rss_2.0Polish Journal of Medical Physics and Engineering FeedSciendo RSS Feed for Polish Journal of Medical Physics and Engineering Journal of Medical Physics and Engineering 's Cover effective and water-equivalent diameters as geometrical size functions for estimating CT dose in the thoracic, abdominal, and pelvic regions<abstract> <title style='display:none'>Abstract</title> <p><italic>Purpose:</italic> The aim of this work was to establish the relationships of patient size in terms of effective diameter (D<sub>eff</sub>) and water-equivalent diameter (D<sub>w</sub>) with lateral (LAT) and anterior-posterior (AP) dimensions in order to predict the specific patient dose for thoracic, abdominal, and pelvic computed tomography (CT) examinations.</p> <p><italic>Methods:</italic> A total of 47 thoracic images, 79 abdominal images, and 50 pelvic images were analyzed in this study. The patient’s images were retrospectively collected from Dr. Kariadi and Kensaras Hospitals, Semarang, Indonesia. The slices measured were taken from the middle of the scan range. The calculations of patient sizes (LAT, AP, D<sub>eff</sub>, and D<sub>w</sub>) were automatically performed by IndoseCT 20b software. D<sub>eff</sub> and D<sub>w</sub> were plotted as functions of LAT, AP, and AP+LAT. In addition, D<sub>w</sub> was plotted as a function of D<sub>eff</sub>.</p> <p><italic>Results:</italic> Strong correlations of D<sub>eff</sub> and D<sub>w</sub> with LAT, AP, and AP+LAT were found. Stronger correlations were found in the D<sub>eff</sub> curves (R<sup>2</sup> &gt; 0.9) than in the D<sub>w</sub> curves (R<sup>2</sup> &gt; 0.8). It was found that the average D<sub>eff</sub> was higher than the average Dw in the thoracic region, the average values were similar in the abdominal and pelvic regions.</p> <p><italic>Conclusion:</italic> The current study extended the study of the relationships between D<sub>eff</sub> and D<sub>w</sub> and the basic geometric diameter LAT, AP, and AP+LAT beyond those previously reported by AAPM. We evaluated the relationships for three regions, i.e. thoracic, abdominal, and pelvic regions. Based on our findings, it was possible to estimate D<sub>eff</sub> and D<sub>w</sub> from only the LAT or AP dimension.</p> </abstract>ARTICLE2021-09-27T00:00:00.000+00:00Trend and prediction of COVID-19 outbreak in Iran: SEIR and ANFIS model<abstract> <title style='display:none'>Abstract</title> <p><italic>Background:</italic> Mathematical and predictive modeling approaches can be used in COVID-19 crisis to forecast the trend of new cases for healthcare management purposes. Given the COVID-19 disease pandemic, the prediction of the epidemic trend of this disease is so important.</p> <p><italic>Methods:</italic> We constructed an SEIR (Susceptible-Exposed-Infected-Recovered) model on the COVID-19 outbreak in Iran. We estimated model parameters by the data on notified cases in Iran in the time window 1/22/2020 – 20/7/2021. Global sensitivity analysis is performed to determine the correlation between epidemiological variables and SEIR model parameters and to assess SEIR model robustness against perturbation to parameters. We Combined Adaptive Neuro-Fuzzy Inference System (ANFIS) as a rigorous time series prediction approach with the SEIR model to predict the trend of COVID-19 new cases under two different scenarios including social distance and non-social distance.</p> <p><italic>Results:</italic> The SEIR and ANFIS model predicted new cases of COVID-19 for the period February 7, 2021, till August 7, 2021. Model predictions in the non-social distancing scenario indicate that the corona epidemic in Iran may recur as an immortal oscillation and Iran may undergo a recurrence of the third peak.</p> <p><italic>Conclusion:</italic> Combining parametrized SEIR model and ANFIS is effective in predicting the trend of COVID-19 new cases in Iran.</p> </abstract>ARTICLE2021-09-27T00:00:00.000+00:00Dosimetry audit of the CyberKnife accelerator with the SHANE phantom<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> The aim of this study was to propose a dosimetric audit of the CyberKnife system. Dosimetry audit is an important part of the quality assurance process in radiotherapy. Most of the proposed dosimetric audits are dedicated to classical medical accelerators. Currently, there is no commonly implemented scheme for conducting a dosimetric audit of the CyberKnife accelerator.