A novel method for determining dose distribution on panoramic reconstruction computed tomography images from radiotherapy computed tomography.

Purpose: Patients with head and neck cancer (HNC) who undergo dental procedures during radiotherapy (RT) face an increased risk of developing osteoradionecrosis (ORN). Accordingly, new tools must be developed to extract critical information regarding the dose delivered to the teeth and mandible. This article proposes a novel approach for visualizing 3-dimensional planned dose distributions on panoramic reconstruction computed tomography (pCT) images. Materials and Methods: Four patients with HNC who underwent volumetric modulated arc therapy were included. One patient experienced ORN and required the extraction of teeth after RT. In the study approach, the dental arch curve (DAC) was defined using an open-source platform. Subsequently, pCT images and dose distributions were generated based on the new coordinate system. All teeth and mandibles were delineated on both the original CT and pCT images. To evaluate the consistency of dose metrics, the Mann-Whitney U test and Student t-test were employed. Results: A total of 61 teeth and 4 mandibles were evaluated. The correlation coefficient between the 2 methods was 0.999, and no statistically significant difference was observed (P>0.05). This method facilitated a straightforward and intuitive understanding of the delivered dose. In 1 patient, ORN corresponded to the region of the root and the gum receiving a high dosage (approximately 70 Gy). Conclusion: The proposed method particularly benefits dentists involved in the management of patients with HNC. It enables the visualization of a 3-dimensional dose distribution in the teeth and mandible on pCT, enhancing the understanding of the dose delivered during RT.

Role of the gel spacer in safely delivering whole pelvic radiation therapy without central shielding in computed tomography-based image-guided adaptive brachytherapy for uterine cervical cancer patients.

BACKGROUND: To protect the rectum and bladder from high dose exposure, the Japanese guidelines for managing uterine cervical carcinoma recommend pelvic irradiation with central shielding (CS). Conversely, the European Society for Radiotherapy and Oncology (ESTRO) and the American Brachytherapy Society (ABS) guidelines recommend delivering ≥85 Gy to high-risk clinical target volume D90 (CTVHR D90%). In this study, we investigated whether a gel spacer can enable the safe delivery of the ESTRO/ABS-recommended doses to the target while observing dose constraints for the OARs without using CS in external beam radiation therapy (EBRT). MATERIALS AND METHODS: Twenty patients who received definitive radiation therapy without CS and were treated by brachytherapy with a gel spacer between 2017 and 2022 were retrospectively reviewed. The cumulative doses of EBRT and brachytherapy treatment outcomes and incidence of adverse events were also examined. RESULTS: The median cumulative CTVHR D90%, rectum D2cm3, and bladder D2cm3 were 86.6 Gy, 62.9 Gy, and 72.0 Gy, respectively. The 2-year local control rate was 95%. There were no CTCAE ≥Grade 3 late gastrointestinal or genitourinary adverse events. CONCLUSIONS: The use of gel spacer can enable ESTRO/ABS-recommended dose constraints even without using CS in EBRT, with favorable outcomes and low adverse event rates.

Acral cutaneous malignant melanoma treated with linear accelerator-based boron neutron capture therapy system: a case report of first patient.

This study reports the first patient treatment for cutaneous malignant melanoma using a linear accelerator-based boron neutron capture therapy (BNCT) system. A single-center open-label phase I clinical trial had been conducted using the system since November 2019. A patient with a localized node-negative acral malignant melanoma and the largest diameter of the tumor ≤ 15 cm who refused primary surgery and chemotherapy was enrolled. After administering boronophenylalanine (BPA), a single treatment of BNCT with the maximum dose of 18 Gy-Eq delivered to the skin was performed. The safety and efficacy of the accelerator-based BNCT system for treating localized cutaneous malignant melanoma were evaluated. The first patient with cutaneous malignant melanoma in situ on the second finger of the left hand did not develop dose-limiting toxicity in the clinical trial. After BNCT, the treatment efficacy was gradually observed, and the patient achieved PR within 6 months and CR within 12 months. Moreover, during the follow-up period of 12 months after BNCT, the patient did not exhibit a recurrence without any treatment-related grade 2 or higher adverse events. Although grade 1 adverse events of dermatitis, dry skin, skin hyperpigmentation, edema, nausea, and aching pain were noted in the patient, those adverse events were relieved without any treatment. This case report shows that the accelerator-based BNCT may become a promising treatment modality for cutaneous malignant melanoma. We expect further clinical trials to reveal the efficacy and safety of the accelerator-based BNCT for cutaneous malignant melanoma.

Nursing management of patients receiving interstitial brachytherapy for head and neck malignancies.

Brachytherapy is a type of radiation therapy in which the radioactive source is directly delivered to the tumor and is used to treat a variety of malignancies. Although the local control effect of brachytherapy is higher than that of external beam radiation therapy (EBRT), it is often the case that brachytherapy is more invasive than conventional EBRT. As a result, patients receiving head and neck brachytherapy confront several physical, nutritional, and pain management issues. The nurses caring for patients with head and neck cancer receiving high-dose rate interstitial brachytherapy (ISBT) should have a thorough understanding of radiation therapy principles, technology, applicator management, and the acute and chronic side effects of ISBT. However, there are no appropriate textbooks or review articles regarding nursing care for head and neck patients undergoing ISBT. The purpose of this article is to provide radiation oncologists and nurses who want to start head and neck ISBT with a comprehensive guide regarding nursing care and to help the wide spread of this treatment strategy.

