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Introduction: The aim of this study was to evaluate the new 2-Dimensional diode array SRS MapCHECK (SunNuclear, Melbourne, USA) with dedicated phantom StereoPHAN (SunNuclear, Melbourne, USA) for the pre-treatment verification of the stereotactic body radiotherapy (SBRT). Material and methods: For the system, the short and mid-long stability, dose linearity with MU, angular dependence, and field size dependence (ratio of relative output factor) were measured. The results of verification for 15 pre-treatment cancer patients (5 brains, 5 lungs, and 5 livers) performed with SRS MapCHECK and EBT3 Gafchromic films were compared. All the SBRT plans were optimized with the Eclipse (v. 15.6, Varian, Palo Alto, USA) treatment planning system (TPS) using the Acuros XB (Varian, Palo Alto, USA) dose calculation algorithm and were delivered to the Varian EDGE® (Varian, Palo Alto, USA) accelerator equipped with a high-definition multileaf collimator. The 6MV flattening-filter-free beam (FFF) was used. Results: Short and mid-long stability of SRS MapCHECK was very good (0.1%-0.2%), dose linearity with MU and dependence of the response of the detector on field size results were also acceptable (for dose linearity R2 = 1 and 6% difference between microDiamond and SRS MapCHECK response for the smallest field of 1 × 1 cm2). The angular dependence was very good except for the angles close to 90° and 270°. For pre-treatment plan verification, the gamma method was used with the criteria of 3% dose difference and 3 mm distance to agreement (3%/3 mm), and 2%/2 mm, 1%/1 mm, 3%/1 mm, and 2%/1 mm. The highest passing rate for all criteria was observed on the SRS MapCHECK system. Conclusions: It is concluded that SRS MapCHECK with StereoPHAN has sufficient potential for pre-treatment verification of the SBRT plans, so that verification of stereotactic plans can be significantly accelerated.

Introduction: Dosimetric verification of Intensity Modulation Radiotherapy treatment plans is usually carried out before the start of treatment. It is of special importance in the case of highly modulated plans, such as plans for patients in whom many tumors are irradiated simultaneously. In this work, we present the results of the verification of multi-target plans performed with the stereotactic HyperArc technique. Material and methods: The results of dosimetric verification of 35 patient plans in the head are presented. The results are analyzed in terms of the number of tumors, and the distance of the tumor from the isocenter. Measurements were carried out with the film method. The gamma methodology was used (3%/2mm). Results: The results showed a very good agreement between measurements and calculations. Conclusions: No dependence of the verification result on the number of targets and the distance between the center of tumor and isocenter was found.

Introduction. The main aim of this study was to evaluate the doses delivered to heart substructures and calculate normal tissue complication probability (NTCP) for the intensity modulation radiotherpy (IMRT) irradiated group of left-sided post-mastectomy patients. Material and methods. In this retrospective study for 30 randomly chosen breast cancer patients, the mean dose, V2, V4, V10, V20 and D2% in the heart substructures were evaluated. Results. The mean heart dose was 12.3 Gy, the mean left anterior descending artery (LAD) dose was 28.5 Gy. The average value of long-term cardiac mortality was 0.17%, pericarditis 0.0%, left ventricle perfusion defects 24.5% and LAD toxicity 0.2%. In the literature, for the IMRT technique for left-sided mastectomy patients, the mean heart dose ranged from 8.7–14.0 Gy and the V20 10.5–14%. Additional studies are needed to describe the cardiac toxicity. Conclusions. It is necessary to contour cardiac substructures for reliable assessment of the dose distribution, although the mean heart dose is simplification for modern radiotherapy techniques.

Purpose The calculation model for the integral quality monitor (IQM) system does not take into account the characteristics of the HD120 multileaf collimator (MLC), which some Varian accelerators are equipped with. Some treatment plans prepared with this collimator are characterized by a high level of modulation. The aim of the work was to prepare a model for that collimator and to determine the influence of modulation on the results of the verification carried out with the use of the IQM system. Methods The short- and long-stability of the IQM detector response were verified by measuring the signal for a 6 MV FFF beam with the static field of 10 × 10 cm2 size. The obtained results were compared with the measurements performed with the PTW Farmer chamber. Next, the signal for 35 static square fields 4 × 4 cm2 , covering the whole field 38 × 20 cm2 , were measured with the IQM. Based on the results of these measurements, the original calculation model has been changed, in order to achieve the smallest differences between calculations and measurements. While tuning the model, the characteristics of the HD120 MLC were included. Measurements were performed for 30 clinical plans (86 arcs) prepared with 6 MV FFF beams. Among those 30 plans, there were 5 multi-target plans with single isocenter. For each plan the modulation complexity score (MCS) was calculated. The measurement results were compared with the calculation results performed with the original and authors' calculation model. Results Very good stability of the short- and long-stability of the IQM detector response were obtained. Measurements performed for 35 static fields revealed that for the manufacturer's and for the authors' models the deviation exceeded 3% for 12 and 5 of the 35 static fields respectively. The differences for the manufacturer's and authors' algorithms were in the range of ±2% for the 15 and 26 of the fields respectively. For original and the authors' models the differences between measured and calculated signals (starting with the segment number 40) were within the range of ±3.5% for 87.6% and 96.7% of all arcs for the respective models. For both models the dependence of the compliance of measurements and calculations on the modulation complexity score was observed. For most of the very modulated arcs the measured signal was at least 3% lower than the calculated one. The largest differences between measurements and calculations were obtained for single isocenter multi-target plans. Conclusions The signal predicted by an algorithm taking into account the real geometry of the collimating system of the Edge accelerator (equipped with the HD120 MLC) made it possible to obtain greater consistency between the measurements and calculations. We characterized the dependence between the modulation complexity score of each arc and the compliance of the measurements and calculations. Much worse results were obtained for single isocenter multi-target plans. This article is protected by copyright. All rights reserved.

