Evaluation of the accuracy of heart dose prediction by machine learning for selecting patients not requiring deep inspiration breath­hold radiotherapy after breast cancer surgery.

Increased heart dose during postoperative radiotherapy (RT) for left-sided breast cancer (BC) can cause cardiac injury, which can decrease patient survival. The deep inspiration breath-hold technique (DIBH) is becoming increasingly common for reducing the mean heart dose (MHD) in patients with left-sided BC. However, treatment planning and DIBH for RT are laborious, time-consuming and costly for patients and RT staff. In addition, the proportion of patients with left BC with low MHD is considerably higher among Asian women, mainly due to their smaller breast volume compared with that in Western countries. The present study aimed to determine the optimal machine learning (ML) model for predicting the MHD after RT to pre-select patients with low MHD who will not require DIBH prior to RT planning. In total, 562 patients with BC who received postoperative RT were randomly divided into the trainval (n=449) and external (n=113) test datasets for ML using Python (version 3.8). Imbalanced data were corrected using synthetic minority oversampling with Gaussian noise. Specifically, right-left, tumor site, chest wall thickness, irradiation method, body mass index and separation were the six explanatory variables used for ML, with four supervised ML algorithms used. Using the optimal value of hyperparameter tuning with root mean squared error (RMSE) as an indicator for the internal test data, the model yielding the best F2 score evaluation was selected for final validation using the external test data. The predictive ability of MHD for true MHD after RT was the highest among all algorithms for the deep neural network, with a RMSE of 77.4, F2 score of 0.80 and area under the curve-receiver operating characteristic of 0.88, for a cut-off value of 300 cGy. The present study suggested that ML can be used to pre-select female Asian patients with low MHD who do not require DIBH for the postoperative RT of BC.

Outcomes of solitary postoperative recurrence of esophageal squamous cell carcinoma diagnosed with FDG-PET/CT and treated with definitive radiation therapy.

BACKGROUND: Surgical resection of esophageal cancer is frequently performed to achieve a complete cure. However, the postoperative recurrence rate is 36.8-42.5%, leading to poor prognosis. Radiation therapy has been used to treat recurrences; solitary recurrence has been proposed as a prognostic factor for radiation therapy, though its significance is unclear. 18F-fluorodeoxyglucose positron emission tomography is a highly accurate diagnostic modality for esophageal cancer. This retrospective study aimed to analyze the outcomes of solitary postoperative recurrences of esophageal squamous cell carcinoma diagnosed with 18F-fluorodeoxyglucose positron emission tomography and treated with definitive radiation therapy. METHODS: We examined 27 patients who underwent definitive radiation therapy for single or multiple postoperative recurrences of esophageal squamous cell carcinoma between May 2015 and April 2021. 18F-fluorodeoxyglucose positron emission tomography/computed tomography was performed within 3 months before the commencement of radiation therapy. Kaplan-Meier, univariate, and multivariate analyses were performed to examine the overall survival and identify potential prognostic factors. RESULTS: The 1-, 2-, and 3-year overall survival rates were 85.2%, 62.6%, and 47.3%, respectively, and solitary recurrence was the only significant factor associated with overall survival (P = 0.003). The 1-, 2-, and 3-year overall survival rates in patients with solitary recurrence were 91.7%, 80.2%, and 80.2%, respectively, and in patients with multiple recurrences they were 80.0%, 50.3%, and 25.1%, respectively. Multivariate analysis also showed solitary recurrence as a significant factor for overall survival. CONCLUSIONS: When diagnosed with 18F-fluorodeoxyglucose positron emission tomography/computed tomography, solitary recurrence appears to have a more favorable prognosis than multiple recurrences.

Pericytes and shear stress each alter the shape of a self-assembled vascular network.

