Multimodality functional imaging using DW-MRI and 18F-FDG-PET/CT during radiation therapy for human papillomavirus negative head and neck squamous cell carcinoma: Meixoeiro Hospital of Vigo Experience.

AIM: To noninvasively investigate tumor cellularity measured using diffusion-weighted magnetic resonance imaging (DW-MRI) and glucose metabolism measured by 18F-labeled fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) during radiation therapy (RT) for human papillomavirus negative (HPV-) head and neck squamous cell carcinoma (HNSCC). METHODS: In this prospective study, 6 HPV- HNSCC patients underwent a total of 34 multimodality imaging examinations DW-MRI at 1.5 T Philips MRI scanner [(n = 24) pre-, during- (2-3 wk), and post-treatment (Tx), and 18F-FDG PET/CT pre- and post-Tx (n = 10)]. All patients received RT. Monoexponential modeling of the DW-MRI data yielded the imaging metric apparent diffusion coefficient (ADC) and the mean of standardized uptake value (SUV) was measured from 18F-FDG PET uptake. All patients had a clinical follow-up as the standard of care and survival status was documented at 1 year. RESULTS: There was a strong negative correlation between the mean of pretreatment ADC (ρ = -0.67, P = 0.01) and the pretreatment 18F-FDG PET SUV. The percentage (%) change in delta (∆) ADC for primary tumors and neck nodal metastases between pre- and Wk2-3 Tx were as follows: 75.4% and 61.6%, respectively, for the patient with no evidence of disease, 27.5% and 32.7%, respectively, for those patients who were alive with disease, and 26.9% and 7.31%, respectively, for those who were dead with disease. CONCLUSION: These results are preliminary in nature and are indicative, and not definitive, trends rendered by the imaging metrics due to the small sample size of HPV- HNSCC patients in a Meixoeiro Hospital of Vigo Experience.

Role of computed tomography on large B-cell non-Hodgkin's lymphoma follow-up and the risk of radiation-induced neoplasm: A retrospective cohort study.

INTRODUCTION: To evaluate the role of surveillance computed tomography (CT) in detection of tumor relapse after complete remission for large-cell lymphoma and to estimate the cancer risk related to those examinations. MATERIALS AND METHODS: We retrospectively identified the cases of large-cell lymphoma diagnosed at our institution during a fifteen years period. We extracted from charts the information needed. Agreement between clinical and radiological evaluation for relapse detection was determined with index kappa and McNemar tests. We analysed the surveillance CT examinations performed to the patients in complete remission with no recurrence during the follow-up period and we estimated the life attributable risk (LAR) of radiation-induced cancer above base line using the approach of the Biological Effects of Ionizing Radiation (BEIR) VII. RESULTS: 184 patients with biopsy confirmed large-cell lymphoma were included. Complete remission was attained in 125 patients. After a median follow-up of 93.73 months, 97 of them remain in remission. Relapse was confirmed in 28 patients; only 3 of them were asymptomatic. Kappa and McNemar analyses revealed good agreement for diagnosis of recurrence and significant difference for exclusion of relapse. Patients in remission received a median of 6 surveillance CT examinations. Fifty-seven patients had total cumulative doses greater than 100mSv. The mean increase in estimated radiation-induced cancer risk was 0.5%. CONCLUSION: Our results suggest that periodic CT examinations have a limited role in detecting relapse in large-cell lymphoma as the clinical surveillance dictates the patient management.

A Monte Carlo simulation for the estimation of patient dose in rest and stress cardiac computed tomography with a 320-detector row CT scanner.

PURPOSE: To estimate organ dose and effective dose for patients for cardiac CT as applied in an international multicenter study (CORE320) with a 320-Detector row CT scanner using Monte Carlo (MC) simulations and voxelized phantoms. The effect of positioning of the arms, off-centering the patient and heart rate on patient dose was analyzed. METHODS: A MC code was tailored to simulate the geometry and characteristics of the CT scanner. The phantoms representing the adult reference male and female were implemented according to ICRP 110. Effective dose and organ doses were obtained for CT acquisition protocols for calcium scoring, coronary angiography and myocardial perfusion. RESULTS: For low heart rate, the normalized effective dose (E) for cardiac CT was higher for female (5.6 mSv/100 mAs) compared to male (2.2 mSv/100 mAs) due to the contribution of female breast tissue. Averaged E for female and male was 11.3 mSv for the comprehensive cardiac protocol consisting of calcium scoring (1.9 mSv); coronary angiography including rest cardiac perfusion (5.1 mSv) and stress cardiac perfusion (4.3 mSv). These values almost doubled at higher heart rates (20.1 mSv). Excluding the arms increased effective dose by 6-8%, centering the patient showed no significant effect. The k-factor (0.028 mSv/mGy.cm) derived from this study leads to effective doses up to 2-3 times higher than the values obtained using now outdated methodologies. CONCLUSION: MC modeling of cardiac CT examinations on realistic voxelized phantoms allowed us to assess patient doses accurately and we derived k-factors that are well above those published previously.

