Improved reconstruction methodology of clinical electron energy spectra based on Tikhonov regularization and generalized simulated annealing

Electron beam radiotherapy is the most widespread treatment modality todeal with superficial cancers. In electron radiotherapy, the energy spectrum isimportant for electron beam modelling and accurate dose calculation. Since thepercentage depth-dose (PDD) is a function of the beam’s energy, the reconstruction of the spectrum from the depth-dose curve represents an inverse problem.Thus, the energy spectrum can be related to the depth-dose by means of anappropriate mathematical model as the Fredholm equation of the first kind.Since the Fredholm equation of the first kind is ill-posed, some regularizationmethod has to be used to achieve a useful solution. In this work the Tikhonovregularization function was solved by the generalized simulated annealing optimization method. The accuracy of the reconstruction was verified by thegamma index passing rate criterion applied to the simulated PDD curves forthe reconstructed spectra compared to experimental PDD curves. Results showa good coincidence between the experimental and simulated depth-dose curvesaccording to the gamma passing rate better than 95% for 1% dose difference(DD)/1 mm distance to agreement (DTA) criteria. Moreover, the results showimprovement from previous works not only in accuracy but also in calculationtime. In general, the proposed method can help in the accuracy of dosimetryprocedures, treatment planning and quality control in radiotherapy.

Features of absorbed radiation doses calculation for cattle’s in Krasnoyarsk krai

The article provides an adapted methodology of absorbed dose calculation for the cattle from the territories with long-term man-made contamination. The methodology was developed according to existing regulatory documents in the RF: veterinarian rules VR 13.73.13/12-00, VR 13.5.13/03-00, methodical instructions MI 13.5.13-00, regulation for the state veterinarian control system in radioactive contamination of veterinary surveillance objects in the Russian Federation. The aim of the work is the development of calculation methodology of absorbed radiation doses for the cattle on the territory with long-term man-made isotopes contamination, taking to the account the radionuclide composition of the soil. Methods. The regulatory documents governing absorbed doses calculation has been analyzed; the contribution of external and internal radiation into total annual absorbed dose has been determined. Results. It has been established, that the calculation of external radiation dose needs to be done considering doses in stable and pasture periods. Pasture period dose is a sum of day and night doses considering day length. According to the data of radio ecological situation in Krasnoyarsk krai the internal radiation dose should be calculated as a sum of 137Cs, 90Sr, 60Co, taking to the account different concentration of these radionuclides in green and coarse fodder. Scientific novelty. The methodology of dose calculation for the cattle according to the radio ecological situation in Krasnoyarsk krai has been introduced for the first time. Practical significance. This methodology is recommended for the specialists of radiological departments of veterinarian laboratories and science officers in the field of agricultural radiobiology.

Decreasing drug waste, reducing drug costs, and improving workflow efficiency through the implementation of automated chemotherapy dose rounding rules in the electronic health record system

Disclaimer In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time. Purpose To decrease drug waste and cost by implementing automated chemotherapy dose rounding rules in the electronic health record (EHR). Dose rounding of chemotherapy is a recognized method for reducing drug waste, and professional organizations have published guidelines recommending dose rounding when possible. Summary On the basis of current literature and guideline recommendations, Mayo Clinic developed system-wide consensus to allow dose rounding for biologic and chemotherapy agents to the nearest vial size if rounding resulted in the dose being within 10% of the originally calculated dose or to a convenient measurable volume, based on concentration of the drug, if rounding to the nearest vial size resulted in the dose being outside the 10% range. Oncology pharmacists reviewed and analyzed all drugs listed in the EHR used in injectable form for the treatment of cancer and developed dose rounding rules. The rules were implemented and applied at the dose calculation stage before provider signature. From January to June 2019, approximately 40,000 cancer treatment doses were administered. The rounding rules saved a total of 9,814 vials of drug, of which 5,329 were for biologic agents and 4,485 were for oncolytic drugs. This resulted in a total 6-month cost savings of $7,284,796 (in 2019 dollars; biologics, $5,727,402; oncolytics, $1,557,394). Conclusion Systematic implementation of dose rounding rules utilizing the EHR can result in significant reduction of drug waste and realization of savings.

