Different radiographic imaging modalities with a proton computed tomography demonstrator

Proton computed tomography aims at improving proton-beam therapy, which is an established method to treat deep-seated tumours in cancer therapy. In treatment planning, the stopping power (SP) within a patient, describing the energy loss of a proton in a tissue, has to be known with high accuracy. However, conventional computed tomography (CT) returns Hounsfield units (HU), which have to be converted to SP values to perform the required treatment planning, thus introducing range uncertainties in the calculated dose distribution. Using protons not only for therapy but also for the preceding planning CT enables the direct measurement of the SP. Hence, this imaging modality eliminates the need for further conversion and therefore offers the possibility to improve treatment planning in proton therapy. In order to examine the principles of such a proton CT (pCT) setup, a demonstrator system, consisting of four double-sided silicon strip detectors and a range telescope, was built. The performance of the pCT demonstrator was tested with measurements at the MedAustron facility in Wiener Neustadt, Austria. In this paper, 2D imaging modalities going beyond the idea of a standard proton radiography, will be discussed. Namely, fluence loss imaging and scattering radiography results obtained with the demonstrator will be shown. The advantage of these modalities is that they do not rely on an additional energy measurement and can therefore be conducted only with the tracker of the demonstrator.

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.

Usulan kriteria pemulangan pasien (patient release) kedokteran nuklir di Indonesia

Nuclear medicine procedures are carried out by applying a radioactive substance to the patient’s body. Thus, the patient can be assumed to be a ‘radiation source’ and needs to follow special provisions so that his presence does not expose nearby individuals unnecessarily. Therefore, when the patient is released from the hospital, it must ensure that the patient’s radiation exposure does not expose the individuals in the vicinity. However, several related regulations have not regulated this in detail. In this paper, a study is carried out regarding the criteria considered in the release of nuclear medicine patients. The method used is a literature study. The study results recommend release criteria through two approaches based on the estimated maximum effective dose that the public may accept, namely conditional release with a calculated dose of less than or equal to 5 mSv and unconditional release with an estimated dose of less than or equal to 1 mSv. Conditional release is the release of a patient provided with post-release guidance, while unconditional release is the release of the patient without being supplied with post-release advice. Keywords: nuclear medicine, patient release, conditional release, unconditional release

Comparison between different Dosimetric Tools based on Intensity-modulated Radiotherapy (IMRT): A Phantom Study

This study examined the gamma passing rate (GPR) consistency during applying different kinds of gamma analyses and dosimeters to IMRT. Methods: Import treatment protocols for QA phantom irradiation have been recalculated. A gamma analysis was used for comparing the measured and calculated dose distribution of IMRT for different gamma criteria (2%/2mm, 3%/3mm, 4%/4mm, 3%/5mm, 3%/5mm). These criteria are evaluated when 5%, 10%, or 15% of the dose distribution is suppressed. Measured and calculated dose distribution was evaluated with gamma analysis to dose difference (DD) with DTA criteria (distance to agreement). IMRT QA plans to 25 patients from various sites were formed with the Varian Eclipse treatment planning system. Results: Results indicate different diverse hardware and software combinations show varied levels of agreement with expected analysis for the same pass-rate criterion. For a dosimetry audit of the IMRT technique, an EPID detector is superior to conventional methods comparable to Gafchromic EPT3 film and 2D array due to cost, time-consuming, and set up error to get result analysis. The gamma passing rate (GPR) average is increased by increasing the low-dose threshold for different dosimetric tools. For EPID, regardless of the gamma criterion employed, the %GP does not appear to be dependent on the low-dose threshold values (5%-15%) because it indicates that fulfilment the low-dose threshold to global normalization has little effect on patient-specific QA outcomes. Conclusions: It is concluded that GPRs differ depending on gamma, dosimetric tools, and the suppressing dose ratio. To get the best results of quality assurance, each institution should thus carefully develop its procedure for gamma analysis by defining the gamma index analysis and gamma criterion using its dosimetric tools.

Povidon-iodine applied for the treatment of chylothorax in children

Introduction. The aim of this study is to demonstrate the experience of non-surgical treatment of congenital and acquired chylothorax in children using povidone-iodine.Material and methods. The study presents results of treatment of 10 patients with chylothorax who had chemical pleurodesis with povidone-iodine. The study covered a time period from 2016 to 2020. The congenital character of the disease was registered in 2 patients, the acquired one - in 8 patients. The main indication for surgery was ineffective conservative therapy, including the withdrawal of feeding and the administration of preparation Octreotide. The procedure consisted of intrapleural injection of 4% povidone-iodine solution into the pleural cavity with the calculated dose of 1 ml/kg and solution exposure for 4 hours. Results. The interpleural administration of povidone-iodine was effective in all patients. Complications of chemical pleurodesis were observed in 2 patients and were associated with pulmonary edema on the injection side. Lymph outflow was stopped on average in 4 days. There was one adverse episode which developed because of the lung malformation incompatible with life. Conclusions. Intrapleural administration of povidone-iodine is an effective treatment of chylothorax in children.

