Alternative treatment for open bite Class III malocclusion in a child with Williams-Beuren syndrome

Williams-Beuren syndrome (WBS) is a rare genetic condition that affects approximately 1 in every 20,000 - 50,000 live births. WBS children have specific skeletal deformities, dental malformations and rare lingual muscle dysfunction. The need for orthodontic and orthognathic therapy has arisen and has been considered a real clinical challenge even for experienced professionals, once it requires a complex and individualized treatment plan. This study reports a case of orthopedic expansion of the maxilla, in which a modified facial mask was used for protraction of the maxillary complex associated with clockwise rotation of the maxilla. In addition, special considerations about treatment time and orthopedic outcomes are discussed.

A síndrome de Williams-Beuren (WBS) é uma doença genética rara, acometendo, aproximadamente, de 1:20.000 a 1:50.000 crianças nascidas. As crianças com WBS têm deformidades esqueléticas específicas, má formações dentárias e, algumas vezes, disfunção muscular da língua. As necessidades ortodônticas e ortognáticas têm sido consideradas um verdadeiro desafio clínico, até mesmo para aqueles profissionais com vasta experiência, uma vez que requerem um plano de tratamento individualizado e complexo. Esse relato de caso aborda uma expansão ortopédica da maxila, em que foi utilizada uma máscara facial modificada para protração do complexo maxilar, acompanhada de uma rotação horária da maxila. Além disso, considerações especiais sobre o tempo de tratamento e resultados ortopédicos são discutidas.

Dosimetry limitations and pre-treatment dose profile correction for sliding window IMRT

This work investigated the dosimetry limitations of the random and systematic uncertainties of sliding window [SW] intensity modulated radiation therapy [IMRT]. A Varian 21EX linear accelerator, Pinnacle[3] treatment planning system and radiographic film dosimetry was used. The limitations of the SW were studied using beam modulation ranging from 2 to 100 MU/beam, DR from 100 to 600 MU min[-1], LV from 1 to 5 cm [s-1] and field size up to 12 x 12 cm[2]. The random and systematic errors were investigated using clinical and flat beams, as well as beams of high profile modulation including linear, exponential, and sinusoidal profiles. The leading edge and plateau of the SW profiles have a significant deformation for higher DR and for beams of < 10 MUs/beam. It was found that the error is directly proportional to the DR and LV, and inversely proportional to the number of MU/beam. The high DR and LV are limiting factors, producing random profile deformation when SW beams of small number of MU/beam are delivered. A very good agreement was found between the planned and delivered geometrical and clinical dose profiles when beams > 10 MUs irradiated by a DR from 100 to 600 MU min[-1] and LV from 1 to 5 cm s[-1]. After the proposed correction, an average difference < 0.5% for clinical profiles was measured for beams irradiated with DR = 600 MU min[-1] and LV= 5 cm s[-1]. It was concluded that this correction methodology may serve as a pre-treatment Quality Assurance tool for SW IMRT beams

Dosimetric and qualitative analysis of kinetic properties of millennium 80 multileaf collimator system for dynamic intensity modulated radiotherapy treatments.

The aim of this paper is to analyze the positional accuracy, kinetic properties of the dynamic multileaf collimator (MLC) and dosimetric evaluation of fractional dose delivery for the intensity modulated radiotherapy (IMRT) for step and shoot and sliding window (dynamic) techniques of Varian multileaf collimator millennium 80. Various quality assurance tests such as accuracy in leaf positioning and speed, stability of dynamic MLC output, inter and intra leaf transmission, dosimetric leaf separation and multiple carriage field verification were performed. Evaluation of standard field patterns as pyramid, peaks, wedge, chair, garden fence test, picket fence test and sweeping gap output was done. Patient dose quality assurance procedure consists of an absolute dose measurement for all fields at 5 cm depth on solid water phantom using 0.6 cc water proof ion chamber and relative dose verification using Kodak EDR-2 films for all treatment fields along transverse and coronal direction using IMRT phantom. The relative dose verification was performed using Omni Pro IMRT film verification software. The tests performed showed acceptable results for commissioning the millennium 80 MLC and Clinac DHX for dynamic and step and shoot IMRT treatments.