Breast--Cancer--Radiotherapy.

The purpose of this study is to verify and validate the dose at various points of
interest in accelerated partial breast irradiation (APBI) treated with the Strut Adjusted
Volume Implant (SAVI) applicator using Thermoluminescent Dosimeters (TLDs). A set
of CT images were selected from a patient’s data who had received APBI using the SAVI
applicator. The images were used to make 3D models. TLDs were calibrated for
Brachytherapy. Various points of interest were marked out and slots were carved in the 3D
models to fit the TLDs. CT scans were taken of the 3D models with expanded SAVI
applicator inserted. A plan was made following B-39 protocol. The TLDs were read and
the absorbed doses were calculated and compared to the delivered doses. The results of this
study show that the overall average reading of the TLDs is within expected value. The TPS
shows overestimated dose calculations for brachytherapy.

The purpose of this study is to investigate the changes of the pericardial dose at different respiratory phases and statuses in accelerated partial breast irradiation (APBI) using Cyberknife M6™ multileaf collimators (CK-MLC). Anonymous 6 female patient files with respiration gated four-dimensional computed tomography (4DCT) sets, and 6 left breast cancer cases with CT images in free-breathing (FB) and deep inhalation breath-hold (BH) were selected. One CT image set from each patient was planned for APBI in Accuray Multiplan™ 5.2, and respectively compared its pericardial dose with those from CT sets of other respiratory phases. All the comparable CT images were fused in the planning system according to the left chest wall, among which the lung gap anterior to the pericardium varies by the lung expansion. For the purpose of this study, the tumor volume was outlined in the media-lower quadrant of the left breast where this lung gap is relatively small. All the plans in this study met the requirements set by the National Surgical Adjuvant Breast and Bowel Project/Radiation Therapy Oncology Group (NSABP/RTOG), specifically protocol B-39/RTOG 0413. From the comparisons in this investigation, the mean relative pericardial dose of the BH CT group showed significant or 45% (p < 0.01) lower value than that of FB CT group. However, in FB 4DCT group, 3 of 6 cases indicated a meaningful reduction (p < 0.05) in 100% inhalation phase when compared with the mean dose over other phases. The inconsistent pericardial doses were displayed in FB 4DCT group due to minimal changes in the anterior lung gap of the pericardium, when the diaphragmatic breathing was dominant in those patients.