novel approach based on mass spectrometry for mutation detection from individual CTCs not requiring WGA and complex bioinformatics pipelines. After establishment of our protocol on tumor cell line-derived single cells, it was validated on CTCs of 33 metastatic melanoma patients and the mutations were compared to those obtained from tumor tissue and ctDNA. Although concordance with tumor tissue was superior for ctDNA over CTC analysis, a larger number of mutations were found within CTCs compared to ctDNA (p = 0.039), including mutations in melanoma driver genes, or those associated with resistance to therapy or metastasis. Thus, our results demonstrate proof-of-principle data that CTC analysis can provide clinically relevant genomic information that is not redundant to tumor tissue or ctDNA analysis.