Dosimetric comparison between coplanar and non coplanar field radiotherapy for ethmoid sinus cancer

<p>Abstract</p> <p>Background</p> <p>To compare non coplanar field (NCF) with coplanar field (CF) -intensity-modulated radiotherapy (IMRT) planning for ethmoid cancer.</p> <p>Methods</p> <p>Seven patients treated with NCF IMRT for ethmoid cancer were studied. A CF IMRT optimization was prepared with the same constraints as for the NCF treatment. The maximum point doses (D max) obtained for the different optic pathway structures (OPS) should differ no more than 3% from those achieved with the NCF IMRT plan. The distribution of the dose in the target volume and in the critical structures was compared between the two techniques, as well as the Conformity (CI) and the Homogeneity Indexes (HI) in the target volume.</p> <p>Results</p> <p>We noted no difference between the two techniques in the OPS for the D1, D2, and D5%, in the inner ear and controlateral lens for the average Dmax, in the temporo-mandibular joints for the average mean dose, in the cord and brainstem for the average D1%. The dose-volume histograms were slightly better with the NCF treatment plan for the planning target volume (PTV) with a marginally better HI but no impact on CI. We found a great improvement in the PTV coverage with the CF treatment plan for two patients with T4 tumors.</p> <p>Conclusion</p> <p>IMRT is one of the treatment options for ethmoid cancer. The PTV coverage is optimal without compromising the protection of the OPS. The impact of non coplanar versus coplanar set up is very slight.</p

Évaluation de l'efficacité des émetteurs d'électrons Auger dans le traitement des tumeurs solides de petite taille par radioimmunothérapie

MONTPELLIER-BU Médecine UPM (341722108) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

²²⁵Ac-Labeled Somatostatin Analogs in the Management of Neuroendocrine Tumors: From Radiochemistry to Clinic

The widespread use of peptide receptor radionuclide therapy (PRRT) represents a major therapeutic breakthrough in nuclear medicine, particularly since the introduction of 177Lu-radiolabeled somatostatin analogs. These radiopharmaceuticals have especially improved progression-free survival and quality of life in patients with inoperable metastatic gastroenteropancreatic neuroendocrine tumors expressing somatostatin receptors. In the case of aggressive or resistant disease, the use of somatostatin derivatives radiolabeled with an alpha-emitter could provide a promising alternative. Among the currently available alpha-emitting radioelements, actinium-225 has emerged as the most suitable candidate, especially regarding its physical and radiochemical properties. Nevertheless, preclinical and clinical studies on these radiopharmaceuticals are still few and heterogeneous, despite the growing momentum for their future use on a larger scale. In this context, this report provides a comprehensive and extensive overview of the development of 225Ac-labeled somatostatin analogs; particular emphasis is placed on the challenges associated with the production of 225Ac, its physical and radiochemical properties, as well as the place of 225Ac–DOTATOC and 225Ac–DOTATATE in the management of patients with advanced metastatic neuroendocrine tumors

Development and Implementation of a Professional Practices Evaluation during Radiopharmaceuticals Administration

Securing both the patient and radiopharmaceuticals (RPs) circuit is an essential concern in nuclear medicine (NM). These circuits converge at the RP administration phase, a key step in patient management in NM. In a continuous quality improvement approach, we developed and implemented an evaluation of professional practices (EPPs) methodology focused on RPs injection to identify and correct deviations from good practices. The nuclear medicine technologists (NMTs) of a single center were evaluated. A specific audit grid was designed for this purpose, covering 4 main themes. Following the audit campaign, an improvement action plan was set up to address the non-conformities observed. Nine NMTs were audited on 4 RPs injections each. The mean total score was 93.36% with, on average, 7.01% and 3.00% of unmet and partially met criteria, respectively. In view of the non-compliance rates of hygiene and radiation protection items, theoretical reviews of these themes were included in the improvement action plan. As a part of the quality assurance system of a healthcare unit, EPPs are useful for identifying and correcting practice deviations at an early stage. They should be regularly repeated and combined with rigorous training and qualification of operators involved in RPs injection

Clinical implementation of PLANET® Dose for dosimetric assessment after [177Lu]Lu-DOTA-TATE: comparison with Dosimetry Toolkit® and OLINDA/EXM® V1.0