</p> <p><italic>Material and methods:</italic> To verify the dosimetric and geometric parameters of the entire radiotherapy process, as is required in E2E test procedure, the CIRS SHANE anthropomorphic phantom was used. A tomography with a resolution of 1.5 mm was prepared, five PTVs (Planning Target Volume) of different volumes were drawn; approximately: 88 cm<sup>3</sup>, 44 cm<sup>3</sup>, 15 cm<sup>3</sup>, 7 cm<sup>3</sup>, 1.5 cm<sup>3</sup>. Five treatment plans were made using the 6D Skull tracking method, FIXED collimators, RayTracing algorithm. Each treatment plan was verified in a slab Phantom, with a PinPoint chamber. The dose was measured by an ionization chamber type TM31010 Semiflex, placed in the center area of the target.</p> <p><italic>Results:</italic> The result of the QA verification in slab phantom was up to 5,0%. The percentage difference for the measurement in the SHANE phantom was: 4.29%, -1.42%, -0.70%, 1.37%, -1.88% respectively for the targets: 88 cm<sup>3</sup>, 44 cm<sup>3</sup>, 15 cm<sup>3</sup>, 7 cm<sup>3</sup>, 1.5 cm<sup>3</sup>.</p> <p><italic>Conclusions:</italic> By analyzing various approaches to small-field dosimetry audits in the literature, it can be assumed that the proposed CyberKnife dosimetric audit using the SHANE phantom is an appropriate method of verification of the radiotherapy process. Particular attention should be paid to the target volume, adjusting it to the system capabilities.</p> </abstract>ARTICLE2021-09-27T00:00:00.000+00:00Quantitative and dosimetric analysis for treating synchronous bilateral breast cancer using two radiotherapy planning techniques<abstract> <title style='display:none'>Abstract</title> <p><italic>Objective:</italic> We compared mono-isocenter and dual-isocenter plans in synchronous bilateral breast cancer (SBBC), which is defined as tumours occurring simultaneously in both breasts, and evaluated the effects of these differences in plans on organs-at-risk (OARs).</p> <p><italic>Materials and methods:</italic> We evaluated 10 women with early stage, nod negative (Tis-2N0M0) SBBC. The treatment dose was determined to be 50 Gy. We used mean dose and V<sub>XGy</sub> to evaluate the OARs. To evaluate the effectiveness of treatment plans, Homogeneity index (HI), conformity index (CI) and sigma index (SI) and monitor units (MU) of monoisocenter (MIT) and dual-isocenter (DIT) plans were compared. During bilateral breast planning, for the single-centre plan, the isocenter was placed at the center of both breasts at a depth of 3-4 cm. For the two-center plan, dual-isocenters were placed on the right and left breasts.</p> <p><italic>Results:</italic> No significant difference between the techniques in terms of the scope of the target volume was observed. Statistically significant results were not achieved in MIT and DIT plans for OARs. Upon comparing MIT and DIT, the right-side monitor unit (MU) value in DIT (p = 0.011) was statistically significantly lower than that in MIT. Upon comparing right-left side MIT and DIT, the MU value (p = 0.028) was significantly lower in DIT than MIT.</p> <p><italic>Conclusion:</italic> SBBC irradiation is more complex than unilateral breast radiotherapy. No significant difference between both techniques and OARs was observed. However, we recommend MIT as a priority technique due to the ability to protect OARs, ease of administration during treatment, and the fact that the patient stays in the treatment unit for a shorter period of time.</p> </abstract>ARTICLE2021-09-27T00:00:00.000+00:00Dose calculation accuracy for photon small fields in treatment planning systems with comparison by Monte Carlo simulations<abstract> <title style='display:none'>Abstract</title> <p><italic>Purpose:</italic> Advanced radiation therapy techniques use small fields in treatment planning and delivery. Small fields have the advantage of more accurate dose delivery, but with the cost of some complications in dosimetry. Different dose calculation algorithms imported in various treatment planning systems (TPSs) which each of them has different accuracy. Monte Carlo (MC) simulation has been reported as one of the accurate methods for calculating dose distribution in radiation therapy. The aim of this study was the evaluation of TPS dose calculation algorithms in small fields against 2 MC codes.