Purpose: Artificial intelligence (AI) employs knowledge models that often behave as a black-box to the majority of users and are not designed to improve the skill level of users. In this study, we aim to demonstrate the feasibility that AI can serve as an effective teaching aid to train individuals to develop optimal intensity modulated radiation therapy (IMRT) plans. Methods and Materials: The training program is composed of a host of training cases and a tutoring system that consists of a front-end visualization module powered by knowledge models and a scoring system. The current tutoring system includes a beam angle prediction model and a dose-volume histogram (DVH) prediction model. The scoring system consists of physician chosen criteria for clinical plan evaluation as well as specially designed criteria for learning guidance. The training program includes six lung/mediastinum IMRT patients: one benchmark case and five training cases. A plan for the benchmark case is completed by each trainee entirely independently pre- and post-training. Five training cases cover a wide spectrum of complexity from easy (2), intermediate (1) to hard (2). Five trainees completed the training program with the help of one trainer. Plans designed by the trainees were evaluated by both the scoring system and a radiation oncologist to quantify planning quality. Results: For the benchmark case, trainees scored an average of 21.6% of the total max points pre-training and improved to an average of 51.8% post-training. In comparison, the benchmark case\'s clinical plans score an average of 54.1% of the total max points. Two of the five trainees\' post-training plans on the benchmark case were rated as comparable to the clinically delivered plans by the physician and all five were noticeably improved by the physician\'s standards. The total training time for each trainee ranged between 9 and 12 h. Conclusion: This first attempt at a knowledge model based training program brought unexperienced planners to a level close to experienced planners in fewer than 2 days. The proposed tutoring system can serve as an important component in an AI ecosystem that will enable clinical practitioners to effectively and confidently use KBP.

BACKGROUND: Neoadjuvant chemoradiotherapy (NACRT) has not been accepted as a general therapy for gastric cancer because of its localized effect and toxicity for radiosensitive organs. However, if radiation therapy could compensate for the limited or inadequate treatment choices available for elderly patients and/or those at high risk, the available therapeutic options for advanced gastric cancer might increase. From this perspective, we present our experiences of five patients with advanced gastric cancer in whom we used NACRT therapy with interesting results.
METHODS: We admitted five patients with clinical Stage III gastric cancer and bulky lymph node metastasis or adjacent organ invasion at the time of diagnosis. A total of 50 Gy of preoperative intensity modulated radiation therapy was delivered to the patients in doses of 2.0 Gy/d, together with a regimen of concomitant chemotherapy comprising two courses of oral tegafur/gimeracil/oteracil (S-1; 65 mg/m2 per day) for three consecutive weeks followed by two weeks of rest, starting at the same time as radiotherapy. All patients underwent no residual tumor resection and a pathological complete response of the primary tumors was achieved in two patients. The incidence of hematological toxicity was low, although the digestive toxicities of anorexia and diarrhea developed in three of the five patients, necessitating termination of radiation therapy at 30 Gy and S-1 at three weeks. However, even 30 Gy of irradiation and half the dose of S-1 resulted in sufficient downstaging, indicating that even a reduced amount of NACRT could confer considerable effects.
CONCLUSIONS: Slightly reduced NACRT might be useful and safe for patients with locally advanced gastric cancer.

OBJECTIVE: To determine the influence of different medical physicists, photon energies, treatment planning systems and treatment machines on the resulting external beam radiotherapy dose distribution for a sample prostate cancer case.
METHODS: A pre-contoured computed tomography (CT) dataset containing planning target volume 1 (PTV1) prostate and seminal vesicles (single dose [SD] 1.8 Gy, total dose [TD] 59.4 Gy), PTV2 prostate (simultaneously integrated boost [SIB], SD 2.0 Gy, TD 66 Gy), PTV3 prostate and seminal vesicles approach (SD 1.8 Gy, TD 73.8 Gy/80.4 Gy SIB) as well as organs at risk (OAR: rectum, bladder, femoral heads, bowel, anus) was offered to the members of the task group IMRT (intensity-modulated radiation therapy) of the German Society for Medical Physics. The purpose was to calculate one combined treatment plan (TP) for PTV1 and PTV2, as well as a separate one for PTV3. Dose volume histograms (DVH), different dose values, conformity index (CI), homogeneity index (HI), gradient index (GI) and a new \"better than average score\" were used to analyse the dose distributions.
RESULTS: Altogether 44 institutions took part in this study and submitted acceptable dose distributions for the PTVs. However, there were statistically significant differences, especially for the doses administered to the OAR, such as rectum, bladder and femoral heads. Differences between the treatment plans were not easily detectable by visual inspection of the isodose distribution. Dose maxima may occur outside the PTV. Even though scoring indices are already published, the new \"better than average score\" was needed to identify a plan that minimises dose to all OAR simultaneously.
CONCLUSIONS: Different medical physicists or dosimetrists, photon energies, treatment planning systems, and treatment machines have an impact on the resulting dose distribution. However, the differences only become apparent when comparing DVH, analysing dose values, comparing CI, HI, GI, as well as reviewing the dose distribution in every single plane. A new score was introduced to identify treatment plans that simultaneously deliver a low dose to all OAR. Such inter- and intra-institutional comparison studies are needed to explore different treatment planning strategies; however, there is still no automatic solution for an \"optimal\" treatment plan.

