Cynthia H. Chuang

Skin toxicity due to intensity-modulated radiotherapy for head-and-neck carcinoma

PURPOSE To investigate the cause of acute skin toxicity observed in the treatment of head-and-neck cancer with extended-field intensity-modulated radiotherapy (EF-IMRT). METHODS AND MATERIALS EF-IMRT was used to treat head-and-neck cancer, with the gross target volume receiving 70 Gy and the clinical target volume 60 Gy. A thermoplastic mask covering the head, neck, and shoulder was used for immobilization. Dosimetric studies were conducted to investigate the possible causes of the skin reactions, such as the bolus effect of the mask, the use of multiple tangential beams with IMRT plans, and the way in which the physicians contoured the lymph nodes. The dose-volume histograms of conventional opposed-lateral fields were compared with that of the multiple tangential EF-IMRT fields. IMRT plans with neck nodes contoured up to and including the skin surface were compared with plans that contoured the neck nodes 5 mm away from the skin surface. In addition, IMRT plans defining the skin as a sensitive structure were compared with plans that did not define the skin as a sensitive structure. All plans were created using an anthropomorphic Rando phantom, and the skin doses were measured with and without the mask. In each measurement, 6 thermoluminescent dosimeters (TLDs) were placed at the lateral and medial surfaces of the neck. RESULTS For all four plans, the measured skin doses with the mask were consistently higher than those without the mask. The average dose increase was about 18% owing to the bolus effect of the mask. Multiple tangential fields used in IMRT plans contributed to an increase in skin dose by about 19% and 27%, with and without the mask, respectively. If the skin of the neck was contoured as a sensitive structure for dose optimization, the volume of skin that received >45 Gy was further reduced by about 20%. Five patients immobilized with head and shoulder masks were treated with EF-IMRT plans with the neck nodes carefully delineated away from the skin surface. The neck skin was identified as a sensitive structure for dose optimization. Grade 1 toxicity was observed in 3 patients, Grade 2 in 1 patient, and Grade 3 in 1 patient toward the end of treatment. CONCLUSION Multiple factors contributed to the observed acute skin reaction for head-and-neck cancer patients treated with EF-IMRT. By taking into consideration the skin as a sensitive structure during inverse planning, it was possible to reduce the skin dose to a tolerable level without compromising tumor target coverage.

Intensity-modulated chemoradiation for treatment of stage III and IV oropharyngeal carcinoma: the University of California-San Francisco experience.

Treatment outcomes for stage III and IV oropharyngeal carcinoma treated with intensity‐modulated radiotherapy (IMRT) and concurrent chemotherapy without prior surgical resection were reviewed.

The need for application‐based adaptation of deformable image registration

PURPOSE To utilize a deformable phantom to objectively evaluate the accuracy of 11 different deformable image registration (DIR) algorithms. METHODS The phantom represents an axial plane of the pelvic anatomy. Urethane plastic serves as the bony anatomy and urethane rubber with three levels of Hounsfield units (HU) is used to represent fat and organs, including the prostate. A plastic insert is placed into the phantom to simulate bladder filling. Nonradiopaque markers reside on the phantom surface. Optical camera images of these markers are used to measure the positions and determine the deformation from the bladder insert. Eleven different DIR algorithms are applied to the full and empty-bladder computed tomography images of the phantom (fixed and moving volumes, respectively) to calculate the deformation. The algorithms include those from MIM Software (MIM) and Velocity Medical Solutions (VEL) and nine different implementations from the deformable image registration and adaptive radiotherapy toolbox for Matlab. These algorithms warp one image to make it similar to another, but must utilize a method for regularization to avoid physically unrealistic deformation scenarios. The mean absolute difference (MAD) between the HUs at the marker locations on one image and the calculated location on the other serves as a metric to evaluate the balance between image similarity and regularization. To demonstrate the effect of regularization on registration accuracy, an additional beta version of MIM was created with a variable smoothness factor that controls the emphasis of the algorithm on regularization. The distance to agreement between the measured and calculated marker deformations is used to compare the overall spatial accuracy of the DIR algorithms. This overall spatial accuracy is also utilized to evaluate the phantom geometry and the ability of the phantom soft-tissue heterogeneity to represent patient data. To evaluate the ability of the DIR algorithms to accurately transfer anatomical contours, the rectum is delineated on both the fixed and moving images. A Dice similarity coefficient is then calculated between the contour on the fixed image and that transferred, via the calculated deformation, from the moving to the fixed image. RESULTS The phantom possesses sufficient soft-tissue heterogeneity to act as a proxy for patient data. Large discrepancies appear between the algorithms and the measured ground-truth deformation. VEL yields the smallest mean spatial error and a Dice coefficient of 0.90. MIM produces the lowest MAD value and the highest Dice coefficient of 0.96, but creates the largest spatial errors. Increasing the MIM smoothness factor above the default value improves the overall spatial accuracy, but the factor associated with the lowest mean error decreases the Dice coefficient to 0.85. CONCLUSIONS Different applications of DIR require disparate balances between image similarity and regularization. A DIR algorithm that is optimized only for its ability to transfer anatomical contours will yield large deformation errors in homogeneous regions, which is problematic for dose mapping. For this reason, these algorithms must be tested for their overall spatial accuracy. The developed phantom is an objective tool for this purpose.

