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Introduction: Osseointegration is an innovative procedure to attach an external prosthetic device directly to the skeleton. The technique has been shown to improve physical function and quality of life relative to conventional socket prosthetic devices. While much of the research in osseointegration has focused on functional outcomes, less is known regarding perioperative pain management. The purpose of this study was to describe perioperative and postoperative pain management approaches received by patients undergoing osseointegration procedures at a tertiary medical center., Materials and Methods: This retrospective study was determined to be exempt from Institutional Review Board review by the Walter Reed National Military Medical Center Department of Research Programs. Perioperative and postoperative pain management approaches received by 41 patients who underwent 76 staged osseointegration procedures from 2016 to 2021 at Walter Reed National Military Medical Center were described., Results: Pain management approaches included perioperative ketamine (51% stage I, 55% stage II), epidurals (76% stage I, 77% stage II) with a median of 3-4 days across stages, peripheral nerve catheters (27% stage I, 16% stage II), and/or single-shot peripheral nerve block (<10% across stages). The median morphine equivalent dose provided during surgery was 65 mg across both stages, with 56% and 54% of patients also requiring opioid medication in the post-anesthesia care unit. In 11 of 76 (15%) procedures, patients required an increase in the rate or concentration of epidural or peripheral nerve catheter infusion. In six (8%) unique recovery periods, patients experienced a dislodged catheter. In 27 of 76 (36%) unique recovery periods, patients experienced a significant increase in postoperative pain requiring acute pain service intervention in the form of catheter adjustment, intravenous pain medications, and/or the addition of intravenous patient-controlled analgesia. Adequate pain control was achieved with minimal epidural or peripheral nerve catheter trouble-shooting and a bolus for 24 patients (89% requiring intervention). Summed 24-hour pain scores (SPI24) did not vary across stages. SPI24 was positively correlated with opioid doses received. Patients with single, relative to multiple, limb amputations had similar SPI24 values (P > .05)., Conclusions: Variability in pain management requirements calls forth opportunities to optimize osseointegration analgesia care and future research. As osseointegration becomes more accessible, the need for optimizing pain management through patient-centered research becomes more salient., (Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2024. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

An updated version of the skin dose computer code VARSKIN, namely VARSKIN 4, was examined to determine the accuracy of the photon model in calculating dose rates with different combinations of source geometry and radionuclides. The reference data for this validation were obtained by means of Monte Carlo transport calculations using MCNP5. The geometries tested included the zero volume sources point and disc, as well as the volume sources sphere and cylinder. Three geometries were tested using source directly on the skin, source off the skin with an absorber material between source and skin, and source off the skin with only an air gap between source and skin. The results of these calculations showed that the non-volume sources produced dose rates that were in very good agreement with the Monte Carlo calculations, but the volume sources resulted in overestimates of the dose rates compared with the Monte Carlo results by factors that ranged up to about 2.5. The results for the air gap showed poor agreement with Monte Carlo for all source geometries, with the dose rates overestimated in all cases. The conclusion was that, for situations where the beta dose is dominant, these results are of little significance because the photon dose in such cases is generally a very small fraction of the total dose. For situations in which the photon dose is dominant, use of the point or disc geometries should be adequate in most cases except those in which the dose approaches or exceeds an applicable limit. Such situations will often require a more accurate dose assessment and may require the use of methods such as Monte Carlo transport calculations.

United States Nuclear Regulatory Commission (USNRC) regulations limit the dose to the skin to 500 mSv per year. This is also the dose limit recommended by the International Commission on Radiological Protection (ICRP). The operational quantity recommended by ICRP for quantifying dose to the skin is the personal dose equivalent, Hp(0.07) and is identical to NRC's shallow dose equivalent, Hs, also measured at a skin depth of 7 mg cm-2. However, whereas ICRP recommends averaging the dose to the skin over an area of 1 cm regardless of the size of the exposed area of skin, USNRC requires the shallow dose equivalent to be averaged over 10 cm. To monitor dose to the skin of the hands of workers handling radioactive materials and particularly in radiopharmaceutical manufacturing facilities, which is the focus of this work, workers are frequently required to wear finger ring dosimeters. The dosimeters monitor the dose at the location of the sensitive element, but this is not the dose required to show compliance (i.e., the dose averaged over the highest exposed contiguous 10 cm of skin). Therefore, it may be necessary to apply a correction factor that enables estimation of the required skin dose from the dosimeter reading. This work explored the effects of finger ring placement and of the geometry of the radioactive materials being handled by the worker on the relationship between the dosimeter reading and the desired average dose. A mathematical model of the hand was developed for this purpose that is capable of positioning the fingers in any desired grasping configuration, thereby realistically modeling manipulation of any object. The model was then used with the radiation transport code MCNP to calculate the dose distribution on the skin of the hand when handling a variety of radioactive vials and syringes, as well as the dose to the dosimeter element. Correction factors were calculated using the results of these calculations and examined for any patterns that may be useful in establishing an appropriate correction factor for this type of work. It was determined that a correction factor of one applied to the dosimeter reading, with the dosimeter placed at the base of the middle finger, provides an adequate estimate of the required average dose during a monitoring period for most commonly encountered geometries. Different correction factors may be required for exceptional or unusual source geometries and must be considered on a case-by-case basis.

