RESUMO
BACKGROUND: Computed Tomography (CT) contributes up to 50% of the medical exposure to the United States population. Children are considered to be at higher risk of developing radiation-induced tumors due to the young age of exposure and increased tissue radiosensitivity. Organ dose estimation is essential for pediatric and adult patient cancer risk assessment. The objective of this study is to validate the VirtualDose software in comparison to currently available software and methods for pediatric and adult CT organ dose estimation. METHODS: Five age groups of pediatric patients and adult patients were simulated by three organ dose estimators. Head, chest, abdomen-pelvis, and chest-abdomen-pelvis CT scans were simulated, and doses to organs both inside and outside the scan range were compared. For adults, VirtualDose was compared against ImPACT and CT-Expo. For pediatric patients, VirtualDose was compared to CT-Expo and compared to size-based methods from literature. Pediatric to adult effective dose ratios were also calculated with VirtualDose, and were compared with the ranges of effective dose ratios provided in ImPACT. RESULTS: In-field organs see less than 60% difference in dose between dose estimators. For organs outside scan range or distributed organs, a five times' difference can occur. VirtualDose agrees with the size-based methods within 20% difference for the organs investigated. Between VirtualDose and ImPACT, the pediatric to adult ratios for effective dose are compared, and less than 21% difference is observed for chest scan while more than 40% difference is observed for head-neck scan and abdomen-pelvis scan. For pediatric patients, 2 cm scan range change can lead to a five times dose difference in partially scanned organs. CONCLUSIONS: VirtualDose is validated against CT-Expo and ImPACT with relatively small discrepancies in dose for organs inside scan range, while large discrepancies in dose are observed for organs outside scan range. Patient-specific organ dose estimation is possible using the size-based methods, and VirtualDose agrees with size-based method for the organs investigated. Careful range selection for CT protocols is necessary for organ dose optimization for pediatric and adult patients.
Assuntos
Envelhecimento/fisiologia , Modelos Biológicos , Exposição à Radiação/análise , Tomografia Computadorizada por Raios X/métodos , Vísceras/fisiologia , Contagem Corporal Total/métodos , Absorção de Radiação/fisiologia , Adolescente , Algoritmos , Criança , Pré-Escolar , Simulação por Computador , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Modelos Estatísticos , Método de Monte Carlo , Especificidade de Órgãos , Doses de Radiação , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
The workload for shielding purposes of modern linear accelerators (linacs) consists of primary and scatter radiation which depends on the dose delivered to isocenter (cGy) and leakage radiation which depends on the monitor units (MUs). In this study, we report on the workload for 10 treatment vaults in terms of dose to isocenter (cGy), monitor units delivered (MUs), number of treatment sessions (Txs), as well as, use factors (U) and modulation factors (CI) for different treatment techniques. The survey was performed for the years between 2006 and 2015 and included 16 treatment machines which represent different generations of Varian linear accelerators (6EX, 600C, 2100C, 2100EX, and TrueBeam) operating at different electron and x-ray energies (6, 9, 12, 16 and 20 MeV electrons and, 6 and 15 MV x-rays). An institutional review board (IRB) approval was acquired to perform this study. Data regarding patient workload, dose to isocenter, number of monitor units delivered, beam energies, gantry angles, and treatment techniques were exported from an ARIA treatment management system (Varian Medical Systems, Palo Alto, Ca.) into Excel spreadsheets and data analysis was performed in Matlab. The average (± std-dev) number of treatment sessions, dose to isocenter, and number of monitor units delivered per week per machine in 2006 was 119 ± 39 Txs, (300 ± 116) × 102 cGys, and (78 ± 28) × 103 MUs respectively. In contrast, the workload in 2015 was 112 ± 40 Txs, (337 ± 124) × 102 cGys, and (111 ± 46) × 103 MUs. 60% of the workload (cGy) was delivered using 6 MV and 30% using 15 MV while the remaining 10% was delivered using electron beams. The modulation factors (MU/cGy) for IMRT and VMAT were 5.0 (± 3.4) and 4.6 (± 1.6) respectively. Use factors using 90° gantry angle intervals were equally distributed (~0.25) but varied considerably among different treatment techniques. The workload, in terms of dose to isocenter (cGy) and subsequently monitor units (MUs), has been steadily increasing over the past decade. This increase can be attributed to increased use of high dose hypo-fractionated regimens (SBRT, SRS) and the increase in use of IMRT and VMAT, which require higher MUs per cGy as compared to more conventional treatment (3DCRT). Meanwhile, the patient workload in terms of treatment sessions per week remained relatively constant. The findings of this report show that variables used for shielding purposes still fall within the recommendation of NCRP Report 151.
