Analysis of the Dose Drop at the Edge of the Target Area in Heavy Ion Radiotherapy

Background. The dose distribution of heavy ions at the edge of the target region will have a steep decay during radiotherapy, which can better protect the surrounding organs at risk. Objective. To analyze the dose decay gradient at the back edge of the target region during heavy ion radiotherapy. Methods. Treatment planning system (TPS) was employed to analyze the dose decay at the edge of the beam under different incident modes and multiple dose segmentation conditions during fixed beam irradiation. The dose decay data of each plan was collected based on the position where the rear edge of the beam began to fall rapidly. Uniform scanning mode was selected in heavy ion TPS. Dose decay curves under different beam setup modes were drawn and compared. Results. The dose decay data analysis showed that in the case of single beam irradiation, the posterior edge of the beam was 5 mm away, and the posterior dose could drop to about 20%. While irradiation in opposite direction, the posterior edge of the beam was 5 mm away, and the dose could drop to about 50%. In orthogonal irradiation of two beams, the posterior edge of the beam could drop to about 30-38% in a distance of 5 mm. Through the data analysis in the TPS, the sharpness of the dose at the back edge of the heavy ion beam is better than that at the lateral edge, but the generated X-ray contamination cannot be ignored. Conclusions. The effect of uneven CT value on the dose decay of heavy ion beam should also be considered in clinical treatment.

Two cases of severe esophageal ulcer caused by chemotherapy for breast cancer after particle beam therapy for esophageal cancer

Background: Particle beam treatment for esophageal cancer can produce a better local therapeutic effect than can conventional radiotherapy. However, events that occur in the esophagus during or after the treatment of other cancers after that are unknown. Case summary: The first patient, a 64-year-old woman, had undergone heavy ion radiotherapy for esophageal cancer. Endoscopic submucosal dissection was performed for local residual tumor. Five years later, cancer was found in the right breast, and the patient underwent partial mastectomy and adjuvant chemotherapy. Six years after heavy ion radiotherapy, oral intake became difficult. A benign esophageal ulcer with circumferential stenosis was observed at the site of heavy particle irradiation. The second patient, a 63-year-old woman, had undergone proton therapy for esophageal cancer and photodynamic therapy for local residual tumor. Four years later, cancer was found in the left breast, and the patient underwent preoperative adjuvant chemotherapy, which reduced the size of the breast cancer. Oral intake became difficult 5 years after proton therapy. Endoscopy showed a benign esophageal ulcer with severe stenosis at the site of proton irradiation. Conclusion: After particle beam therapy for esophageal cancer, patients who undergo chemotherapy for other cancers may develop an esophageal ulcer. Keywords: Particle beam therapy; esophageal cancer; esophageal ulcer; breast cancer; chemotherapy

Visualized Analysis of Heavy Ion Radiotherapy: Development, Barriers and Future Directions

BackgroundHeavy ion radiotherapy (HIRT) has great advantages as tumor radiotherapy.MethodsBased on 1,558 literatures from core collections of Web of Science from 1980 to 2020, this study visually analyzes the evolution of HIRT research, and sorts out the hotspots and trends of HIRT research using CiteSpace software.ResultsResearch on HIRT has received more extensive attention over the last 40 years. The development of HIRT is not only closely related to radiation and oncology, but also closely related to the development of human society. In terms of citation frequency, “International Journal of Radiation Oncology*Biology*Physics” was the top journal. In terms of influence, “Radiotherapy and Oncology” was the top journal. “Radiation therapy” and “carbon ion radiotherapy” were the two most frequently used keywords in this field.ConclusionThe evolution of the HIRT research has occurred in approximately three stages, including technological exploration, safety and effectiveness research and technological breakthroughs. Finally, some suggestions for future research are put forward.

Maxillo-mandibular osteoradionecrosis following C-ion radiotherapy: Clinical notes and review of literature

Osteoradionecrosis (ORN) is one of the most feared complications after head and neck radiotherapy. Among head and neck sites, the mandible is the most commonly involved bone. Heavy ion radiotherapy delivers high-dose distribution focused to the target while simultaneously sparing of the adjacent organs but there are anyway some reported cases of ORN. Cases in literature reported well-known risk factors for its developing (e.g. tobacco and alcohol abuse, diabetes), but other are still debated (e.g. teeth extraction during radiotherapy). Prevention is mandatory but multimodal care may be required, tailoring all treatments on the patient needs. This study, after a brief revision of the literature, reports and a case of maxillo-mandibular ORN following carbon-ion (C-ion) radiotherapy and its treatment.