Normal Tissue Complication Probability Model for Acute Radiation Dermatitis in Patients With Head and Neck Cancer Treated With Carbon Ion Radiation Therapy.

PURPOSE: This study aimed to explore the prognostic factors associated with acute radiation dermatitis (ARD). A normal tissue complication probability (NTCP) model for ARD in patients with head and neck cancer treated with carbon ion radiation therapy was developed. MATERIALS AND METHODS: A total of 187 patients were included in the analysis, and the endpoint was ≥grade 2 ARD. The biological and physical dose-surface parameters associated with ARD were used in the logistic regression model. The mean areas under the receiver operating characteristic curve in the internal cross-validation and Akaike's corrected Information Criterion were examined for model evaluation and selection. The multivariate logistic regression NTCP models were established based on factors with weak correlation. RESULTS: Tumor volume, planning target volume to the skin, radiation technique and all dose-surface parameters were significantly associated with ARD (P < .05). Models with high performance for grade 2 to 3 ARD were constructed. The most significant prognostic predictors were S40Gy(relative biological effectiveness,RBE) and S20Gy (absolute surface area receiving RBE-weighted dose of 40 Gy (RBE) or physical dose of 20 Gy). The internal cross-validation-based areas under the receiver operating characteristic curve for models with S40Gy(RBE) and S20Gy were 0.78 and 0.77, respectively. The biological and physical dose-surface parameters had similar performance at various dose levels. However, the performance of the multivariate NTCP models based on 2 factors was not better than that of the univariate models. CONCLUSIONS: NTCP models for ARD may provide a basis for the development of individualized treatment strategies and reduce the incidence of severe ARD in patients with head and neck cancer receiving carbon ion radiation therapy. Furthermore, biological and physical dose-surface parameter-based models are comparable. However, further validation with more evaluation parameters is warranted.

Implementation of a rapid response system at an isolated radiotherapy facility through simulation training.

A rapid response system is required in a radiotherapy department for patients experiencing a critical event when access to an emergency department is poor due to geographic location and the patient is immobilised with a fixation device. We, therefore, rebuilt the response system and tested it through onsite simulations. A multidisciplinary core group was created and onsite simulations were conducted using a Plan-Do-Study-Act cycle. We identified the important characteristics of our facility, including its distance from the emergency department; the presence of many staff with little direct contact with patients; the treatment room environment and patient fixation with radiotherapy equipment. We also examined processes in each phase of the emergency response: detecting an emergency, calling the medical emergency team (MET), MET transportation to the site and on-site response and patient transportation to the emergency department. The protocol was modified, and equipment was updated. On-site simulations were held with and without explanation of the protocol and training scenario in advance. The time for the MET to arrive at the site during a 2017 simulation prior to the present project was 7 min, whereas the time to arrive after the first simulation session was shortened to 5 min and was then shortened further to 4 min in the second session, despite no prior explanation of the situation. A multidisciplinary project for emergency response with on-site simulations was conducted at an isolated radiation facility. A carefully planned emergency response is important not only in heavy ion therapy facilities but also in other departments and facilities that do not have easy access to hospital emergency departments.

Relationship between oral mucositis and the oral bacterial count in patients with head and neck cancer undergoing carbon ion radiotherapy: A prospective study.

BACKGROUND AND PURPOSE: Acute adverse events, such as oral mucositis, can affect treatment success in patients undergoing head and neck radiotherapy. In this study, we aimed to identify the relationship between oral mucositis and oral bacterial counts during carbon ion radiotherapy (C-ion RT) in patients with head and neck cancer. MATERIALS AND METHODS: This prospective study included patients with head and neck tumors treated with C-ion RT between 2017 and 2019. C-ion RT consisted of treatment at 57.6, 64.0, or 70.4 Gy (relative biological effectiveness) in 16 fractions. Bacterial counts in the saliva and the back of the tongue were measured using a rapid oral bacteria quantification system. The relationship between the oral bacterial count and oral mucositis was subsequently analyzed. RESULTS: In total, 46 patients were included in the analysis. The bacterial count in the saliva gradually increased from the commencement of C-ion RT and peaked at 16 fractions. Bacterial counts at the back of the tongue were already high at the beginning of C-ion RT; however, they decreased with continued treatment, peaked at 16 fractions, and subsequently decreased again. Patients with bacterial counts exceeding the mean before C-ion RT (high-count group) did not experience more severe mucositis than those with counts below the mean (low-count group). However, patients in the high-count group tended to experience faster-onset mucositis and slower healing than those in the low-count group. CONCLUSION: Bacterial counts may aid in the development of clinical strategies for C-ion RT-induced oral mucositis.

Carbon Ion Radiotherapy at the Gunma University Heavy Ion Medical Center: New Facility Set-up.

Carbon ion radiotherapy (C-ion RT) offers superior dose conformity in the treatment of deep-seated tumors compared with conventional X-ray therapy. In addition, carbon ion beams have a higher relative biological effectiveness compared with protons or X-ray beams. C-ion RT for the first patient at Gunma University Heavy Ion Medical Center (GHMC) was initiated in March of 2010. The major specifications of the facility were determined based on the experience of clinical treatments at the National Institute of Radiological Sciences (NIRS), with the size and cost being reduced to one-third of those at NIRS. The currently indicated sites of cancer treatment at GHMC are lung, prostate, head and neck, liver, rectum, bone and soft tissue. Between March 2010 and July 2011, a total of 177 patients were treated at GHMC although a total of 100 patients was the design specification during the period in considering the optimal machine performance. In the present article, we introduce the facility set-up of GHMC, including the facility design, treatment planning systems, and clinical preparations.