</p> <p><italic>Methods:</italic> A linac head was simulated in 2 MC codes, MCNPX, and GATE. Then three small fields (0.5×0.5, 1×1 and 1.5×1.5 cm<sup>2</sup>) were simulated with 2 MC codes, and also these fields were planned with different dose calculation algorithms in Isogray and Monaco TPS. PDDs and lateral dose profiles were extracted and compared between MC simulations and dose calculation algorithms.</p> <p><italic>Results:</italic> For 0.5×0.5 cm<sup>2</sup> field mean differences in PDDs with MCNPX were 2.28, 4.6, 5.3, and 7.4% and with GATE were -0.29, 2.3, 3 and 5% for CCC, superposition, FFT and Clarkson algorithms respectively. For 1×1 cm<sup>2</sup> field mean differences in PDDs with MCNPX were 1.58, 0.6, 1.1 and 1.4% and with GATE were 0.77, 0.1, 0.6 and 0.9% for CCC, superposition, FFT and Clarkson algorithms respectively. For 1.5×1.5 cm<sup>2</sup> field mean differences in PDDs with MCNPX were 0.82, 0.4, 0.6 and -0.4% and with GATE were 2.38, 2.5, 2.7 and 1.7% for CCC, superposition, FFT and Clarkson algorithms respectively.</p> <p><italic>Conclusions:</italic> Different dose calculation algorithms were evaluated and compared with MC simulation in small fields. Mean differences with MC simulation decreased with the increase of field sizes for all algorithms.</p> </abstract>ARTICLE2021-09-27T00:00:00.000+00:00Dosimetric impact of FFF over FF beam using VMAT for brain neoplasms treated with radiotherapy<abstract> <title style='display:none'>Abstract</title> <p><italic>Background:</italic> This study was conducted to assess the dosimetric impact of FFF beam plans on high-grade brain neoplasms using the VMAT technique when compared with FF beam plans.</p> <p><italic>Material and Methods:</italic> Thirty patients with high-grade brain neoplasms, who had received radiotherapy using VMAT technique retrospectively were selected for this study. All the patients were planned for VMAT using 6MV_FF beam and the same plan was re-optimized using 6MV_FFF beam keeping the same dose constraint. Radiotherapy dose distribution on planning target volume (PTV) and organs at risk (OAR), target conformity index (CI), Homogeneity Index (HI), Low dose volume in the patient (V<sub>5</sub>, V<sub>10</sub>, V<sub>20</sub>, and V<sub>30</sub>), and Integral dose to the whole body in both plans were compared.</p> <p><italic>Results:</italic> The PTV coverage and OAR’s showed no significant differences in dose distribution between the FFF and FF beam VMAT planning. There was a reduction of the average maximum dose in the right eye, left eye, right optic nerve, and left optic nerve using FFF beams. The reduction in average low dose volume was observed in V<sub>5</sub>, V<sub>10</sub>, V<sub>20</sub>, V<sub>30</sub>, and Mean Dose. Also, a significant reduction was observed in the integral dose to the whole body using the FFF beam.</p> <p><italic>Conclusions:</italic> Using FFF beams with VMAT is doable for the treatment of high-grade brain neoplasms, and the delivery mode of the FFF beam in VMAT may yield similar results to FF beam which should be confirmed in a large scale prospective clinical trial.</p> </abstract>ARTICLE2021-09-27T00:00:00.000+00:00Determination of DQE as a quantitative assessment of detectors in digital mammography: Measurements and calculation in practice<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> Advances in digital detector technology and methods of image presentation in digital mammography now offer the possibility of implementing mathematical assessment methods to quantitative image analysis. The aim of this work was to develop new software to simplify the application of the existing international standard for DQE in digital mammography and show in detail how it can be applied, using a Siemens Mammomat Inspiration as a model.</p> <p><italic>Material and methods:</italic> Consistent with the IEC standard a 2 mm Al filter at the tube exit and images in DICOM format as raw data, without applying any additional post-processing were used. Measurements were performed for W/Rh anode/filter combination and different tube voltage values (26 ÷ 34 kV) without any anti-scatter grid. To verify new software doses ranging from 20-600 µGy were used in measurements. Exposure (air kerma) was measured using a calibrated radiation meter (Piranha Black 457, RTI Electronics AB, Sweden). MTF was determined, using an edge test device constructed specifically for this work.