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1.
PLoS One ; 19(6): e0303367, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38889134

RESUMEN

Science journalists, traditionally, play a key role in delivering science information to a wider audience. However, changes in the media ecosystem and the science-media relationship are posing challenges to reliable news production. Additionally, recent developments such as ChatGPT and Artificial Intelligence (AI) more generally, may have further consequences for the work of (science) journalists. Through a mixed-methodology, the quality of news reporting was studied within the context of AI. A content analysis of media output about AI (news articles published within the time frame 1 September 2022-28 February 2023) explored the adherence to quality indicators, while interviews shed light on journalism practices regarding quality reporting on and with AI. Perspectives from understudied areas in four European countries (Belgium, Italy, Portugal, and Spain) were included and compared. The findings show that AI received continuous media attention in the four countries. Furthermore, despite four different media landscapes, the reporting in the news articles adhered to the same quality criteria such as applying rigour, including sources of information, accessibility, and relevance. Thematic analysis of the interview findings revealed that impact of AI and ChatGPT on the journalism profession is still in its infancy. Expected benefits of AI related to helping with repetitive tasks (e.g. translations), and positively influencing journalistic principles of accessibility, engagement, and impact, while concerns showed fear for lower adherence to principles of rigour, integrity and transparency of sources of information. More generally, the interviewees expressed concerns about the state of science journalism, including a lack of funding influencing the quality of reporting. Journalists who were employed as staff as well as those who worked as freelancers put efforts in ensuring quality output, for example, via editorial oversight, discussions, or memberships of associations. Further research into the science-media relationship is recommended.


Asunto(s)
Inteligencia Artificial , Periodismo , Humanos , Ciencia , Europa (Continente) , Italia , Medios de Comunicación de Masas , Portugal
2.
JCO Precis Oncol ; 7: e2300156, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-38061007

RESUMEN

PURPOSE: Reliable biomarkers for response monitoring during radium-223 treatment in patients with metastatic castration-resistant prostate cancer (mCRPC) are lacking. Circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), obtained from liquid biopsies, are shown to have prognostic value in mCRPC. The aim of this study was to determine the value of CTCs and ctDNA for response evaluation of radium-223. METHODS: In this prospective multicenter study, longitudinal blood draws and imaging were performed in 28 patients with mCRPC and predominantly bone disease, who were treated with radium-223. CTCs were counted (CELLSEARCH CTC test), while fraction of ctDNA was estimated by measuring aneuploidy of cell-free DNA (cfDNA; modified Fast Aneuploidy Screening Test-Sequencing System). CTC counts and aneuploidy score (AS) were categorized as low (<5) and high (≥5). Primary and secondary clinical end points were failure-free survival (FFS), and overall survival (OS) and development of extraosseous metastases, respectively. Additionally, CTC count and AS were related to alkaline phosphatase (ALP) and total tumor volume in bone (TTVbone) on positron emission tomography-computed tomography with 68gallium prostate-specific membrane antigen. RESULTS: FFS was longer in patients with a low CTC count or AS either at baseline or after 12 weeks, whereas for OS, only a significant association with CTC count was observed. Liquid biopsy results correlated well with ALP and TTVbone at baseline, but not with change in both parameters after three cycles of radium-223. AS and CTC count were significantly correlated. CONCLUSION: CTC count and AS of cfDNA at baseline and during treatment predict clinical response to radium-223 in patients with mCRPC, warranting future evaluation of their value in treatment guidance.


