Electron stream effect in 0.35 Tesla magnetic resonance image guided radiotherapy for breast cancer.

Purpose: This research aimed to analyze electron stream effect (ESE) during magnetic resonance image guided radiotherapy (MRgRT) for breast cancer patients on a MR-Linac (0.35 Tesla, 6MV), with a focus on the prevention of redundant radiation exposure. Materials and methods: RANDO phantom was used with and without the breast attachment in order to represent the patients after breast conserving surgery (BCS) and those received modified radical mastectomy (MRM). The prescription dose is 40.05 Gy in fifteen fractions for whole breast irradiation (WBI) or 20 Gy single shot for partial breast irradiation (PBI). Thirteen different portals of intensity-modulated radiation therapy were created. And then we evaluated dose distribution in five areas (on the skin of the tip of the nose, the chin, the neck, the abdomen and the thyroid.) outside of the irradiated field with and without 0.35 Tesla. In addition, we added a piece of bolus with the thickness of 1cm on the skin in order to compare the ESE difference with and without a bolus. Lastly, we loaded two patients' images for PBI comparison. Results: We found that 0.35 Tesla caused redundant doses to the skin of the chin and the neck as high as 9.79% and 5.59% of the prescription dose in the BCS RANDO model, respectively. For RANDO phantom without the breast accessory (simulating MRM), the maximal dose increase were 8.71% and 4.67% of the prescription dose to the skin of the chin and the neck, respectively. Furthermore, the bolus we added efficiently decrease the unnecessary dose caused by ESE up to 59.8%. Conclusion: We report the first physical investigation on successful avoidance of superfluous doses on a 0.35T MR-Linac for breast cancer patients. Future studies of MRgRT on the individual body shape and its association with ESE influence is warranted.

Precise mapping of hilar cholangiocarcinoma with a skip lesion by SpyGlass cholangioscopy: A case report.

BACKGROUND: Cholangiocarcinoma (CC) is a very aggressive cancer with a poor prognosis. As surgery is the only curative therapy, preoperative evaluation of the tumor extent is essential for surgical planning. Although high-quality image modalities such as computed tomography and magnetic resonance imaging have been used extensively in preoperative evaluation, the accuracy is low. To obtain precise localization of tumor spread arising from the hilar region preoperatively, the development of an acceptable imaging modality is still an unmet need. CASE SUMMARY: A 52-year-old female presented to our emergency department with jaundice, abdominal pain, and fever. Initially, she was treated for cholangitis. Endoscopic retrograde cholangiopancreatography with the cholangiogram showed long segment filling defect in the common hepatic duct with dilatation of bilateral intrahepatic ducts. Transpapillary biopsy was performed, and the pathology suggested intraductal papillary neoplasm with high-grade dysplasia. After treatment of cholangitis, contrasted-enhanced computed tomography revealed a hilar lesion with undetermined Bismuth-Corlette classification. SpyGlass cholangioscopy showed that the lesion involved the confluence of the common hepatic duct with one skip lesion in the posterior branch of the right intrahepatic duct, which was not detected by previous image modalities. The surgical plan was modified from extended left hepatectomy to extended right hepatectomy. The final diagnosis was hilar CC, pT2aN0M0. The patient has remained disease-free for more than 3 years. CONCLUSION: SpyGlass cholangioscopy may have a role in precision localization of hilar CC to provide surgeons with more information before the operation.

Biomarkers of Favorable vs. Unfavorable Responses in Locally Advanced Rectal Cancer Patients Receiving Neoadjuvant Concurrent Chemoradiotherapy.

Colorectal cancer is the second leading cause of cancer death globally. The gold standard for locally advanced rectal cancer (LARC) nowadays is preoperative concurrent chemoradiation (CCRT). Approximately three quarters of LARC patients do not achieve pathological complete response and hence suffer from relapse, metastases and inevitable death. The exploration of trustworthy and timely biomarkers for CCRT response is urgently called for. This review focused upon a broad spectrum of biomarkers, including circulating tumor cells, DNA, RNA, oncogenes, tumor suppressor genes, epigenetics, impaired DNA mismatch repair, patient-derived xenografts, in vitro tumor organoids, immunity and microbiomes. Utilizing proper biomarkers can assist in categorizing appropriate patients by the most efficient treatment modality with the best outcome and accompanied by minimal side effects. The purpose of this review is to inspect and analyze accessible data in order to fully realize the promise of precision oncology for rectal cancer patients.