</p> <p><italic>Results:</italic> It has been demonstrated that with the new software the DQE can be measured with the accuracy required by the international standard IEC 62220-1-2. DQE has been presented as a function of spatial frequency for W/Rh anode/filter combination and different tube voltage.</p> <p><italic>Conclusions:</italic> New software was used successfully to analyze image quality parameters for the Siemens Mammomat Inspiration detector. This was done on the basis of an internationally accepted methodology. In the next step, mammographs with different detector types can be compared.</p> </abstract>ARTICLE2021-09-27T00:00:00.000+00:00Contribution of soil in the annual effective dose due to radon in the air of some dwellings in the city of Karbala, Iraq<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> The radon isotopes are not as significant as (<sup>222</sup>Rn) due to the decay of the natural radionuclides (<sup>235</sup>U), (<sup>232</sup>Th) and (<sup>238</sup>U) due to their short half-life, at most. (<sup>222</sup>Rn) can be classified as among the most harmful radioactive elements in the world.</p> <p><italic>Material and method:</italic> In this analysis, the closed-can technique was used with solid-state nuclear track detectors (CR-39). After forty days of closed dosimeter buried in the soil of the garden, and ninety days from the closed position in the air of some dwellings were collected dosimeter and stripped of nuclear detectors impact of closed groups. For 8 hours, CR-39 detectors were chemically etched by (6.25 N) NaOH solution at 70°C and then registered within an optical microscope.</p> <p><italic>Result:</italic> The levels of soil radon concentrations ranged from 28.44±0.58 to 479.76±2.43 Bq/m<sup>3</sup> with a mean value of 220.33±1.64 Bq/m<sup>3</sup>, while the concentration of radon in the air of certain dwellings varied from (1.95±0.27 to 46.82±0.75) Bq/m<sup>3</sup> with an average value of 21.51±0.54 Bq/m<sup>3</sup>. In comparison, the annual effective dose attributed to radon in soil ranged from 0.71±0.09 mSv/y to 12.10±0.38 mSv/y with an average value of 5.55±0.261 mSv/y, while the annual effective dose in air differed from (0.04±0.02 mSv/y) to (1.18±0.12 mSv/y) with an average value of (0.60±0.09 mSv/y).</p> <p><italic>Conclusion:</italic> Neglecting the effects of other radon sources, the percentage share of the annual effective dose due to radon in soil measured in the air home, ranged from 0.005±0.001 to 0.453±0.074 with an average value of 0.130±0.040. Weak correlation between concentrations of radon in households and soil air. But roughly speaking, one can say that in soil air every 1000 Bq/m<sup>3</sup> and 1000 mSv/y contributes around 130 Bq/m<sup>3</sup> and 130 mSv/y in indoor air.</p> </abstract>ARTICLE2021-09-27T00:00:00.000+00:00An infrared-based device for non-invasive monitoring of eyelid movement during sleep<abstract> <title style='display:none'>Abstract</title> <p>The increased movement of eyes and eyelids is characteristic of the rapid eye movement (REM) sleep stage, making it an important indicator in sleep monitoring. A device was designed to detect this activity in a non-invasive way by means of measuring infrared light intensity reflected off the eyelid. The system converts the light intensity into current through a photodetector, performs analog signal processing and analog to digital conversion (ADC). The data is transmitted wirelessly to a computer, where the results can be displayed, stored and analyzed with a dedicated software, which also provides control over the device. The hardware is embedded in a mask, which is put over the patient's eyes. User safety in terms of mechanical, electrical and optical dangers has been ensured. The device was tested on a napping subject.</p> </abstract>ARTICLE2014-03-07T00:00:00.000+00:00Calibration of Gafchromic XR-RV3 film under interventional radiology conditions<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> The purpose of the study was the calibration of Gafchromic films in clinical interventional radiology conditions and the assessment of the influence of dose range, the shape of the fitting curve, and its practical application. The aim of the work was to show how practically perform calibration in a wide range of doses.</p> <p><italic>Material and methods:</italic> Gafchromic XR–RV3 films were included in the study. The calibration was performed for A and B film series separately. Doses from the range of 0 – 8 Gy were used. Film dosimeters were read out in reflective mode with a commercial flatbed scanner.