Assuntos
Institutos de Câncer/estatística & dados numéricos , Aceleradores de Partículas , Carga de Trabalho/estatística & dados numéricos , Humanos , Radioterapia Conformacional , Espalhamento de Radiação , Inquéritos e Questionários , Fatores de TempoRESUMO
BACKGROUND: Wire localization (WL) of nonpalpable breast cancers on the day of surgery is uncomfortable for patients and impacts operating room efficiency. Radioactive seed localization (RSL) before the day of surgery avoids these disadvantages. In this study we compare outcomes of our initial 6-month experience with RSL to those with WL in the preceding 6 months. METHODS: Lumpectomies for invasive or intraductal cancers localized with a single (125)iodine seed (January-June 2012) were compared with those using 1 wire (July-December 2011). Surgeons and radiologists did not change. Positive and close margins were defined as tumor on ink and tumor ≤1 mm from ink, respectively. Demographic and clinical characteristics and outcomes were compared between RSL and WL patients. RESULTS: There were 431 RSL and 256 WL lumpectomies performed. Clinicopathologic characteristics did not differ between groups. Most seeds (90 %) were placed before the day of surgery. Positive margins were present in 7.7 % of RSL versus 5.5 % of WL patients, and 16.9 % of RSL versus 19.9 % of WL had close margins (p = 0.38). The median operative time was longer for lumpectomy and sentinel lymph node biopsy (SLNB) in the RSL group (55 vs. 48 min, p < 0.0001). There was no significant difference in the volume of tissue excised between groups. CONCLUSIONS: In the first 6 months of RSL, operative scheduling was simplified, while rates of positive and close margins were similar to those seen after many years of experience with WL. Operative time was slightly longer for RSL lumpectomy and SLNB; we anticipate this will decrease with experience.
Assuntos
Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/patologia , Carcinoma Intraductal não Infiltrante/patologia , Carcinoma Lobular/patologia , Radioisótopos do Iodo , Mastectomia Segmentar , Inoculação de Neoplasia , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/cirurgia , Carcinoma Ductal de Mama/diagnóstico por imagem , Carcinoma Ductal de Mama/cirurgia , Carcinoma Intraductal não Infiltrante/diagnóstico por imagem , Carcinoma Intraductal não Infiltrante/cirurgia , Carcinoma Lobular/diagnóstico por imagem , Carcinoma Lobular/cirurgia , Feminino , Seguimentos , Humanos , Pessoa de Meia-Idade , Gradação de Tumores , Prognóstico , Estudos Prospectivos , Cintilografia , Fatores de TempoRESUMO
PURPOSE: Patient exposure rate measurements verify published patient dose rate data and characterize dose rates near 2-18-fluorodeoxyglucose ((18)F-FDG) patients. A specific dose rate constant based on patient exposure rate measurements is a convenient quantity that can be applied to the desired distance, injection activity, and time postinjection to obtain an accurate calculation of cumulative external radiation dose. This study reports exposure rates measured at various locations near positron emission tomography (PET) (18)F-FDG patients prior to PET scanning. These measurements are normalized for the amount of administered activity, measurement distance, and time postinjection and are compared with other published data. METHODS: Exposure rates were measured using a calibrated ionization chamber at various body locations from 152 adult oncology patients postvoid after a mean uptake time of 76 min following injection with a mean activity of 490 MBq (18)F-FDG. Data were obtained at nine measurement locations for each patient: three near the head, four near the chest, and two near the feet. RESULTS: On contact with, 30 cm superior to and 30 cm lateral to the head, the mean (75th percentile) dose rates per unit injected activity at 60 min postinjection were 0.482 (0.511), 0.135 (0.155), and 0.193 (0.223) µSv∕MBq h, respectively. On contact with, 30 cm anterior to, 30 cm lateral to and 1 m anterior to the chest, the mean (75th percentile) dose rates per unit injected activity at 60 min postinjection were 0.623 (0.709), 0.254 (0.283), 0.190 (0.218), and 0.067 (0.081) µSv∕MBq h respectively. 30 cm inferior and 30 cm lateral to the feet, the mean (75th percentile) dose rates per unit injected activity at 60 min postinjection were 0.024 (0.022) and 0.039 (0.044) µSv∕MBq h, respectively. CONCLUSIONS: The measurements for this study support the use of 0.092 µSv m(2)∕MBq h as a reasonable representation of the dose rate anterior from the chest of patients immediately following injection. This value can then be reliably scaled to the desired time and distance for planning and staff dose evaluation purposes. At distances closer than 1 m, a distance-specific dose rate constant of 0.367 µSv∕MBq h at 30 cm is recommended for accurate calculations. An accurate patient-specific dose rate constant that accounts for patient-specific variables (e.g., distribution and attenuation) will allow an accurate evaluation of the dose rate from a patient injected with an isotope rather than simply utilizing a physical constant.