A Silent Response to the Obesity Epidemic Decline in US Physician Weight Counseling

Background:Guidelines recommend that physicians screen all adults for obesity and offer an intensive counseling and behavioral interventions for weight loss for obese adults. Current trends of weight-related counseling are unknown in the setting of the US obesity epidemic. Objectives:To describe primary care physician (PCP) weight-related counseling, comparing counseling rates in 1995–1996 and 2007–2008. Research Design:Data analysis of outpatient PCP visits in 1995–1996 and 2007–2008, as reported in the National Ambulatory Medical Care Survey. Subjects:A total of 32,519 adult primary care visits with PCPs. Measures:Rates of counseling for weight, diet, exercise, and a composite variable, weight-related counseling (defined as counseling for weight, diet, or exercise) between survey years. Adjusted analyses controlled for patient and visit characteristics. Results:Weight counseling declined from 7.8% of visits in 1995–1996 to 6.2% of visits in 2007–2008 [adjusted odds ratios, 0.64; 95% confidence intervals, 0.53, 0.79]. Rates of receipt of diet, exercise, and weight-related counseling similarly declined. Greater declines in odds of weight-counseling receipt were observed among those with hypertension (47%), diabetes (59%), and obesity (41%), patients who stand the most to gain from losing weight. Conclusions:Rates of weight counseling in primary care have significantly declined despite increased rates of overweight and obesity in the United States. Further, these declines are even more marked in patients with obesity and weight-related comorbidities, despite expectations to provide such care by both patients and policymakers. These findings have implications for determining deliverable, novel ways to engage PCPs in addressing the obesity epidemic.

What My Doctor Didn't Tell Me: Examining Health Care Provider Advice to Overweight and Obese Pregnant Women on Gestational Weight Gain and Physical Activity

BACKGROUND Appropriate gestational weight gain (GWG) is vital, as excessive GWG is strongly associated with postpartum weight retention and long-term obesity. How health care providers counsel overweight and obese pregnant women on appropriate GWG and physical activity remains largely unexplored. METHODS We conducted semistructured interviews with overweight and obese women after the birth of their first child to ascertain their experiences with GWG. A grounded theory approach was used to identify themes on provider advice received about GWG and physical activity during pregnancy. RESULTS Twenty-four women were included in the analysis. Three themes emerged in discussions regarding provider advice on GWG: 1) Women were advised to gain too much weight or given no recommendation for GWG at all, 2) providers were perceived as being unconcerned about excessive GWG, and 3) women desire and value GWG advice from their providers. On the topic of provider advice on exercise in pregnancy, three themes were identified: 1) Women received limited or no advice on appropriate physical activity during pregnancy, 2) women were advised to be cautious and limit exercise during pregnancy, and 3) women perceived that provider knowledge on appropriate exercise intensity and frequency in pregnancy was limited. CONCLUSIONS This study suggests that provider advice on GWG and exercise is insufficient and often inappropriate, and thus unlikely to positively influence how overweight and obese women shape goals and expectations in regard to GWG and exercise behaviors. Interventions to help pregnant women attain healthy GWG and adequate physical activity are needed.