Asunto(s)
Ácidos Nucleicos Libres de Células , Neoplasias de la Próstata Resistentes a la Castración , Masculino , Humanos , Neoplasias de la Próstata Resistentes a la Castración/genética , Neoplasias de la Próstata Resistentes a la Castración/radioterapia , Neoplasias de la Próstata Resistentes a la Castración/tratamiento farmacológico , Estudios Prospectivos , Biomarcadores de Tumor/genética , Biopsia Líquida , Aneuploidia
3.
J Nucl Med ; 64(10): 1556-1562, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37536738

RESUMEN

CT and bone scintigraphy are not useful for response evaluation of bone metastases to 223Ra treatment in metastatic castration-resistant prostate cancer (mCRPC). PET using 68Ga prostate-specific membrane antigen 11 (68Ga-PSMA) is a promising tool for response evaluation of mCRPC. The aim of this study was to determine the utility of 68Ga-PSMA PET/CT for response evaluation of 223Ra treatment in patients with mCRPC. Methods: Within this prospective, multicenter, imaging discovery study, 28 patients with mCRPC, eligible for 223Ra treatment, were included between 2019 and 2022. Patients received 223Ra according to the standard of care. Study procedures included CT, bone scintigraphy, and 68Ga-PSMA PET/CT at baseline, after 3 and 6 cycles of 223Ra treatment, and on treatment failure. Response to 223Ra treatment was visually assessed on all 3 imaging modalities. Total tumor volume within bone (TTVbone) was determined on 68Ga-PSMA PET/CT. Intrapatient heterogeneity in response was studied using a newly developed image-registration tool for sequential images of PET/CT. Results were compared with failure-free survival (good responders vs. poor responders; cutoff, 24 wk) and alkaline phosphatase (ALP) response after 3 cycles. Results: Visual response assessment criteria could not distinguish good responders from poor responders on 68Ga-PSMA PET/CT and bone scintigraphy. For 68Ga-PSMA PET/CT, TTVbone at baseline was lower in good responders than in poor responders, whereas TTVbone increased in both groups during treatment. TTVbone was higher in patients with new extraosseous metastases during 223Ra treatment. Although TTVbone and ALP correlated at baseline, changes in TTVbone and ALP on treatment did not. 68Ga-PSMA response of TTVbone showed intrapatient heterogeneity in most patients. Conclusion: mCRPC patients with lower TTVbone on 68Ga-PSMA PET/CT have the best clinical outcome after 223Ra treatment. Response is highly heterogeneous in most patients. A decrease in ALP, which occurred in most patients, was not correlated with a decrease in TTVbone, which might make one question the value of ALP for disease monitoring during 223Ra treatment in clinical practice.


Asunto(s)
Neoplasias de la Próstata Resistentes a la Castración , Neoplasias de la Próstata , Masculino , Humanos , Tomografía Computarizada por Tomografía de Emisión de Positrones/métodos , Neoplasias de la Próstata Resistentes a la Castración/diagnóstico por imagen , Neoplasias de la Próstata Resistentes a la Castración/radioterapia , Estudios Prospectivos , Resultado del Tratamiento , Neoplasias de la Próstata/diagnóstico por imagen , Neoplasias de la Próstata/terapia , Neoplasias de la Próstata/patología , Radioisótopos de Galio/uso terapéutico , Estudios Retrospectivos , Antígeno Prostático Específico
4.
Nat Commun ; 14(1): 1968, 2023 04 08.
Artículo en Inglés | MEDLINE | ID: mdl-37031196

RESUMEN

Response to androgen receptor signaling inhibitors (ARSI) varies widely in metastatic castration resistant prostate cancer (mCRPC). To improve treatment guidance, biomarkers are needed. We use whole-genomics (WGS; n = 155) with matching whole-transcriptomics (WTS; n = 113) from biopsies of ARSI-treated mCRPC patients for unbiased discovery of biomarkers and development of machine learning-based prediction models. Tumor mutational burden (q < 0.001), structural variants (q < 0.05), tandem duplications (q < 0.05) and deletions (q < 0.05) are enriched in poor responders, coupled with distinct transcriptomic expression profiles. Validating various classification models predicting treatment duration with ARSI on our internal and external mCRPC cohort reveals two best-performing models, based on the combination of prior treatment information with either the four combined enriched genomic markers or with overall transcriptomic profiles. In conclusion, predictive models combining genomic, transcriptomic, and clinical data can predict response to ARSI in mCRPC patients and, with additional optimization and prospective validation, could improve treatment guidance.