Purpose According to the available international recommendations, at least one independent verification of the calculations of number of monitor unit (MU) is required for every patient treated by teleradiotherapy. The aim of this study was to estimate the differences of dose distributions calculated with two treatment planning systems: Eclipse (Varian) and Oncentra MasterPlan (Elekta). Materials and methods The analysis was performed for 280 three-dimensional conformal radiotherapy treatment (3D-CRT) plans with photon beams from Varian accelerators: CL 600C/D X6 MV (109 plans), CL 2300C/D X6 MV (43 plans), and CL 2300C/D X15 MV (128 plans). The mean doses in the planning target volume (PTV) and doses at the isocenter point obtained with Eclipse and Oncentra MasterPlan (OMP) were compared with Wilcoxon matched-pairs signed rank test. Additionally, the treatment planning system (TPS) calculations were compared with dosimetric measurements performed in the inhomogeneous phantom. Results Data were analysed for 6 MV plans and for 15 MV plans separately, independently of the treatment machine. The dose values calculated in Eclipse were significantly (p Conclusions OMP calculations were introduced as the independent MU verification tool with the first action level range equal to 3.5%.

Objective: The objective of the study was to determine the correct CTV-PTV margin, depending on the method used to verify the PG position. In the study, 3 methods of CBCT image superimposition were assessed as based on the location of the prostate gland (CBCT images), a single gold marker, and pubic symphysis respectively. Materials and methods: The study group consisted of 30 patients undergoing irradiation therapy at the University Hospital in Zielona Góra. The therapy was delivered using the VMAT (Volumetric Modulated Arc Therapy) protocol. CBCT image-based superimposition (prostate-based alignment) was chosen as the reference method. The uncertainty of the PG positioning method was determined and the margin to be used was determined for the CBCT-based reference method. Then, changes in the position of the prostate gland relative to these determined using the single marker and pubic symphysis-based methods were determined. The CTV-PTV margin was calculated at the root of the sum of the squares for the doubled value of method uncertainty for the CBCT image-based alignment method and the value of the difference between the locations of planned and actual isocenters as determined using the method of interest and the CBCT-based alignment method for which the total number of differences accounted for 95% of all differences. Results: The CTV-PTV margins to be used when the prostate gland is positioned using the CBCT imaging, single marker, and pubic symphysis-based methods were determined. For the CBCT-based method, the following values were obtained for the Vrt, Lng, and Lat directions respectively: 0.43 cm, 0.48 cm, 0.29 cm. For the single marker-based method, the respective values were 0.7 cm, 0.88 cm, and 0.44 cm whereas for the pubic symphysis-based method these were 0.65 cm, 0.76 cm, and 0.46 cm. Conclusions: Regardless of the method, the smallest margin values were obtained for the lateral direction, with the CBCT-based method facilitating the smallest margins to be used. The largest margins were obtained using the single marker-based alignment method.

Background The No Action Protocol (NAL) was used to diminish the systematic set-up error. Recently, owing to the development of image registration technologies, the on-line positioning control is more often used. This method significantly reduces the CTV–PTV margin at the expense of the lengthening of a treatment session. The efficiency of NAL in decreasing the total treatment time for Head&Neck patients was investigated. Methods Results of set-up control of 30 patients were analyzed. The set-up control was carried out on-line. For each patient and each fraction, the set-error and the time needed for making the set-up control procedure were measured. Next, retrospectively, the NAL was applied to this data. The number of initial errors (without interventions) and after NAL protocol were compared in terms of errors larger than 3 and 4 mm. The average and total time used for portal control was calculated and compared. Results The number of setup errors in the posterior-anterior, inferior-superior, and right–left directions ≥3 mm and ≥4 mm were 98, 79, and 91 sessions and 44, 38 and 30 sessions out of 884 sessions. After NAL protocol the number of errors ≥3 mm and ≥4 mm decreased to 84, 57, and 39 sessions and 31, 15 and 10 sessions, respectively. The average time needed for one set-up control was 5.1 min. NAL protocol allows saving 4049 min for the whole group. Conclusions For locations where the random set-up errors are small, the NAL enables a very precise treatment of patients. Implementation of this protocol significantly decreases the total treatment time.

Purpose: The purpose of the study was to investigate the dependence of tissue inhomogeneity correction factors (ICFs) on the photon beam quality index (QI). Materials and Methods: Heterogeneous phantoms, comprising semi-infinite slabs of the lung (0.10, 0.20, 0.26 and 0.30 g/cm3), adipose tissue (0.92 g/cm3) and bone (1.85 g/cm3) in water, were constructed in the Eclipse treatment planning system. Several calculation models of 6 MV and 15 MV photon beams for quality index (TPR20,10) = 0.670±k*0.01 and TPR20,10 = 0.760±k*0.01, k = -3, -2, -1, 0, 1, 2, 3 respectively were built in the Eclipse. The ICFs were calculated with the anisotropic analytical algorithm (AAA) for several beam sizes and points lying at several depths inside of and below inhomogeneities of different thicknesses. Results: The ICFs increased for lung and adipose tissues with increasing beam quality (TPR20,10), while decreased for bone. Calculations with AAA predict that the maximum difference in ICFs of 1.0% and 2.5% for adipose and bone tissues, respectively. For lung tissue, changes of ICFs of a maximum of 9.2% (6 MV) and 13.8% (15 MV). For points where charged particle equilibrium exists, a linear dependence of ICFs on TPR20,10 was observed. If CPE doesn’t exist, the dependence became more complex. For points inside of the low-density inhomogeneity, the dependence of the ICFs on energy was not linear but the changes of ICFs were smaller than 3.0%. Measurements results carried out with the CIRS phantom were consistent with the calculation results. Conclusions: A negligible dependence of the ICFs on energy was found for adipose and bone tissue. For lung tissue, in the CPE region, the dependence of ICFs on different beam quality indexes with the same nominal energy may not be neglected, however, this dependence was linear. Where there is no CPE, the dependence of the ICFs on energy was more complicated.