</p> <p><italic>Results:</italic> Among various degrees of a polynomial function, the best fit, which fulfilled the chosen criterion of 95% agreement between measured and reconstructed doses and simple equation criterion, was observed for third-degree polynomial. The fitting curve where the dose is the function of optical density (logMPV) was demonstrated to be more precise than the fitting curve based on MPV only. To minimize the difference between dose absorbed by the film and dose reconstructed from the fitting curve below 5% it is necessary to divide the calibration range of 0 – 8 Gy into two subranges for use in interventional radiology. This difference was set at a maximum level of 3.8% and 1.9% for the lowand high-dose range, respectively. Each series of films may have a slightly different calibration curve, especially for the low dose range. A deviation of up to 36% between two batches of Gafchromic film was observed.</p> <p><italic>Conclusions:</italic> For the third-degree polynomial fitting function (one of the recommended in the literature) calibration should be done into low and high dose ranges and for each batch separately. A systematic error higher than 20% could be introduced when the fitting curve from one film batch is applied to the other film batch.</p> </abstract>ARTICLE2021-07-01T00:00:00.000+00:00Detailed Monte Carlo analysis of the secondary photons coming out of the therapeutic X-ray beam of linear accelerator<abstract> <title style='display:none'>Abstract</title> <p>External photon beam radiotherapy is often used in tumor treatment. The photons are generated from the target which had stricken by the primary electron beam (incident particles). The photon beam contains the primary photons coming directly from the target and secondary photons coming from the photon interactions with head component materials (scattered photons). Altogether is thereafter used in radiotherapy treatment. This Monte Carlo study aims to investigate and evaluate the secondary radiations (photons) in terms of fluence, energy fluence, spectral distribution, mean energy and angular spread distribution.</p> <p>The secondary photons, which contributed in radiotherapy treatment, are examined and evaluated in number (fluence) and energy. At the phantom surface, the secondary photons originated in the whole linac head are mainly coming from the primary collimator. In 0.45% of secondary photons coming from the whole linac head, the primary collimator contributes by 86% and they are more energetic. However, the flattening filter and the secondary collimator contribute together by less than 14% and their photons are less energetic and then can deteriorate the beam dosimetry quality. To improve the radiotherapy treatment quality, the number of photons of low energy should be as low as possible in the clinical beam. Our work can be a basic investigation to use in the improvement of linac head configuration and specially the beam modifiers.</p> </abstract>ARTICLE2021-07-01T00:00:00.000+00:00Comparison of helical tomotherapy with multi-field intensity-modulated radiotherapy treatment plans using simultaneous integrated boost in high-risk prostate cancer<abstract> <title style='display:none'>Abstract</title> <p><italic>Purpose:</italic> The aim of this study is to compare the dosimetric results of Helical Tomotherapy (HT) and Multi-field IMRT treatment plans using a Simultaneous Integrated Boost (SIB) technique in the treatment of High-Risk Prostate Cancer (HRPCa) with pelvic nodal radiation.</p> <p><italic>Methods:</italic> Seventeen patients planned with HT and 7,8 and 9 fields IMRT were investigated. All plans were designed with the prescribed dose of 54.0 Gy to the PTVln while simultaneously delivering 74.0 Gy to the PTVPS in 30 fractions. Dosimetric data of PTV and OARs were compared.</p> <p><italic>Results:</italic> HT gives a better CI and HI of PTV<sub>PS</sub> compared to multi-field IMRT plans. HT plans significantly improved target coverage (HT:0.95 vs multi-field IMRT: 0.52, 0.49 and 0.49 respectively, p &lt; 0.001). Bladder mean dose(Gy) (HT: 45.6 vs multi-field IMRT: 53.6, 53.3 and 52.7 respectively, p = 0.004) and D<sub>66%</sub>(Gy) dose (HT: 35.3 vs multi-field IMRT: 46.7, 47.0 and 44.9 respectively, p = 0.006) were lower in HT. But multi-field IMRT plans significantly reduced the rectum volume receiving more than 75 Gy; (HT V<sub>75%</sub> (%) 2.7 vs multi-field IMRT 0.8, 1.4 and 0.9 respectively, p = 0.008). HT provided better sparing of the right and left femoral head receiving a mean dose. The penile bulb and small bowel doses were the highest in HT compared with multi-field IMRT.