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The end of the 19th and the beginning of the 20th century marked a period of fundamental discoveries in the physics of ionising radiation (X radiation and radioactivity). Isolating radium, a highly radioactive element, immediately opened the way to its application for medical therapeutic purposes. It turned out that the sources of ionising radiation are very effective for changes localised on the skin and at small depths under the skin but not for lesions at greater depths. Interestingly, the inventor of the modern telephone, Alexander Graham Bell, was the first to come up with the idea of placing radium sources in glass tubes and placing them directly in the pathologically changed tissues of the patients to be treated (at greater depths). That period marked the beginning of a highly successful era in radium therapy, involving the use of capsules and needles filled with radium, which eventually led to the development of modern brachytherapy. Unfortunately, for several decades people believed in the universally therapeutic properties of radium, so that (fortunately in smaller quantities) it was added to water, food, hygiene products, etc.

Background/Aim. Coronavirus disease 2019 (COVID-19) significantly affects patients with any type of chronic disease, especially the ones with neoplasm. The aim of this study was to investigate the impact of the COVID-19 pandemic on the weekly number of external beam (EB) radiotherapy (RT) (EBRT) fractions and monthly brachytherapy (BT) applications without intentional hypofractionation. We also investigated how the pandemic affected the number of EBRT patients younger or older than 70 years. Methods. The Affidea Radiotherapy Center, Banja Luka (BL RT Center), provides RT to the population (1.15 million) of the Republic of Srpska (Bosnia and Herzegovina). We analyzed the period of 14 months before the onset and the same period during COVID-19. Results. The average weekly number of EBRT fractions from January 2019 to the end of February 2020 was 680.5 [standard deviation (SD) 67.4], and from March 2020 to the end of April 2021, it was 617.1 (SD 96.4). During April 2020, the weekly number of the EBRT de-creased by 67.9% compared to the same period in 2019, while in March 2021, it fell by 42.4%. Paired samples t-test showed that the occurrence of the COVID-19 pandemic had a statistically significant effect [t(60) = 4.627, p < 0.05] on the reduction in the number of weekly EBRT fractions in the BL RT Center. When comparing number of EBRT patients over 70 years old to those fewer than 70 years old, the decrease was 16.3% vs. 1.6%, respectively. The Wilcoxon signed-rank test revealed that the COVID-19 pandemic had a statistically significant effect (Z = -2.42, p = 0.016) on reducing the number of monthly BT applications. Conclusion. A statistically significant decline in EBRT and BT was observed in BL RT Center for the first fourteen months of the pandemic. The "waves" of the pandemic "closed" the medical wards needed for the diagnosis and therapy of oncology patients and converted them into COVID-19 wards. Therefore, some oncology patients who would have had an indication for RT never received

Background/Aim. In the past two decades, we have witnessed the emergence of new radiation therapy techniques, radiotherapy treatment planning system (TPS) with calculating algorithms for the dosage calculation in a patient, units for multislice computed tomography (CT) and image-guided treatment delivery. The aim of the study was investigating the significant difference in dosimetric calculation of radiotherapy TPS in relation to the values obtained by measuring on the linear accelerator (LINAC), and the accuracy of dosimetric calculation between calculating algorithms Analytical Anisotropic Algorithm (AAA) and Acuros XB in various tissues and photon beam energies. Methods. For End-to-End test we used the hetero-geneous phantom CIRS Thorax002LFC, which anatomically represents human torso with a set of inserts known as relative electron densities (RED) for obtaining a CT calibration curve, comparable to the “reference” CIRS 062M phantom. For the AAA and Acuros XB algorithms and for 6 MV and 16 MV photon beams in the TPS Varian Eclipse 13.6, four 3D conformal (3DCRT), and one intensity modulated (IMRT) and volumetric modulated arc (VMAT) radiotherapy plans were made. Measurements of the absolute dose in Thorax phantom, by PTW-Semiflex ionization chamber, were carried out on three Varian-DHX LINACs. Results. The difference between “reference” and measured CT conversion curves in the bone area was 3%. For 476 phantom measurements, the difference between measured and TPS calculated dose of 3–6%, was found in 30 (6.3%) cases. According to regression analysis, the standardized Beta coefficient for relative errors, 6 MV vs. 16 MV, was 0.337 (33.7%, p < 0.001). Mean relative errors for AAA and Acuros XB, using Mann-Whitney test, for bones were 1.56% and 2.64%, respectively (p = 0.004). Conclusion. End-to-End test on Thorax002LFC phantom proved the accuracy of TPS dose calculation in relation to the one delivered to a patient by LINAC. There was a significant difference for photon energies relative errors (higher values are obtained for 16 MV vs. 6 MV). A statistically significant minor relative error in AAA vs. Acuros XB was found for the bone.

The purpose of this work was to evaluate computed tomography simulators used in radio-therapy treatment planning in Serbia, Croatia, and Bosnia and Herzegovina. A survey of quality assurance programmes of 24 computed tomography simulators in 16 facilities was conducted. A dedicated CT-to-ED phantom was scanned at 120 kV and 140 kV, to obtain CT-to-ED conversion curves as well as CTDIvol. Thoracal phantoms were scanned in the standard and extended field of view to evaluate the dosimetric effect on treatment planning and delivery. The mean age of the measured scanners was 5.5 years. The mean water HU value was –6.5 (all scanners, all voltages) and air HU value was –997. Extended field of view computed tomography data differ from the standard field of view and differences between conversion curves have significant dosimetric impact. The CTDI data showed a large range of values between centers. Better quality assurance of computed tomography simulators in all countries is recommended. The CT-to-ED curve could be used as default at one voltage and per manufacturer. Extended field of view imaging can be used, but treatment planning should be avoided in the regions out of the standard field of view.

