AAPM Medical Physics Practice Guideline 14.a: Yttrium-90 microsphere radioembolization.

Radioembolization using Yttrium-90 (90 Y) microspheres is widely used to treat primary and metastatic liver tumors. The present work provides minimum practice guidelines for establishing and supporting such a program. Medical physicists play a key role in patient and staff safety during these procedures. Products currently available are identified and their properties and suppliers summarized. Appropriateness for use is the domain of the treating physician. Patient work up starts with pre-treatment imaging. First, a mapping study using Technetium-99m (Tc-99m ) is carried out to quantify the lung shunt fraction (LSF) and to characterize the vascular supply of the liver. An MRI, CT, or a PET-CT scan is used to obtain information on the tumor burden. The tumor volume, LSF, tumor histology, and other pertinent patient characteristics are used to decide the type and quantity of 90 Y to be ordered. On the day of treatment, the appropriate dose is assayed using a dose calibrator with a calibration traceable to a national standard. In the treatment suite, the care team led by an interventional radiologist delivers the dose using real-time image guidance. The treatment suite is posted as a radioactive area during the procedure and staff wear radiation dosimeters. The treatment room, patient, and staff are surveyed post-procedure. The dose delivered to the patient is determined from the ratio of pre-treatment and residual waste exposure rate measurements. Establishing such a treatment modality is a major undertaking requiring an institutional radioactive materials license amendment complying with appropriate federal and state radiation regulations and appropriate staff training commensurate with their respective role and function in the planning and delivery of the procedure. Training, documentation, and areas for potential failure modes are identified and guidance is provided to ameliorate them.

AAPM task group report 305: Guidance for standardization of vendor-neutral reject analysis in radiography.

Reject rate analysis is considered an integral part of a diagnostic radiography quality control (QC) program. A rejected image is a patient radiograph that was not presented to a radiologist for diagnosis and that contributes unnecessary radiation dose to the patient. Reject rates that are either too high or too low may suggest systemic department shortcomings in QC mechanisms. Due to the lack of standardization, reject data often cannot be easily compared between radiography systems from different vendors. The purpose of this report is to provide guidance to help standardize data elements that are required for comprehensive reject analysis and to propose data reporting and workflows to enable an effective and comprehensive reject rate monitoring program. Essential data elements, a proposed schema for classifying reject reasons, and workflow implementation options are recommended in this task group report.

131I Intake and Regulatory Compliance Following Administration of Capsular 131I Sodium Iodide for Treatment of Thyroid Disorders.

ABSTRACT: Intake of 131I by nuclear medicine technologists and physician Authorized Users was evaluated using bioassay data from administration of 131I sodium iodide in capsular form during a 5-year period. Maximum estimated annual intake of 131I sodium iodide, based on bioassay measurements performed at 24 hours post administration, ranged from 10.9 to 35.6 kBq for all staff. Intake by Authorized Users was higher than that by nuclear medicine technologists due to state requirement for Authorized Users to physically administer therapeutic dosages of radiopharmaceuticals. All intake values were less than 10% of the 131I thyroid ALI of 50 microcurie3 (1,850 kBq), indicating that monitoring may be discontinued for staff participating in routine administration of 131I capsules in which volatilization is not suspected. Elimination of bioassay performance has permitted more flexibility in patient scheduling and improved workflow and efficiency.

Use of Reduced Activity Seeds in Breast Radioactive Seed Localization.