Periodic intermediate checks on the equipment used for calibration activity accredited for the conformity with the international norm ISO/IEC 17025 are an essential issue for monitoring the validity of calibration laboratory's results. These checks should be carried out according to a procedure defined by each accredited laboratory. The results of these checks should not exceed the acceptance criteria established in the laboratory and statistical techniques shall be applied to the reviewing of the results. In this work, a simple method of carrying out intermediate checks on working standards used for calibrations of ionizing radiation dosimeters in a

Purpose Interfraction tumor setup variations in radiotherapy are often reduced with image guidance procedures. Clinical target volume (CTV)-planning target volume (PTV) margins are then used to deal with residual errors. We have investigated characterization of setup errors in patient populations with explicit modelling of occurring interfraction time trends. Methods The core of a "trendline characterization" of observed setup errors in a population is a distribution of trendlines, each obtained by fitting a straight line through a patient's daily setup errors. Random errors are defined as daily deviations from the trendline. Monte Carlo simulations were performed to predict the impact of offline setup correction protocols on residual setup errors in patient populations with time trends. A novel CTV-PTV margin recipe was derived that assumes that systematic underdosing of tumor edges in multiple consecutive fractions, as caused by trend motion, should preferentially be avoided. Similar to the well-known approach by van Herk et al. for conventional error characterization (no explicit modelling of trends), only a predefined percentage of patients (generally 10%) was allowed to have nonrandom (systematic + trend) setup errors outside the margin. Additionally, a method was proposed to avoid erroneous results in Monte Carlo simulations with setup errors, related to decoupling of error sources in characterizations. The investigations were based on a database of daily measured setup errors in 835 prostate cancer patients that were treated with 39 fractions, and on Monte Carlo-generated patient populations with time trends. Results With conventional characterization of setup errors in patient populations with time trends, predicted standard deviations of residual systematic errors ( Σ res ) after application of an offline correction protocol could be underestimated by more than 50%, potentially resulting in application of too small margins. With the new trendline characterization this was avoided. With the novel CTV-PTV margin recipe with an allowed 10% of patients having nonrandom errors outside the margin, the observed percentage was 10.0% ± 0.2%. When using conventional characterization of errors and the van Herk margin recipe, on average 58.0% ± 24.3% of patients had errors outside the margin, while 10% was prescribed. For populations with no time trends, the novel recipe simplifies to the generally applied M = 2.5 Σ + 0.7 σ formula proposed by van Herk et al. CONCLUSIONS: In populations with time trends in setup errors, the use of trendline characterizations in Monte Carlo simulations for establishment of residual errors after a setup correction protocol can avoid application of erroneous margins. The novel margin recipe can be used to accurately control the percentage of patients with nonrandom errors outside the margin. In case of daily image guidance of patients with multiple targets with differential motion, the recipe can be used to establish margins for the targets that are not the primary target for the image guidance (e.g., nodal regions). Probabilistic planning might be improved by using trendline characterization for modelling of setup errors. Population analyses of interfraction setup errors need to take into account potential time trends.

BackgroundA non-invasive tool for the assessment of ulcerative colitis (UC) activity is needed for treatment control.PurposeTo determine the efficacy of intravoxel incoherent motion (IVIM) in assessing inflammatory activity in UC.Material and MethodsIn this prospective study, 20 adult patients underwent 3.0-T magnetic resonance imaging (MRI) IVIM diffusion-weighted imaging (DWI) with 10 b-values (0–900 s/mm2) 0–6 days after biopsies entailing colonoscopy. The inflammatory activity of large bowel segments was graded on endoscopy with Mayo score and on pathology with a six‑grade classification system. IVIM‑derived parameters (f, D, and D*) calculated from regions of interest placed within the bowel wall were correlated with both scores (56 and 34 bowel segments, respectively). Radiologists were blinded to endoscopy and pathology results. A T-test and Wilcoxon rank sum test was used in comparisons and receiver operating characteristic curve analysis was performed.ResultsStatistically significant differences were found between histopathologically inactive or mild activity and moderate to severe activity in f (respectively: mean = 0.19 and mean = 0.28, P = 0.024; area under the curve [AUC] = 0.723, sensitivity 0.82, specificity 0.59, accuracy 0.67 for a 0.185 cut-off value) and D (mean = 1.34 × 10−3mm2/s and mean = 1.07 × 10−3mm2/s, P = 0.0083; AUC = 0.735, sensitivity 0.91, specificity 0.54, accuracy 0.66 for cut-off value 1.24 × 10−3mm2/s). No significant difference in D* was noted. No significant correlation between Mayo endoscopic subscore, and f, D, nor D* was found.ConclusionIVIM perfusion fraction correlates with UC activity and might represent emerging tool in assessment of inflammatory activity.

Aim The aim of the study was to analyze the long-term stability of electron beams generated by the Novac11™ IORT accelerator. Background Novac11™ (NRT ® ) is a mobile electron accelerator designed to irradiate small areas of tissue, up to 10 cm in diameter, with electron beams during surgical procedures. It is characterized by a great mobility guaranteed by a number of degrees of freedom enabling irradiation in the conditions of an operating theatre. Materials and methods Over the period of January 2013 and September 2016, the measurement sessions of the output of clinically used beam qualities (6, 8 and 10 MeV) were carried out 41 times. Because of the unsatisfactory long-term stability, an extra procedure of tuning of the magnetron, suggested by the manufacturer, was introduced in October 2015, 15 measurements were performed since then. The output of the Novac11™ accelerator was measured in the reference conditions recommended by the IAEA Report 398, the measurements of the charge in the ionization chamber at the reference depth were carried out with a Dose1™ electrometer and a plane-parallel chamber PPC05™ from IBA ® . Results The introduction of the tuning of the magnetron procedure resulted in satisfactory long-term stability of the measured outputs below 2%. Conclusions After the introduction of the STV parameter tuning procedure, the long-term stability of the Novac11™ output increased considerably and is within the values declared by the manufacturer.