Blood vessel morphology is dictated by mechanical and biochemical cues. Flow-induced shear stress and pericytes both play important roles, and they have previously been studied using on-chip vascular networks to uncover their connection to angiogenic sprouting and network stabilization. However, it is unknown which shear stress values promote angiogenesis, how pericytes are directed to sprouts, and how shear stress and pericytes affect the overall vessel morphology. Here, we employed a microfluidic device to study these phenomena in three-dimensional (3D) self-assembled vasculature. Computational fluid dynamics solver (COMSOL) simulations indicated that sprouts form most frequently at locations of relatively low shear stresses (0.5-1.5 dyn cm-2). Experimental results show that pericytes limit vascular diameter. Interestingly, when treated with imatinib or crenolanib, which are chemotherapeutic drugs and inhibitors of platelet-derived growth factor receptor ß (PDGFRß), the pericyte coverage of vessels decreased significantly but vessel diameter remained unchanged. This furthers our understanding of the mechanisms underlying vascular development and demonstrates the value of this microfluidic device in future studies on drug development and vascular biology.

Tumor size before image-guided brachytherapy is an important factor of local control after radiotherapy for cervical squamous cell carcinoma: analysis in cases using central shielding.

We analyzed the local control (LC) of cervical squamous cell carcinoma treated by computed tomography (CT)-based image-guided brachytherapy (IGBT) using central shielding (CS). We also examined the value of tumor diameter before brachytherapy (BT) as a factor of LC. In total, 97 patients were analyzed between April 2016 and March 2020. Whole-pelvic (WP) radiotherapy (RT) with CS was performed, and the total pelvic sidewall dose was 50 or 50.4 Gy; IGBT was delivered in 3-4 fractions. The total dose was calculated as the biologically equivalent dose in 2 Gy fractions, and distribution was modified manually by graphical optimization. The median follow-up period was 31.8 months (6.3-63.2 months). The 1- and 2-year LC rates were 89% and 87%, respectively. The hazard ratio was 10.11 (95% confidence interval: 1.48-68.99) for local recurrence in those with a horizontal tumor diameter ≥ 4 cm compared to those with < 4 cm before BT. In CT-based IGBT for squamous cell carcinoma, favorable LC can be obtained in patients with a tumor diameter < 4 cm before BT. However, if the tumor diameter is ≥ 4 cm, different treatment strategies such as employing interstitial-BT for dose escalation may be necessary.

New field-in-field with two reference points method for whole breast radiotherapy: Dosimetric analysis and radiation-induced skin toxicities assessment.

The usefulness of the field-in-field with two reference points (FIF w/ 2RP) method, in which the dose reference points are set simultaneously at two positions in the irradiation field and the high-dose range is completely eliminated, was examined in the present study with the aim of decreasing acute skin toxicity in adjuvant breast radiotherapy (RT). A total of 573 patients with breast cancer who underwent postoperative whole breast RT were classified into 178 cases with wedge (W) method, 142 cases with field-in-field without 2 reference points (FIF w/o 2RP) method and 253 cases with FIF w/ 2RP method. Using the FIF w/ 2RP method, the high-dose range was the lowest among the three irradiation methods. The planning target volume (PTV) V105% and the breast PTV for evaluation (BPe) V105% decreased to 0.09 and 0.10%, respectively. The FIF w/ 2RP method vs. the FIF w/o 2RP method had a strong association (η) with PTV V105% (η=0.79; P<0.001) and BPe V105% (η=0.76; P<0.001). The FIF w/ 2RP method had a significant impact on lowering the skin toxicity grade in weeks 3 and 4, and increasing the occurrence of skin toxicity grade 0. The FIF w/ 2RP method vs. the W method had a moderate association with skin toxicity grade at week 3 (η=0.49; P<0.001). Using the FIF w/ 2RP method, the high-dose range V105% of the target decreased to 0%, and skin adverse events were decreased in conjunction. For patients with early-stage breast cancer, particularly patients with relatively small-sized breasts, the FIF w/ 2RP method may be an optimal irradiation method.

Investigation into the Effect of Breast Volume on Irradiation Dose Distribution in Asian Women with Breast Cancer.