Comparison of the Therapeutic Potential of Rat and Human Mesenchymal Stromal Cells and Their Conditioned Media in Local Radiation Lesions

Background: To compare the results of the use of mesenchymal stromal cells (MSCs) of human gingival mucosa and MSCs of rat gingival mucosa, their conditioned media, and to evaluate their effect on tissue regeneration in local radiation injury (LRI). Material and methods: The study included 120 white male Wistar rats weighing 210 ± 30 g at the age of 8–12 weeks, randomized into 6 groups (20 animals each): control (C), animals did not receive therapy; control with the introduction of culture medium concentrate (CM) three times for 1, 14, 21 days; administration of human gingival mucosa MSCs (HM) at a dose of 2 million per 1 kg three times for 1, 14, 21 days; administration of human gingival mucosa MSCS conditioned medium concentrate (HMCM) at a calculated dose of 2 million cells per 1 kg three times for 1, 14, 21 days; administration of rat gingival mucosal MSCs (RM) at a dose of 2 million cells per 1 kg three times for 1, 14, 21 days; administration of rat gingival mucosal MSCS (RMCM) conditioned medium concentrate at a calculated dose of 2 million cells per 1 kg three times for 1, 14, 21 days. Each laboratory animal was observed 17 times: on 1, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98, 105, 112 day after the burn simulation. Histological (hematoxylin-eosin staining) and immunohistochemical (CD31, CD68, VEGF, PGP 9.5, MMP2,9, Collag 1, TIMP 2) studies were performed. LRI was modeled on an X-ray machine at a dose of 110 Gy. MSCs were cultured according to the standard method up to 3–5 passages, the conditioned medium was taken and concentrated 10 times. The immunophenotype of MSCs (CD34, CD45, CD90, CD105, CD73, HLA-DR) and viability (7‑ADD) were determined by flow cytofluorimetry. Results: In a comparative analysis with the control group (C), starting from the 42nd day of the study, a tendency to reduce the area of skin ulcers in animals in all groups was observed, despite the fact that not all days had statistically significant differences. On day 112th, complete healing of skin ulcers in the CM group was observed in 40 % of animals in the HM group – in 60 %, in the HMCM group – in 20 % of animals, in the RMCM group–20 %, and in the C and RM groups there were no animals with a prolonged wound defect. Positive expression of the VEGF marker was observed in groups C and CM on the 28th day and in experimental groups (HM, HMCM, RM, RMCM) on the 112th day. A statistically significant increase in the CD68 marker was observed in groups C, RM, and RMCM, while the remaining groups showed a decrease in the number of macrophages.

Development of an Electronic Portal Imaging Device Dosimetry Method

Support arm backscatter and off-axis effects of an electronic portal imaging device (EPID) are challenging for radiotherapy quality assurance. Aiming at the issue, we proposed a simple yet effective method with correction matrices to rectify backscatter and off-axis responses for EPID images. First, we measured the square fields with ionization chamber array (ICA) and EPID simultaneously. Second, we calculated the dose-to-pixel value ratio and used it as the correction matrix of the corresponding field. Third, the correction value of the large field was replaced with that of the same point in the small field to generate a correction matrix suitable for different EPID images. Finally, we rectified the EPID image with the correction matrix, and then the processed EPID images were converted into the absolute dose. The calculated dose was compared with the measured dose via ICA. The gamma pass rates of 3%/3 mm and 2%/2 mm (5% threshold) were 99.6% ± 0.94% and 95.48% ± 1.03%, and the average gamma values were 0.28 ± 0.04 and 0.42 ± 0.05, respectively. Experimental results verified our method accurately corrected EPID images and converted pixel values into absolute dose values such that EPID was an efficient radiotherapy dosimetry tool.

Dosimetric Validation of a System to Treat Moving Tumors Using Scanned Ion Beams That Are Synchronized With Anatomical Motion