Background/Aim. For patients with left-sided breast cancer, a major concern is the dose of radiation delivered to the heart, because of increased risk of exposure and consequently increased risk of major coronary events and side effects. In order to reduce the dose to the heart during breast irradiation, deep inspiration breath-hold (DIBH) technique was implemented in our institution. The aim of this retrospective study was to compare dosimetric parameters of DIBH on the heart, left anterior descending artery (LAD) and ipsilateral lung (IL), compared with free breathing (FB) technique. Methods. Twenty patients who underwent radiotherapy with DIBH at our institution were retrospectively analyzed. Two computed tomography (CT) scans were acquired for each patient, FB-CT and DIBH-CT. Plans consisted of two opposed tangential segmented beams and one direct beam with small dose contribution. Doses to the heart, LAD, and IL were assessed. Results. Dosimetric comparison between FB and DIBH for mean dose to the heart was 5.17 Gy vs. 3.68 Gy, respectively (p < 0.0001), and the mean percentage of the volume receiving 25 Gy was 4.63% vs. 0.85%, respectively (p < 0.0001). Mean dose for LAD was 26.09 Gy vs. 11.89 Gy, respectively (p = 0.00014). Mean percentage of the volume receiving 20 Gy for the IL was 15.16% vs. 13.26% (p = 0.0007) for FB and DIBH, respectively. Conclusion. Implementation of DIBH technique in radiotherapy treatment of patients with left-sided breast cancer statistically significantly reduces the dose delivered to the surrounding organs at risk, particularly to the heart and LAD, with optimal target coverage.

Background/Aim. Brain metastases occur in 20%–30% of all patients with systemic cancer. We aimed at investigating whether patients with oligometastatic brain disease treated with whole brain radiotherapy (WBRT) and simultaneous integrated boost of brain metastases (SIBmets) improved overall survival (clinical outcomes) compared with patients from the Radiation Therapy Oncology Group (RTOG) 9508 database, treated with WBRT and sequential stereotactic radiosurgery (SRS) boost. Methods. WBRT with SIBmets, using the RapidArc (RA) (Varian Medical Systems, Palo Alto, CA) volumetric modulated arc technique (VMAT), was delivered to 15 patients with computed tomography/ magnetic resonance imaging (CT/MRI) findings of 1–3 brain metastases with a diameter less than 40 mm for the largest lesion. Radiotherapy (RT) plans consisted of WBRT, with a prescribed dose of 20 Gy in 5 fractions, with SIBmets which was also 20 Gy (gray units) in 5 fractions. Results. A group of 15 patients included 8 males and 7 females with the mean age of 56.3 years. Three patients were in the RTOG Recursive Partitioning Analysis (RPA) Class I and other 12 patients in RPA Class II. Four patients had one metastasis and 11 patients had two metastases. Calculated mean survival time (MST) was 7.49 ± 4.36 months with no statistically significant difference compared to RTOG 9508 results (MST = 6.5 months) (p = 0.197). The local control rate for 7 patients after three months was 85.7%. Conclusion. WBRT with SIBmets and WBRT + SRS are clinically equivalent treatment options for the patients with oligometastatic brain disease. In comparison to the WBRT + SRS, the treatment by WBRT + SIBmets technique reduces the treatment time and improves the patient’s treatment comfort.

Introduction: Using computed tomography (CT) and treatment planning systems (TPS) in radiotherapy, due to the difference in photon beam energy on CT and linear accelerator, it is necessary to convert Hounsfield units (HU) to relative electron density (RED) values. The aim of this dosimetric study was to determine whether there is a significant effect of potential in the CT tube, field of view size (FOV), and phantom dimensions on the CT conversion curve CT-RED. The second aim is whether there are significant differences between the CT-RED obtained by the Computerized Imaging Reference Systems (CIRS) Thorax 002LFC phantom and the "reference" curve in the TPS, obtained by the CIRS 062M pelvis phantom, at the same CT conditions. Methods: Heterogeneous CIRS 062M and CIRS Thorax 002LFC phantoms were used, which anatomically and dimensionally represent the human pelvis, head, and thorax, with a set of known RED inserts. They were scanned on a CT LightSpeed GE simulator and obtained CT-RED. Results: The high voltage in the CT tube had a significant effect on the HU (t = 10.72, p < 0.001) for RED values >1.1, while FOV as a parameter did not show statistical significance for the 062M pelvis phantom. Comparing the slopes (062M pelvis and head) of the CT-RED for RED ≥ 1.1, the obtained value is t = 1.404 (p = 0.163). In the case of a 062M pelvis and a 002LFC phantom, we have seen a difference in RED values (for the same HU value) of 5 % in the RED region ≥ 1.1 (bone). Conclusion: Patients should be imaged on a CT simulator only at the potential of the CT tube on which the conversion curve was recorded. The influence of the FOV and scanned phantom dimensions is not statistically significant on the appearance of the calibration curve (RED ≥ 1.1). [ABSTRACT FROM AUTHOR]