Aim To investigate the influence of several factors on the accuracy of dose measurements and feasibility of application of small Gafchromic detectors for postal audit. Background Our experience showed that precision of dose measurements with small pieces of Gafchromic films may be significantly improved. Materials and methods Gafchromic films with dimensions of 1[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]1, 2[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]2 and 3[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]3[[ce:hsp sp="0.25"/]]cm 2 were exposed to 6[[ce:hsp sp="0.25"/]]MV X-rays at dose levels of 50[[ce:hsp sp="0.25"/]]cGy-210[[ce:hsp sp="0.25"/]]cGy. The single- and multichannel methods (MM) were used for dose measurements. Detectors were scanned with an Epson V750PRO flatbed colour scanner. For 1[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]1 and larger detector sizes, separate calibration curves were established. The influence of the following factors was investigated: the heterogeneity of Gafchromic detectors group for single- and MM, ambient thermal detector conditions, the dose delivered on the measurement accuracy, application of two separate calibration curves for the smallest and larger pieces of films. Results The MM improves significantly the precision of dose measurement. The uncertainty attributed to detector active layer differences and scanner instabilities was about 1[[ce:hsp sp="0.25"/]]cGy (1 StDev) regardless of dose and detector size. The ambient temperature of the environment in which films were stored after irradiation influenced the dose reading. Significant difference of transmission for detectors sized 1[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]1 and 2[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]2cm 2 was observed. The maximal difference between applied dose and dose reading performed was 1.1%. Conclusions The MM with a scaling protocol leads to a very high precision of dose measurements. The ambient thermal detector environment causes significant changes of measured signal. The detector size has relevant impact on dose reading.

Introduction: Commissioning of the treatment-planning system includes the accuracy of dose calculations in the inhomogeneous absorber. Several results of measurements with regard to inhomogeneity correction factors (CFs) have been published. However, the dependence of CFs on photon-beam energy may preclude such results from being applied to the photon beams of general users. Purpose: The aim of this study was to assess the dependence of CFs on the photon-beam energy. Materials and methods: CFs were calculated by the Batho method for several slab geometries comprised of concentrations of lung tissue and water of 0.25 and 1.00 g/cm3, respectively. The CFs were calculated at 6 MV (TPR20 10 = 0.67 ± k * 0.01) and 15 MV (TPR20 10 = 0.76 ± k * 0.01) where k = -3, -2, -1, 0, 1, 2, 3. All calculations were performed in the region where a charged-particle equilibrium exists. Results: Changes in CFs of less than 2% were observed across the considered energy ranges. With a change in TPR20,10 of 0.01, both at 6 and 15 MV at a depth of 5 cm below the lung; and lung thicknesses of 3, 5 and 8 cm over a fi eld surface area of 10 × 10 cm2, the change in CF never exceeded 2.4%. The dependences of changes in CFs in terms of TPR20,10 were 1.74% and 1.20% for field surface areas of 5 × 5 cm2 and 20 × 20 cm2, respectively. A comparison of 42 linear accelerators (LINACs) exhibiting 6 MV and 15 MV of energy installed in Poland showed that the maximum differences in terms of TPR20,10 at 6 MV and 15 MV were 4.2% and 2.2%, respectively. Conclusion: A linear dependence of CFs on energy was observed. According to observations, the smaller the surface area of the field and deeper the point of interest below the lung, the more dependent CFs are on energy.

Purpose: To optimise the intravoxel incoherent motion (IVIM) imaging of the liver on a 3.0T scanner by assessing parameter reproducibility on free-breathing (FB) and respiratory-triggered (RT) sequences acquired with different numbers of signal averages (NSA). Material and methods: In this prospective study 20 subjects (M/F: 10/10; age: 25-62 years, mean: 39 years) underwent IVIM magnetic resonance imaging (MRI) on a 3.0T scanner using an 18-channel phase-arrayed coil and four different echo-planar sequences, each with 10 b values: 0, 10, 30, 50, 75, 100, 150, 200, 500, and 900 s/mm2. Images were acquired with FB and RT with NSA = 1-4 (FBNSA1-4, RTNSA1-4) and with NSA = 3-6 (FBNSA3-6, RTNSA3-6). Subsequently, for the assessment of reproducibility of IVIM-derived parameters (f, D, D*), each subject was scanned again with an identical protocol during the same session. IVIM parameters were calculated. The distribution of IVIM-parameters for each DWI sequence were given as the median value with first and third quartile. Inter-scan reproducibility for each IVIM parameter was evaluated using coefficient of variance and Bland-Altman difference. Differences between FB sequence and RT sequence were tested using non-parametric Wilcoxon signed-rank test. Results: Mean coefficient of variance (%) for f, D, and D* ranged from 60 to 64, from 58 to 84, and from 82 to 99 for FBNSA1-4 sequence; from 50 to 69, from 41 to 97, and from 80 to 82 for RTNSA1-4 sequence; from 22 to 27, 15, and from 70 to 80 for FBNSA3-6 sequence; and from 21 to 32, from 12 to, and from 50 to 80 for RTNSA3-6 sequence, respectively. Conclusions: Increasing the number of signal averages for IVIM acquisitions allows us to improve the reproducibility of IVIM-derived parameters. The sequence acquired during free-breathing with NSA = 3-6 was optimal in terms of reproducibility and acquisition time.

Purpose: An interplay between detector motion and MLC motion is a source of measurement error, when dose for dynamic arc is measured using a dosimetry system moving relative to the beam central axis during its rotation with a gantry. The purpose of this study is to develop and to evaluate a method of quantitative testing of a sag/flex of such dosimetry systems. Methods: The method is based on evaluation of relative differences between signals measured for two single arc beams, where a narrow slit field is sliding during gantry movement in opposite directions. The component of a measurement error related to the interplay effect was first assessed based on theoretical computer simulations and then on measurements for four dosimetry systems. The sag pattern of EPID and 2D array was extracted from the measurement results. Results: The simulations showed a 4 mm difference in field width and 3.3% difference in relative signals at beam axis between test beams where the slit field swept over 19 cm in opposite directions ( sinusoidal sag pattern with amplitude of 1 mm was assumed). The signal differences exceeding 4% and 5% were measured for EPID and 2D array, respectively. Conclusions: Even relatively small detector sag (less than 1 mm) can produce significant measurement error; therefore, the detector sag test should be an obligatory component of a validation of rotating dosimetry systems used for QA of dynamic arcs.