International audienceBackground The aim of this study was to compare a commercial dosimetry workstation (PLANET® Dose) and the dosimetry approach (GE Dosimetry Toolkit® and OLINDA/EXM® V1.0) currently used in our department for quantification of the absorbed dose (AD) to organs at risk after peptide receptor radionuclide therapy with [ 177 Lu]Lu-DOTA-TATE. Methods An evaluation on phantom was performed to determine the SPECT calibration factor variations over time and to compare the Time Integrated Activity Coefficients (TIACs) obtained with the two approaches. Then, dosimetry was carried out with the two tools in 21 patients with neuroendocrine tumours after the first and second injection of 7.2 ± 0.2 GBq of [ 177 Lu]Lu-DOTA-TATE (40 dosimetry analyses with each software). SPECT/CT images were acquired at 4 h, 24 h, 72 h and 192 h post-injection and were reconstructed using the Xeleris software (General Electric). The liver, spleen and kidneys masses and TIACs were determined using Dosimetry Toolkit® (DTK) and PLANET® Dose. The ADs were calculated using OLINDA/EXM® V1.0 and the Local Deposition Method (LDM) or Dose voxel-Kernel convolution (DK) on PLANET® Dose. Results With the phantom, the 3D calibration factors showed a slight variation (0.8% and 3.3%) over time, and TIACs of 225.19 h and 217.52 h were obtained with DTK and PLANET® Dose, respectively. In patients, the root mean square deviation value was 8.9% for the organ masses, 8.1% for the TIACs, and 9.1% and 7.8% for the ADs calculated with LDM and DK, respectively. The Lin’s concordance correlation coefficient was 0.99 and the Bland–Altman plot analysis estimated that the AD value difference between methods ranged from − 0.75 to 0.49 Gy, from − 0.20 to 0.64 Gy, and from − 0.43 to 1.03 Gy for 95% of the 40 liver, kidneys and spleen dosimetry analyses. The dosimetry method had a minor influence on AD differences compared with the image registration and organ segmentation steps. Conclusions The ADs to organs at risk obtained with the new workstation PLANET® Dose are concordant with those calculated with the currently used software and in agreement with the literature. These results validate the use of PLANET® Dose in clinical routine for patient dosimetry after targeted radiotherapy with [ 177 Lu]Lu-DOTA-TATE

Clinical implementation of PLANET® Dose for dosimetric assessment after [177Lu]Lu-DOTA-TATE: comparison with Dosimetry Toolkit® and OLINDA/EXM® V1.0

The aim of this study was to compare a commercial dosimetry workstation (PLANET® Dose) and the dosimetry approach (GE Dosimetry Toolkit® and OLINDA/EXM® V1.0) currently used in our department for quantification of the absorbed dose (AD) to organs at risk after peptide receptor radionuclide therapy with [177Lu]Lu-DOTA-TATE.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias Atómicas Nucleares y Moleculares (CICANUM

Implementation of patient dosimetry in the clinical practice after targeted radiotherapy using [177Lu-[DOTATO,Tyr3]-octreotate

Background: This study’s aim was to develop our dosimetric methodology using a commercial workstation for the routine evaluation of the organs at risk during peptide receptor radionuclide therapy (PRRT) with 177Lu. Methods: First, planar and SPECT sensitivity factors were determined on phantoms. The reconstruction parameters were optimized by SPECT/CT image acquisition using a NEMA IEC phantom containing a 500 ml bottle of 177Lu, to simulate a kidney. The recovery coefficients were determined on various phantoms. For the red marrow, this was calculated using a NEMA IEC phantom that contained a centrally placed bottle of 80 ml of 177Lu (to model the L2- L4 red marrow) flanked by two 200 ml bottles with 177Lu to simulate the kidneys. Then, SPECT/CT images were acquired at 4, 24, 72, and 192 h after injection in 12 patients with neuroendocrine tumors who underwent PRRT with 177Lu-DOTATATE. SPECT data were reconstructed using the iterative ordered subset expectation maximization (OSEM) method, with six iterations and ten subsets, attenuation, scatter, recovery resolution corrections, and a Gaussian post-filter of 0.11 cm. The liver, spleen, kidneys, and red marrow dose per administered activity (AD/A admin) values were calculated with the Medical Internal Radiation Dose (MIRD) formalism and the residence times (Dosimetry toolkit® application) using standard and CT imaging-based organ masses (OLINDA/EXM® V1.0 software). Results: Sensitivity factors of 6.11 ± 0.01 and 5.67 ± 0.08 counts/s/MBq were obtained with planar and SPECT/CT acquisitions, respectively. A recovery coefficient of 0.78 was obtained for the modeled L2–L4 red marrow. The mean AD/A admin values were 0.43 ± 0.13 mGy/MBq [0.27–0.91] for kidneys, 0.54 ± 0.58 mGy/MBq [0.12–2.26] for liver, 0. 61 ± 0.13 mGy/MBq [0.42–0.89] for spleen, and 0.04 ± 0.02 mGy/MBq [0.01–0.09] for red marrow. The AD/A admin values varied when calculated using the personalized and standard organ mass, particularly for kidneys (p = 1 × 10−7 ), spleen (p = 0.0069), and red marrow (p = 0.0027). Intra-patient differences were observed especially in organs close to or including tumor cells or metastases. Conclusions: The obtained AD/A admin values were in agreement with the literature data. This study shows the technical feasibility of patient dosimetry in clinical practice and the need to obtain patient-specific information.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias Atómicas Nucleares y Moleculares (CICANUM)UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Físic