Reports on irradiation dose distribution in breast cancer radiotherapy with sufficient sample size are limited in Asian patients. Elucidating dose distribution in Asian patients is particularly important as their breast volume differs compared to patients in Europe and North America. Here, we examined dose distribution in the irradiation field relative to breast volume for three irradiation methods historically used in our facility. We investigated the influence of breast volume on each irradiation method for Asian women. A total of 573 women with early-stage breast cancer were treated with breast-conserving surgery and adjuvant radiotherapy. Three methods were compared: wedge (W), field-in-field (FIF), and wedge-field-in-field (W-FIF). In patients with small breast volume, FIF decreased low- and high-dose areas within the planning target volume, and increased optimal dose area more than W. In patients with medium and large breast volumes, FIF decreased high-dose area more than W. The absolute values of correlation coefficients of breast volume to low-, optimal-, and high-dose areas and mean dose were significantly lower in FIF than in W. The correlation coefficients of V107% were 0.00 and 0.28 for FIF and W, respectively. FIF is an excellent irradiation method that is less affected by breast volume than W in Asian breast cancer patients.

Single institutional experience of radiation therapy for angiosarcoma of the scalp without cervical lymph node metastases: Impact of concurrent chemoradiation with maintenance chemotherapy using taxanes on patient prognosis.

Cutaneous angiosarcoma is a rare aggressive malignant tumor. Concurrent chemoradiation (CCRT) with maintenance chemotherapy using taxanes is one of the primary treatments. The aim of the present study was to retrospectively analyze the efficacy of CCRT with maintenance chemotherapy using taxanes in localized angiosarcoma of the scalp without cervical lymph node metastases. A total of 19 patients treated with radiation therapy for localized angiosarcomas of the scalp without cervical lymph node metastases were enrolled. The overall survival (OS), progression-free survival (PFS), and local control (LC) rates were calculated using Kaplan-Meier analysis. Univariate analyses were performed for various potential prognostic factors for OS, PFS, and LC. The median radiation dose was 70 Gy (range, 60-70 Gy), and the fractional dose was 2 Gy. Radiation therapy alone, radiation therapy + interleukin-2, surgery + CCRT with maintenance chemotherapy, CCRT with maintenance chemotherapy, and CCRT without maintenance chemotherapy were administered to 2, 4, 2, 9 and 2 patients, respectively. The 1- and 3-year OS, PFS, and LC rates were 88 and 52%, 47 and 33%, and 74 and 56%, respectively. CCRT with maintenance chemotherapy and surgery were significant prognostic factors for PFS (P=0.036 and 0.025, respectively). Therefore, CCRT with maintenance chemotherapy using taxanes might be effective in treating localized angiosarcomas of the scalp without cervical lymph node metastases.

Interobserver variability of 3.0-tesla and 1.5-tesla magnetic resonance imaging/computed tomography fusion image-based post-implant dosimetry of prostate brachytherapy.

This study aimed to compare the interobserver variabilities in magnetic resonance imaging (MRI)/computed tomography (CT) fusion image-based post-implant dosimetry of permanent prostate brachytherapy (PPB) between 1.5-T and 3.0-T MRI. The study included 60 patients. Of these patients, 30 underwent 1.5-T MRI and CT 30 days after seed implantation (1.5-T group), and 30 underwent 3.0-T MRI and CT 30 days after seed implantation (3.0-T group). All patients received PPB alone. Two radiation oncologists performed MRI/CT fusion image-based post-implant dosimetry, and the interobserver variabilities of dose-volume histogram (DVH) parameters [dose (Gy) received by 90% of the prostate volume (prostate D90)], percentage of the prostate volume receiving at least the full prescribed dose (prostate V100), percentage of the prostate volume receiving at least 150% of the prescribed dose (prostate V150), dose (Gy) received by 5% of the urethral volume (urethral D5) and the urethral volume receiving at least 150% of the prescribed dose (urethral V150)] were retrospectively estimated using the paired Student's t test and Pearson's correlation coefficient. The Pearson's correlation coefficients of all DVH parameters were higher in the 3.0-T group than in the 1.5-T group (1.5-T vs 3.0-T: prostate D90, 0.65 vs 0.93; prostate V100, 0.62 vs 0.82; prostate V150, 0.97 vs 0.98; urethral D5, 0.92 vs 0.93; and urethral V150, 0.88 vs 0.93). In the paired Student's t test, no significant differences were observed in any of the DVH parameters between the two radiation oncologists in the 3.0-T group (0.068 ≤ P ≤ 0.842); however, significant differences were observed in prostate D90 (P = 0.004), prostate V100 (P = 0.011) and prostate V150 (P = 0.002) between the oncologists in the 1.5-T group. The interobserver variability of DVH parameters in the MRI/CT fusion image-based post-implant dosimetry analysis of brachytherapy was lower with 3.0-T MRI than with 1.5-T MRI.

