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The aim of this work is to verify the potential use of GAFchromic(TM) EBT3 and FILMQA(TM) pro software for patient specific quality assurance (QA) for stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) treatment plans in clinical routine use. In particular, encephalic, pulmonary and lymph node treatments plans were selected for this study. The agreement between the calculated and measured dose distributions were evaluated in terms of ɣ index with 3%3mm, 2%2mm, 1.5%1.5mm and 3%1.5mm criteria. The obtained results were then compared to the routine pre-treatment verification method which uses electronic portal imaging device (EPID) and EPIQA analysis software. EBT3-FilmQA method results show a mean ɣ index passing rate >95% with 2%1.5mm analysis criteria and an improvement of about 7% compared with EPID-EPIQA method results.

The objective of this work is to demonstrate the feasibility of 2D dosimetry using optically stimulated luminescent (OSL) films based on MgB4O7:Ce,Li and to identify current limitations of this material for this application. A small quantity of test films was produced and read using a laser-scanning OSL reader after irradiation. The OSL luminescence and dosimetric properties were also investigated. The results demonstrate the advantage of the fast luminescence lifetime associated with Ce3+ emission (∼31.5 ns) for 2D dosimetry based on laser-scanning readout, since it minimizes the need for pixel-bleeding correction. The signal could be bleached satisfactorily using a fluorescence lamp and a long-pass filter. A dose response curve could be obtained with pieces of films simulating steep dose gradients and the dose response obtained using the signal from the center of such piece films was linear up to 10 Gy. Short and long-term phosphorescence components were observed in the luminescence signal of MgB4O7:Ce,Li, but their contribution with respect to the fast OSL signal is relatively small and should decrease with increasing laser scan rates. In spite of the high OSL sensitivity and linear response, the main disadvantage of MgB4O7:Ce,Li at the moment is the lack of a better understanding of the processes responsible for the sensitivity changes and fading of the OSL signal. Although the bleaching applied here allowed to reduce the residual OSL signal to minimum levels (

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES Dosimeters used in practices that involve ionizing radiation are essential, mainly in diagnostic radiology and radiotherapy. Radiation dosimetry allows the quality control, recording and assessment of the entrance exposure inside the body during a treatment. However, none of the currently available dosimeters enables accurate dose measurements in large areas or irregular surfaces of the human body. Thus, in order to improve dosimetric tools, it is being investigated the development of flexible and impermeable dosimetric films, formed by a polymer matrix of polyvinyl chloride (PVC), with microcrystals of MgB4O7:Ce,Li, produced by solid state synthesis and optically stimulated luminescence (OSL) emitters. The crystals with different characteristics were inserted in plastic matrices to verify their dosimetric behavior. Some of the possible solvents for the production of the films were evaluated, observing their effects on the crystals in OSL emission. The structural properties were analyzed by x-ray diffraction, before and after the chemical action of each solvent. The sensitivity of the film to radiation dose have been verified. In this way, the results showed that acetone-benzene solution is the most favorable for the production of films because it does not cause large changes in the structure and luminescent properties of the crystals. In addition, the results have shown that these films can contribute significantly to the production of new 2D dosimeters favorable to dose measurements near the skin surface. A utilização de dosímetros é imprescindível em práticas que envolvam o uso de radiação ionizante, especialmente, na área de radiodiagnóstico e radioterapia. Esta ferramenta permite o controle de qualidade, registro e avaliação da exposição de entrada no interior do corpo durante um tratamento. No entanto, nenhum dos dosímetros, atualmente disponíveis, possibilita a medição de dose com precisão em vastas áreas do corpo humano ou em superfícies com configurações irregulares. Sendo assim, no intuito de melhorar as ferramentas dosimétricas, este trabalho investigou o desenvolvimento de filmes dosimétricos flexíveis e impermeáveis, com o cloreto de polivinila (PVC) como matriz polimérica, carregado com micro cristais MgB4O7:Ce,Li, produzidos por síntese do estado sólido e emissores de luminescência opticamente estimulada (OSL). Estes cristais com diferentes características foram inseridos em matrizes plásticas, a fim de verificar seu comportamento dosimétrico. Avaliou-se alguns dos possíveis solventes para a produção dos filmes, observando seus efeitos sobre os cristais quanto à emissão OSL. Propriedades estruturais foram analisadas por difração de raio X, antes e depois da ação química de cada solvente. A sensibilidade dos filmes a doses de radiação também foi verificada. Desta maneira, os resultados mostraram que dentre os solventes analisados, a solução acetona-benzeno é a mais favorável para a produção dos filmes, por não ocasionar grandes mudanças na estrutura e nas propriedades luminescentes dos cristais. Além disso, os resultados têm mostrado que estes filmes podem contribuir de maneira significativa para produção de novos dosímetros 2D favoráveis a medições de doses próximos à superfície da pele. São Cristóvão, SE

Pooperaciniame krūties vėžio gydymo etape, spindulinės terapijos apšvitos taikiniu įprastai yra likęs minkštasis krūtinės ląstos audinys ir susiformavęs pooperacinis randas. Dėl netaisyklingų paviršiaus kontūrų ir dėl to, jog planuojamas taikinio tūris (angl. planning tumour volume – PTV) yra kūno paviršiuje, kokybiškai apšvitinti gydymui paskirtąja doze (2Gy per frakciją) yra gana sudėtinga. Todėl naudojamas „papildomas kūnas“ – bolusas, su kuriuo paskirtosios dozės maksimumas yra paciento kūno paviršiuje. Pavyzdžiui, lauko, kurio energija Emax = 6 MeV, paskirtosios dozes maksimumas yra paciento kūno paviršiuje naudojant 1 ar 1,5 cm storio bolusą. Šiame darbe spindulinio gydymo planavimas buvo atliekamas trimate (3D) planavimo sistema, kūno fantomą švitinant linijiniu greitintuvu. Planavimo sistemos apskaičiuoti rezultatai lyginami su 2D dozimetrijos metodu gautais rezultatais. Nustatyta, kad boluso padėties keitimas apšvitos lauko riboje su kūnu gali padidinti arba sumažinti viso gydymo suminę dozę, kuri yra svarbi užtikrinant spindulinio gydymo kokybę., Remaining soft tissue of the chest wall and postoperative scar are the usual irradiation targets in post-mastectomy breast cancer treatment stage. Due to the irregular surface contour and to the fact that the planned target volume (PTV) is a patient‘s body surface (skin and scar), the main problem is to treat the surface with prescribed dose (2 Gy per fraction). In such a case, additional body – so called „bolus” is applied. Application of a bolus with a specific thickness allows the increase of the skin dose. Bolus application enables delivering of the maximum prescribed dose on a skin. For example, for Emax = 6 MeV irradiation, thickness of the bolus usually is 1 or 1.5 cm (this thickness is equal to the depth of the build-up region). In this work 3D treatment planning system was used to plan the dose on the phantoms surface. Irradiation was performed by linear accelerator Clinac DMX. Calculated treatment plan doses were compared with 2D film dosimetry results. It was found that the bolus shift at the edge of the irradiation field may contribute to the increased or decreased total dose of the treatment and therefore influence the quality of the treatment procedure.