Assuntos
Fluordesoxiglucose F18/administração & dosagem , Neoplasias/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/métodos , Adulto , Humanos , RadiometriaRESUMO
PURPOSE: Effective dose (E) is useful as a dose index for patient exposures in interventional radiology; therefore, the authors estimated E from the kerma-area product (P(KA)) utilized during hepatic embolization interventional radiology cases performed at a cancer center and determined the variation of such doses over a representative patient population. METHODS: A single-center, IRB-approved retrospective study was performed to estimate doses from consecutive hepatic embolization procedures performed during 2006. Organ doses E and E/P(KA) were determined from patient height, weight, P(KA), procedure geometry factors, beam quality, the PCXMC Monte Carlo model, and the International Commission on Radiological Protection organ weighting factors. RESULTS: One hundred thirteen patients were included in the study population, 72 males and 41 females, with a median age of 63 yr (29-89 yr), weight of 79 kg (42-111 kg), height of 170 cm (147-188 cm), and P(KA) of 233 Gy cm2 (9-1020 Gy cm2). E was directly correlated with P(KA) r2 = 0.8 (p < 0.01), with a median E/P(KA) of 0.18 mSv Gy(-1) cm(-2) (0.12-0.33 mSv Gy(-1) cm(-2)). The E/P(KA) ratio was inversely and exponentially correlated with weight r2 = 0.9 (p < 0.001). The median E (mSv) for the study patient population was 44 mSv (2.0-255 mSv). CONCLUSIONS: Values of E can be estimated utilizing patient-specific and procedure-specific parameters. The strong inverse correlation of E/P(KA) with patient weight allows simple estimation of E from P(KA) and patient weight. There is a wide variation in effective dose in oncologic hepatic embolizations with doses up to an order of magnitude higher than diagnostic imaging of the abdomen by CT radiology. Variation is likely due to patient geometry, clinical technique factors, and procedure complexity.
Assuntos
Embolização Terapêutica/métodos , Artéria Hepática , Neoplasias Hepáticas/irrigação sanguínea , Neoplasias Hepáticas/terapia , Doses de Radiação , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Peso Corporal , Feminino , Humanos , Neoplasias Hepáticas/fisiopatologia , Masculino , Pessoa de Meia-Idade , Estudos RetrospectivosRESUMO
OBJECTIVE: As public awareness of medical radiation exposure increases, there has been heightened awareness among patients and physicians of the importance of holistic benefit-and-risk discussions in shared medical decision making. CONCLUSION: We examine the rationale for informed consent and risk communication, draw on the literature on the psychology of radiation risk communication to increase understanding, examine methods commonly used to communicate radiation risk, and suggest strategies for improving communication about medical radiation benefits and risk.
Assuntos
Tomada de Decisões , Medo , Consentimento Livre e Esclarecido , Neoplasias Induzidas por Radiação/prevenção & controle , Neoplasias Induzidas por Radiação/psicologia , Relações Médico-Paciente , Opinião Pública , Lesões por Radiação/prevenção & controle , Lesões por Radiação/psicologia , Humanos , Educação de Pacientes como Assunto , Doses de Radiação , Proteção Radiológica , Medição de Risco , Fatores de RiscoRESUMO
PURPOSE: To correlate operator lens dose to patient-delivered kerma-area-product (P(KA)) to evaluate the usefulness of P(KA) as a surrogate for operator eye dose if collar monitor readings are unavailable or deemed unreliable, and to evaluate if unprotected lens dose is clinically significant. MATERIALS AND METHODS: A retrospective review of peak skin doses for consecutive interventional radiology procedures performed during 2006 that had P(KA) estimates recorded was performed. Unshielded operator lens dose equivalents (LDE) were obtained from dosimetry monitors worn outside the collar shield of operating interventional radiologists. Operator LDE were correlated with patient P(KA). RESULTS: Average LDE for 2006 was 35.7 mSv ± 32.7 (range 5.2-89.9 mSv). Patient-delivered P(KA) correlated directly with LDE, where 1 Gy cm(2) to the patient resulted in an average of 4.2 µSv to the unprotected eyes of the primary operator (r(2) = 0.7). CONCLUSIONS: P(KA) may be useful as a surrogate measure of operator LDE if collar monitor readings are unavailable or deemed unreliable. For this study, the dose-effect threshold for cataract formation could be surpassed for some physicians within 11 years if lens dose-mitigating strategies are not routinely employed.