Asunto(s)
Neoplasias de la Próstata Resistentes a la Castración , Masculino , Humanos , Neoplasias de la Próstata Resistentes a la Castración/tratamiento farmacológico , Neoplasias de la Próstata Resistentes a la Castración/genética , Neoplasias de la Próstata Resistentes a la Castración/patología , Androstenos/uso terapéutico , Feniltiohidantoína/uso terapéutico , Nitrilos/uso terapéutico , Biomarcadores de Tumor/genética , Resultado del Tratamiento
5.
J Pharmacol Exp Ther ; 384(1): 173-186, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36310034

RESUMEN

Acalabrutinib is a covalent Bruton tyrosine kinase (BTK) inhibitor approved for relapsed/refractory mantle cell lymphoma and chronic lymphocytic leukemia/small lymphocytic lymphoma. A major metabolite of acalabrutinib (M27, ACP-5862) was observed in human plasma circulation. Subsequently, the metabolite was purified from an in vitro biosynthetic reaction and shown by nuclear magnetic resonance spectroscopy to be a pyrrolidine ring-opened ketone/amide. Synthesis confirmed its structure, and covalent inhibition of wild-type BTK was observed in a biochemical kinase assay. A twofold lower potency than acalabrutinib was observed but with similar high kinase selectivity. Like acalabrutinib, ACP-5862 was the most selective toward BTK relative to ibrutinib and zanubrutinib. Because of the potency, ACP-5862 covalent binding properties, and potential contribution to clinical efficacy of acalabrutinib, factors influencing acalabrutinib clearance and ACP-5862 formation and clearance were assessed. rCYP (recombinant cytochrome P450) reaction phenotyping indicated that CYP3A4 was responsible for ACP-5862 formation and metabolism. ACP-5862 formation Km (Michaelis constant) and Vmax were 2.78 µM and 4.13 pmol/pmol CYP3A/min, respectively. ACP-5862 intrinsic clearance was 23.6 µL/min per mg. Acalabrutinib weakly inhibited CYP2C8, CYP2C9, and CYP3A4, and ACP-5862 weakly inhibited CYP2C9 and CYP2C19; other cytochrome P450s, UGTs (uridine 5'-diphospho-glucuronosyltransferases), and aldehyde oxidase were not inhibited. Neither parent nor ACP-5862 strongly induced CYP1A2, CYP2B6, or CYP3A4 mRNA. Acalabrutinib and ACP-5862 were substrates of multidrug resistance protein 1 and breast cancer resistance protein but not OATP1B1 or OATP1B3. Our work indicates that ACP-5862 may contribute to clinical efficacy in acalabrutinib-treated patients and illustrates how proactive metabolite characterization allows timely assessment of drug-drug interactions and potential contributions of metabolites to pharmacological activity. SIGNIFICANCE STATEMENT: This work characterized the major metabolite of acalabrutinib, ACP-5862. Its contribution to the pharmacological activity of acalabrutinib was assessed based on covalent Bruton tyrosine kinase binding kinetics, kinase selectivity, and potency in cellular assays. The metabolic clearance and in vitro drug-drug interaction potential were also evaluated for both acalabrutinib and ACP-5862. The current data suggest that ACP-5862 may contribute to the clinical efficacy observed in acalabrutinib-treated patients and demonstrates the value of proactive metabolite identification and pharmacological characterization.


Asunto(s)
Citocromo P-450 CYP3A , Humanos , Adulto , Agammaglobulinemia Tirosina Quinasa , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2 , Citocromo P-450 CYP2C9 , Proteínas de Neoplasias , Inhibidores de Proteínas Quinasas/uso terapéutico
6.
Cancers (Basel) ; 14(18)2022 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-36139564

