Faculty Bibliography

Purpose: To carry out a large international validation of how dose prediction quality translates to plan quality in a radiotherapy knowledge-based planning (KBP) process.
Method(s): We collected dose predictions for head-and-neck cancer radiotherapy from 21 different research groups internationally who participated in the OpenKBP Grand Challenge. Each research group used the same training dataset (n=200) and validation dataset (n=40) to develop their methods. These methods predicted dose on a testing dataset (n=100), and those 2100 unique dose predictions were input to a previously published plan optimization method to generate 2100 treatment plans. The predictions and plans were compared to the ground truth dose via: (1)error, the mean absolute voxel-by-voxel difference in dose; and (2) quality, the mean and maximum deviation across 23 dose-volume histogram (DVH) criteria.
Result(s): The range in median prediction error among the top 20 methods was 2.3Gy to 12.0Gy, which was 6.8Gy wider than the range in median plan error of 2.1Gy to 5.0Gy. One method also achieved significantly lower prediction error (P<0.05; one-sided Wilcoxon test) than all the other methods, however, it generated plans with error that was not significantly lower than 28.6% of the other methods. Additionally, predicted dose was consistently lower quality than plan dose. Half (n=1050) of all predictions and plans had an average deviation that was 0.1Gy worse and 0.8Gy better than the ground truth dose, respectively. Similarly, half of all predictions had a maximum deviation that was 3.7Gy worse than the ground truth dose, which was 1.0Gy worse than half of all plans.
Conclusion(s): Many dose prediction methods can achieve low error, however, optimization often improves upon the predictions and eliminates significant differences between prediction methods. Thus, it is critical that we improve the optimization stage in KBP to get better utility out of the existing high-quality dose prediction methods

The placenta functions to nourish and protect the fetus. Imaging of the placenta can have a profound impact on patient management, owing to the morbidity and mortality associated with various placental conditions. To fully appreciate placental pathology, its physiology, anatomy, and variant anatomy will be outlined. Placental conditions affecting the mother and fetus include molar pregnancies, placental hematoma, abruption, previa, accreta, vasa previa, choriocarcinoma, and retained products of conception. Ultrasonography remains the definitive modality in diagnosing most of these conditions, with magnetic resonance imaging remaining an adjunctive measure. Computed tomography is occasionally used in cases of trauma and tumor staging.

Adnexal masses are often seen in the gravid patient. With current advances in technology, an increased number of adnexal masses are incidentally discovered on antenatal screening ultrasonography examinations. Sonography is the first-line imaging modality for any adnexal mass. However, further evaluation with magnetic resonance imaging (MRI) may be critical for diagnosis. For example, MRI can determine whether a mass contains fat, which can be useful in the diagnosis of a teratoma. Characteristic features of nonneoplastic and neoplastic ovarian lesions seen on sonography and MRI will be discussed. Radiologic features that help distinguish benign from malignant neoplasms will be described. Additional lesions specific to the gravid state must be considered in the differential diagnosis when appropriate, such as hyperstimulated ovaries, hyperreactio luteinalis, theca lutein cyst, and luteomas.

BACKGROUND: The p53 tumor suppressor gene is altered in up to 70% of colorectal cancers. MATERIALS AND METHODS: We infected the colorectal cancer cell lines SW620 and KM12L4, in which p53 is mutated, with the replication-defective adenovirus Ad5/CMV/p53 to evaluate the effects of adenovirus-mediated wild-type p53 gene transfer. Gene transduction was measured by cytochemical staining of cells infected with the Ad5/CMV/beta-gal virus and expression of the wildtype p53 protein in these cells was demonstrated by immunoblotting. RESULTS: Significant suppression of in vitro cell proliferation and induction of apoptosis (as measured by TUNEL assay labeling) were observed following Ad5/CMV/p53 infection. More importantly, similar effects were observed in vivo in an established nude mouse subcutaneous tumor model; significant suppression of tumor growth (60%-70%) and induction of apoptosis were observed following intratumoral injections of Ad5/CMV/p53. CONCLUSION: This form of therapy may provide a novel approach to colorectal cancer.