Radioactive seed localization procedures, using I seeds of typical activity 3.7 MBq and higher, are performed to localize nonpalpable lesions in the breast for surgical excision and pathology analysis. This study evaluated the use and dosimetry of I seeds of activity <3.7 MBq in radioactive seed localization procedures through retrospective health record review, Monte Carlo simulation, and experimental detection. An average seed strength at the time of specimen excision of 2.48 ± 0.629 MBq was used in 295 radioactive seed localization procedures at Gundersen Health System in La Crosse, Wisconsin, US. The average explanted seed activity served as a basis for Monte Carlo simulation of an I IsoAid Advantage seed embedded in soft tissue, which scored the dose deposited to soft tissue. Tabulated values of the dose to postsurgical residual tissue as a function of explanted tumor radius were shown and compared with previously published results. Use of seeds of activity from 1.44 to 3.7 MBq at the time of excision did not adversely affect seed detection and excision. The absorbed dose to residual tissue calculated using Monte Carlo was an average of 1.4 times larger than previously published results when scaled to identical seed strengths. This study demonstrates that seeds of activity <3.7 MBq can be used for radioactive seed localization procedures with no loss in efficacy and a benefit of reduced radiation dose to patients. This is important because the estimated radiation dose to residual tissue is approximately 1.4 times higher than previously indicated.

Early Results of Lung Cancer Screening and Radiation Dose Assessment by Low-dose CT at a Community Hospital.

BACKGROUND: The National Lung Screening Trial showed a reduction in overall and cancer-specific mortality for patients screened with low-dose computed tomography (LDCT) versus chest radiograph. Some question whether this can be achieved in community healthcare settings. Our aim was to analyze lung cancer screening outcomes and administered radiation dose using LDCT scans at a community hospital. PATIENTS AND METHODS: We retrospectively reviewed the records of 680 patients who underwent LDCT between June 2014 and December 2015, and who met Centers for Medicare and Medicaid Services lung cancer screening criteria: asymptomatic, aged 55 to 77 years, smoked within the last 15 years, and ≥ 30 pack-year history. Effective and absorbed doses were calculated and correlated with gender and body mass index. RESULTS: Among the 133 patients (19.6%) with a positive screening result (Lung Imaging Reporting and Data System score of 3 or 4), 18 lung cancers were identified in 16 patients, 56.3% (9 of 16) of which were stage I non-small-cell lung cancer. The false-positive rate was 82.8% (95% confidence interval, 73.6%-89.8%). Mean estimated effective dose using dose length product and size-specific dose estimate using water equivalent diameter were 1.2 mSv and 3.7 mGy for women and 1.4 mSv and 3.9 mGy for men, respectively. All dosing metrics were strongly correlated with body mass index (P < .0001). CONCLUSIONS: Over half of screening patients diagnosed with non-small-cell lung cancer in our community had stage I disease, which we anticipate translating into significantly improved mortality. Patient radiation dose from LDCT scans is approximately one-fifth that from standard CT chest examinations.

Estimates of effective dose for CT scans of the lower extremities.

PURPOSE: To determine the dose-length product (DLP)-effective dose (ED) (DLP/ED) conversion coefficient (k) tables for the lower extremities that can be used for calculating ED. MATERIALS AND METHODS: Dose calculations were performed on standard phantoms using a validated Monte Carlo calculation tool. Calculations were performed to obtain ED values for tube voltages from 80 kV to 140 kV in steps of 20 kV for the following examinations: hip (femur), knee, ankle, and computed tomographic (CT) angiography of the lower extremities. Values of the DLP were calculated by multiplying measured CT dose index values by the scan length; k values resulted as the quotients of the ED and DLP values. DLP/ED coefficients averaged over the range of voltage values and their standard deviations were determined for the given lower-extremity CT examinations for all age groups and for both sexes. RESULTS: Coefficients depend strongly on the phantom age and size, but little on the kilovolt value. In the case of the newborn, for example, k values were 0.0612, 0.0046, 0.0014, and 0.047 for hip, knee, ankle, and CT angiography, respectively, while in the case of the adult, these respective values were 0.0110, 0.0004, 0.0002, and 0.0062. A substantial difference up to 20% between coefficients in male and female phantoms was observed for CT angiographic examination. CONCLUSION: DLP/ED conversion coefficients are provided for lower extremities and allow estimation of ED for commonly used clinical musculoskeletal CT and CT angiographic protocols.

