KiHoon Sung

Cardiac dose reduction with breathing adapted radiotherapy using self respiration monitoring system for left-sided breast cancer

Purpose To quantify the cardiac dose reduction during breathing adapted radiotherapy using Real-time Position Management (RPM) system in the treatment of left-sided breast cancer. Materials and Methods Twenty-two patients with left-sided breast cancer underwent CT scans during breathing maneuvers including free breathing (FB), deep inspiration breath-hold (DIBH), and end inspiration breath-hold (EIBH). The RPM system was used to monitor respiratory motion, and the in-house self respiration monitoring (SRM) system was used for visual feedback. For each scan, treatment plans were generated and dosimetric parameters from DIBH and EIBH plans were compared to those of FB plans. Results All patients completed CT scans with different breathing maneuvers. When compared with FB plans, DIBH plans demonstrated significant reductions in irradiated heart volume and the heart V25, with the relative reduction of 71% and 70%, respectively (p < 0.001). EIBH plans also resulted in significantly smaller irradiated heart volume and lower heart V25 than FB plans, with the relative reduction of 39% and 37%, respectively (p = 0.002). Despite of significant expansion of lung volume using inspiration breath-hold, there were no significant differences in left lung V25 among the three plans. Conclusion In comparison with FB, both DIBH and EIBH plans demonstrated a significant reduction of radiation dose to the heart. In the training course, SRM system was useful and effective in terms of positional reproducibility and patient compliance.

The Predictive Value of Tumor Size, Volume, and Markers During Radiation Therapy in Patients With Cervical Cancer.

Objectives We investigated the prognostic significance of changes in primary tumor volume and serum squamous cell carcinoma antigen (SCC-ag) levels during radiation therapy (RT) in patients with cervical cancer. Methods We conducted a review of 40 patients treated with RT. All patients received external beam RT and intracavitary brachytherapy. The primary tumor volume and squamous cell carcinoma antigen levels were measured pre-RT and mid-RT. Overall survival (OS) and progression free survival (PFS) were estimated, and possible prognostic factors for survival were analyzed. Results The correlation coefficient between primary tumor volume reduction rate (pTVRR) and serum squamous cell carcinoma antigen reduction rate in all patients was 0.550 (P < 0.001). In univariate analysis, stage more than II (P <0.001), pre-RT pTV of 55 cm3 or more (P = 0.05), mid-RT tumor size of 4 cm or more (P = 0.004), and pTVRR of 90% or less (P = 0.031) were significant unfavorable prognostic factors for PFS, whereas stage (P = 0.009) was the only significant prognostic factor for OS. Multivariable analysis revealed that none of these factors were independently associated with PFS or OS. Conclusions There was a significant correlation between pTVRR and squamous cell carcinoma antigen reduction rate. Our findings indicate that the tumor parameters such as pre-RT pTV, mid-RT tumor size, and pTVRR are associated with PFS in women with cervical cancer.

Dose gradient curve: A new tool for evaluating dose gradient

Purpose Stereotactic radiotherapy, which delivers an ablative high radiation dose to a target volume for maximum local tumor control, requires a rapid dose fall-off outside the target volume to prevent extensive damage to nearby normal tissue. Currently, there is no tool to comprehensively evaluate the dose gradient near the target volume. We propose the dose gradient curve (DGC) as a new tool to evaluate the quality of a treatment plan with respect to the dose fall-off characteristics. Methods The average distance between two isodose surfaces was represented by the dose gradient index (DGI) estimated by a simple equation using the volume and surface area of isodose levels. The surface area was calculated by mesh generation and surface triangulation. The DGC was defined as a plot of the DGI of each dose interval as a function of the dose. Two types of DGCs, differential and cumulative, were generated. The performance of the DGC was evaluated using stereotactic radiosurgery plans for virtual targets. Results Over the range of dose distributions, the dose gradient of each dose interval was well-characterized by the DGC in an easily understandable graph format. Significant changes in the DGC were observed reflecting the differences in planning situations and various prescription doses. Conclusions The DGC is a rational method for visualizing the dose gradient as the average distance between two isodose surfaces; the shorter the distance, the steeper the dose gradient. By combining the DGC with the dose-volume histogram (DVH) in a single plot, the DGC can be utilized to evaluate not only the dose gradient but also the target coverage in routine clinical practice.

Cardiac risk index as a simple geometric indicator to select patients for the heart-sparing radiotherapy of left-sided breast cancer

This is a dosimetric study to identify a simple geometric indicator to discriminate patients who meet the selection criterion for heart‐sparing radiotherapy (RT). The authors proposed a cardiac risk index (CRI), directly measurable from the CT images at the time of scanning.

A Case of Primary Breast Diffuse Large B-Cell Lymphoma Treated with Chemotherapy Followed by Elective Field Radiation Therapy: A Brief Treatment Pattern Review from a Radiation Oncologist's Point of View

We here report a case of primary breast lymphoma (PBL). A 44-year-old woman presented with a painless mass in the right breast. Fine needle aspiration cytology and excisional biopsy were performed. Excisional biopsy revealed low grade lymphoma, which was subsequently confirmed with histopathology and diagnosed as diffuse large B-cell lymphoma (DLBCL). A chest computed tomography scan revealed a 3.5 cm sized breast mass with skin thickening and a small sized lymphadenopathy in the ipsilateral axilla. Radiation therapy including the right whole breast and ipsilateral axilla and supraclavicular lymph node was performed after the patient received four courses of R-CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone plus rituximab) chemotherapy. At the follow-up period of 42 months, the patient is surviving with no evidence of disease. No morbidities occurred in this patient during the follow-up period. We also briefly review the current practice pattern in PBL patients with DLBCL.