The computer code VARSKIN is used extensively to calculate dose to the skin resulting from contaminants on the skin or on protective clothing covering the skin. The code uses six pre-programmed source geometries, four of which are volume sources, and a wide range of user-selectable radionuclides. Some verification of this code had been carried out before the current version of the code, version 3.0, was released, but this was limited in extent and did not include all the source geometries that the code is capable of modeling. This work extends this verification to include all the source geometries that are programmed in the code over a wide range of beta radiation energies and skin depths. Verification was carried out by comparing the doses calculated using VARSKIN with the doses for similar geometries calculated using the Monte Carlo radiation transport code MCNP5. Beta end-point energies used in the calculations ranged from 0.3 MeV up to 2.3 MeV. The results showed excellent agreement between the MCNP and VARSKIN calculations, with the agreement being within a few percent for point and disc sources and within 20% for other sources with the exception of a few cases, mainly at the low end of the beta end-point energies. The accuracy of the VARSKIN results, based on the work in this paper, indicates that it is sufficiently accurate for calculation of skin doses resulting from skin contaminations, and that the uncertainties arising from the use of VARSKIN are likely to be small compared with other uncertainties that typically arise in this type of dose assessment, such as those resulting from a lack of exact information on the size, shape, and density of the contaminant, the depth of the sensitive layer of the skin at the location of the contamination, the duration of the exposure, and the possibility of the source moving over various areas of the skin during the exposure period if the contaminant is on protective clothing.

Members of the public visiting hospitalized patients undergoing nuclear medicine procedures or brachytherapy are exposed to radiation emanating from the patient. The radiation protection staff at the hospital is responsible for ensuring that the doses to these visitors are kept as low as is reasonably achievable and are maintained below applicable regulatory limits. These limits are normally expressed in terms of the effective dose to the visitor. Direct measurement of the effective dose, however, is not feasible, and the use of a quantity that provides a reasonable estimate, referred to as a surrogate, is required. This study used Monte Carlo radiation transport calculations to examine the feasibility of using bedside survey results, in units of roentgens per hour, as a surrogate for estimating the effective dose to a person who may be present at the survey location. The Monte Carlo code used in this work was MCNP Version 5. In these calculations, both the patient and the visitor were modeled using modified Medical Internal Radiation Dose anthropomorphic phantoms. Radioactive material that emitted monoenergetic photons was located in several of the patient's organs in turn, and the bedside exposure rates and the effective doses at the same location were calculated. The calculations were repeated for several visitor locations, both at bedside along the length of the bed, and at increasing distances from the bed. The ratios of the exposure rates to the effective dose rates at each location gave an indication of the utility of the exposure rate measurements in providing a reasonable estimate of the effective dose. The results indicated that the survey data provided estimates of the effective dose within recommended accuracy for many exposure situations, but underestimated the effective dose to the visitor for other situations, especially locations close to bedside and for lower energy radiations. Use of appropriate correction factors based on this work could improve the utility of the survey data for the underestimated situations, and the exposure rate data could still be used to estimate the dose to a visitor within recommended accuracy, provided the estimated dose does not approach too closely to the applicable limit.

The use of the personal dose equivalent Hp(10), as measured by one or more dosimeters, in estimating the effective dose equivalent H(E) and the effective dose E was examined for situations in which a protective apron is worn by the monitored person during medical procedures. The photon energy range considered was between 0.03-1.0 MeV. Several methods recommended in the technical literature for this purpose were assessed and their ability to provide reasonable estimates for H(E) and E were compared. The assessments were theoretical and used Monte Carlo transport methods and an anthropomorphic phantom to calculate H(E), E, and Hp(10). The results showed that all of the recommended methods, using either one or more dosimeters, were applicable to this situation but that most gave good results only within limited photon energy ranges, outside of which they either considerably over-or under-estimated the doses. Some provided good estimates over the entire energy range considered.