SU-E-T-188: Evaluation of a 3D Patient Relevant Dose QA Tool: Multiple Institutional Studies

PURPOSE

To evaluate 3DVHTM as a patient dose-verification and analysis tool through multiple institutional studies. Virtual patient doses were measured and compared among different vendors' treatment planning systems (TPS) and delivered by different vendors' LINACS so that we better understand the uncertainty of entire process within a patient undergone radiotherapy.

METHODS

One head-and-neck (H&N) and one lung patient were selected in this study. The DICOM images/RT structures along with clinical protocols including prescription doses (59.4Gy for H&N and 70.2Gy for lung) and normal‐tissues tolerances were distributed to six institutions. Based on the same criteria, each institution generated their IMRT plans for the patients. Four different TPS and six different LINACS were used. The conventional per‐beam IMRT QA using MapCHECK was performed by all participants. All the measured and calculated data were sent back to one institution for 3DVH analysis. Through the use of planned-dose-perturbation (PDP)TM algorithm (Sun Nuclear Corp.), the 'actual-DVHs' were generated and then compared to the 'reference-DVHs' from plans. Their differences represented errors induced from the combination of TPS dose-calculation algorithm and beam-delivery systems.

RESULTS

All plans in the study have met the clinical criteria. The 3D matching rates for 3%global/3mm (DD/DTA) ranged from 95.8-99.9% for H&N and 93.5-100% for lung. The dose-difference-histogram for PTV had a mean of 0.67% [0-2%] for H&N cases and 1% [0.6-2.8%] for lung cases. The QA tool was able to spot the doses outside 3%/3mm criteria for critical structures much easier than conventional planar QA methods. In addition, the hot/cold spots at the boundaries of collimators are attributed to the uncertainty of collimator-positioning greater than 1-mm.

CONCLUSIONS

The analysis of IMRT plans in this study has shown that 3DVH is a vital QA tool for assessing clinically relevant doses as well as diagnosing potential systematic errors from both TPS and delivery systems.

SU-E-T-402: Coordinate Transformation after Stereotactic Frame Reapplication in Gamma Knife Radiosurgery

PURPOSE

In Gamma Knife (GK) radiosurgery, the occurrence of reapplying the stereotactic frame due to collision with the collimator leads to re- examination and re-planning. For the treatment of vascular lesions, it is a burden not only to physicians but also to patients to get invasive angiography procedure again. To avoid undergoing second angiography examination, and reduce re-planning time, a mathematical coordinate transformation method using the stereotactic images has been developed.

METHODS

The MR or CT images of a patient brain before and after frame reapplication can be correlated with each other using the Affine transformation. The transformation parameters which minimize the RMS error of the original and transformed coordinates between the images were determined using a genetic algorithm. Three CT image studies of skull phantom were used for the verification of the algorithm. Moreover, five MR image studies of patients who underwent more than one GK procedure were used for the clinical evaluation. The coordinates under the original treatment plan were converted to new coordinates using the transformation matrix, and their dosimetric outcomes were compared.

RESULTS

The RMS error in the coordinate transformation of skull phantom and clinical images was 0.3 mm and 0.6 mm, respectively. For total 9 treatment lesions of 0.2 ∼14.1 cc, 3% and 11% RMS error in the irradiation time and target coverage were found respectively. The patients with only translational movement during the frame reapplication showed similar plan conversion results with the original plan. Also, deeply-located lesions showed a better RMS error of 3% in the conformity index than superficial lesions close to the skull.

CONCLUSIONS

New treatment plans were obtained by applying the coordinate transformation to the original plans after the frame reapplication. The converted plans maintained the quality of the original plans with a little change in dose distribution arising from head rotation. This work was supported by a grant no. 04-2011-0320110130 from the Seoul National University Hospital Research Fund and a National Research Foundation of Korea (NRFK) grant funded by the Korean government (MEST) (Grant No. K20901000001-09E0100-00110).

Neoadjuvant chemoradiotherapy and multivisceral resection for primary locally advanced adherent colon cancer: a single institution experience

BACKGROUND

Although there is an extensive body of literature on the role of neoadjuvant chemoradiotherapy (CRT) in the management of rectal cancer, its role in primary locally advanced adherent colon cancer (LAACC) is unclear.

OBJECTIVE

To analyzed the outcomes of neoadjuvant CRT and multivisceral resection in the management of LAACC patietns.

METHODS

We retrospectively reviewed our institutional Colorectal Carcinoma Database for 33 patients with potentially resectable, non-metastatic primary LAACC who received neoadjuvant CRT followed by multivisceral resection. CRT consisted of external beam radiation (45-50 Gy in 25 daily fractions) and concurrent 5-FU infusion (225 mg/m(2)/day).