The combination of volumetric arc radiation therapy and boost high-dose rate interstitial brachytherapy for T3N2c tongue cancer: a technical report.

Currently, tongue cancers are primarily managed by surgery, and interstitial brachytherapy is only recommended for a selected group of early state T1-2N0 patients who refuse surgery or are medically inoperable. In this report, a case with T3N2cM0 tongue cancer who has been effectively treated by the combination of concurrent chemoradiotherapy involving volumetric arc therapy and boost high-dose rate interstitial brachytherapy is presented. Of course, surgery remains the main treatment strategy for tongue cancer patients; however, the authors believe that if volumetric arc therapy is carefully planned to reduce the mandible dose as much as possible and high-dose rate interstitial brachytherapy with a mouthpiece that protects the mandible is combined, it is possible to treat T3N2 disease, and this can be considered for patients who want to preserve organ function.

Hydrogel spacer injection to the meso-sigmoid to protect the sigmoid colon in cervical cancer brachytherapy: A technical report.

Purpose: The use of a hydrogel spacer inserted into recto-vaginal fossa is a valuable strategy to mitigate radiation exposure to the rectum during radiation therapy for female pelvic malignancies. However, when the sigmoid colon is in proximity to the cervix, radiation exposure to the sigmoid colon cannot be adequately mitigated with a hydrogel spacer injected into the recto-vaginal fossa. Here, we presented a case, in which a hydrogel spacer was injected into the meso-sigmoid to protect the sigmoid colon. Material and methods: A 73-year-old female diagnosed with T3b stage IIIC2r uterine cervical cancer (FIGO 2018) underwent high-dose-rate interstitial brachytherapy consisting of 24 Gy in 4 fractions, following concurrent chemoradiotherapy with external beam radiation therapy of 50 Gy in 25 fractions of whole pelvic radiation therapy. In the initial brachytherapy, the sigmoid colon was in close contact with the uterine cervix. In the second brachytherapy, attempts to create a space between the sigmoid colon and uterine cervix using injected artificial ascites were unsuccessful due to rapid absorption of fluid. In the third and fourth brachytherapy fractions, 5 mL of hydrogel was injected into the meso-sigmoid through a pouch of Douglas under trans-rectal ultrasonography guidance. Dose ratio of sigmoid colon D2cc and high-risk clinical target volume (HR-CTV) D90 of each brachytherapy were evaluated. Results: Dose ratio of the sigmoid colon D2cc to HR-CTV D90 was 1.03, 0.43, 0.56, and 0.47 in each respective brachytherapy session, indicating dose escalation to HR-CTV whilst achieving acceptable sigmoid dose with hydrogel spacer injected into the meso-sigmoid. Conclusions: The dose ratio of the sigmoid colon to HR-CTV D90 was decreased by introducing a hydrogel spacer into the meso-sigmoid. In cases where the sigmoid colon is in proximity to the cervical tumor, this novel technique can be considered to achieve better clinical outcomes.

Salvage image-guided freehand interstitial brachytherapy for pelvic sidewall recurrence after hysterectomy for uterine malignancies.

PURPOSE: Pelvic sidewall recurrence after hysterectomy for uterine malignances has a poor prognosis, and the salvage therapy for this type of recurrence is still challenging. The purpose of this study was to investigate the efficacy of freehand high-dose-rate interstitial brachytherapy (HDR-ISBT) through the perineum using transrectal ultrasonography for this disease. METHODS AND MATERIALS: We retrospectively evaluated 42 patients with pelvic sidewall recurrence after hysterectomy for uterine cervical and endometrial cancers. We investigated patients' characteristics, the 2-year local control and survival rates, and late adverse events of the rectum and bladder. RESULTS: The 2-year overall survival, local control, and progression-free survival rates were 73.7% (95% confidence interval [CI], 60.8-89.3%), 69.4% (95% CI, 55.4-80.1%), and 37.3% (95% CI, 24.6-56.5%), respectively. In Cox multivariate analysis, tumor size at recurrence (<45 mm vs. ≥45 mm) (p = 0.04) and disease-free periods after hysterectomy (<10 months vs. ≥10 months) (p < 0.01) were significant prognostic factors for overall survival. Lymph node metastasis at recurrence (p < 0.01) was also a significant prognostic factor for progression-free survival. Three patients experienced Grade 3-4 late proctitis (7%). CONCLUSIONS: Transperineal freehand salvage HDR-ISBT using transrectal ultrasonography was demonstrated to be a curative treatment option for patients with pelvic sidewall recurrence following hysterectomy. Based on the findings of this study, we emphasize the importance of HDR-ISBT for pelvic sidewall recurrence.

