The aim of the study was to investigate surface and buildup region doses for 6 MV and 15 MV photon beams using a Markus parallel-plate ionization chamber, GafChromic EBT3 film, and MOSFET detector for different field sizes and beam angles. The measurements were made in a water equivalent solid phantom at the surface and in the buildup region of the 6 MV and 15 MV photon beams at 100 cm source-detector distance for 5 × 5, 10 × 10, and 20 × 20 cm 2 field sizes and 0 ∘ , 30 ∘ , 60 ∘ , and 80 ∘ beam angles. The surface doses using 6 MV photon beams for 10 × 10 cm 2 field size were found to be 20.3%, 18.8%, and 25.5% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface doses using 15 MV photon beams for 10 × 10 cm 2 field size were found to be 14.9%, 13.4%, and 16.4% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface dose increased with field size for all dosimeters. As the angle of the incident radiation beam became more oblique, the surface dose increased. The effective measurement depths of dosimeters vary; thus, the results of the measurements could be different. This issue can lead to mistakes at surface and buildup dosimetry and must be taken into account.
Accurate dose measurement in the buildup region is extremely difficult. Studies have reported that treatment planning systems (TPS) cannot calculate surface dose accurately. The aim of the study was to compare the film measurements and TPS calculations for surface dose in head and neck cancer treatment using intensity modulated radiation therapy (IMRT). IMRT plans were generated for 5 head and neck cancer patients by using Varian Eclipse TPS. Quality assurance (QA) plans of these IMRT plans were created on rando phantoms for surface dose measurements. EBT3 films were cut in size of 2.5 x 2.5 cm 2 and placed on the left side, right side and the center of larynx and then the films were irradiated with 6 MV photon beams. The measured doses were compared with TPS. The results of TPS calculations were found to be lower compared to the EBT3 film measurements at all selected points. The lack of surface dose calculation in TPS should be considered while evaluating the radiotherapy plans.
The evaluation of lung doses for radiation pneumonia risk in stereotactic body radiotherapy: A comparison of intensity modulated radiotherapy, intensity modulated arc therapy, cyberknife and helical tomotherapy
INTRODUCTIONNon-small cell lung cancer (NSCLC) covers 75 -80% of all lung cancer patients. Approximately 15-20% of patients are localized and early stage. Generally, the 5-year survival rate is 60-70% when surgical treatment is performed in these patients. However, a significant proportion of patients with NSCLC are unsuitable for surgery because of the difficulties of lung surgery. In this case, radiotherapy is an important option, especially for patients without distant metastasis. In conventional radiotherapy, the probability of tumor control is 50% while its
Purpose/Objective(s): To compare quality of life (QOL) between two weeks intermediate course (IC) and long course (LC) preoperative radiation therapy for rectal cancer. Materials/Methods: Fourty seven patients with T3 rectal cancer were randomized to two weeks IC and LC preoperative radiation therapy in this prospective study. Initially, pelvic MRI, PET / CT in the treatment position were performed all patient. IC consisted of radiation therapy 30 Gy, 3 Gy/ fraction, with concurrent chronomodulated capecitabine 825 mg/m2/BID/daily. LC was 50.4 Gy, 1.8 Gy/fraction, with concurrent chronomodulated capecitabine 825 mg/m2/BID/Daily (based on Brunch Study). In both of arms surgery was performed in 8 to 12 weeks after chemoradiotherapy (CRT). Toxicity was evaluated according to the Radiation Therapy Oncology Group scoring system. QOL was measured using the EORTC QLQ-CR29. Assessments were performed at baseline and 3, 6 months after CRT in patients who had not relapsed. Evaluated response of therapy with PET/CT before surgery. Results: On acute side effect evaluation; skin (100% vs 68%, p:0,002), and haematological (28% vs 0%, p:0,007) have been seen more on LC CRT patients. On QOL; anal and urinary incontinence, body image, dysuria, urinary frequency and sexual desire; there hasn't been seen any important differences. In IC CRT patients erection (p:0,01) and dyspareunia (p:0,06) problems have been detected more than LC CRT patients. For both arms pathological complete response rates were detected 18% (4/22 vs 4/22 pts) and Sphincter-sparing surgery were similar for both arms (%86,3). Conclusion: LC and IC CRT in the local advanced rectum cancer treatment, has ensured similar results on quality of life evaluation, pathological complete response rates. In terms of acute side affects IC CRT was better than LC CRT. On these results IC CRT seems to be able to take the place of LC CRT.
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