Background. Irradiation of a larger volume of the target may lead to an increase of the doses delivered to the surrounding organs at risk (OAR) for post-prostatectomy patients with a higher risk of nodal involvement. It was anticipated that IMRT significantly improved OAR sparing. The aim of this study was to provide a dosimetric comparison between conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) treatment plans for patients with prostate cancer irradiated to the prostate bed and pelvic lymph-nodal area. Materials and methods. The 3D-CRT and IMRT plans were created for ten patients after prostatectomy. The treatment plans were generated for the prostate bed (PTV1) and the pelvic lymph nodes (PTV2). The sum of PTV1 and PTV2 was irradiated to a mean dose of 46 Gy in 23 fractions, and additionally PTV1 was irradiated to a mean dose of 18 Gy in 9 fractions. Target coverage and the doses delivered to the pelvic bones, the rectum, the bladder, the bowel bag, and the femurs, were compared between techniques. The Wilcoxon signed-rank test was used to compare the dosimetric parameters. Results. The dosimetric quality of 3D-CRT and IMRT plans were comparable for target coverage (the mean value of PTV1 V95%, the mean value of PTV2 V95% all > 99%). The IMRT plans resulted in significant reductions in the pelvic bones V30[%], V40[%], the rectum V40[%], V50[%], V60[%], the bladder V40[%], V50[%], V60[%], the bowel bag V45[cc] and the femurs V40[%]. Conclusions . The analysis presented in this paper demonstrates that the IMRT technique reduces the delivered dose to the OARs. Most interesting was the possibility of reducing the delivered dose to the pelvic bones and the bowel bag. This allowed us to expect a decreased risk of acute hematologic toxicity and acute gastrointestinal toxicity.

Aim: The aim of the study was to compare several methods of dose prescription, the mean dose, the median dose, the effective dose and the generalized Equivalent Uniform Dose (gEUD). Background: The dose distribution in the planning target volume is never fully homogenous. Depending on the dose prescription method for the same prescribed dose different biologically equivalent doses are delivered. The latest ICRU Report 83 proposes to prescribe the dose to the median dose in the PTV. Several other methods are also in common use. It is important to know what are differences of doses actually delivered depending on the dose prescription method. Materials and methods: The study was performed for three groups of patients treated radically with external beams in Brzozow, over the 2012-2013 period. The groups were of patients with breast, lung and prostate cancer. There were 10 patients in each group. For each patient all metrics, i.e. the mean dose, the median dose, the effective dose and the generalized Equivalent Uniform Dose, were calculated. The influence of the dose homogeneity in the PTV on the results is also evaluated. The gEUD was used as a reference dose prescription method. Results: For all patients, an almost perfect correlation between the median dose and the gEUD was obtained. Worse correlation was obtained between other metrics and the gEUD. The median dose is almost always a little higher than the gEUD, but the ratio of these two values never exceeded 1.013. Conclusion: The median dose seems to be a good and simple method of dose prescription.

This paper describes the role of the Polish Secondary Standard Dosimetry Laboratory (SSDL) in quality assurance in radiotherapy by means of providing calibration of ionisation chambers, TLD postal dosimetry audits and end-to-end audits for radiation therapy. A historical review of the methods and results are presented. The influence of the SSDL in Warsaw on radiation protection of patients in Poland is discussed. The International Atomic Energy Agency together with World Health Organisation (IAEA/WHO), through its network of SSDLs around the world, propagates newly developed methods for calibration and auditing. Suitable high quality equipment was provided by the IAEA, as well as special materials and technical support to the SSDL in Warsaw. The activity of the SSDL and the services provided for Polish radiotherapy centres have resulted in a reduction of discrepancies between planned doses and doses delivered to patients. The newly tested IAEA methods of end-to-end on-site dosimetry audits allow for monitoring and improving the quality of IMRT in Poland. The traceability of standards used for the calibration of therapy level dosimeters from Polish radiotherapy centres is assured by the IAEA dosimetry laboratory. The consistency of methods performed in the Polish SSDL with the ISO:17025 norm is supervised by the Polish Centre for Accreditation - a member of International Laboratory Accreditation Cooperation (ILAC), for calibration and testing. Due to the rapid technological development of radiotherapy, special attention has to be paid to newly developed methods for dosimetry auditing and institutions which provide services for assuring radiation safety of patients.

Volumetric Modulated Radiotherapy (VMAT) implementation requires additional Quality Assurance (QA) tests to assure stable machine performance especially in terms of dynamic parameters synchronization. The lack of a twin machine for TrueBeam led us to the investigation of backup workflow with Clinacs 2300C/D. These Clinacs were upgraded to make them VMAT-enabled. This study aimed to compare long-term VMAT performance QA on 3 accelerators: TrueBeam (TB) and 2 Clinacs (V4 and V5). All VMAT test plans were provided by Varian. The test set consisted of initial and advanced tests. Initial tests were intended to check the gravity effect on Multileaf Collimator (MLC) and dosimetry system. As the results of these tests were correct and there was visual inspection applied for MLC positioning accuracy analysis, they were not presented in the paper. We focused on 2 advanced tests: dose rate vs gantry speed and dose rate vs MLC speed. The idea of the advanced test was to compare segments irradiated with the same fluence but different dose rate, gantry speed or MLC speed. Test sets were irradiated weekly on average for 12 months. These tests were analysed following Varian procedures and criteria using in-house-developed software. Apart from that we calculated correlation between all segments pairs and performed profile analysis. According to Varian criteria, all tests for TrueBeam were very well within the tolerances. Dose rate vs gantry speed tests for Clinacs were within allowed limits while as many as 28% and 6% of dose rate vs MLC speed tests failed for Clinacs V4 and V5, respectively. The profile analysis revealed tests for which the difference between measured and planned dose was over 3% and still met the criteria. The correlation analysis showed that VMAT plans on TrueBeam were irradiated repeatably because all segments were strongly correlated. There was no correlation between the segment with the highest MLC speed and the other segments on Clinacs in dose rate vs MLC speed test. This segment was irradiated randomly. TrueBeam is more reliable than upgraded Clinacs 2300C/D for VMAT performance. That is why in our centre the one of upgraded Clinac that performed tests better served only as a backup machine for VMAT technique, and the second one was excluded from clinical use for this technique.