Stereotactic Body Radiotherapy as Monotherapy or Post–External Beam Radiotherapy Boost for Prostate Cancer: Technique, Early Toxicity, and PSA Response

PURPOSE High dose rate (HDR) brachytherapy has been established as an excellent monotherapy or after external-beam radiotherapy (EBRT) boost treatment for prostate cancer (PCa). Recently, dosimetric studies have demonstrated the potential for achieving similar dosimetry with stereotactic body radiotherapy (SBRT) compared with HDR brachytherapy. Here, we report our technique, PSA nadir, and acute and late toxicity with SBRT as monotherapy and post-EBRT boost for PCa using HDR brachytherapy fractionation. PATIENTS AND METHODS To date, 38 patients have been treated with SBRT at the University of California-San Francisco with a minimum follow-up of 12 months. Twenty of 38 patients were treated with SBRT monotherapy (9.5 Gy × 4 fractions), and 18 were treated with SBRT boost (9.5 Gy × 2 fractions) post-EBRT and androgen deprivation therapy. PSA nadir to date for 44 HDR brachytherapy boost patients with disease characteristics similar to the SBRT boost cohort was also analyzed as a descriptive comparison. RESULTS SBRT was well tolerated. With a median follow-up of 18.3 months (range, 12.6-43.5), 42% and 11% of patients had acute Grade 2 gastrourinary and gastrointestinal toxicity, respectively, with no Grade 3 or higher acute toxicity to date. Two patients experienced late Grade 3 GU toxicity. All patients are without evidence of biochemical or clinical progression to date, and favorably low PSA nadirs have been observed with a current median PSA nadir of 0.35 ng/mL (range, <0.01-2.1) for all patients (0.47 ng/mL, range, 0.2-2.1 for the monotherapy cohort; 0.10 ng/mL, range, 0.01-0.5 for the boost cohort). With a median follow-up of 48.6 months (range, 16.4-87.8), the comparable HDR brachytherapy boost cohort has achieved a median PSA nadir of 0.09 ng/mL (range, 0.0-3.3). CONCLUSIONS Early results with SBRT monotherapy and post-EBRT boost for PCa demonstrate acceptable PSA response and minimal toxicity. PSA nadir with SBRT boost appears comparable to those achieved with HDR brachytherapy boost.

The Return of Bedside Rounds: An Educational Intervention

BackgroundBedside rounds have decreased in frequency on teaching services. Perceived barriers toward bedside rounds are inefficiency and patient and house staff lack of preference for this mode of rounding.ObjectivesTo evaluate the impact of a bedside rounding intervention on the frequency of bedside rounding, duration of patient encounters and rounding sessions, and patient and resident attitudes toward bedside rounds.DesignA pre- and postintervention design, with a bedside rounding workshop midway through two consecutive internal medicine rotations, with daily resident interviews, patient surveys, and an end-of-the-year survey given to all Medicine house staff.ParticipantsMedicine house staff and medicine patients.MeasuresFrequency of bedside rounds, duration of new patient encounters and rounding sessions, and patient and house staff attitudes regarding bedside rounds.ResultsForty-four residents completed the bedside rounding workshop. Comparing the preintervention and postintervention phases, bedside rounds increased from <1% to 41% (p < 0.001). The average duration of walk rounding encounters was 16 min, and average duration of bedside rounding encounters was 15 min (p = 0.42). Duration of rounds was 95 and 98 min, respectively (p = 0.52). Patients receiving bedside rounds preferred bedside rounds (99% vs. 83%, p = 0.03) and perceived more time spent at the bedside by their team (p < 0.001). One hundred twelve house staff (71%) responded, with 73% reporting that bedside rounds are better for patient care. House staff performing bedside rounds were less likely to believe that bedside rounds were more educational (53% vs. 78%, p = 0.01).ConclusionsBedside rounding increased after an educational intervention, and the time to complete bedside rounding encounters was similar to alternative forms of rounding. Patients preferred bedside rounds and perceived more time spent at the bedside when receiving bedside rounds. Medicine residents performing bedside rounds were less likely to believe bedside rounds were more educational, but all house staff valued the importance of bedside rounding for the delivery of patient care.