Imaging an intrapulmonary solitary fibrous tumor with CT and F-18 FDG PET/CT.

Intrapulmonary solitary fibrous tumors (SFTs) are extremely rare neoplasms. We report a case of an intrapulmonary SFT and describe the findings of computed tomography (CT) and F-18 fluorodeoxyglucose positron emission tomography. The case indicates that a benign intrapulmonary SFT can present as a ground-glass nodule in the early stages of disease and may appear as a well-defined, lobular, homogeneously enhanced mass with slow growth on chest CT images. To our knowledge, this is the first report describing the natural course of an intrapulmonary SFT over 16 years based on the findings of chest CT and F-18 fluorodeoxyglucose positron emission tomography/CT.

Chemoradiotherapy for locally advanced lung cancer patients with interstitial lung abnormalities.

INTRODUCTION: Although chemoradiotherapy for locally advanced lung cancer has the potential for cure, treatment is avoided in patients with interstitial lung disease because of the risk for severe radiation pneumonitis. Interstitial lung abnormalities (ILA) can be evaluated using high-resolution computed tomography (HRCT) to assess interstitial changes. In this study, we retrospectively examined the feasibility and efficacy of chemoradiotherapy for locally advanced lung cancer patients with ILA. METHODS: Patients who underwent chemoradiotherapy for locally advanced lung cancer at Okayama University Hospital between 2012 and 2015 were reviewed retrospectively. HRCT prior to treatment was evaluated by one pulmonologist and two radiologists using a sequential reading method. RESULTS: Of the 77 patients enrolled in this study, ILA was present in 25 (32.5%) and indeterminate ILA in 24 patients; 28 patients did not have ILA. Desaturation at rest (SpO2 < 95%) and honeycombing on HRCT were not observed in ILA patients. Only one patient with ILA had a low vital capacity (%VC < 80%). Severe radiation pneumonitis (≥Grade 2) occurred in 36.0% of the patients with ILA, but it was controllable; Grade 4 or 5 was not observed. Multivariate analysis showed that >25% of the lung volume receiving >20 Gy was risk factors of severe radiation pneumonitis, but ILA was not. The 2-year survival rates of patients with and without ILA were 56.8% and 74.1%, respectively, but the difference was not significant (P = 0.33). CONCLUSIONS: Chemoradiotherapy was feasible and effective in some patient population with ILA without desaturation, low VC and honeycombing on HRCT.

Dose-Volume Parameters Predict Radiation Pneumonitis after Surgery with Induction Concurrent Chemoradiotherapy for Non-small Cell Lung Cancer.