RESUMEN

Circulating tumor cell (CTC)- and/or tumor-derived extracellular vesicle (tdEV) loads in the blood of metastatic castration-resistant prostate cancer (CRPC) patients are associated with worse overall survival and can be used as predictive markers of treatment response. In this study, we investigated the quantity/quality of CTCs and tdEVs in metastatic castration-naive prostate cancer (CNPC) and CRPC patients, and whether androgen deprivation therapy (ADT) affects CTCs and tdEVs. We included 104 CNPC patients before ADT initiation and 66 CRPC patients. Blood samples from 31/104 CNPC patients were obtained 6 months after ADT. CTCs and tdEVs were identified using ACCEPT software. Based on the morphology, CTCs of metastatic CNPC and CRPC patients were subdivided by manual reviewing into six subclasses. The numbers of CTCs and tdEVs were correlated in both CNPC and CRPC patients, and both CTCs (p = 0.013) and tdEVs (p = 0.005) were significantly lower in CNPC compared to CRPC patients. Qualitative differences in CTCs were observed: CTC clusters (p = 0.006) and heterogeneously CK expressing CTCs (p = 0.041) were significantly lower in CNPC patients. CTC/tdEV numbers declined 6 months after ADT. Our study showed that next to CTC-load, qualitative CTC analysis and tdEV-load may be useful in CNPC patients.

7.
Clin Pharmacol Drug Dev ; 11(11): 1294-1307, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-36029150

RESUMEN

Acalabrutinib is a Bruton tyrosine kinase (BTK) inhibitor approved to treat adults with chronic lymphocytic leukemia, small lymphocytic lymphoma, or previously treated mantle cell lymphoma. As the bioavailability of the acalabrutinib capsule (AC) depends on gastric pH for solubility and is impaired by acid-suppressing therapies, coadministration with proton-pump inhibitors (PPIs) is not recommended. Three studies in healthy subjects (N = 30, N = 66, N = 20) evaluated the pharmacokinetics (PKs), pharmacodynamics (PDs), safety, and tolerability of acalabrutinib maleate tablet (AT) formulated with pH-independent release. Subjects were administered AT or AC (orally, fasted state), AT in a fed state, or AT in the presence of a PPI, and AT or AC via nasogastric (NG) route. Acalabrutinib exposures (geometric mean [% coefficient of variation, CV]) were comparable for AT versus AC (AUCinf 567.8 ng h/mL [36.9] vs 572.2 ng h/mL [38.2], Cmax 537.2 ng/mL [42.6] vs 535.7 ng/mL [58.4], respectively); similar results were observed for acalabrutinib's active metabolite (ACP-5862) and for AT-NG versus AC-NG. The geometric mean Cmax for acalabrutinib was lower when AT was administered in the fed versus the fasted state (Cmax 255.6 ng/mL [%CV, 46.5] vs 504.9 ng/mL [49.9]); AUCs were similar. For AT + PPI, geometric mean Cmax was lower (371.9 ng/mL [%CV, 81.4] vs 504.9 ng/mL [49.9]) and AUCinf was higher (AUCinf 694.1 ng h/mL [39.7] vs 559.5 ng h/mL [34.6]) than AT alone. AT and AC were similar in BTK occupancy. Most adverse events were mild with no new safety concerns. Acalabrutinib formulations were comparable and AT could be coadministered with PPIs, food, or via NG tube without affecting the PKs or PDs.


Asunto(s)
Inhibidores de la Bomba de Protones , Pirazinas , Adulto , Humanos , Disponibilidad Biológica , Equivalencia Terapéutica , Inhibidores de la Bomba de Protones/efectos adversos , Inhibidores de la Bomba de Protones/farmacocinética , Pirazinas/efectos adversos , Pirazinas/farmacocinética , Comprimidos , Inhibidores de Proteínas Quinasas/efectos adversos , Inhibidores de Proteínas Quinasas/farmacocinética
8.
Eur Urol Open Sci ; 33: 61-71, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34632423