PRECONCEPTION PREDICTORS OF WEIGHT GAIN DURING PREGNANCY Prospective Findings from the Central Pennsylvania Women's Health Study

OBJECTIVES We examined preconception (prepregnancy) predictors of pregnancy weight gain and weight gain that exceeds the 2009 Institute of Medicine (IOM) recommendations based on pre-pregnancy body mass index (BMI), in a prospective study. METHODS Data are from a population-based cohort study of 1,420 women who were interviewed at baseline and 2 years later. The analytic sample includes 103 women who were not pregnant at baseline and gave birth to full-term singletons during the follow-up period. Preconception maternal weight category as well as health behaviors, psychosocial stress, parity, and age were examined as predictors of pregnancy weight gain and of weight gain in excess of the IOM recommendations using multiple linear and logistic regression analysis. RESULTS Pregnancy weight gain averaged 33.01 pounds, with 51% of women gaining weight in excess of the 2009 IOM recommendations for their preconception weight category. Preconception overweight (BMI = 25-29.9) increased the odds of excessive pregnancy weight gain nearly threefold, whereas preconception physical activity levels meeting activity guidelines reduced the odds of excessive weight gain but was marginally statistically significant. CONCLUSION Although future research examining the role of physical activity in relation to pregnancy weight gain is needed, preconception overweight and physical activity levels are prime targets for interventions to avoid excessive pregnancy weight gain.

Exploring Knowledge and Attitudes Related to Pregnancy and Preconception Health in Women with Chronic Medical Conditions

Women with chronic medical conditions are at increased risk for pregnancy-related complications, yet little research has addressed how women with diabetes, hypertension, and obesity perceive their pregnancy-associated risks or make reproductive health decisions. Focus groups were conducted with 72 non-pregnant women stratified by chronic condition (diabetes, hypertension, obesity) and by previous live birth. Participants discussed their intention for future pregnancy, preconception health optimization, perceived risk of adverse pregnancy outcomes, and contraceptive beliefs. Four major themes were identified, with some variation across medical conditions and parity: (1) Knowledge about pregnancy risks related to chronic medical conditions was limited; (2) Pregnancy intentions were affected by diabetes and hypertension, (3) Knowledge about optimizing preconception health was limited; and (4) Lack of control over ability to avoid unintended pregnancy, including limited knowledge about how medical conditions might affect contraceptive choices. Women with diabetes and hypertension, but not obesity, were generally aware of increased risk for pregnancy complications, and often expressed less intention for future pregnancy as a result. However, diabetic and hypertensive women had little knowledge about the specific complications they were at risk for, even among those who had previously experienced pregnancy complications. Neither chronic condition nor perceived risk ensured intent to engage in preconception health promotion. We observed knowledge deficits about pregnancy-related risks in women with diabetes, hypertension, and obesity, as well as lack of intent to engage in preconception health promotion and pregnancy planning. These findings have important implications for the development of preconception care for women with chronic medical conditions.

Image-Guided Robotic Stereotactic Body Radiotherapy for Benign Spinal Tumors: The University of California San Francisco Preliminary Experience

We evaluate our preliminary experience using the Cyberknife® Radiosurgery System in treating benign spinal tumors. A retrospective review of 16 consecutively treated patients, comprising 19 benign spinal tumors, was performed. Histologic types included neurofibroma [11], chordoma [4], hemangioma [2], and meningioma [2]. Three patients had Neurofibromatosis Type 1 (NF1). Only one tumor, recurrent chordoma, had been previously irradiated, and as such not considered in the local failure analysis. Local failure, for the remaining 18 tumors, was based clinically on symptom progression and/or tumor enlargement based on imaging. Indications for spine stereotactic body radiotherapy (SBRT) consisted of either adjuvant to subtotal resection (5/19), primary treatment alone (12/19), boost following external beam radiotherapy (1/19), and salvage following previous radiation (1/19). Median tumor follow-up is 25 months (2–37), and one patient (with NF1) died at 12 months from a stroke. The median total dose, number of fractions, and prescription isodose was 21 Gy (10–30 Gy), 3 fx (1–5 fx), 80% (42–87%). The median tumor volume was 7.6 cc (0.2–274.1 cc). The median V100 (volume V receiving 100% of the prescribed dose) and maximum tumor dose was 95% (77–100%) and 26.7 Gy (15.4–59.7 Gy), respectively. Three tumors progressed at 2, 4, and 36 months post-SR (n=18). Two tumors were neurofibromas (both in NF1 patients), and the third was an intramedullary hemangioblastoma. Based on imaging, two tumors had MRI documented progression, three had regressed, and 13 were unchanged (n=18). With short follow-up, local control following Cyberknife spine SBRT for benign spinal tumors appear acceptable.