</p> <p><italic>Conclusions:</italic> HT achieved better dose distribution to target compared to multi-field IMRT. This study suggests HT as a reasonable option for the treatment of HRPCa patients.</p> </abstract>ARTICLE2021-07-01T00:00:00.000+00:00Using X-ray diffraction in characterization of bone remodeling and nanocomposites in ovariectomized rats osteopenia model<abstract> <title style='display:none'>Abstract</title> <p>Sedentary lifestyle and physiological menopause are among the risk factors of osteopenia, especially in elderly people. However, bone mineral density decrease can also be observed in young individuals, for instance, due to deficiency of female sex hormones after surgical interventions, particularly ovariectomy. Our research enabled us to assess the efficacy of whole-body vibration in preventing the loss of bone mineral density in the ovariectomy rat osteopenia model. Thus, whole-body vibration with acceleration level 0.3 g and frequency 50 Hz was used on young female rats, which had been subjected to ovariectomy (n = 18). It had been conducted for 24 weeks, exposure time – 30 minutes per day, 5 times a week. Assessment of mineral component loss of the tibia was performed by means of X-ray diffraction. Bone remodeling was assessed by determining hormones: parathyroid hormone and calcitonin, Ca and P in the blood. X-ray diffraction is an effective method, which enables the evaluation a nanocomposites structure of the bone tissue in the experiment. In the article, we applied this method to determine the loss of bone mineral mass after ovariectomy and the impact of whole-body vibration under such conditions. In the ovariectomy group, the volume of a mineral component significantly decreased starting already from the 16th week (р&lt;0.05) versus control. However, in the group with ovariectomy + whole-body vibration, the loss of a mineral component was insignificant during 8-16 weeks of the investigation, compared with the control group. On the 24th day, the spectrums almost did not differ from ovariectomized rats group. Meanwhile, hormone levels changed in ovariectomized rats group. It should be emphasized that the aforementioned whole-body vibration parameters do not cause severe bone damage or further negative consequences.</p> </abstract>ARTICLE2021-07-01T00:00:00.000+00:00New possibilities of graphics software in the analysis of thermograms of patient’s lower limbs – a technical note<abstract> <title style='display:none'>Abstract</title> <p>The analysis involved thermograms of the lower limbs of a patient suffering from symptomatic L-S segment discopathy with spinal root compression syndrome (symptomatic lumbar discopathy) qualified for surgical treatment. The thermograms were obtained using the Flir Ebx 50 camera. They were developed with the use of the software included with the Flir Ebx 50 camera, as well as the Origin Pro 2020 data analysis and graphing software. ROIs (Regions of Interest) were specified and analyzed in terms of temperature (average, maximum or minimum) temperature distributions, isotherms, and specified surface areas limited by selected isotherms. According to the analysis of the thermograms, the images obtained with Origin Pro 2020 enable a more advanced presentation of the temperature distribution, by taking into account the isotherms with selected temperatures and by calculating the area limited by a given isotherm (or between two isotherms) they allow to introduce an additional surface parameter related to specific isotherms. It provides additional information (parameter) in comparison with analogous ROIs on healthy and pathologic limbs in the same patient.</p> </abstract>ARTICLE2021-07-01T00:00:00.000+00:00Effects of flattening filter (FF) and flattening filter-free (FFF) beams on small-field and large-field dose distribution using the VMAT treatment plan<abstract> <title style='display:none'>Abstract</title> <p><italic>Introduction:</italic> The aim of the study was to evaluate the influence of flattening filter (FF) and flattening filter-free (FFF) beams on small-field and large-field dose distribution using the VMAT treatment plan.