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Radioactive iodine ( 131 I) therapy may be used to treat thyroid cancer in end-stage renal disease patients who undergo hemodialysis. Because iodine uses predominantly renal clearance, treatment management in hemodialysis patients may be problematic, and no formal recommendations on hemodialysis currently exist. This work details our experience with treating thyroid cancer with iodine in chronic renal failure patients who require hemodialysis and details the dosimetry results obtained during treatment to ensure that the dose to the bone marrow (BM) was acceptable. Methods: We treated 6 patients in the metabolic radiotherapy unit after thyroid stimulation. Two hemodialysis sessions in the metabolic radiotherapy unit were performed at 42 and 90 h after radiopharmaceutical administration. BM toxicity was estimated with activity measurements from blood samples and with whole-body measurements that were regularly repeated during hospitalization and measured with a γ-counter. The patients underwent thyroid and hematologic monitoring to assess treatment efficacy and therapeutic toxicity in the short, medium, and long term. Results: Whole-body activity was reduced on average by 66.7% (range, 60.1%-71.5%) after the first dialysis session and by 53.3% (range, 30.4%-67.8%) after the second. The mean estimated total absorbed dose to the BM was 0.992 Gy for all patients (range, 0.431-2.323 Gy). We did not observe any significant hematologic toxicity, and the clinical, biologic, and ultrasound test results confirmed the success of ablative treatment for most patients. Conclusion: In hemodialysis patients with thyroid cancer, an 131 I activity approximately 30% lower than the nominal dose appears to strike an appropriate balance between absence of BM toxicity and therapeutic efficacy. To avoid overirradiation, we recommend pretherapeutic dosimetry studies for metastatic patients to calculate the amount of activity to be administered. We also recommend dosimetry monitoring during the hemodialysis sessions performed after therapeutic dose administration and under the same conditions., (© 2020 by the Society of Nuclear Medicine and Molecular Imaging.)

Objective and Study Design: Photodynamic therapy (PDT) is an emerging treatment modality for various diseases, especially for dermatological conditions. Although, the standard PDT protocol for the treatment of actinic keratoses in Europe has shown to be effective, treatment-associated pain is often observed in patients. Different modifications to this protocol attempted to decrease pain have been investigated. The decrease in fluence rate seems to be a promising solution. Moreover, it has been suggested that light fractionation significantly increases the efficacy of PDT. Based on a flexible light-emitting textile, the FLEXITHERALIGHT device specifically provides a fractionated illumination at a fluence rate more than six times lower than that of the standard protocol. In a recently completed clinical trial of PDT for the treatment of actinic keratosis, the non-inferiority of a protocol involving illumination with the FLEXITHERALIGHT device after a short incubation time and referred to as the FLEXITHERALIGHT protocol has been assessed compared to the standard protocol. In this paper, we propose a comparison of the two above mentioned 635 nm red light protocols with 37 J/cm 2 in the PDT treatment of actinic keratosis: the standard protocol and the FLEXITHERALIGHT one through a mathematical modeling., Methods: This mathematical modeling, which slightly differs from the one we have already published, enables the local damage induced by the therapy to be estimated., Results: The comparison performed in terms of the local damage induced by the therapy demonstrates that the FLEXITHERALIGHT protocol with lower fluence rate, light fractionation and shorter incubation time is somewhat less efficient than the standard protocol. Nevertheless, from the clinical trial results, the FLEXITHERALIGHT protocol results in non-inferior response rates compared to the standard protocol., Conclusion: This finding raises the question of whether the PDT local damage achieved by the FLEXITHERALIGHT protocol (respectively, the standard protocol) is sufficient (respectively, excessive) to destroy actinic keratosis cells. Lasers Surg. Med. 49:686-697, 2017. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)