Purpose The objective was to optimise the number of b-values for diffusion kurtosis imaging (DKI) of the liver and pancreas in MR examinations to ensure reliable results with the shortest possible acquisition time. Methods Twenty healthy volunteers underwent DKI at 3.0 T Siemens Magnetom Skyra using 7 b-values (b = 0, 200, 500, 750, 1000, 1500, 2000 s/mm2). The regions of interest (ROIs) were placed in the liver (right lobe, left lobe) and pancreas (head, tail). DKI parameters (Dapp, Kapp) for ROIs were calculated for 7 b-values utilising the nonlinear least-squares (NLLS) Marquardt-Levenberg algorithm. All calculations were repeated for ten subsets of data, with the number of b-values reduced to 4. DKI parameters calculated for subsets were compared with parameters calculated for all 7 b-values. Results The correlation coefficient between DKI parameters calculated for 7 b-values and subsets ranged from 0.65 to 1.00. The coefficient of variation (CoV) of DKI parameters calculated for a group of volunteers varied from 8% to 42% and was not affected by the reduction of the b-values number. Only one subset of data (b = 0, 500, 1500 and 2000 s/mm2) simultaneously met two criteria: no statistical difference (p Conclusions DKI acquisition with 4 b-values (b = 0, 500, 1500 and 2000 s/mm2), compared to DKI acquisition utilising 7 b-values, allowed for the reduction of acquisition time by 36%, without affecting the calculated DKI parameters.

Aim The goal of this prospective study was to assess the effectiveness of a hypofractionated accelerated regime in treatment of the larynx cancer. Background Multiple radiotherapy delivery regimes are used for treatment of the larynx cancer. Hypofractionated regimes could provide similar results with reduced use of radiotherapy facilities. Material and methods 223 patients with squamous cell carcinoma of the upper or middle larynx have been treated with 63[[ce:hsp sp="0.25"/]]Gy delivered in 28 fractions of 2.25[[ce:hsp sp="0.25"/]]Gy during 38 days, 5 fractions per week. The study endpoints were overall survival, progression-free survival, early and late treatment toxicity. Standard and accelerated radiotherapy groups from the study published by Hliniak et al.[[ce:cross-ref id="crf0065" refid="bib0275"]] 20 served as controls. Results Five-year actuarial overall survival was 87.5% in the study group, 84.5% in the control group receiving accelerated radiotherapy (33 fractions of 2.0[[ce:hsp sp="0.25"/]]Gy, 6 fractions per week) and 86.2% in the control group (33 fractions of 2.0[[ce:hsp sp="0.25"/]]Gy, 5 fractions per week). Five-year progression-free survival was 73.6%, 77.2% and 66.2%, respectively. Overall, treatment toxicity and complication rates did not differ between the study group and the control groups. Conclusions The hypofractionated accelerated radiotherapy protocol using 5 fractions per week reduced the use of radiotherapy facilities. There was no significant difference in overall survival and progression-free survival between the study and control groups treated with accelerated or standard radiotherapy.

The aim of the study was to verify the accuracy of calculations of dose distributions for electron beams performed using the electron Monte Carlo (eMC) v.10.0.28 algorithm implemented in the Eclipse treatment planning system (Varian Medical Systems). Implementation of the objective of the study was carried out in two stages. In the first stage the influence of several parameters defined by the user on the calculation accuracy was assessed. After selecting a set of parameters for which the best results were obtained a series of tests were carried. The tests were carried out in accordance with the recommendations of the Polish Society of Medical Physics (PSMP). The calculation and measurement of dose rate under reference conditions for semi quadratic and shaped fields were compared by individual cut-outs. We compared the calculated and measured percent depth doses, profiles and output factors for beams with an energy of 6, 9, 12, 15 and 18 MeV, for semi quadratic fields and for three different SSDs 100, 110, and 120 cm. All tests were carried out for beams generated in the Varian 2300CD Clinac linear accelerator. The results obtained during the first stage of the study demonstrated that the highest compliance between the calculations and measurements were obtained for the mean statistical uncertainty equal to 1, and the parameter responsible for smoothing the statistical noise defined as medium. Comparisons were made showing similar compliance calculations and measurements for the calculation grid of 0.1 cm and 0.25 cm and therefore the remaining part of the study was carried out for these two grids. In stage 2 it was demonstrated that the use of calculation grid of 0.1 cm allows for greater compliance of calculations and measurements. For energy 12, 15 and 18 MeV discrepancies between calculations and measurements, in most cases, did not exceed the PSMP action levels. The biggest differences between measurements and calculations were obtained for 6 MeV energy, for smallest fields and large SSD distances. Despite these discrepancies between calculations the model was adopted for clinical use.

This paper presents the situation of the profession of medical physicists in Poland. The official recognition of the profession of medical physicist in Polish legislation was in 2002. In recent years, more and more Universities which have Physics Faculties introduce a medical physics specialty. At present, there are about 15 Universities which offer such programmes. These Universities are able to graduate about 150 medical physicists per year. In 2002, the Ministry of Health introduced a programme of postgraduate specialization in medical physics along the same rules employed in the specialization of physicians in various branches of medicine. Five institutions, mostly large oncology centres, were selected as teaching institutions, based on their experience, the quality of the medical physics professionals, staffing levels, equipment availability, lecture halls, etc. The first cycle of the specialization programme started in 2006, and the first candidates completed their training at the end of 2008, and passed their official state exams in May 2009. As of January 2016, there are 196 specialized medical physicists in Poland. Another about 120 medical physicists are undergoing specialization. The system of training of medical physics professionals in Poland is well established. The principles of postgraduate training and specialization are well defined and the curriculum of the training is very demanding. The programme of specialization was revised in 2011 and is in accordance with EC and EFOMP recommendations.

The aim of the study was to investigate the influence of thermoplastic masks material (Klarity Medical&Equipment Co., Guangzhou, China) with different diameters of holes (ϕ 0.25 cm and ϕ 0.40 cm) on the dose distribution in the build-up region for photon beams. Measurements were made for external radiation beams produced by the linear accelerator (TrueBeam, Varian Medical Systems, Inc., Palo Alto, CA, USA) using the Markus parallel plane ionization chamber and the Unidos electrometer (both from PTW, Freiburg, Germany). Measurements were made in a solid water phantom for two photon energies 6 MV and 15 MV, at 90 cm source to skin distance, for four fields of 5 cm × 5 cm, 10 cm × 10 cm, 15 cm × 15 cm and 20 cm × 20 cm. Compared to the open field, the maximum dose with mask was closer to the surface of the phantom by about 1.4 mm and 1.2 mm for 6 MV and 15 MV X-Rays, respectively. The surface dose increase from 10% to 42% for 6 MV and from 5% to 28% for 15 MV X-Rays.