The solitary fibrous tumor (SFT) was first described as a mesenchymal tumor of fibroblastic type, present in the pleura. The head and neck area is the third most common site of SFT occurrence. Numb chin syndrome (NCS) is a rare neurological symptom. The current report describes the case of a 39-year-old female patient referred to the present hospital with NCS, which was later observed to be due to a large SFT in the infratemporal fossa. Computed tomography and magnetic resonance images were taken and subsequent examination of these images revealed a space occupying mass (52×50×40 mm) in the infratemporal fossa. An open biopsy was performed on the lower part of the right auricula following angiography assisted vascular embolization of the maxillary artery. Pathological diagnosis was verified as SFT. Despite the tumor size and anatomical site, the SFT was successfully reduced in size by treatment with intensity modulated radiation therapy (IMRT) alone, with no recurrence. IMRT treatment of SFT may be effective as a future potential option for locally advanced head and neck SFT.

OBJECTIVE: To compare the dose to critical structures using HDR brachytherapy versus IMRT in pediatric tumors.
METHODS: Two sarcoma cases, for which both HDR and IMRT could be options, were selected for this case study. Case 1 targeted a volume on the posterior neck/upper back with an HDR prescription of 600cGy × 5 fractions, 3000cGy total. The IMRT prescription used was 180cGy × 25 fractions, 4500cGy total with a boost of 180cGy × 6 fractions, 1080cGy. The IMRT PTV used was a 0.5cmexpansion of the HDR PTV; the boost PTV was identical to the HDR treatment plan. Case 2 targeted a volume on the palette of the mouth with an HDR prescription of 300cGy × 12 fractions, 3600cGy total. The IMRT prescription used was 180cGy × 28 fractions, 5040cGy total. A 0.5cm expansion of the HDR PTV was used for the IMRT PTV. In both cases, for both HDR and IMRT, at least 95% of the PTV received 100% prescription dose, following Children\'s Oncology Group protocols.
RESULTS: Case 1 : the mean doses to the body, brachial plexus, esophagus, spinal cord and thyroid were higher using IMRT than HDR. Integral dose was 6.6 times higher using IMRT than HDR. Case 2: the mean doses to the body, mandible, and parotids were higher using IMRT than HDR. Integral dose was 2.9 times higher using IMRT than HDR.
CONCLUSIONS: This study shows the potential benefit of treating with HDR compared to IMRT in select pediatric cases. These results suggest that HDR can be superior to IMRT in the sparing of critical structures and in delivering less integral dose to the patient while still achieving adequate target coverage. However, lower mean doses to critical structures must also be weighed against the possibility of complications from HDR\'s very high hotspots.

OBJECTIVE: While bone invasion and hyperostosis are frequent phenomena in meningiomas, primary intraosseous meningiomas are rare and their occurrence in the skull base is an extraordinary exception. Moreover, radiation-induced meningiomas represent a unique clinical dilemma given the fact that patients with these tumors had often received a prior full course of radiotherapy.
METHODS: A 42-year-old man presented with a 3-month history of progressively worsening facial asymmetry. His medical history was consistent for a posterior cranial fossa irradiation at the age of 6 years for a non-confirmed brain stem tumor. On admission his Karnofsky performance status was graded as 50% and his neurological examination showed a complete right facial nerve paralysis and hearing impairment. Computed tomography and magnetic resonance imaging demonstrated an osteolytic tumor invading the whole right petrous bone without intracranial involvement.
METHODS: As the tumor reached the external auditory canal, a tissue sample was obtained locally. Pathological examination of the lesion identified a grade II clear cell meningioma and the patient was consequently addressed for an intensity modulated radiation therapy. His condition remained unchanged till the most recent follow-up examination, 8 months later.
CONCLUSIONS: To the best of our knowledge, a radiation induced osteolytic clear cell meningioma of the petrous bone has not been previously reported. As little literature exists regarding the use of adjuvant therapies for these tumors, intensity modulated radiation therapy remains an attractive treatment option in case of pervious irradiation and general status alteration.

A 59-year-old man presented with an unresectable bulky giant basal cell carcinoma on his upper back. A trial of chemotherapy did not help relieve his symptoms or reduce the tumor. He was referred for and received definitive radiation therapy via IMRT with dramatic regression. The patient had been unable to lie on his back for many years but currently can sleep comfortably on his back without pain, which has dramatically improved his quality of life.

Basaloid squamous cell carcinoma (BSCC) is a rare variant of squamous cell carcinoma (SCC), which is highly aggressive, with a tendency for multifocality, local invasion, and with a high metastatic potential. Less than forty cases of BSCC of the sinonasal tract have been reported in the literature, and no reports were found on sinonasal BSCC arising from the ethmoid sinus. We report the case of a 78-year-old man who presented with BSCC arising from the ethmoid sinus with extensive bone destruction and intracranial extension. He was treated with craniofacial resection followed by adjuvant intensity-modulated radiation therapy to the tumor bed (60 Gy in 30 fractions), and the upper neck lymph nodes (50 Gy in 25 fractions). At the patient\'s last follow-up, four months after diagnosis, there was no evidence of disease. Aggressive management using craniofacial resection followed by adjuvant radiation therapy with or without radiosensitizing chemotherapy seems to be a reasonable approach to this challenging disease.

Superior vena cava (SVC) syndrome results from clear cell renal cell carcinoma and is a challenge in clinical practice due to its pathological complexity and a lack of research data. The current study presents a 49-year-old female with symptoms of exertional dyspnea and increased fatigue, which had persisted for 15 months, as well as bilateral edema in the lower limbs for two days. A transesophageal echocardiogram demonstrated a right atrial mass originating from the inferior vena cava (IVC; size, 14×8 cm) that caused a tricuspid inflow obstruction. Following a partial resection of the thrombus, a clear cell renal cell carcinoma was identified by histological examination. The patient received intensity-modulated radiation therapy following refusal of other therapeutic methods. The eleven-month follow-up indicated that the tumor on the kidney and IVC was stable. Intensity-modulated radiation therapy may be beneficial to patients with clear cell renal cell carcinoma and SVC syndrome. However, additional studies are required to obtain further data regarding the treatment of this syndrome.