PurposeThe purpose of this study was to validate the dosimetric performance of scanned ion beam deliveries with motion-synchronization to heterogenous targets.MethodsA 4D library of treatment plans, comprised of up to 10 3D sub-plans, was created with robust and conventional 4D optimization methods. Each sub-plan corresponded to one phase of periodic target motion. The plan libraries were delivered to a test phantom, comprising plastic slabs, dosimeters, and heterogenous phantoms. This phantom emulated range changes that occur when treating moving tumors. Similar treatment plans, but without motion synchronization, were also delivered to a test phantom with a stationary target and to a moving target; these were used to assess how the target motion degrades the quality of dose distributions and the extent to which motion synchronization can improve dosimetric quality. The accuracy of calculated dose distributions was verified by comparison with corresponding measurements. Comparisons utilized the gamma index analysis method. Plan quality was assessed based on conformity, dose coverage, overdose, and homogeneity values, each extracted from calculated dose distributions.ResultsHigh pass rates for the gamma index analysis confirmed that the methods used to calculate and reconstruct dose distributions were sufficiently accurate for the purposes of this study. Calculated and reconstructed dose distributions revealed that the motion-synchronized and static deliveries exhibited similar quality in terms of dose coverage, overdose, and homogeneity for all deliveries considered. Motion-synchronization substantially improved conformity in deliveries with moving targets. Importantly, measurements at multiple locations within the target also confirmed that the motion-synchronized delivery system satisfactorily compensated for changes in beam range caused by the phantom motion. Specifically, the overall planning and delivery approach achieved the desired dose distribution by avoiding range undershoots and overshoots caused by tumor motion.ConclusionsWe validated a dose delivery system that synchronizes the movement of the ion beam to that of a moving target in a test phantom. Measured and calculated dose distributions revealed that this system satisfactorily compensated for target motion in the presence of beam range changes due to target motion. The implication of this finding is that the prototype system is suitable for additional preclinical research studies, such as irregular anatomic motion.

Eighteen-year results of treatment of uveal melanoma using Ruthenium-106 + Rhodium-106 brachytherapy

The objective of the study was to evaluate the results of Ruthenium-106 (106Ru) + Rhodium-106 (106Rh) brachytherapy in uveal melanoma (UM) patients.The data for the period 2001–2018 were taken from the Belarusian Cancer Registry and medical records of patients with clinically diagnosed uveal melanoma who received treatment at the N. N. Alexandrov National Cancer Centre of Belarus. A total of 383 patients were included in the study. 106Ru + 106Rh β-ophthalmic applicators were used for brachytherapy (BT). The calculated dose to the tumor apex was 120–130 Gy, while the reduced 100–110 Gy was administered to tumors close to the optic nerve. To analyze the treatment outcomes, patients were divided into three groups based on a basal diameter of a tumor.Out of a total 383 patients, complete tumor resolution was observed in 282 (73.6 %), tumor stabilization was present in 76 (19.8 %). Continued tumor growth and tumor relapse were observed in 34 (9.13 %) and 50 (13.05 %) patients, respectively. 59 (15.1 %) patients underwent enucleation. The metastatic disease developed in 47 (12.3 %) cases. BT adverse effects were observed in 21.3 % cases. The relapse-free survival in the group of patients with a basal tumor diameter of up to 9 mm was 76.0 ± 6.3 %, which was higher than that in the groups with a large basal diameter (p = 0.002). Over a 15-year follow-up period, almost half of the patients (52.2 ± 15.6 %) with a tumor base of more than 12 mm relapsed.Considering the high rates of the continued tumor growth during treatment in patients with a basal tumor diameter of more than 12 mm, combined therapy must be used in this group.

A COMPARATIVE STUDY ON THE TOTAL DOSE REQUIREMENTS AND HEMODYNAMIC ALTERATIONS WITH AND WITHOUT THE APPLICATION OF PRIMING PRINCIPLE AMONG PATIENTS INDUCED WITH PROPOFOL

Background:- Propofol given at standard induction dose, is known to produce haemodynamic instability, especially hypotension. Application of “priming principle” helps to reduce the total dose of propofol. Objectives:- To study the total dose requirements of propofol and peri-intubation haemodynamic stability in patients undergoing surgery under GACV when priming principle is applied. Methodology:- This was an observational study among 54 ASA I and II patients undergoing surgery under GACV, who were randomly divided into three groups of 18 patients each. All patients received fentanyl 1 mcg/kg over 30 seconds followed by propofol. Group 1 patients received the total (100%) calculated dose of propofol. Group 2 and 3 patients received 20% and 40% of the dose respectively as priming dose, and the remaining was given 30 seconds later, until there was loss of eyelash reex. The total dose of propofol given, the heart rate, systolic and diastolic blood pressures, mean arterial pressures at various time intervals before, during and after induction and intubation, and complications observed were compared and statistically analysed using SPSS 2.0. Results:- The mean induction dose of propofol was signicantly lower in the priming groups (71.7 ± 17.2mg in group 2 and 80.0 ± 17.1mg in group 3) compared to group1 (107.9 ± 8.0mg). The fall in mean arterial pressure was signicantly lower in groups 2 and 3 (p<0.05) compared to group1 at one minute post-induction. Conclusion:-Application of priming principle reduces the induction dose of propofol and is associated with better peri-intubation haemodynamic stability.