RESUMEN

CONTEXT: In December 2020, the US Food and Drug Administration approved a 68Ga-labeled prostate-specific membrane antigen ligand (68Ga-PSMA-11) for positron emission tomography (PET) in patients with suspected prostate cancer (PCa) metastasis who are candidates for initial definitive therapy. 68Ga-PSMA PET is increasingly performed for these patients and is usually combined with computed tomography (CT). In recent years, 68Ga-PSMA PET has been combined with high-resolution magnetic resonance imaging (MRI), which is beneficial for T staging and may further enhance the staging of primary PCa. OBJECTIVE: To compare the diagnostic accuracy of 68Ga-PSMA PET/MRI with 68Ga-PSMA PET/CT for staging of primary PCa. EVIDENCE ACQUISITION: A comprehensive literature search was performed using Embase, PubMed/Medline, Web of Science, Cochrane Library, and Google Scholar up to June 24, 2021 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Risk of bias was assessed using the QUADAS-2 tool. EVIDENCE SYNTHESIS: The search identified 2632 articles, of which 27 were included. The diagnostic accuracy of 68Ga-PSMA PET/MRI, measured as the pooled natural logarithm of diagnostic odds ratio (lnDOR), was 2.27 (95% confidence interval [CI] 1.21-3.32) for detection of extracapsular extension (ECE), 3.50 (95% CI 2.14-4.86) for seminal vesicle invasion (SVI), and 4.73 (95% CI 2.93-6.52) for lymph node metastasis (LNM). For 68Ga-PSMA PET/CT, the analysis showed lnDOR of 2.45 (95% CI 0.75-4.14), 2.94 (95% CI 2.26-3.63), and 2.42 (95% CI 2.07-2.78) for detection of ECE, SVI, and LNM, respectively. The overall risk of bias and applicability concerns were assessed as moderate and low, respectively. CONCLUSIONS: 68Ga-PSMA PET/MRI shows high diagnostic accuracy equivalent to that of 68Ga-PSMA PET/CT for detection of ECE, SVI, and LNM in staging of PCa. There is an urgent need for direct comparison of the two diagnostic tests in future research. PATIENT SUMMARY: The use of radioactively labeled molecules that bind to prostate-specific membrane antigen (68Ga-PSMA) for positron emission tomography (PET) scans combined with either computed tomography (CT) or magnetic resonance imaging (MRI) is increasing for prostate cancer diagnosis. There is a need for direct comparison of the two tests to demonstrate the benefit of 68Ga-PSMA PET/MRI for determining tumor stage in prostate cancer. TAKE HOME MESSAGE: After the recent US Food and Drug Administration approval of 68Ga-labeled prostate-specific membrane antigen ligand (68Ga-PSMA) positron emission tomography (PET) for staging of primary prostate cancer (PCa), it is expected that the use of this imaging modality will increase rapidly. Our review of the literature shows that 68Ga-PSMA PET/magnetic resonance imaging has high diagnostic accuracy equivalent to that of 68Ga-PSMA PET/computed tomography in primary PCa staging. There is an urgent need for direct head-to-head comparison of the two diagnostic tests in future research.

9.
Eur J Cancer ; 150: 179-189, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33932725

RESUMEN

BACKGROUND: Circulating tumour cell (CTC)-derived organoids have the potential to provide a powerful tool for personalised cancer therapy but are restrained by low CTC numbers provided by blood samples. Here, we used diagnostic leukapheresis (DLA) to enrich CTCs from patients with metastatic prostate cancer (mPCa) and explored whether organoids provide a platform for ex vivo treatment modelling. METHODS: We prospectively screened 102 patients with mPCa and performed DLA in 40 patients with ≥5 CTCs/7.5 mL blood. We enriched CTCs from DLA using white blood cell (WBC) depletion alone or combined with EpCAM selection. The enriched CTC samples were cultured in 3D to obtain organoids and used for downstream analyses. RESULTS: The DLA procedure resulted in a median yield of 5312 CTCs as compared with 22 CTCs in 7.5 mL of blood. Using WBC depletion, we recovered 46% of the CTCs, which reduced to 12% with subsequent EpCAM selection. From the isolated and enriched CTC samples, organoid expansion succeeded in 35%. Successful organoid cultures contained significantly higher CTC numbers at initiation. Moreover, we performed treatment modelling in one organoid cell line and identified substantial tumour heterogeneity in CTCs using single cell DNA sequencing. CONCLUSIONS: DLA is an efficient method to enrich CTCs, although the modest success rate of culturing CTCs precludes large scale clinical application. Our data do suggest that DLA and subsequent processing provides a rich source of viable tumour cells. Therefore, DLA offers a promising alternative to biopsy procedures to obtain sufficient number of tumour cells to study sequential samples in patients with mPCa. TRIAL REGISTRATION NUMBER: NL6019.