Consequences of increased use of computed tomography imaging for trauma patients in rural referring hospitals prior to transfer to a regional trauma centre.

BACKGROUND: Computed tomography (CT) plays an integral role in the evaluation and management of trauma patients. As the number of referring hospital (RH)-based CT scanners increased, so has their utilization in trauma patients before transfer. We hypothesized that this has resulted in increased time at RH, image duplication, and radiation dose. METHODS: A retrospective chart review was completed for trauma activations transferred to an ACS-verified Level II Trauma Centre (TC) during two time periods: 2002-2004 (Group 1) and 2006-2008 (Group 2). 2005 data were excluded as this marked the transition period for acquisition of hospital-based CT scanners in RH. Statistical analysis included t test and χ(2) analysis. P<0.05 was considered significant. RESULTS: 1017 patients met study criteria: 503 in group 1 and 514 in group 2. Mean age was greater in group 2 compared to group 1 (40.3 versus 37.4, respectively; P=0.028). There were 115 patients in group 1 versus 202 patients in group 2 who underwent CT imaging at RH (P<0.001). Conversely, 326 patients in group 1 had CT scans performed at the TC versus 258 patients in group 2 (P<0.001). Mean time at the RH was similar between the groups (117.1 and 112.3min for group 1 and 2, respectively; P=0.561). However, when comparing patients with and without a pretransfer CT at the RH, the median time at RH was 140 versus 67min, respectively (P<0.001). The number of patients with duplicate CT imaging (n=34 in group 1 and n=42 in group 2) was not significantly different between the two time periods (P=0.392). Head CTs comprised the majority of duplicate CT imaging in both time periods (82.4% in group 1 and 90.5% in group 2). Mean total estimated radiation dose per patient was not significantly different between the two groups (group 1=8.4mSv versus group 2=7.8mSv; P=0.192). CONCLUSIONS: A significant increase in CT imaging at the RH prior to transfer to the TC was observed over the study periods. No associated increases in mean time at the RH, image duplication at TC, total estimated radiation dose per patient, and mortality rate were observed.

Applying Image Gently SM and Image Wisely SM in nuclear medicine.

Although computed tomography (CT) scan radiation dose has drawn much attention, radiation dose from nuclear medicine procedures should not be overlooked. An estimated 19.7 million nuclear medicine procedures are done annually in the United States, with patient radiation dose comparable to that from CT scans. Nuclear medicine departments should implement Image Gently SM and Image Wisely SM recommendations to reduce nuclear medicine patient radiation dose. Pediatric administered radiopharmaceutical doses should be compared with the North American Consensus Guidelines for Administered Radiopharmaceutical Activities in Children and Adolescents, and adult doses should be compared with national and international standards. In a 2011 patient quality and safety initiative at Gundersen Lutheran Health System, 24 pediatric protocols and 52 adult protocols were compared with standards. Doses not comparable to the recommended values were adjusted accordingly and the resultant image quality evaluated. Additional steps to reduce patient radiation dose include decision support to reduce inappropriate ordering, technique optimization for the CT portion of single-photon emission computed tomography/computed tomography and positron emission tomography/computed tomography scans, use of vendor's dose reduction camera and software technology, use of shorter lived radiopharmaceuticals, and "right sizing" patient doses by weight.

Radiological incident preparedness for community hospitals: a demonstration project.

In November 2007, the Wisconsin Division of Public Health Hospital Disaster Preparedness Program State Expert Panel on Radiation Emergencies issued a report titled The Management of Patients in a Radiological Incident. Gundersen Lutheran Health System was selected to conduct a demonstration project to implement the recommendations in that report. A comprehensive radiological incident response plan was developed and implemented in the hospital's Trauma and Emergency Center, including the purchase and installation of radiation detection and identification equipment, staff education and training, a tabletop exercise, and three mock incident test exercises. The project demonstrated that the State Expert Panel report provides a flexible template that can be implemented at community hospitals using existing staff for an approximate cost of $25,000.