Assuntos
Catarata/etiologia , Cristalino/efeitos da radiação , Oncologia/métodos , Exposição Ocupacional , Doses de Radiação , Lesões por Radiação/etiologia , Radiografia Intervencionista/efeitos adversos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Catarata/prevenção & controle , Criança , Pré-Escolar , Relação Dose-Resposta à Radiação , Feminino , Dosimetria Fotográfica , Humanos , Masculino , Pessoa de Meia-Idade , Cidade de Nova Iorque , Lesões por Radiação/prevenção & controle , Reprodutibilidade dos Testes , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Pele/efeitos da radiação , Adulto JovemRESUMO
PURPOSE: To evaluate the impact of common radiation-shielding strategies, used alone and in combination, on scattered dose to the fluoroscopy operator's eye. MATERIALS AND METHODS: With an operator phantom positioned at the groin, upper abdomen, and neck, posteroanterior low-dose fluoroscopy was performed at the phantom patient's upper abdomen. Operator lens radiation dose rate was recorded with a solid-state dosimeter with and without a leaded table skirt, nonleaded and leaded (0.75 mm lead equivalent) eyeglasses, disposable tungsten-antimony drapes (0.25 mm lead equivalent), and suspended and rolling (0.5 mm lead equivalent) transparent leaded shields. Lens dose measurements were also obtained in right and left 15° anterior obliquities with the operator at the upper abdomen and during digital subtraction angiography (two images per second) with the operator at the patient's groin. Each strategy's shielding efficacy was expressed as a reduction factor of the lens dose rate compared with the unshielded condition. RESULTS: Use of leaded glasses alone reduced the lens dose rate by a factor of five to 10; scatter-shielding drapes alone reduced the dose rate by a factor of five to 25. Use of both implements together was always more protective than either used alone, reducing dose rate by a factor of 25 or more. Lens dose was routinely undetectable when a suspended shield was the only barrier during low-dose fluoroscopy. CONCLUSIONS: Use of scatter-shielding drapes or leaded glasses decreases operator lens dose by a factor of five to 25, but the use of both barriers together (or use of leaded shields) provides maximal protection to the interventional radiologist's eye.
Assuntos
Traumatismos Oculares/prevenção & controle , Dispositivos de Proteção dos Olhos , Cristalino/efeitos da radiação , Exposição Ocupacional , Doses de Radiação , Lesões por Radiação/prevenção & controle , Proteção Radiológica/instrumentação , Radiografia Intervencionista/efeitos adversos , Radiologia Intervencionista , Angiografia Digital/efeitos adversos , Desenho de Equipamento , Traumatismos Oculares/etiologia , Fluoroscopia/efeitos adversos , Humanos , Cidade de Nova Iorque , Imagens de Fantasmas , Lesões por Radiação/etiologia , Radiografia Intervencionista/instrumentação , Espalhamento de RadiaçãoRESUMO
PURPOSE: To estimate the peak radiation skin doses for interventional radiology cases performed at a cancer center, identify procedure types likely to result in skin doses exceeding the American College of Radiology's 3 Gy follow-up level, and determine a kerma area product (P(KA)) for use in monitoring. MATERIALS AND METHODS: A single-center retrospective study was performed to estimate doses from consecutive procedures performed during 2006. Of 6,598 procedures, 3,925 (60%) had P(KA) recorded and were included. Forty-three procedure types are represented. RESULTS: The median estimated peak skin dose was 39 mGy (third quartile, 205 mGy). In 2.6% of the cases, the estimated skin dose exceeded 3 Gy. No procedures resulted in skin doses greater than 15 Gy, and 94% of the cases resulted in skin doses less than 1 Gy. Procedure types with instances of skin doses greater than 1 Gy included hepatic, portal, and other arterial embolizations; diagnostic arteriography; biliary drainages; stent placements and catheter exchanges; nephrostomy/nephroureterostomy; urinary catheter exchanges; inferior vena cava filters; foreign body retrieval; abscess drainage; catheter exchange; and fistulography. Hepatic embolizations, nonhepatic arterial embolizations, and biliary drain/stent procedures were most likely to result in skin doses greater than 1 Gy. Significant variations in skin dose were noted within the same procedure type. No patients were noted to have developed any sequelae from radiation. CONCLUSIONS: It is unlikely that typical cases in an oncologic interventional radiology practice would exceed the Joint Commission's "reviewable sentinel event" skin dose level of 15 Gy. A P(KA) trigger of 300 Gy cm(2) could be used in the authors' clinic to identify follow-up requirements.
