ABSTRACT
Aim: This study intended to compare the dosimetric parameters using different definitions of prescription point A in high dose rate (HDR) brachytherapy of cervical cancer patients. Background: Manchester point A has been widely used for prescribing dose in brachytherapy. However, due to certain limitations of this point, a new definition of point A has been recommended by the American Brachytherapy Society (ABS). Materials and Methods: We retrospectively investigated 55 computed tomography-based plans of 20 cervical cancer patients treated with Ir-192-based intracavitary HDR brachytherapy. The dose of 7 Gy in 3 fractions each was prescribed to point A using revised Manchester definition of point A (AMAN) and ABS guideline definition (AABS). The effect of both definitions on various parameters including dose to point A and 90% of tumor volume (D90), dose received by 2cc volume of bladder, rectum and small bowel and treatment volume receiving 100% of prescription dose (V100) was analyzed. Results: Mean percentage difference of point AMAN dose and AABS dose with respect to prescription dose was 1.25% ± 1.43% and 1.21% ± 1.01%, respectively. Mean V100 was 80.4 ± 20.45cc and 88.47 ± 16.78cc for AMAN and AABS plans, respectively, while mean percentage difference between prescribed dose and D90 was found to be –37.90% ± 25.06% and –30.47% ± 25.50% respectively for both the definitions. Conclusion: Doses to both Manchester point A and ABS point A may be recorded during the transition period. However, ABS point A can be preferred over the Manchester point A as it conforms better with the desired dosimetric outcome and is found to be more static.
ABSTRACT
O presente estudo propôs avaliar, cefalometricamente, a alteração do ponto A no plano sagital após mudança na inclinação dos incisivos superiores. Métodos: 21 pares de telerradiografias tomadas, no início e no final do tratamento ortodôntico, foram coletados de uma clínica particular na cidade de Aracaju (SE). A amostra foi dividida em dois grupos, de acordo com a movimentação dos incisivos pós-tratamento: Ipro, onde os incisivos proclinaram (n=12); e Iretro, onde os incisivos retroinclinaram (n=9). O ponto A e a inclinação dos incisivos maxilares foram mensurados em relação às linhas ortogonais formadas pelo plano horizontal de Frankfurt e pelo plano pterigoideo vertical. Todos os dados foram medidos duas vezes, com um intervalo de 15 dias, e as médias foram submetidas ao teste t emparelhado e ao teste de correlação de Pearson. Resultados: quando os incisivos maxilares proclinaram 5,26°, o ponto A retraiu 1,54 mm (r=0,75; p < 0,0001), em uma taxa de 1:3,4 mm/graus. Quando os incisivos maxilares retroinclinaram 5,44º, o ponto A avançou 0,71 mm (r=0,81; p < 0,05), em uma taxa de 1:7,7 mm/graus. Conclusão: o ponto A é influenciado diretamente pela alteração na inclinação dos incisivos superiores e tende a acompanhar o movimento do ápice destes dentes.
This study aims to cephalometrically evaluate the changes at point A on the sagittal plane by measuring dental incisor inclinations before and after treatment. Methods: a total of 21 pairs of pre- and post-treatment lateral cephalograms were collected from a private clinic in Aracaju (SE). The sample was divided into 2 groups according to incisors inclination after treatment: Ipro, proclination after treatment (n=12) and Iretro: retroclination after treatment (n=9). The point A and the maxillary incisor inclinations were measured in relation to the orthogonal lines formed between the Frankfurt horizontal and the pterygoid vertical planes. Data were measured twice within a fifteen day interval, and means were subjected to the paired t and Pearson's correlation tests. Results: when maxillary incisors proclined 5.26° degrees, point A retracted 1.54 mm (r=0.75; p < 0.0001), establishing a ratio of 1:3.4 mm/degrees. When the maxillary incisors retroclined 5.44 degrees, the point A advanced 0.71 mm (r=0.81; p < 0.05), establishing a ratio of 1:7.7 mm/degrees. Conclusion: the point A is directly affected by changes in the upper incisor inclinations and tends to follow the apex movement of these teeth.
Subject(s)
Bone Remodeling , Cephalometry , Tooth Movement Techniques , Orthodontics, Corrective/trendsABSTRACT
This study, involving thirty-two patients with carcinoma of uterine cervix treated by high dose rate intracavitary irradiation using a remotely controlled afterloading system, compares the doss at point A and B with the Curie-minutes prescription. A linear least-square regression analysis was used to compare the two sets of date. Correlation coefficients between doses at points A and B arid the Ci-min prescription are 0.92(p<0.001) and 0.90 (p<0.001), respectively, and linear relationship is observed between these two system. The limitation and significance of the comparison of the two approaches to intracavitary dosimetry is discussed.
Subject(s)
Female , Humans , Cervix Uteri , Dioctyl Sulfosuccinic Acid , Prescriptions , Uterine Cervical NeoplasmsABSTRACT
In brachytherapy of uterine cervical cancer using a high dose rate remote afterloading system, it is of prime importance to deliver a accurate dose in each fractionated treatment by minimizing the difference between the pre-treatment planned and post-treatment calculated doses. The post-treatment calculated point A dose was not much different from the pretreatment planned dose (500 cGy). The average+/-standard deviation was 500+/-18 cGy and 84 percent of 82 intracavitary radiotherapy was within the range of 500+/-25 cGy.