An ultra-low-dose protocol for computed tomography-guided lung radiofrequency ablations.

To evaluate the safety and efficacy of ultra-low-dose (ULD) protocol for computed tomography (CT)-guided lung radiofrequency ablation (RFA). Patients who had undergone lung RFA between November 2017 and January 2021 were consecutively and retrospectively included. Thirty patients were treated using a conventional standard protocol (SP), including helical acquisitions with mA automatic adjustment and sequential CT at 80 kVp; and 31, with a ULD protocol defined with helical acquisitions with fixed mA and sequential series at 100 kVp. These parameters were selected from those used for a diagnostic lung low-dose CT scanner. Patient characteristics, dose indicators, technical efficacy (minimal margin [MM], recurrence during follow-up), and complications (pneumothorax, alveolar haemorrhage, and haemoptysis) were recorded. We included 61 patients (median age, 65 [54-73] and 33 women), with no significant differences according to the type of protocol, except for the type of anaesthesia. Even if the number of helical acquisitions did not significantly change, all dose indicators significantly decreased by 1.5-fold-3-fold. The median dose-length-product and effective dose, with their ranges, respectively, were 465 mGy cm (315-554) and 6.5 mSv (4.4-7.8) in the SP group versus 178 mGy cm (154-267) and 2.5 mSv (2.2-3.7) in the ULD group, (p< 001). The ULD group exhibited lower intraoperator variability and better interoperator alignment than those of the SP group. The MM was not significantly different between the two groups (4.6 mm versus 5 mm,p= 16). One local recurrence was observed in each group at 8 months in the SP and at one year in the ULD group (p= 1). The complication rates did not differ significantly. Implementing an ULD protocol during lung RFA may provide similar efficacy, a reduction of dose indicators, and intra- and interoperator variability, without increasing complication rates, compared to those associated with an SP.

A study of dose indicators during intra-arterial catheter implantation for liver chemotherapy.

The aim of the present study was to describe patient dose indicator levels during intra-arterial catheter (IAC) implantation for liver chemotherapy, and to determine factors affecting the dose indicators. Between January 2017 and January 2019, 61 patients with hepatic metastases from colorectal cancer were retrospectively included. Interventions were carried out in a standardised manner by three experienced radiologists on the same angiographic table without changes in protocol parameters. For each patient, clinical, radiological and dosimetry data were collected, including the air kerma area product (KAP), part of KAP due to the fluoroscopy and fluoroscopy time (FT), total kerma at the reference interventional point and peak skin dose (PSD). Local dose reference levels (RLs) were determined as the third quartile of the patient dose distributions. Univariate and multivariate analysis of factors affecting dose indicators was performed. The mean KAP was 111 Gy cm2, the mean reference point air kerma (Ka,r) was 648 mGy, the mean PSD was 613 mGy, and the mean FT was 3190 s (62% of the KAP). The mean cone beam computed tomography dose was 37.3 ± 11.8 Gy cm2, which accounted for 37% of the KAP. The RL could be proposed taking into account the third quartiles (KAP = 164.6 Gy cm2, Ka,r = 904.5 mGy, FT = 4011 s and standard deviation = 772.7 mGy). The factors affecting dose indicators were related to the patients (sex, cardiovascular risk factors, weight, body mass index), to the vascular anatomies (coeliac trunk angulation) and to the procedures (number of embolised arteries). This study allowed a better understanding of dose indicators and factors affecting these indicators during the implantation of IACs for hepatic chemotherapy, which is a long and difficult procedure. Local dose RLs were determined. Multicentre, multi-equipment studies are necessary.