Assuntos
Carga Corporal (Radioterapia) , Neoplasias/diagnóstico por imagem , Neoplasias/epidemiologia , Radiologia Intervencionista/estatística & dados numéricos , Radiometria/estatística & dados numéricos , Fenômenos Fisiológicos da Pele , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/cirurgia , New York/epidemiologia , Doses de Radiação , Radiografia , Eficiência Biológica Relativa , Estudos Retrospectivos , Adulto JovemRESUMO
PURPOSE: Estimate organ and effective doses from computed tomography scans of pediatric oncologic patients using patient-specific information. MATERIALS AND METHODS: With IRB approval patient-specific scan parameters and patient size obtained from DICOM images and vendor-provided dose monitoring application were obtained for a cross-sectional study of 1250 pediatric patients from 0 through 20â¯y-olds who underwent head, chest, abdomen-pelvis, or chest-abdomen-pelvis CT scans. Patients were categorized by age. Organ doses and effective doses were estimated using VirtualDose™ CT based on patient-specific information, tube current modulation (TCM), and age-specific realistic phantoms. CTDIvol, DLP, and dose results were compared with those reported in the literature. RESULTS: CTDIvol and DLP varied widely as patient size varied. The 75th percentiles of CTDIvol and DLP were no greater than in the literature with the exception of head scans of 16-20â¯y-olds and of abdomen-pelvis scans of larger patients. Eye lens dose from a head scan was up to 69â¯mGy. Mean organ doses agreed with other studies at maximal difference of 38% for chest and 41% for abdomen-pelvis scans. Mean effective dose was generally higher for older patients. The highest effective doses were estimated for the 16-20â¯y-olds as: head 3.3â¯mSv, chest 4.1â¯mSv, abdomen-pelvis 10.0â¯mSv, chest-abdomen-pelvis 14.0â¯mSv. CONCLUSION: Patient-specific organ and effective doses have been estimated for pediatric oncologic patients from <1 through 20â¯y-olds. The effect of TCM was successfully accounted for in the estimates. Output parameters varied with patient size. CTDIvol and DLP results are useful for future protocol optimization.
Assuntos
Neoplasias/diagnóstico por imagem , Doses de Radiação , Tomografia Computadorizada por Raios X , Adolescente , Tamanho Corporal , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Estudos Retrospectivos , Adulto JovemRESUMO
BACKGROUND: This study estimates the length of time a patient might trigger security radiation detection devices after thallium 201 cardiac imaging. The US Department of Homeland Security is supporting the purchase and deployment of radiation detection pagers and portal monitors. Concurrently, there are an increasing number of cardiac perfusion imaging studies being performed using Tl-201. Therefore there is a higher probability that patients who have undergone nuclear medicine procedures could trigger alarms resulting in security questions. METHODS AND RESULTS: The length of time patients could trigger such devices is estimated based on the radiopharmacokinetics of Tl-201 and potential radioactive contaminants as well as the capabilities of current sensitive radiation detection devices, assuming the radioactive sources are distributed in and attenuated by the patient. It is estimated that patients may trigger portable pager devices for up to 33 days and may trigger portal detectors for up to 51 days after studies using Tl-201. This is much longer than length of time for a patient to trigger such alarms after technetium 99m myocardial imaging tests, which is potentially up to 6 days. CONCLUSIONS: It should be standard practice for patients to be issued information cards that indicate the potential time for triggering security radiation detectors after diagnostic cardiac procedures involving the use of Tl-201 or other radiopharmaceuticals.
Assuntos
Coração/diagnóstico por imagem , Miocárdio/patologia , Compostos Radiofarmacêuticos/farmacocinética , Medidas de Segurança , Radioisótopos de Tálio/farmacocinética , Viagem , United States Government Agencies , Calibragem , Humanos , Cinética , Perfusão , Imagens de Fantasmas , Radiometria/instrumentação , Cintilografia , Fatores de Tempo , Estados UnidosRESUMO
The purpose of this retrospective study was to evaluate the whole-body clearance kinetics of I-3F8 monoclonal antibody, an anti-ganglioside 2 antibody, used in the treatment of pediatric patients with late-stage neuroblastoma (NB). Serial whole-body dose rate measurements were obtained on pediatric patients participating in phase I dose escalation studies of therapeutic I-3F8. Whole-body retention fractions were derived and fit for each treatment to exponential curves to determine both the effective half-lives and corresponding clearance fractions. 27 patients were administered I-3F8 over the course of cyclical administrations with a median administered activity of 2.5 GBq (range, 1-8.14 GBq), typically every 2-4 d for up to 9 treatment cycles. Based on whole-body dose rate measurements, there was a large variability in the calculated mono-exponential clearance effective half-life time, with a mean of 26.4 h (range, 12.4-45.5 h). The data from a subset of 12 treatments were fit to a bi-exponential curve with a rapid clearance component mean effective half-time of 16.9 h (range, 4.3-26 h) and a slower clearance component mean effective half-time of 65.5 h (range, 16.9-136 h). The use of whole-body dose rate measurements, obtained for patient-release and other radiation safety considerations, can be useful in estimating whole-body clearance kinetics for photon emitting radionuclide labeled mAbs and other therapeutic radiopharmaceuticals. In the case of I-3F8 for pediatric NB therapy, the demonstrated variability in effective half-time suggests the need for patient-specific tracer dosimetry for both optimization of treatment and radiation safety precaution decision-making.