Single-Fractionated Stereotactic Radiosurgery for Intracranial Meningioma in Elderly Patients: 25-Year Experience at a Single Institution.

BACKGROUND: Stereotactic radiosurgery (SRS) has been accepted as a therapeutic option for intracranial meningiomas; however, the detailed data on outcomes in elderly patients remain unclear. OBJECTIVE: To delineate the efficacy of SRS for meningiomas in elderly patients. METHODS: The outcomes of 67 patients aged ≥65 yr who underwent SRS for benign intracranial meningioma (World Health Organization grade I) between 1990 and 2014 at our institution were retrospectively analyzed. The median age was 71 yr (range, 65-83 yr), and the mean and median follow-up were 62 and 52 mo (range, 7-195 mo), respectively. Tumor margins were irradiated with a median dose of 16 Gy, and the median tumor volume was 4.9 cm3 (range, 0.7-22.9 cm3). RESULTS: Actuarial local tumor control rates at 3, 5, and 10 yr after SRS were 92%, 86%, and 72%, respectively. Previous surgery and parasagittal/falcine location were statistically significant predictive factors for failed tumor control. Mild or moderate adverse events were noted in 9 patients. No severe adverse event was observed. A higher margin dose was significantly associated with adverse events by univariate analysis. CONCLUSION: SRS is one of the standard therapies for meningiomas in elderly patients, providing both favorable tumor control and a low risk of adverse events under minimum invasiveness.

Detection of residual metastatic tumor in the brain following Gamma Knife radiosurgery using a single or a series of magnetic resonance imaging scans: An autopsy study.

The aim of the present study was to investigate the usefulness of magnetic resonance image (MRI) for the detection of residual tumors following Gamma Knife radiosurgery (GKR) for brain metastases based on autopsy cases. The study investigated two hypotheses: i) Whether a single MRI may detect the existence of a tumor; and ii) whether a series of MRIs may detect the existence of a tumor. The study is a retrospective case series in a single institution. A total of 11 brain metastases in 6 patients were treated with GKR between 2002 and 2011. Histopathological specimens from autopsy were compared with reconstructed follow-up MRIs. The maximum diameters of the lesions on MRI series were measured, and the size changes classified. The primary sites in the patients were the kidneys (n=2), lung (n=1), breast (n=1) and colon (n=1), as well as 1 adenocarcinoma of unknown origin. The median prescribed dose for radiosurgery was 20 Gy (range, 18-20 Gy), and median time interval between GKR and autopsy was 10 months (range, 1.6-20 months). The pathological outcomes included 7 remissions and 4 failures. Enhanced areas on gadolinium-enhanced MRI contained various components: Viable tumor cells, tumor necrosis, hemorrhage, inflammation and vessels. Regarding the first hypothesis, it was impossible to distinguish pathological failure from remission with a single MRI scan due to the presence of various components. Conversely, in treatment response (remission or failure), on time-volume curves of MRI scans were in agreement with pathological findings, with the exception of progressive disease in the acute phase (0-3 months). Thus, regarding the second hypothesis, time-volume curves were useful for predicting treatment responses. In conclusion, it was difficult to predict treatment response using a single MRI, and a series of MRI scans were required to detect the existence of a tumor.

Long-Term Outcomes of Single-Session Stereotactic Radiosurgery for Cerebellar Arteriovenous Malformation, with a Median Follow-Up of 10 Years.

OBJECTIVE: Cerebellar arteriovenous malformation (C-AVM) is poorly tolerated because of its aggressive natural history. The aim of this study was to delineate long-term outcomes of Gamma Knife stereotactic radiosurgery (GKRS) for C-AVM. METHODS: The outcomes of 45 patients who underwent GKRS for C-AVMs at our institution were retrospectively analyzed. Event-free survival was defined as free from any neurologic deficits caused by AVMs or adverse phenomena from the treatment. RESULTS: The median age and follow-up were 41 years (range, 6-77 years) and 120 months (range, 5-291 months), respectively. The median volume and Pollock-Flickinger radiosurgical AVM score were 1.3 cm3 (range, 0.1-8.3 cm3) and 1.26 (range, 0.5-2.06), respectively. Actuarial obliteration rates were 46%, 75%, and 90% at 3, 5, and 6 years, respectively. Multivariate analysis showed that the maximal diameter ≤15 mm (P = 0.021) and margin dose >20 Gy (P = 0.0008) were significantly associated with better obliteration. Four patients experienced posttreatment hemorrhages, and annual hemorrhage rates were 1.9% and 0.30% before and after obliteration, respectively. One patient died because of hemorrhage, whereas the other 3 patients spontaneously recovered. Perifocal edema was confirmed in 8 (16%); however, no symptomatic edema was observed. Overall, neurologic deteriorations were noted in 4 patients; 3 were because of posttreatment hemorrhage, and 1 was because of pretreatment angiography. The event-free survival rates were 96%, 93%, and 93% at 4, 10, and 15 years, respectively. CONCLUSIONS: GKRS is a reasonable intervention for C-AVMs. Symptomatic complications are rare, and the long-term outcomes are favorable.