Is SBRT Boost Feasible for PET Positive Lymph Nodes for Cervical Cancer? Evaluation using Tumor Control Probability and QUANTEC Criteria.

PURPOSE: This study aimed to examine the feasibility of stereotactic body radiation therapy (SBRT) as an external beam radiation therapy boost to positron emission tomography (PET) positive lymph nodes (LN) in patients with cervical cancer and to evaluate overall tumor control probability (TCP) increase. METHODS AND MATERIALS: Ten patients with cervical cancer and PET positive LN metastasis who received external beam radiation therapy (45 Gy), followed by a 3-dimensional conformal radiation therapy boost (5.4-9 Gy) and tandem-and-ovoid high-dose-rate brachytherapy (16-30 Gy) were retrospectively enrolled in this study. SBRT plans were generated using 21 Gy, 24 Gy, or 30 Gy as a replacement for 3-dimensional conformal radiation therapy boost. The 2 Gy-per-fraction equivalent dose maps were made using an α/ß value of 10 for PET positive LNs and 3 for organs at risk (OARs). TCP values were calculated using a logistic TCP model, where 2 input parameters (D50 and Gamma50 = 2) were modeled by 2 clinical outcomes: our institution and the literature. OAR sparing was evaluated using Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) dose limits. RESULTS: Thirty percent of 10 patients receiving conventional boost experienced recurrence. The TCP of the SBRT schemes was 88% ± 7% (97% ± 2%; 21 Gy), 96% ± 1% (99% ± 0%; 24 Gy), and 99% ± 1% (100% ± 0%; 30 Gy), and the conventional LN-boost TCP value was 25% ± 11% (58% ± 15%) when TCP input parameters were based on published clinical outcome data for LN SBRT treatments (institutional outcome data). The tumor coverage doses (D90) of the SBRT boost plans were on average 32.34 Gyαß=10 (21 Gy), 37.78 Gyαß=10 (24 Gy), and 55.54Gyαß=10 (30 Gy) higher than the conventional LN boost plan. The QUANTEC OAR dose constraints were met for the bladder, rectum, and bowel in all cases for the SBRT LN 21 Gy group, and in 90% and 70% of cases in the SBRT LN 24 Gy and SBRT LN 30 Gy groups, respectively. CONCLUSIONS: An SBRT boost dose of 30 Gy can be delivered without compromising QUANTEC OAR limits. The use of SBRT increases TCP values, regardless of the input parameters.

Management of solitary and multiple brain metastases from breast cancer.

As local and systemic control of breast cancer improves, metastasis to the brain remains a common event requiring a specialized management approach. Women diagnosed with breast cancer who develop brain metastases have superior overall survival compared to patients with other forms of metastatic carcinoma. This article summarizes some of the unique aspects of care for patients with breast cancer metastases to the brain.

Hounsfield unit changes over time in contusions of the brain.

In the United States, traumatic brain injuries are an important cause of death and disability, often with significant financial and legal consequences. Although it is generally accepted by neuroradiologists that the density of cerebral contusions decreases over time, previous research has not addressed this phenomenon directly. In the current study, we reviewed charts of patients who had suffered cerebral contusions and had at least two subsequent computed tomography scans in order to determine whether Hounsfield Units, a measure of density, decreased over time. We found that 100% of contusions decreased in Hounsfield Units over time. In addition, we found that the rate of decrease in density appears to be higher in the first 100 days after the injury. These findings are especially applicable in the area of forensics. For example, they could be used to determine the relative age of two separate brain contusions in the same patient.