Assuntos
Anticorpos Monoclonais/farmacocinética , Radioisótopos do Iodo/farmacocinética , Neuroblastoma/metabolismo , Neuroblastoma/radioterapia , Contagem Corporal Total/métodos , Adolescente , Adulto , Anticorpos Monoclonais/uso terapêutico , Anticorpos Monoclonais Murinos , Carga Corporal (Radioterapia) , Criança , Pré-Escolar , Feminino , Meia-Vida , Humanos , Imunoglobulina G/uso terapêutico , Radioisótopos do Iodo/uso terapêutico , Cinética , Masculino , Taxa de Depuração Metabólica , Radioimunoterapia/métodos , Compostos Radiofarmacêuticos/farmacocinética , Compostos Radiofarmacêuticos/uso terapêutico , Dosagem Radioterapêutica , Eficiência Biológica Relativa , Estudos RetrospectivosRESUMO
PURPOSE: Most radiation protection programs, regulations and guidance apply specific restrictions to the occupational exposure of pregnant workers. The aim of this study was to compile data from the declared pregnant woman (DPW) radiation protection program over more than 5years at a large, high-volume, comprehensive oncology academic/medical institution and to evaluate for effectiveness against existing regulations and guidance. METHODS: A retrospective review was performed of the data collected as part of the DPW radiation protection program from January 2010 through May 2016, including the number of declared pregnancies, worker category, personal and fetal dosimetry monitoring measurements, workplace modifications, as well as the monthly and total recorded badge results during the entire pregnancy. RESULTS: 245 pregnancies were declared. The mean monthly fetal radiation dosimetry result was 0.009mSv with a median of 0.005mSv and a maximum of 0.39mSv. The mean total dose over the entire pregnancy was estimated to be 0.08mSv with a median of 0.05mSv and a maximum of 0.89mSv. Only 8 (3.2%) of the 245 declared pregnancies required that workplace modifications be implemented for the worker. CONCLUSIONS: The implementation of a declared pregnancy and fetal assessment program, careful planning, an understanding of the risks, and minimization of radiation dose by employing appropriate radiation safety measures as needed, can allow medical staff to perform procedures and normal activities without incurring significant risks to the conceptus, or significant interruptions of job activities for most medical workers.
Assuntos
Centros Médicos Acadêmicos , Exposição Ocupacional/prevenção & controle , Exposição à Radiação/prevenção & controle , Proteção Radiológica/métodos , Feminino , Feto/efeitos da radiação , Humanos , GravidezRESUMO
UNLABELLED: The purpose of this retrospective study was to determine whether lymphoscintigraphy (LSG) for sentinel lymph node (SNL) mapping in a woman with a breast mass presents an unacceptable risk to her fetus. We assessed radiation-absorbed dose to various organs from 99mTc-sulfur colloid (TSC) LSG using standard internal absorbed dose assessment methodologies for both reference phantoms as well as for phantom models using the specific patient population characteristics such as total body and injected organ mass. The study also projected the radiation-absorbed dose to the fetus from LSG for SLN mapping. METHODS: Data from 1,021 nonpregnant women with early-stage breast cancer who underwent SLN mapping and biopsy procedures were analyzed. Patients had a single-site intradermal injection of unfiltered TSC in 0.05 mL normal saline: 3.7 MBq (0.1 mCi) on the morning of surgery (1-d protocol) or 18.5 MBq (0.5 mCi) on the afternoon before surgery (2-d protocol). A standard internal dose calculation methodology was used to calculate absorbed doses to various organs and to a modeled fetus at 3-, 6-, and 9-mo gestation from the injection site as well as from systemic activity. RESULTS: The highest estimated absorbed doses were observed for the reference 9-mo-pregnant model under the 2-d protocol. Absorbed doses of 14.9, 0.214, 0.062, 0.151, 0.004, 0.163, 0.075, and 0.014 mGy were received by the injected breast, heart, liver, lung, ovaries, thymus, total body, and fetus, respectively. Effective doses from the 2-d protocol were estimated to be 0.460, 0.186, and 0.245 mSv for the reference population, the total Memorial Sloan-Kettering Cancer Center (MSKCC) study patient population, and childbearing-age MSKCC patient population (i.e., <45 y old), respectively. CONCLUSION: SLN procedures lead to a negligible dose to the fetus of 0.014 mGy or less. This is much less than the National Council on Radiation Protection and Measurements limit to a pregnant woman. Calculations using actual patient population characteristics resulted in lower organ dose estimates than more conservative reference models.