A parametrization of the CT number of a substance and its use for stoichiometric calibration.

A method to carry out stoichiometric calibrations of CT scanners employed in radiotherapy treatment planning is proposed. The method is based on a simple parametrization of the CT number of a substance, which involves only two variables to describe the substance (electron density and one effective atomic number) and one parameter to describe the beam. The method was tested experimentally on a group of beams. A set of no tissue-like substances of known densities and elemental compositions were employed as calibrators. CT number-to-density curves (RED curves) were calculated with the proposed parametrization and compared to those measured with a commercial density phantom. Differences between the electron densities assigned by the calculated RED curves and the measured ones were in the range 0.009-0.019 (RMS). The proposed method may be employed to carry out accurate stoichiometric calibrations by using only one suitable substance as calibrator, not necessarily tissue-like.

Tomografía computarizada multicorte en un servicio de radiodiagnóstico: estudio de las dosis impartidas durante 1 año / Multislice CT in a diagnostic imaging department: radiation doses delivered in 1 year

Objetivo Conocer detalladamente los exámenes de tomografía computarizada (TC) realizados en un servicio de radiodiagnóstico y su contribución a las dosis de radiación recibidas por los pacientes. Material y métodos Se han llevado a cabo 2 estudios, uno retrospectivo de 1 año sobre los datos administrativos y otro prospectivo de 1 mes para conocer la actividad de los 2 equipos de TC multicorte del servicio, y obtener el número total de exámenes, las distribuciones de edad de los pacientes y las frecuencias de los distintos tipos de exploración. Con esos datos y los resultados de medidas dosimétricas se han estimado los valores de dosis típicos para cada tipo de examen, su contribución a la dosis colectiva y la dosis colectiva total debida a los exámenes de TC del hospital. Resultados Se efectuaron un total de 15.038 exploraciones a 12.678 pacientes en el año del estudio retrospectivo. Los tipos de exploración más frecuentes son las de cráneo (38,2%), abdomen-pelvis (17,5%), tórax-abdomen (11,7%), tórax (9,3%) y columna lumbosacra (6,8%). Hay protocolos que presentan valores de los índices de dosis superiores a los de referencia propuestos por expertos europeos. La dosis colectiva total de los exámenes de TC del hospital se ha estimado en 70 persona.Sv. Los exámenes de abdomen-pelvis contribuyen con el 31% del total. Conclusiones Este trabajo ha servido para conocer con detalle la práctica con TC en un servicio de radiodiagnóstico, las posibilidades de mejora en el uso de los equipos y para estimar las dosis de radiación (AU)

Objective To determine the usage of CT in our diagnostic imaging department and the dose of radiation CT delivered to patients. Material and methodsWe carried out two studies, a retrospective study on the administrative data from one year and a prospective study over one month, to determine the amount of activity of the two multislice CT scanners in our department. We recorded the total number of examinations, the different types of examination performed, and the age distributions of the patients examined. We used these data and the results of dosimetric measurements to estimate the typical radiation dose for each type of examination, its contribution to the collective radiation dose, and the total collective radiation dose from CT examinations at our hospital. ResultsThe retrospective study found that 15038 examinations were performed in 12678 patients in one year. The most common CT examinations were cranial (38.2%), abdomen-pelvis (17.5%), chest-abdomen (11.7%), chest (9.3%), and lumbar-sacral spine (6.8%). Some protocols used doses of radiation that were higher than those recommended by European experts. The total collective dose of radiation delivered to patients at our hospital by CT was estimated at 70 person.Sv. Abdomen-pelvis examinations contributed 31% of the total dose. ConclusionsThis study has provided detailed knowledge about the use of CT in our diagnostic imaging department, about the dose of radiation delivered, and about possibilities for improving the use of our CT scanners (AU)

[Multislice CT in a diagnostic imaging department: radiation doses delivered in 1 year.]. / Tomografía computarizada multicorte en un servicio de radiodiagnóstico: estudio de las dosis impartidas durante 1 año.