Nowadays in radiotherapy, much effort is taken to minimize the irradiated volume and consequently minimize doses to healthy tissues. In our work, we tested the hypothesis that the mean dose distribution calculated from a few first fractions can serve as prediction of the cumulated dose distribution, representing the whole treatment. We made our tests for 25 prostate cancer patients treated with three orthogonal fields technique. We did a comparison of dose distribution calculated as a sum of dose distribution from each fraction with a dose distribution calculated with isocenter shifted for a mean setup error from a few first fractions. The cumulative dose distribution and predicted dose distributions are similar in terms of gamma (3 mm 3%) analysis, under condition that we know setup error from seven first fractions. We showed that the dose distribution calculated for the original plan with the isocenter shifted to the point, defined as the original isocenter corrected of the mean setup error estimated from the first seven fractions supports our hypothesis, i.e. can serve as a prediction for cumulative dose distribution.

Aim To verify the reproducibility of patients irradiated after mastectomy on the immobilization system designed and manufactured for our hospital and to compare the Internal Protocol (IP) with the modified-No Action Level Protocol. Background Application of forward IMRT techniques requires a good reproducibility of patient positioning. To minimize the set-up error, an effective immobilization system is important. Materials and methods The study was performed for two groups of 65 each. In the first group, portal images for anterior field were taken in 1–3 fractions and, subsequently, three times a week. In this group, the mNAL protocol was used. In the second group, the IP was used. The portal images from the anterior field and from the gantry 0 were taken during the 1–3 and 10 fractions. In both groups, image registration was performed off-line. For each group the systematic and random errors and PTV margin were calculated. Results In the first group the value of the population systematic errors and random errors were 1.6 ± 1.6 mm for the left–right, and 1.5 ± 1.7 mm for the cranial–caudal directions, respectively, 1.7 ± 1.3 mm, and 1.9 ± 1.3 mm for the second group. The PTV margins for the left–right and cranial–caudal directions were 5.1 and 4.9 mm for the first group and 5.4 and 6.4 mm for the second group. Conclusions For patients immobilized with our support device treated according to the mNAL protocol or IP, a good set-up reproducibility was obtained. Implementation of IP limits the number of required images.

Background Late rectal injury is a common side effect of external beam radiotherapy for prostate cancer. Aim The aim of this study was to evaluate what total dose may be safely delivered for prostate patients for 3DCRT and IMRT techniques and the CTV–PTV margin. Materials and methods 3DCRT and IMRT plans were prepared for 12 patients. For each patient PTV was defined with CTV–PTV margins of 0.4, 0.6, …, 1.0 cm, and total doses of 70, 72, …, 80 Gy, with 2 Gy dose fraction. NTCP values for the rectum were calculated using the Lyman model. Both techniques were compared in terms of population mean DVH. Results Significantly smaller NTCPs for IMRT were obtained. For both techniques diminishing the margin CTV–PTV of 2 mm leads to decreasing the NTCP of about 0.03. For total dose of 80 Gy the NTCP was smaller than 10% for the 4 mm margin only. The QUANTEC dose volume constraints were more frequently fulfilled for the IMRT technique than for the 3DCRT technique. Conclusions The IMRT technique is safer for prostate patients than the 3DCRT. If very high total doses are applied the CTV–PTV margin of 0.4 cm and the IMRT technique should be used. If the CTV–PTV margin of 0.6 cm is applied, the NTCP is smaller than 10% for the 3DCRT and IMRT techniques for the total doses smaller than 74 Gy and 78 Gy, respectively.

Purpose Basing on CBCT images we noticed, that there are several different problems with reproducibility of bolus positioning, especially air gap occurrence. The aim of this study was to determine the influence of air gaps between bolus and phantom on dose distribution in build-up region for X6 MV. The novelty of the work is using low-density boluses fabricated with 3D printer. Methods Depth dose measurements were performed for X6 MV 10×10 cm2 open field, generated with Varian CL 2300 C/D. The measurements were carried out with the Markus plane parallel ionization chamber (PTW, 0.055 cm3 volume), connected to Unidos (PTW) electrometer. As 1 cm thick beam spoilers we used 3D-printed thermoplastic polyurethane (TPU) cuboids filled with 5%, 10%, 15% and 20% honeycomb structure (thickness of 0.5 g/cm2; 0.17 g/cm2; 0.22 g/cm2). To generate air gap we used homemade styrofoam frames. Measurements were performed at a physical depth of 1, 5, 10 and 15 mm for all beam spoilers without air gaps and with 10, 20, 30 and 40 mm air gaps, at constant 90 cm SSD. Results Our results showed that beam spoilers without air gap increased the dose in build-up region. The bigger spoiler filling is, the larger is surface dose. The same dependence can be seen on Percentage Depth-Dose curves, irrespectively of air gap size. Regardless of spoiler percentage filling with honeycomb structure, the larger air gap size is, the smaller dose on 1 mm depth. Conclusions Influence of beam spoiler filling and air gap on dose distribution in build-up region for X6 MV was investigated. Beam spoiler increased the dose in build-up region. The larger thickness of beam spoiler (larger filling) - the larger influence on build-up dose. Occurrence of air gaps lowers the surface dose. However, the influence of air gap in the range of 10–40 mm is not very visible. For bolus with density of 0.22 g/cm2; regardless of air gap size, the dose on 1 mm depth was always larger than 95% of maximum dose. The issue will be investigated for wedged and dynamic fields.