Assuntos
Neoplasias da Mama/patologia , Metástase Linfática/diagnóstico , Cintilografia/métodos , Tecnécio/farmacologia , Adulto , Idoso , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/diagnóstico por imagem , Feminino , Humanos , Exposição Materna , Pessoa de Meia-Idade , Imagens de Fantasmas , Gravidez , Complicações Neoplásicas na Gravidez , Radiografia , Radiometria , Cintilografia/efeitos adversos , Padrões de Referência , Estudos Retrospectivos , Biópsia de Linfonodo SentinelaRESUMO
BACKGROUND: Radiation, for either diagnosis or treatment, is used extensively in the field of oncology. An understanding of oncology radiation safety principles and how to apply them in practice is critical for nursing practice. Misconceptions about radiation are common, resulting in undue fears and concerns that may negatively impact patient care. Effectively educating nurses to help overcome these misconceptions is a challenge. Historically, radiation safety training programs for oncology nurses have been compliance-based and behavioral in philosophy. METHODS: A new radiation safety training initiative was developed for Memorial Sloan-Kettering Cancer Center (MSKCC) adapting elements of current adult education theories to address common misconceptions and to enhance knowledge. A research design for evaluating the revised training program was also developed to assess whether the revised training program resulted in a measurable and/or statistically significant change in the knowledge or attitudes of nurses toward working with radiation. An evaluation research design based on a conceptual framework for measuring knowledge and attitude was developed and implemented using a pretest-intervention-posttest approach for 15% of the study population of 750 inpatient registered oncology nurses. RESULTS: As a result of the intervention program, there was a significant difference in nurse's cognitive knowledge as measured with the test instrument from pretest (58.9%) to posttest (71.6%). The evaluation also demonstrated that while positive nursing attitudes increased, the increase was significant for only 5 out of 9 of the areas evaluated. CONCLUSION: The training intervention was effective for increasing cognitive knowledge, but was less effective at improving overall attitudes. This evaluation provided insights into the effectiveness of training interventions on the radiation safety knowledge and attitude of oncology nurses.
Assuntos
Atitude do Pessoal de Saúde , Educação Continuada em Enfermagem/normas , Conhecimentos, Atitudes e Prática em Saúde , Capacitação em Serviço/normas , Exposição Ocupacional , Enfermagem Oncológica/educação , Efeitos da Radiação , Lesões por Radiação/prevenção & controle , Radioterapia (Especialidade)/educação , Segurança , Adulto , Institutos de Câncer , Competência Clínica , Educação Continuada em Enfermagem/métodos , Avaliação Educacional , Medo , Fertilidade/efeitos da radiação , Humanos , Capacitação em Serviço/métodos , Cidade de Nova Iorque , Exposição Ocupacional/efeitos adversos , Exposição Ocupacional/análise , Saúde Ocupacional , Avaliação de Programas e Projetos de SaúdeRESUMO
This paper examines the educational philosophy of radiation safety education programs at medical institutions. The regulatory mandates for radiation safety training have traditionally emphasized competency-based training. This emphasis led to the adoption of a behaviorist philosophy that requires predetermined responses to certain situations. The behaviorist approach determines the roles of teacher and learner as well as the methods to be used. This paper examines these roles and methods and the influence of a highly regulated environment on the adoption of the behaviorist model. The paper also suggests that other educational philosophies, such as the progressive philosophy, should be examined to provide a rich foundation for improving the educational experience and outcomes.
Assuntos
Currículo , Educação Médica/métodos , Física Médica/educação , Medicina Nuclear/educação , Filosofia Médica , Proteção Radiológica , Gestão da Segurança , Competência Profissional , Estados UnidosRESUMO
UNLABELLED: Combined whole-body dual-tracer ((18)F-FDG and (11)C-acetate) PET/CT is increasingly used for staging hepatocellular carcinoma, with only limited studies investigating the radiation dosimetry data of these scans. The aim of the study was to characterize the radiation dosimetry of combined whole-body dual-tracer PET/CT protocols. METHODS: Consecutive adult patients with hepatocellular carcinoma who underwent whole-body dual-tracer PET/CT scans were retrospectively reviewed with institutional review board approval. OLINDA/EXM 1.1 was used to estimate patient-specific internal dose exposure in each organ. Biokinetic models for (18)F-FDG and (11)C-acetate as provided by ICRP (International Commission on Radiological Protection) publication 106 were used. Standard reference phantoms were modified to more closely represent patient-specific organ mass. With patient-specific parameters, organ equivalent doses from each CT series were estimated using VirtualDose. Dosimetry capabilities for tube current modulation protocols were applied by integrating with the latest anatomic realistic models. Effective dose was calculated using ICRP publication 103 tissue-weighting coefficients for adult male and female, respectively. RESULTS: Fourteen scans were evaluated (12 men, 2 women; mean age ± SD, 60 ± 19.48 y). The patient-specific effective dose from (18)F-FDG and (11)C-acetate was 6.08 ± 1.49 and 1.56 ± 0.47 mSv, respectively, for male patients and 6.62 ± 1.38 and 1.79 ± 0.12 mSV, respectively, for female patients. The patient-specific effective dose of the CT component, which comprised 2 noncontrast whole-body scans, to male and female patients was 21.20 ± 8.94 and 14.79 ± 3.35 mSv, respectively. Thus, the total effective doses of the combined whole-body dual-tracer PET/CT studies for male and female patients were 28.84 ± 10.18 and 23.19 ± 4.61 mSv, respectively. CONCLUSION: Patient-specific parameters allow for more accurate estimation of organ equivalent doses. Considering the substantial radiation dose incurred, judicious medical justification is required with every whole-body dual-tracer PET/CT referral. Although radiation risks may have less impact for the population with cancer because of their reduced life expectancy, the information is of interest and relevant for both justification, to evaluate risk/benefit, and protocol optimization.