</p> <p><italic>Material and methods:</italic> Dose distribution calculations were performed for the VMAT technique in two locations: the larynx (small irradiation field; average 30.1 cm<sup>2</sup>) and gynecology (large irradiation field; average 173.1 cm<sup>2</sup>) using X-6MV flattening filter (FF) and flattening filter-free (FFF) beams. The following values were compared: the number of monitor units, minimum doses, average doses in PTV and maximum average doses in OaR (spinal cord – in larynx radiotherapy, bladder and rectum - in gynecological radiotherapy) and RPI (Radiation Planning Index) coefficient.</p> <p><italic>Results and Discussion:</italic> The performed statistical tests indicate that there is a significant difference (p &lt;0.05) between the number of monitor units in the irradiation of large (gynecological) fields between the FF and FFF beams. The dose distributions show no statistically significant differences between the flattening filter and flattening-free filter beams (regardless of the field size).</p> <p><italic>Conclusions:</italic> Due to the smaller number of monitor units, it is recommended to use flattening filter beams (FF) for large-field radiotherapy.</p> </abstract>ARTICLE2021-07-01T00:00:00.000+00:00The role of the spatially fractionated radiation therapy in the management of advanced bulky tumors<abstract> <title style='display:none'>Abstract</title> <p>Spatially fractionated radiation therapy (SFRT) refers to the delivery of a single large dose of radiation within the target volume in a heterogeneous pattern using either a custom GRID block, multileaf collimators, and virtual methods such as helical tomotherapy or synchrotron-based microbeams. The potential impact of this technique on the regression of bulky deep-seated tumors that do not respond well to conventional radiotherapy has been remarkable. To date, a large number of patients have been treated using the SFRT techniques. However, there are yet many technical and medical challenges that have limited their routine use to a handful of clinics, most commonly for palliative intent. There is also a poor understanding of the biological mechanisms underlying the clinical efficacy of this approach. In this article, the methods of SFRT delivery together with its potential biological mechanisms are presented. Furthermore, technical challenges and clinical achievements along with the radiobiological models used to evaluate the efficacy and safety of SFRT are highlighted.</p> </abstract>ARTICLE2021-07-01T00:00:00.000+00:00Evaluation of clinical implications in the use of dose to water versus dose to medium by using NTCP and TCP models for urinary bladder tumours<abstract> <title style='display:none'>Abstract</title> <p><italic>Purpose:</italic> To analyze the dosimetric and radiobiological differences between dose to water versus dose to medium for patients with carcinoma of the urinary bladder.</p> <p><italic>Materials and Methods:</italic> 15 patients with cancer of urinary bladder were selected for the study. VMAT plans were generated for each patient. The dose distributions were calculated in the modes dose to water and to medium with the Monaco treatment planning system. A dosimetric comparative analysis has been made between the two modes of planning in this study. Subsequently, NTCP and TCP were determined for OARs and targets respectively.</p> <p><italic>Results:</italic> The mean dose to 2 cc of the rectum, small bowel, left and right femoral heads respectively was higher by 0.8, 1.2, 2.7, and 2.2% for the dose to water calculation. Similarly, the mean dose to D<sub>2</sub>, D<sub>50</sub>, and D<sub>98</sub> for PTV was higher by 0.4, 0.3, and 0.3% for dose to water calculation. Such small dose differences had little effect on the values of TCP and NTCP.</p> <p><italic>Conclusion:</italic> For patients with the urinary bladder there were very small differences between results between calculations carried out in dose to medium and dose to water modes.