RESULTS

There were 21 males and 12 females. Median age was 64 (31-83) and median follow-up was 36 months. All patients had microscopically clear resection margins (R0). Complete pathologic response was documented in 1 patient (3%) and 66% had ypT4b disease. Post-operative complications were observed in 36% of patients with no 30-day mortality. The 3-year overall survival and 3-year disease-free survival were 85.9% and 73.7% respectively. Two patients developed a local recurrence.

CONCLUSIONS

Neoadjuvant CRT and en-bloc multivisceral resection may result in high rates of R0 resection and excellent local control with acceptable morbidity and mortality in selected patients with LAACC.

Discovery of genetic variants for fatty acid binding proteins of pig (Brief Report)

Abstract. Back fat thickness (BFT) and intramuscular fat (IMF) contents are known as major issues affecting meat performance. Several types of fatty acid-binding proteins (FABPs), which involve signal transduction pathways, are abundantly presented in tissues such as intestine, liver, kidney, mammary gland, heart, and red skeletal muscle (Nechtelberger et al. 2001). FABPs have been reported to be differentially expressed genes during porcine adipogenesis (Samulin et al. 2008) and related to fat deposition (Szczerbal et al. 2007). Accordingly FABPs may be candidate genes to explain variation of fat related traits in pigs. Therefore, it is an essential process to search genetic variants that may provide useful genetic information to study associations with quantitative loci (QTL).

Correlation between hyporesponsiveness to Toll-like receptor ligands and liver dysfunction in patients with chronic hepatitis C virus infection

Hepatitis C virus (HCV)-associated antigens, such as the core and nonstructural antigens, activate host innate immune systems via Toll-like receptors (TLRs). We previously showed that chronic exposure to the core antigen induces hyporesponsiveness to TLR ligands in antigen-presenting cells via activation of TLR2 and that stimulation with TLR ligands results in impaired IL-6 production by peripheral blood monocytes from HCV-infected patients. In the present study, peripheral blood mononuclear cells (PBMCs) isolated from patients with chronic HCV or hepatitis B virus (HBV) infection were stimulated with TLR ligands to determine the production of IL-6 and IL-8 and to identify the clinical parameters associated with hyporesponsiveness to TLR ligands in patients with chronic HCV infection. The results showed that pro-inflammatory cytokine responses to TLR ligands were suppressed in PBMCs isolated from HCV-infected, but not HBV-infected, patients. The reduced cytokine responses to TLR ligands seen in HCV-infected patients correlated with platelet counts and serum prothrombin time levels. In contrast, there was no correlation between TLR-induced cytokine responses and serum levels of core antigen. Thus, hyporesponsiveness to TLR ligands in HCV-infected patients is correlated with liver dysfunction. In conclusion, both host factors and viral factors may be involved in the generation of hyporesponsiveness to TLR ligands in patients with chronic HCV infection.

A nonrandomized observational trial of short-term preoperative endocrine therapy in ER-positive breast cancer to investigate change in genomic expression using the 21-gene breast cancer assay

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Background: Preoperative systemic treatment is commonly employed for women with locally advanced breast cancer. Women with early-stage breast cancer, whose resections may be delayed for 30 to 60 days while they undergo preoperative evaluation, may benefit from receiving preoperative endocrine therapy while awaiting surgery. One rationale for not initiating such treatment is that the cancer may be rendered less chemosensitive. The 21-gene assay is a proven predictor of chemotherapy responsiveness. The objective of this study is to examine the association between recurrence score (RS) and ER, PR, and HER2 RT-PCR values in core biopsy and surgical specimens from patients treated with short term pre-operative endocrine therapy.

Methods: Pre- and postmenopausal women with clinical T1-N0-M0, sonographically visible, ER-positive, HER2-negative breast cancer were eligible. Patients were treated with 4-8 weeks of preoperative endocrine therapy; letrozole if postmenopausal or tamoxifen if premenopausal. Clinical breast examination and ultrasound were conducted every two weeks, with the final ultrasound immediately prior to surgery. Tumor blocks from the core biopsy and surgical excision were submitted to Genomic Health, Inc., where RS, ER, PR, and HER2 results were obtained from each of the paired specimens.

Results: Nineteen matching core biopsy and surgical specimens were available for analysis. Pearson correlation coefficients between core biopsy and excisional sample results were 0.89 for RS, 0.87 for ER, 0.72 for PR, and 0.77 for HER2. On average, small but statistically significant increases in RS and decreases in ER and PR were observed (all p < 0.005 from paired t-test). No obvious associations between these markers and clinical response were observed.

Conclusions: In this small, hypothesis-generating study, paired RS and RT-PCR for ER/PR/HER2 remained correlated after short-term preoperative endocrine therapy. This study provides no suggestion of decreasing chemosensitivity during preoperative endocrine therapy, but additional research is warranted to explore these findings further.