The phenomenon of vertebral body drift in neurofibromatosis and its implications for surgical safety.

OBJECTIVE: To report on the phenomenon of body drift in neurofibromatosis scoliosis and discuss its implication on surgical safety. MATERIALS AND METHODS: Ten dystrophic neurofibromatosis scoliosis (NF) and ten adolescent idiopathic scoliosis (AIS) were studied by radiographs, CT, and MRI. The curve characteristics and a detailed analysis of the morphology of the apical and three adjacent vertebral segments above and below were done. The coronal alignment and the presence of a drift of the vertebral body in relationship to the lamina were carefully studied in both groups and compared. RESULTS: The mean cobb angle in the NF group was 77.6°, and 63.7° in the AIS group. All the studied vertebra in the NF group had extensive pedicle changes, which were more severe at the apical and periapical regions. Body drift was noted in 29 vertebral segments, with 9/10 of apical segments showing a significant drift. The body drift was associated with significant pedicle dystrophic changes and was independent of the curve magnitude. In comparison, in AIS, no body drift was noted despite a larger deformity and more severe vertebral rotation. CONCLUSION: The 'body drift' phenomenon was unique to neurofibromatosis scoliosis and was secondary to severe pedicle morphology changes. This was present even in curves less than 60° and could result in cord injury while instrumenting the concave pedicle. Therefore, a thorough preoperative assessment and planning by a 3D CT are mandatory.

Alert system for monitoring changes in patient anatomy during radiation therapy of head and neck cancer.

The purpose of this study is to validate a previously developed algorithm for alerting clinicians when to consider re-CT simulation due to changes in the patient's anatomy during radiation therapy of head and neck cancer. Cone beam computed tomography (CBCT) data were collected prospectively for 77 patients. Each CBCT was mathematically compared to a reference CBCT using the gamma index. We defined the match quality parameter (MQP) as an indicator of CBCT image similarity, where a negative MQP value indicates a poorer CBCT match than the match between the first two CBCT acquired during treatment. If three consecutive MQP values were below a chosen threshold, an "alert" is triggered to indicate action required, for example, possible re-CT simulation. The timing of image review requests made by the radiation therapists and any re-CT/re-plan decisions were documented for each patient's treatment course. The MQP for each patient (including any re-plans) was calculated in a manner that was blinded from the clinical process. The MQP as a function of fraction number was compared to actual clinical decisions in the treatment progress to evaluate alert system performance. There was a total of 93 plans (including re-plans) with 34 positives (action required) and 59 negatives (no action required). The sensitivity of the alert system was 0.76 and the false positive rate was 0.37. Only 1 case out of the 34 positive cases would have been missed by both the alert system and our clinical process. Despite the false negatives and false positives, analysis of the timing of alert triggers showed that the alert system could have resulted in seven fewer clinical misses. The alert system has the potential to be a valuable tool to complement human judgment and to provide a quality assurance safeguard to help improve the delivery of radiation treatment of head and neck cancer.

Yet anOther Dose Algorithm (YODA) for independent computations of dose and dose changes due to anatomical changes.

Objective.To assess the viability of a physics-based, deterministic and adjoint-capable algorithm for performing treatment planning system independent dose calculations and for computing dosimetric differences caused by anatomical changes.Approach.A semi-numerical approach is employed to solve two partial differential equations for the proton phase-space density which determines the deposited dose. Lateral hetereogeneities are accounted for by an optimized (Gaussian) beam splitting scheme. Adjoint theory is applied to approximate the change in the deposited dose caused by a new underlying patient anatomy.Main results.The dose engine's accuracy was benchmarked through three-dimensional gamma index comparisons against Monte Carlo simulations done in TOPAS. For a lung test case, the worst passing rate with (1 mm, 1%, 10% dose cut-off) criteria is 94.55%. The effect of delivering treatment plans on repeat CTs was also tested. For non-robustly optimized plans the adjoint component was accurate to 5.7% while for a robustly optimized plan it was accurate to 4.8%.Significance.Yet anOther Dose Algorithm is capable of accurate dose computations in both single and multi spot irradiations when compared to TOPAS. Moreover, it is able to compute dosimetric differences due to anatomical changes with small to moderate errors thereby facilitating its use for patient-specific quality assurance in online adaptive proton therapy.

Anatomical changes in vertebra in dystrophic scoliosis due to neurofibromatosis and its implications on surgical safety.

STUDY DESIGN: Detailed radiological analysis by multimodality imaging. OBJECTIVE: To document anatomical changes jeopardizing instrumentation safety in Neurofibromatosis deformity correction surgeries. MATERIALS AND METHODS: The apical and 3 adjacent vertebral segments above and below amounting to 70 segments in 10 NF scoliosis were studied by radiographs, CT and MRI. The changes in lamina, pedicle and vertebral body that could jeopardize pedicle screw and sublaminar wire placement were documented and changes were appropriately classified. RESULTS: Extensive anatomical changes were noted. These changes were more severe at the apex and independent of the curve severity. Both laminae were normal in only 36 (Type 1), rest had either gross asymmetry in length and shape (Type 2; 21) or also in sloping (Type 3; 13). Of the 140 pedicles, normal pedicles were found only in 48 (Type 1); while they were divergent (Type 2; 4) or abnormally elongated with only thinning (Type 3a; 26); or with sclerosis (3b; 34); or very curved and wavy (3c; 23) and even fractured or indistinct (Type 4; 5). It was notable that 92 of the 140 pedicles were unsuitable for pedicle screws. A unique phenomenon of body drift was identified in 29 segments which could jeopardize screw placement and rib dislocation into the canal was found in 18 segments. CONCLUSION: Gross anatomical changes jeopardizing both sublaminar wire strength and trajectory of pedicle screws were common in NF and independent of curve severity. Therefore, detailed preoperative assessment and planning by a 3D CT are essential.

[Systemic changes during the use of hormonal contraceptives]. / Izuchenie sistemnykh izmenenii pri primenenii gormonal'nykh kontratseptivov.

PIP: Systemic changes in the female were investigated before and during treatment with the combined oral contraceptives Ovidon and Rigevidon. The latter compound, with its estrogen/gestagen component reduced by 1/3 as compared to Ovidon, was shown to be less frequently associated with gastrointestinal disorders, headaches, weight changes, and produce smaller systemic changes. (author's modified)^ieng