Asunto(s)
Separación Celular , Leucaféresis , Células Neoplásicas Circulantes/patología , Neoplasias de la Próstata/patología , Anciano , Anciano de 80 o más Años , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , ADN de Neoplasias/genética , Heterogeneidad Genética , Humanos , Masculino , Persona de Mediana Edad , Metástasis de la Neoplasia , Células Neoplásicas Circulantes/efectos de los fármacos , Células Neoplásicas Circulantes/metabolismo , Organoides , Estudios Prospectivos , Neoplasias de la Próstata/sangre , Neoplasias de la Próstata/genética , Neoplasias de la Próstata/terapia , Resultado del Tratamiento , Células Tumorales Cultivadas
10.
Genome Med ; 13(1): 86, 2021 05 18.
Artículo en Inglés | MEDLINE | ID: mdl-34006333

RESUMEN

Here, we describe a novel approach for rapid discovery of a set of tumor-specific genomic structural variants (SVs), based on a combination of low coverage cancer genome sequencing using Oxford Nanopore with an SV calling and filtering pipeline. We applied the method to tumor samples of high-grade ovarian and prostate cancer patients and validated on average ten somatic SVs per patient with breakpoint-spanning PCR mini-amplicons. These SVs could be quantified in ctDNA samples of patients with metastatic prostate cancer using a digital PCR assay. The results suggest that SV dynamics correlate with and may improve existing treatment-response biomarkers such as PSA. https://github.com/UMCUGenetics/SHARC .


Asunto(s)
Biomarcadores de Tumor , ADN Tumoral Circulante , Variación Estructural del Genoma , Técnicas de Diagnóstico Molecular , Secuenciación de Nanoporos , Neoplasias/diagnóstico , Neoplasias/genética , Biología Computacional/métodos , Femenino , Humanos , Biopsia Líquida/métodos , Masculino , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Diagnóstico Molecular/normas , Especificidad de Órganos/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Análisis de Secuencia de ADN
11.
J Nucl Med ; 61(11): 1607-1614, 2020 11.
Artículo en Inglés | MEDLINE | ID: mdl-32169916

RESUMEN

For individual treatment decisions in patients with metastatic prostate cancer (mPC), molecular diagnostics are increasingly used. Bone metastases are frequently the only source for obtaining metastatic tumor tissue. However, the success rate of CT-guided bone biopsies for molecular analyses in mPC patients is approximately only 40%. PET using 68Ga prostate-specific membrane antigen (68Ga-PSMA) is a promising tool to improve the harvest rate of bone biopsies for molecular analyses. The aim of this study was to determine the success rate of 68Ga-PSMA-guided bone biopsies for molecular diagnostics in mPC patients. Methods: Within a prospective multicenter whole-genome sequencing trial (NCT01855477), 69 mPC patients underwent 68Ga-PSMA PET/CT before bone biopsy. The primary endpoint was the success rate (tumor percentage ≥ 30%) of 68Ga-PSMA-guided bone biopsies. At biopsy sites, 68Ga-PSMA uptake was quantified using rigid-body image registration of 68Ga-PSMA PET/CT and interventional CT. Actionable somatic alterations were identified. Results: The success rate of 68Ga-PSMA-guided biopsies for molecular analyses was 70%. At biopsy sites categorized as positive, inconclusive, or negative for 68Ga-PSMA uptake, 70%, 64%, and 36% of biopsies were tumor-positive (≥30%), respectively (P = 0.0610). In tumor-positive biopsies, 68Ga-PSMA uptake was significantly higher (P = 0.008), whereas radiodensity was significantly lower (P = 0.006). With an area under the curve of 0.84 and 0.70, both 68Ga-PSMA uptake (SUVmax) and radiodensity (mean Hounsfield units) were strong predictors for a positive biopsy. Actionable somatic alterations were detected in 73% of the sequenced biopsies. Conclusion: In patients with mPC, 68Ga-PSMA PET/CT improves the success rate of CT-guided bone biopsies for molecular analyses, thereby identifying actionable somatic alterations in more patients. Therefore, 68Ga-PSMA PET/CT may be considered for guidance of bone biopsies in both clinical practice and clinical trials.


