Search

Introduction/Objective Left breast cancer patients undergoing radiotherapy are at higher risk of cardiovascular diseases (CVD), as a partial volume of the heart is anatomically close to target volume. This may cause CVD in the years following cancer treatment. The aim of this work was to develop a scoring system which identifies patients with increased risk of development of CVD, as a consequence of the left breast irradiation. Methods The patients followed up in this study were treated during 2009. Eight years later, they were invited to participate in a study where they underwent a cardiology evaluation. Their current condition was statistically correlated to the doses received by their heart and left anterior descendant artery (LAD). Results Out of 114 patients, 31 women were evaluable for cardiology assessment. Out of these 31 subjects, six women were with a history of CVD before cancer treatment. Four women never developed any kind of heart associated disease, while in the other 27, newly onset CVD were diagnosed ranging from hypertension to myocardial infarction, strongly positively correlated to doses to heart and LAD (p = 0.003). Severity of developed cardiovascular toxicity was formulated through the correlation of mean heart and mean LAD doses with CVD developed in the form of a scoring system. Conclusion The doses to critical organs depend on patient anatomy and technique of irradiation. The cardiovascular complications are proven as consequence of radiotherapy. Scoring system based on doses received by heart and LAD is a reliable tool in predicting CVD.

The study was aimed to check the radiotherapy treatment accuracy and definition of action levels during implementation of in vivo dosimetry as a part of quality assurance program. The calibration and correction factors for in vivo entrance dose measurements for six n-type Isorad semiconductor diodes were determined as recommended by the European Society for Radiotherapy and Oncology Booklet No. 5. The patients for in vivo measurements have been divided in groups, according to the treatment site/techique, in order to investigate and detect the groups where the uncertainty was larger or where a systematic error occurred. The tolerance/action levels for all groups were also defined and checked. In this study, the entrance dose measurements were performed for total of 451 treatment fields, and 338 patients over one year period. The mean value and the standard deviation for different groups were: breast +1.0% ± 2.89%(1 SD), brain, and head and neck - +0.74% ± 2.04%(1 SD), and isocentric pelvis and abdomen - +0.1% ± 2.86%(1 SD). All measurements - +0.72% ± 2.64%(1 SD). In our experience, systematic in vivo dosimetry proved to be a very useful tool for quality assurance of patient's plan and treatment, both in detecting systematic errors and for estimating the accuracy of radiotherapy treatment delivery.

Background: Clinical implementation of enhanced dynamic wedges (EDW) requires, as any other dynamic treatment, very serious quality assurance (QA) program. In this work, we presented the results of six-month evaluation of Varian enhanced dynamic wedges and detailed QA program for those wedges. Methods: The Sun Nuclear Daily QA Check 2 was used for QA purpose. The QA program included daily and monthly checks. The daily QA program included central axis dose and wedge angle measurements. Within the monthly QA program wedge factors and delivered STTs from the Dynalog files were checked. Results: Our daily QA measurements of dose and wedge angle showed the reproducibility error less than ±1.5%. On the other hand, monthly QA measurements of wedge factor the reproducibility error was less than ±0.5%. The monthly QA check of delivered STTs showed excellent agreement. Conclusion: During the six-month quality control we observed a good reproducibility in the delivery of EDW treatment. Also, the Sun Nuclear Daily QA Check 2 showed to be very satisfying in QA of the EDW treatment.

Abstract Background Independent external audits play an important role in quality assurance programme in radiation oncology. The audit supported by the IAEA in Serbia was designed to review the whole chain of activities in 3D conformal radiotherapy (3D-CRT) workflow, from patient data acquisition to treatment planning and dose delivery. The audit was based on the IAEA recommendations and focused on dosimetry part of the treatment planning and delivery processes. Methods The audit was conducted in three radiotherapy departments of Serbia. An anthropomorphic phantom was scanned with a computed tomography unit (CT) and treatment plans for eight different test cases involving various beam configurations suggested by the IAEA were prepared on local treatment planning systems (TPSs). The phantom was irradiated following the treatment plans for these test cases and doses in specific points were measured with an ionization chamber. The differences between the measured and calculated doses were reported. Results The measurements were conducted for different photon beam energies and TPS calculation algorithms. The deviation between the measured and calculated values for all test cases made with advanced algorithms were within the agreement criteria, while the larger deviations were observed for simpler algorithms. The number of measurements with results outside the agreement criteria increased with the increase of the beam energy and decreased with TPS calculation algorithm sophistication. Also, a few errors in the basic dosimetry data in TPS were detected and corrected. Conclusions The audit helped the users to better understand the operational features and limitations of their TPSs and resulted in increased confidence in dose calculation accuracy using TPSs. The audit results indicated the shortcomings of simpler algorithms for the test cases performed and, therefore the transition to more advanced algorithms is highly desirable.

Purpose The transition from three-dimensional conformal therapy (3DCRT) to intensity modulated (IMRT) or volumetric modulated arc therapy (VMAT) requires implementation of complex advanced dosimetry, fully commissioned treatment planning system (TPS), machine and other equipment and skills of employees. IMRT/VMAT is implemented in our clinic one year ago. Methods Twenty-one gynecological patient treated in our clinic was selected for the study. Patients were planned for 3D CRT, but due to unacceptable doses to organs at risk (QUANTEC), treatment plans for IMRT or VMAT were generated, and dosimetrically verified before treatment delivery. The TPS used was Monaco 5.11 (Elekta) with Monte Carlo (VMAT) and Collapsed Cone (3DCRT) algorithm.The treatments were delivered by Versa HD (Elekta, Crawley, UK) using 10 MV (VMAT) and 15MV (3DCRT). The patients were prescribed 50.4 Gy/28 fractions (4) and 45 Gy/25 fractions (17 patients). The coverage of PTV and doses to organs at risk were recorded, both for VMAT/IMRT treatment and 3DCRT. Results Coverage PTV: The ICRU 83 criteria for PTV coverage were fulfilled in all 3DCRT/VMAT/IMRT plans. Doses to OARS: in average, the V45 in small bowel in IMRT/VMAT plans was approximately 6 times smaller than the same of 3DCRT plans. The V45 of small bowels was in average 45cm3 in IMRT/VMAT plans, while in 3DCRT plans it was 233 cm3. In case of femoral head, significant reduction in V30 (9.8 % vs. 33.1%) and mean dose in case of IMRT/VMAT plans. Rectum was planned with significantly less dose in terms of V30 (79.5% vs 95.2%) in IMRT/VMAT plans. Bladder was better spared in VMAT plans in terms of V40 (51% vs. 91%), but maximum dose was higher in VMAT plans than in 3DCRT (50.1 Gy to 48.1 Gy in average). Homogeneity index was in average 0.11 for VMAT plans and 0.09 for 3DCRT plans. Conclusion Both 3DCRT and IMRT/VMAT provided good coverage of PTV, but analysis of dosimetric data revealed significant differences in normal tissue doses. The advanced treatment planning, evaluation, dosimetric evaluation and delivery is far more complex than the same for 3DCRT,but patient benefit (OAR sparing) confirms necessity for implementation of advanced techniques. [ABSTRACT FROM AUTHOR]