Dosimetric Evaluation of a Treatment Planning System Using the Aapm Medical Physics Practice Guideline 5.a (MPPG 5.a) Validation Tests

In this work, the AAPM Medical Physics Practice Guideline 5.a (MPPG 5.a) validation tests package was used to evaluate the dosimetric performance of a new version of the Eclipse treatment planning system (TPS) algorithms. A series of tests were developed and comparisons between TPS calculated and corresponding beam data measurements have been performed for basic beam validation, heterogeneity correction and IMRT/VMAT dose validation tests. Measurements were performed using a Varian IX Linear Accelerator with the 6 MV, 6MV FFF and 18 MV photon beams, and 6, 9, 12, 16, 20 MeV electron beams. Results for basic dose validation tests yielded differences within 3% for all point doses and pass rate greater than 95% for all depth profiles using 3%/3mm criteria. For testing the ability of the TPS in accounting for tissue inhomogeneity, corresponding comparisons were performed with the presence of a heterogeneous media to simulate an air inhomogeneity. Results showed a mean deviation between the TPS calculated and measured of 1.9%, reaching a maximum of 2.8% for the AAA algorithm. For IMRT/VMAT validation tests, our local criteria passing rate of 95% was used, but no consensus of the tolerance exists. Our results agree well with the data reported accuracy in previous studies of Eclipse TPS. In summary, the AAPM MPPG 5.a validation tests are a valuable package for evaluating dose calculation accuracy and are very useful for TPS upgrade checks, commissioning tests and routine TPS QA.

Diagnostic reference levels in digital mammography: A systematic review

Diagnostic reference levels (DRLs) in digital mammography (DM) serve as a useful benchmark for dose monitoring and optimization, allowing comparison amongst countries, institutions and mammography units. A systematic review of DRLs in DM, published in 2014, reported a lack of consistent and internationally accepted protocol in DRLs establishment, thereby resulting in wide variations in methodologies which complicates comparability between studies. In 2017, the International Commission of Radiation Protection (ICRP) published additional guidelines and recommendations to provide clarity in the protocol used in DRLs establishment. With the continuing evolvement of technology, optimization of examinations and updates in guidelines and recommendations, DRLs should be revised at regular intervals. This systematic review aims to provide an update and identify a more consistent protocol in the methodologies used to establish DRLs. Searches were conducted through Web of Science, PubMed-MEDLINE, ScienceDirect, CINAHL and Google Scholar, which resulted in 766 articles, of which 19 articles were included after screening. Relevant data from the included studies were summarized and analyzed. While the additional guidelines and recommendations have provided clarifications in the methodologies used in DRLs establishment, such as data source (i.e., the preference to use data derived from patient instead of phantoms to establish DRLs), protocol (i.e., stratification of DRLs by compressed breast thickness and detector technology, and the use of median value for DRLs quantity instead of mean) and percentiles used to establish DRLs (i.e., set at the 75th percentile with a minimum sample size of 50 patients), other differences such as the lack of a standard dose calculation method used to estimate mean glandular dose continues to complicate comparisons between studies and different DM systems. This systematic review update incorporated the updated guidelines and recommendations from ICRP which will serve as a useful resource for future research efforts related to DRLs, dose monitoring and optimization.

Evaluation of a treatment planning system developed for clinical boron neutron capture therapy and validation against an independent Monte Carlo dose calculation system

Boron neutron capture therapy (BNCT) for the treatment of unresectable, locally advanced, and recurrent carcinoma of the head and neck cancer has been approved by the Japanese government for reimbursement under the national health insurance as of June 2020. A new treatment planning system for clinical BNCT has been developed by Sumitomo Heavy Industries, Ltd. (Sumitomo), NeuCure® Dose Engine. To safely implement this system for clinical use, the simulated neutron flux and gamma ray dose rate inside a water phantom was compared against experimental measurements. Furthermore, to validate and verify the new planning system, the dose distribution inside an anthropomorphic head phantom was compared against a BNCT treatment planning system SERA and an in-house developed Monte Carlo dose calculation program. The simulated results closely matched the experimental results, within 5% for the thermal neutron flux and 10% for the gamma ray dose rate. The dose distribution inside the head phantom closely matched with SERA and the in-house developed dose calculation program, within 3% for the tumour and a difference of 0.3 Gyw for the brain.