Asunto(s)
Neoplasias Óseas/secundario , Huesos/patología , Ácido Edético/análogos & derivados , Biopsia Guiada por Imagen/métodos , Oligopéptidos/farmacocinética , Tomografía Computarizada por Tomografía de Emisión de Positrones/métodos , Neoplasias de la Próstata/diagnóstico por imagen , Neoplasias de la Próstata/patología , Radiofármacos/farmacocinética , Anciano , Neoplasias Óseas/patología , Ácido Edético/farmacocinética , Isótopos de Galio , Radioisótopos de Galio , Humanos , Masculino , Persona de Mediana Edad , Técnicas de Diagnóstico Molecular , Estudios Prospectivos
12.
Med Phys ; 44(3): 1113-1119, 2017 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-28097674

RESUMEN

PURPOSE: In the design of nuclear medicine treatment and examination rooms, an important consideration is the shielding required for ionizing radiation from the radioactive isotopes used. The shielding in the walls is normally limited to a height lower than the actual ceiling height. The direct radiation, possibly with build-up correction, can be calculated relatively easily. However, little data are available to estimate the dose contribution from ionizing radiation traveling over the wall shielding and scattering off the ceiling. We aim to determine the contribution of the ceiling scatter to the radiation dose outside nuclear medicine rooms. METHODS: Monte Carlo simulations were performed using Gate for different heights of lead shielding in the wall, and different ceiling heights. A point source in air of 99m Tc (141 keV), 131 I (365 keV) or 18 F (511 keV) was placed 1.0 m above the floor, 3.0 m from the lead shielding. Simulations of ceiling scatter only and for the total radiation dose were performed for these 3 isotopes, 5 different ceiling heights and 4-8 different wall shielding heights, resulting in a total of 165 simulations. This allowed us to compare the contribution of the radiation passing through the shielding and the ceiling scatter. RESULTS: We find that the shielding required for the primary radiation, measured in half-value layers, is an important factor in determining the relative contribution of ceiling scatter. When more than about 4 half-value layers of shielding are used, ceiling scatter becomes the dominant factor and should be taken into account in the shielding design. In many practical cases for low energy photons (e.g. from 99m Tc; 141 keV; half-value layer of 0.26 mm lead), 2 mm of lead is used and ceiling scatter is a dominating factor contributing >~70% of the dose outside the shielded room. For higher energies (e.g. 18 F; 511 keV; half-value layer of 3.9 mm lead) the ceiling scatter is typically less than about 15% when 8 mm of lead shielding is used. CONCLUSIONS: We have performed simulations that allow an estimation of the contribution of ceiling scatter to the radiation dose outside a room, based on the ceiling height, shielding height, and isotope used. This will allow for improved shielding designs in nuclear medicine departments.


Asunto(s)
Simulación por Computador , Arquitectura y Construcción de Instituciones de Salud , Método de Montecarlo , Protección Radiológica , Radiación Ionizante , Dispersión de Radiación , Aire , Arquitectura y Construcción de Instituciones de Salud/instrumentación , Arquitectura y Construcción de Instituciones de Salud/métodos , Radioisótopos de Flúor , Radioisótopos de Yodo , Plomo , Modelos Teóricos , Medicina Nuclear/instrumentación , Medicina Nuclear/métodos , Compuestos de Organotecnecio , Fotones , Dosis de Radiación , Equipos y Suministros de Radiación , Protección Radiológica/métodos
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