</p> </abstract>ARTICLE2021-03-18T00:00:00.000+00:00Effects of detection system parameters on cross-correlations between MUAPs generated from parallel and inclined muscle fibres<abstract> <title style='display:none'>Abstract</title> <p>The aim of this study was to investigate the effects of inter-electrode distance (IED), electrode radius (ER) and electrodes configurations on cross-correlation coefficient (CC) between motor unit action potentials (MUAPs) generated in a motor unit (MU) of parallel fibres and in a MU of inclined fibres with respect to the detection system. The fibres inclination angle (FIA) varied from 0° to 180° by a step of 5°. Six spatial filters (the longitudinal single differential (LSD), longitudinal double differential (LDD), bi-transversal double differential (BiTDD), normal double differential (NDD), an inverse binomial filter of order two (IB2) and maximum kurtosis filter (MKF)), three values of IED and three values of ER were considered.</p> <p>A cylindrical multilayer volume conductor constituted by bone, muscle, fat and skin layers was used to simulate the MUAPs.</p> <p>The cross-correlation coefficient analysis showed that with the increase of the FIA, the pairs of MUAPs detected by the IB2 system were more correlated than those detected by the five other systems. For each FIA, the findings also showed that the MUAPs pairs detected by BiTDD, NDD, IB2 and MKF systems were more correlated with smaller IEDs than with larger ones, while inverse results were found with the LSD and LDD systems. In addition, the pairs of MUAPs detected by the LDD, BiTDD, IB2 and MKF systems were more correlated with large ERs than with smaller ones. However, inverse results were found with the LSD and NDD systems.</p> </abstract>ARTICLE2021-03-18T00:00:00.000+00:00Uncertainties in the measurement of relative doses in radiotherapy<abstract> <title style='display:none'>Abstract</title> <p>Both the measurement of the dose and the measurement of its distribution, like any other measurements, are subject to measurement uncertainties. These uncertainties affect all dose calculations and dose distributions in a patient’s body during treatment planning in radiotherapy. Measurement uncertainty is not a medical physicist’s error, but an inevitable element of their work. Planning the dose distribution in a patient’s body, we often try to reduce it in the volume of critical organs (OaR - Organ at Risk) or increase the minimum dose in the PTV region by a few percent. It is believed that the measurement uncertainty should be taken into account in these calculations at the stage of treatment planning. The paper presents the method of calculating the measurement uncertainty for different physical quantities in radiotherapy as percentage depth dose, profile function and output factor, due to the fact that these quantities have a particular impact on the calculated dose distributions in a patient’s body. The uncertainties that must be taken into account in planning treatment the planned dose per fraction and real in PTV, maybe different up to 4%.</p> </abstract>ARTICLE2021-03-18T00:00:00.000+00:00Evaluation of glandular dose in mammography in presence of breast cysts using Monte Carlo simulation<abstract> <title style='display:none'>Abstract</title> <p><italic>Background:</italic> Normalized glandular dose (DgN) is an important dosimetric quantity in mammography.</p> <p><italic>Aim:</italic> In this study, the effect of the presence of breast cysts and their size, number and location on DgN is evaluated.</p> <p><italic>Materials and methods:</italic> The effect of the presence of cysts in breast was examined using MCNPX code. This was performed by taking homogeneous breast phantoms containing spheroid breast cysts into account. The radius of the cysts, numbers of the cysts, and depth of the cysts, and their location were variable. Various electron energies were also considered. Finally, these results were compared with the results of a cyst-less breast phantom.</p> <p><italic>Results:</italic> The results show that the effect of the presence of cysts in the breast depends on the size, number and location of cysts. The presence of cysts at lower depths leads to a decrease in the DgN values, compared to the breast phantom without cysts. The presence of cysts in the breast phantom has an effect of -7 to +14 percent on the DgN values under the conditions considered in this modeling. This effect is independent of the X-ray tube voltage, the breast phantom thickness, and glandular ratio, and depends only on the number and size and location of the cysts. The bigger radius and number of cysts, the greater effect on DgN value.</p> </abstract>ARTICLE2021-03-18T00:00:00.000+00:00en-us-1