OBJECTIVE: To determine the usage of CT in our diagnostic imaging department and the dose of radiation CT delivered to patients. MATERIAL AND METHODS: We carried out two studies, a retrospective study on the administrative data from one year and a prospective study over one month, to determine the amount of activity of the two multislice CT scanners in our department. We recorded the total number of examinations, the different types of examination performed, and the age distributions of the patients examined. We used these data and the results of dosimetric measurements to estimate the typical radiation dose for each type of examination, its contribution to the collective radiation dose, and the total collective radiation dose from CT examinations at our hospital. RESULTS: The retrospective study found that 15038 examinations were performed in 12678 patients in one year. The most common CT examinations were cranial (38.2%), abdomen-pelvis (17.5%), chest-abdomen (11.7%), chest (9.3%), and lumbar-sacral spine (6.8%). Some protocols used doses of radiation that were higher than those recommended by European experts. The total collective dose of radiation delivered to patients at our hospital by CT was estimated at 70 person.Sv. Abdomen-pelvis examinations contributed 31% of the total dose. CONCLUSIONS: This study has provided detailed knowledge about the use of CT in our diagnostic imaging department, about the dose of radiation delivered, and about possibilities for improving the use of our CT scanners.

Valoración de calidad de imagen y dosis en exámenes de tomografía computarizada helicoidal de abdomen y de pelvis en pacientes con linfoma / Evaluation of image quality and dose in abdominal and pelvic helical CT in patients with lymphoma

Objetivo: Valorar la calidad de los exámenes de tomografía computarizada (TC) de abdomen y de pelvis para la indicación de linfoma, de acuerdo con los criterios propuestos en la Guía de la Comisión Europea (CE). Material y métodos: Los criterios se evaluaron en una muestra de 100 pacientes, procedentes de cinco hospitales públicos de la Comunidad de Madrid, estudiados mediante TC helicoidal de corte único. Cinco radiólogos, uno de cada centro participante en el estudio, evaluaron de forma independiente el cumplimiento de los criterios de imagen en los exámenes seleccionados. Se ha definido el indice de calidad de imagen (ICI) para el examen completo de abdomen y pelvis. En paralelo se efectuaron medición de las dosis para estimar los valores del índice de dosis en TC (IDTC), producto de dosis por longitud (PDL) y dosis efectiva (E). Resultados: Se ha encontrado un alto cumplimiento de los criterios de imagen individual en el abdomen. En la pelvis el cumplimiento ha sido menor, especialmente para tres criterios. El ICI por centro se encuentra entre el 83 y el 92%, con grados variables de desviación interna. Los valores medios de IDTCw por centro estuvieron entre 16 y 23 mGy; los de PDL entre 430 y 750 mGy/cm, y la dosis efectiva entre 7 y 12 mSv. En general, no se ha encontrado correlación entre el ICI y la dosis al paciente (PDL) en la totalidad de la muestra (r = 0,04) ni por centros (r ¾ 0,36). Conclusiones: Se ha confirmado la utilidad de los criterios de calidad de la CE. Se ha elaborado una lista única de criterios de calidad de imagen y sugerimos niveles de dosis de referencia para exámenes de TC de abdomen-pelvis en pacientes con linfoma

Objective: The aim of this study is to evaluate the quality of pelvic and abdominal CT images performed for lymphoma according to the criteria proposed in the European Commission Guidelines on radiation imaging.( En castellano dice: la Guia de la Comisión Europea. Lo que pasa es que hay muchas guias publicadas por la Comisión: aseguranse que sea esta la citada) Material and methods: The criteria were evaluated in a sample of 100 patients attended at five public hospitals in the Autonomous Community of Madrid. All patients underwent single-slice helical CT studies. Fulfillment of the imaging criteria in the selected images was evaluated by five radiologists, one from each center, working independently. The Index of Image Quality (IIQ) was determined for the complete abdominal and pelvic examination. The dose was also measured to estimate the values of the CT Dose Index (CTDIw), Dose by Length Product (DLP), and effective dose (E). Results: A high rate of fulfillment of the criteria was found for individual abdominal images. In the pelvis, the rate of fulfillment was lower, especially for three criteria. The IIQ for each center was between 83%-92%, with variable degrees of internal deviation. The mean values of CTDIw per center were between 16-23 mGy; DLP values were between 430 and 750 mGy cm, and the effective dose was 7-12 mSv. In general, no correlation was found between IIQ and dose per patient, either for the entire sample (r = 0.04) or by centers (r£0.36). Conclusions: The utility of the European Union's Quality Criteria was confirmed. We have elaborated a single list of criteria of image quality and suggest reference dosage levels for abdominal-pelvic CT examinations in patients with lymphoma