Assuntos
Acetatos , Radioisótopos de Carbono , Carcinoma Hepatocelular/diagnóstico por imagem , Fluordesoxiglucose F18 , Neoplasias Hepáticas/diagnóstico por imagem , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Imagem Corporal Total , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Traçadores Radioativos , Radiometria , Estudos Retrospectivos , RiscoRESUMO
PURPOSE: To validate radiation safety instructions to patients and to evaluate the potential radiation doses to members of the public after (125)I or (103)Pd prostate implantation. METHODS AND MATERIALS: Radiation dose rate measurements were made in the immediate postoperative period on 636 consecutive patients with stage T1-T2 prostate cancer who underwent transperineal (125)I or (103)Pd implantation at Memorial Sloan-Kettering Cancer Center during the period from August 1995 through January 2003. RESULTS: The mean radiation dose rate at the anterior skin surface following a prostate implant was 37 microSv/hr for (125)I and 8 microSv/hr for (103)Pd. At 30 cm from the anterior skin surface, these dose rates were reduced to 6 microSv/hr for (125)I and 3 microSv/hr for (103)Pd. At 1 m from the anterior skin surface the dose rates from both types of implants were reduced to less than 1 microSv/hr. The effect of body weight on dose rates from (125)I sources was examined for a select sub-group of patients and the measured dose rate was found to decrease with increasing body weight. In another group of patients, dose rate measurements were made on both lateral skin surfaces and were less than 16.8 microSv/hr in all cases. Assuming a 33% occupancy factor and utilizing the mean measured dose rate for (125)I, the time required to reach an effective dose equivalent limit of 5 mSv for caregivers was estimated to be 19 days on contact with the skin surface. Using a similar calculation, the lifetime doses for (125)I at a distance of 30 cm from the anterior skin surface, as well as the lifetime doses for (103)Pd on contact with the skin surface and at 30 cm from the anterior skin surface can be shown to be less than 5 mSv. CONCLUSIONS: The large number of cases available for this study permits a validation of radiation safety recommendations and provides concrete information from which the permitted exposure times following implantation can be estimated. The data support the conclusion that patients treated with these implants do not represent a radiation risk to members of the public.
Assuntos
Braquiterapia/efeitos adversos , Neoplasias da Próstata/radioterapia , Humanos , Radioisótopos do Iodo , Masculino , Paládio , Educação de Pacientes como Assunto , Monitoramento de Radiação , Radioisótopos , RadiometriaRESUMO
This paper presents the results of a one year survey of treated fields for 3 treatment machines at our New Jersey regional center. One machine predominantly treated IMRT prostate patients using a sliding window technique. The others were not equipped to deliver IMRT. Information obtained for each treated field included patient number, modality, monitor units delivered, gantry angle, and time. Data was obtained directly from our record and verify system and analyzed using a spreadsheet. We studied workload (MU/week), patient load, and average MU per patient as a function of time, as well as angular distributions and number of treatment fractions per patient. We also calculated the fraction of time the beam was on during treatments. By the end of the survey year, the workload of the IMRT machine reached approximately 100,000 MU/week and that of the non-IMRT machines was approximately 40-45000 MU/week. This was due predominantly to the higher number of monitor units for IMRT plans. Patient loads were not significantly different for the 3 machines. Duty cycle was 14% and 16% for the non-IMRT machines and 27% for the IMRT machine. The difference in workload for IMRT treatments relative to non-IMRT treatments confirms an earlier study performed at our institution using a much smaller data sample. One needs to consider the increase in leakage associated with this higher workload when designing shielding for an IMRT room.
Assuntos
Exposição Ambiental/análise , Exposição Ambiental/estatística & dados numéricos , Aceleradores de Partículas/instrumentação , Aceleradores de Partículas/estatística & dados numéricos , Monitoramento de Radiação/métodos , Radioterapia Conformacional/instrumentação , Radioterapia Conformacional/estatística & dados numéricos , Coleta de Dados , New York , Doses de Radiação , Dosagem Radioterapêutica , Radioterapia Conformacional/métodosRESUMO
There have been a number of persons who have estimated that the use of multi-leaf collimation and IMRT techniques increase the workload in treatment rooms to the extent that assumptions used in shielding calculations should reflect these increased workloads. This paper examines the workloads in a large department with treatment machines of varying energies and techniques. While the sample size examined is limited, the data presented demonstrate that the standard assumptions may still be sufficiently conservative that no substantive changes may be needed.