Implementation of patient dosimetry in the clinical practice after targeted radiotherapy using [177Lu-[DOTA0, Tyr3]-octreotate

Abstract Background This study’s aim was to develop our dosimetric methodology using a commercial workstation for the routine evaluation of the organs at risk during peptide receptor radionuclide therapy (PRRT) with 177Lu. Methods First, planar and SPECT sensitivity factors were determined on phantoms. The reconstruction parameters were optimized by SPECT/CT image acquisition using a NEMA IEC phantom containing a 500 ml bottle of 177Lu, to simulate a kidney. The recovery coefficients were determined on various phantoms. For the red marrow, this was calculated using a NEMA IEC phantom that contained a centrally placed bottle of 80 ml of 177Lu (to model the L2-L4 red marrow) flanked by two 200 ml bottles with 177Lu to simulate the kidneys. Then, SPECT/CT images were acquired at 4, 24, 72, and 192 h after injection in 12 patients with neuroendocrine tumors who underwent PRRT with 177Lu-DOTATATE. SPECT data were reconstructed using the iterative ordered subset expectation maximization (OSEM) method, with six iterations and ten subsets, attenuation, scatter, recovery resolution corrections, and a Gaussian post-filter of 0.11 cm. The liver, spleen, kidneys, and red marrow dose per administered activity (AD/A admin) values were calculated with the Medical Internal Radiation Dose (MIRD) formalism and the residence times (Dosimetry toolkit® application) using standard and CT imaging-based organ masses (OLINDA/EXM® V1.0 software). Results Sensitivity factors of 6.11 ± 0.01 and 5.67 ± 0.08 counts/s/MBq were obtained with planar and SPECT/CT acquisitions, respectively. A recovery coefficient of 0.78 was obtained for the modeled L2–L4 red marrow. The mean AD/A admin values were 0.43 ± 0.13 mGy/MBq [0.27–0.91] for kidneys, 0.54 ± 0.58 mGy/MBq [0.12–2.26] for liver, 0.61 ± 0.13 mGy/MBq [0.42–0.89] for spleen, and 0.04 ± 0.02 mGy/MBq [0.01–0.09] for red marrow. The AD/A admin values varied when calculated using the personalized and standard organ mass, particularly for kidneys (p = 1 × 10−7), spleen (p = 0.0069), and red marrow (p = 0.0027). Intra-patient differences were observed especially in organs close to or including tumor cells or metastases. Conclusions The obtained AD/A admin values were in agreement with the literature data. This study shows the technical feasibility of patient dosimetry in clinical practice and the need to obtain patient-specific information

Radiocurability by targeting tumor necrosis factor-alpha using a bispecific antibody in carcinoembryonic antigen transgenic mice.

International audiencePURPOSE: Tumor necrosis factor-alpha (TNF-alpha) enhances radiotherapy (RT) killing of tumor cells in vitro and in vivo. To overcome systemic side effects, we used a bispecific antibody (BsAb) directed against carcinoembryonic antigen (CEA) and TNF-alpha to target this cytokine in a CEA-expressing colon carcinoma. We report the evaluation of this strategy in immunocompetent CEA-transgenic mice. METHODS AND MATERIALS: The murine CEA-transfected colon carcinoma MC-38 was used for all experiments. In vitro, clonogenic assays were performed after RT alone, TNF-alpha alone, and RT plus TNF-alpha. In vivo, the mice were randomly assigned to treatment groups: control, TNF-alpha, BsAb, BsAb plus TNF-alpha, RT, RT plus TNF-alpha, and RT plus BsAb plus TNF-alpha. Measurements of endogenous TNF-alpha mRNA levels and evaluation of necrosis (histologic evaluation) were assessed per treatment group. RESULTS: In vitro, combined RT plus TNF-alpha resulted in a significant decrease in the survival fraction at 2 Gy compared with RT alone (p < 0.00001). In vivo, we observed a complete response in 5 (50%) of 10, 2 (20%) of 10, 2 (18.2%) of 11, and 0 (0%) of 12 treated mice in the RT plus BsAb plus TNF-alpha, RT plus TNF-alpha, RT alone, and control groups, respectively. This difference was statistically significant when TNF-alpha was targeted with the BsAb (p = 0.03). The addition of exogenous TNF-alpha to RT significantly increased the endogenous TNF-alpha mRNA level, particularly when TNF-alpha was targeted with BsAb (p < 0.01). The percentages of necrotic area were significantly augmented in the RT plus BsAb plus TNF-alpha group. CONCLUSION: These results suggest that targeting TNF-alpha with the BsAb provokes RT curability in a CEA-expressing digestive tumor syngenic model and could be considered as a solid rationale for clinical trials