Purpose The purpose of this study was to assess the effect of variations of the beam quality (TPR20,10) for photon beams on tissue inhomogeneity correction factors (ICFs). Methods A total of 90 three-dimensional conformal radiotherapy (3DCRT) treatment plans for three locations (3DCRT lung, gynaecological, prostate) and 15 SRS lung plans were considered for this study. For 3DCRT plans, the ICFs were calculated for a range of beam qualities. For 6 MV, the range of TPR20,10 was 0.670 ± 3%, and for 15 MV, the range of TPR20,10 was 0.760 ± 3%. The stereotactic plans were prepared with two 6 MV beams from a Varian TrueBeam accelerator - one generated with a flattening filter (X6, TPR20,10 = 0.688) and one flattening filter free (X6FFF, TPR20,10 = 0.632). Calculations were performed using Eclipse treatment planning system (TPS) with the anisotropic analytical algorithm (AAA). ICFs were also measured in a CIRS Tissue Simulation Phantom (thorax with lungs) for two fields 5 × 5 and 10 × 10 for X6 and X6FFF beams. PTW Farmer and semiflex ionization chambers were used for measurements. Results Calculations for 3DCRT plans showed that the 6% variations in energy (TPR20,10) lea to average changes of ICFs of 2.0% (6 MV) and 2.6% (15 MV) for lung cases. For gynaecological and prostate patients, the mean differences of ICFs were less than 1%. The difference of 5.6% of TPR20,10 values between X6 and X6 FFF for lung SRS treatment plans led to a difference of ICFs of less than 2%. Measurements with the CIRS phantom also demonstrated differences of ICFs consistently less than 5% between X6 and X6 FFF beams. Conclusions The influence of energy on inhomogeneity correction factors is rather small. Correction factors measured on one accelerator may be used for another accelerator with similar energy provided quality control tests are performed.

W opracowaniu przedstawiono zestaw testow, ktore zdaniem Polskiego Towarzystwa Fizyki Medycznej, powinny być wykonywane dla monitorow używanych do prezentowania obrazu zapisanego w postaci cyfrowej. Dokument ten powstał z inicjatywy Zarządu Głownego Polskiego Towarzystwa Fizyki Medycznej, został opracowany na podstawie dostępnych publikacji przez fizykow z Zakładu Fizyki Medycznej Centrum Onkologii w Warszawie we wspołpracy z zespołem konsultantow powołanych przez Zarząd Głowny PTFM.

Coraz powszechniej klisza rentgenowska jest wypierana przez detektory cyfrowe. Obraz zapisany w postaci cyfrowej jest następnie prezentowany z użyciem monitorow, zwykle diagnostycznych. W niniejszym dokumencie przedstawiono zestaw testow, ktore zdaniem Polskiego Towarzystwa Fizyki Medycznej, powinny być wykonywane dla monitorow używanych do prezentowania obrazu zapisanego w postaci cyfrowej. Dokument ten powstał z inicjatywy Zarządu Głownego Polskiego Towarzystwa Fizyki Medycznej, został opracowany na podstawie dostępnych publikacji przez fizykow z Zakładu Fizyki Medycznej Centrum Onkologii w Warszawie we wspołpracy z zespołem konsultantow powołanych przez Zarząd Głowny PTFM.

W opracowaniu przedstawiono zestaw testow specjalistycznych, ktore zdaniem Polskiego Towarzystwa Fizyki Medycznej, powinny być wykonywane w mammografii z detektorem filmowym. Dokument ten powstał z inicjatywy Zarządu Głownego Polskiego Towarzystwa Fizyki Medycznej i został opracowany, na podstawie dostępnych publikacji oraz obowiązującego prawa, przez fizykow z Zakładu Fizyki Medycznej Centrum Onkologii w Warszawie we wspołpracy z zespołem konsultantow powołanych przez Zarząd Głowny PTFM.

The aim of this study was to propose a method to predict the minimum achievable mean lung dose (MLD) and corresponding dosimetric parameters for organs-at-risk (OAR) based on individual patient anatomy. For each patient, the dose for 36 equidistant individual multileaf collimator shaped fields in the treatment planning system (TPS) was calculated. Based on these dose matrices, the MLD for each patient was predicted by the homemade DosePredictor software in which the solution of linear equations was implemented. The software prediction results were validated based on 3D conformal radiotherapy (3D-CRT) and volumetric modulated arc therapy (VMAT) plans previously prepared for 16 patients with stage III non–small-cell lung cancer (NSCLC). For each patient, dosimetric parameters derived from plans and the results calculated by DosePredictor were compared. The MLD, the maximum dose to the spinal cord (D max cord ) and the mean esophageal dose (MED) were analyzed. There was a strong correlation between the MLD calculated by the DosePredictor and those obtained in treatment plans regardless of the technique used. The correlation coefficient was 0.96 for both 3D-CRT and VMAT techniques. In a similar manner, MED correlations of 0.98 and 0.96 were obtained for 3D-CRT and VMAT plans, respectively. The maximum dose to the spinal cord was not predicted very well. The correlation coefficient was 0.30 and 0.61 for 3D-CRT and VMAT, respectively. The presented method allows us to predict the minimum MLD and corresponding dosimetric parameters to OARs without the necessity of plan preparation. The method can serve as a guide during the treatment planning process, for example, as initial constraints in VMAT optimization. It allows the probability of lung pneumonitis to be predicted.

Purpose: There is a need to develop predictive tests that would allow identifying cancer patients with a high risk of developing side effects to radiotherapy. We compared the predictive value of three functional assays: the G0 aber ration assay, the G2 aberration assay and the alkaline comet assay in lymphocytes of breast cancer and gynaecological cancer patients. Material and methods: Peripheral blood was collected from 35 patients with breast cancer and 34 patients with gy naecological cancer before the onset of therapy. Chromosomal aberrations were scored in lymphocytes irradiated in the G0 or G 2 phase of the cell cycle. DNA repair kinetics was performed with the alkaline comet assay following irradiation of unstimulated lymphocytes. The results were compared with the severity of early and late side effects to radiotherapy. Results: No correlation was observed between the results of the assays and the severity of side effects. Moreover, each assay identified different patients as radiosensitive. Conclusions: There is no simple correlation between the in vitro sensitivity of lymphocytes and the risk of developing early and late side effects. J Contemp Brachyther 2012; 4, 4: 219‐226 DOI: 10.5114/jcb.2012.32556