To clarify the relationship between dose-volume histogram (DVH) parameters and radiation pneumonitis (RP) after surgery in cases of non-small cell lung cancer (NSCLC) treated with induction concurrent chemoradiotherapy (CCRT). Patients with NSCLC treated with induction CCRT (chemotherapy: cisplatin and docetaxel; radiotherapy: 2.0 Gy fractions once daily for a total of 46 Gy) before surgery were reviewed. We calculated the percentage of lung volume receiving at least 20 Gy (V20) and the mean lung dose (MLD) for the total lung volume and the lung remaining after resection. Factors affecting the incidence of RP at grade 2 or higher (≥ G2 RP) were analyzed. Eighteen of 49 patients (37%) experienced ≥G2 RP. The V20 and MLD for the lung remaining after resection (V20r and MLDr) were significant predictors according to the multivariate analysis (p=0.007 and 0.041, respectively). The incidence of ≥G2 RP was 8% in patients with V20r<10%, and 13% in patients with MLDr<5.6 Gy, respectively. The optimal approach to reduce the rate of postoperative RP in patients with induction CCRT for NSCLC is to keep the V20r below 10% and/or the MLDr below 5.6 Gy in the radiotherapy planning.

A rapid caliber change in the inferior vena cava during multiphasic contrast-enhanced computed tomography may signal an acute anaphylactic reaction to nonionic contrast medium.

Severe anaphylactic reactions to an intravenous nonionic iodine contrast medium (NICM) are uncommon but can result in permanent morbidity or death if not managed appropriately. An anaphylactic reaction to an NICM typically manifests as clinical symptoms that include an itchy nose, sneezing, and skin redness. To our knowledge, a rapid change in the caliber of the inferior vena cava (IVC) during multiphasic contrast-enhanced computed tomography (CT) has not been reported. Here, we report the computed tomographic findings in three cases of hypovolemic shock caused by an anaphylactic reaction to an NICM. We suspect that a decrease in caliber of the IVC during multiphasic contrast-enhanced CT may be a predictor of an allergic-like reaction to an NICM. Patients in whom physicians and radiographers detect a rapid caliber change in the IVC during multiphasic contrast-enhanced CT should be managed carefully.

Evaluation of Setup Errors at the Skin Surface Position for Whole Breast Radiotherapy of Breast Cancer Patients.

We used image-processing software to analyze the setup errors at the skin surface position of breast cancer patients (n=66) who underwent post-operative whole breast irradiation at our hospital in 2014-2015. The sixty-six digital reconstructed radiographs (DRR) were created at the treatment planning for each patient. The lineacgraphies (n=377) were taken after the patients' setup during radiotherapy. The lineacgraphies and DRR were superimposed at the skin surface position for each patient with the image-processing software. We measured the deviations of the isocenters for the nipple-lung (X) direction and craniocaudal (Y) direction and the deviation of the rotation angle of the XY axes between the lineacgraphy and DRR on the superimposed images. The systematic error (µ, Σ) and random error (σ) were calculated from the X and Y deviations and rotation angle deviation. The µ of X, Y, and rotation angle were 0.01 mm, -1.2 mm, and 0.05°, respectively. The Σ of X, Y, and rotation angle were 1.8 mm, 1.5 mm, and 0.9°, respectively. The σ of X, Y, and rotation angle were 2.0 mm, 1.5 mm, and 1.0°, respectively. Our analyses thus revealed that evaluations using image-processing software at the skin surface position in routine breast radiotherapy result in sufficiently small setup errors.

The role of dentistry other than oral care in patients undergoing radiotherapy for head and neck cancer.

The usefulness of dental approaches, such as oral management, has gained recognition among patients treated for head and neck cancer. In particular, oral management plays a very important role before, during, and after treatment in patients undergoing radiotherapy, chemotherapy, or a combination of both. However, specialized dentistry knowledge and techniques that are useful for patients undergoing radiotherapy for head and neck cancer have yet to be reported. Therefore, in this review article, our aim is to introduce dental approaches in radiotherapy for patients with head and neck cancer that have been developed and are currently being used at our institute.

Comparison of implant quality between intraoperatively built custom-linked seeds and loose seeds in permanent prostate brachytherapy using sector analysis.

We compared the implant quality of intraoperatively built custom-linked (IBCL) seeds with loose seeds in permanent prostate brachytherapy. Between June 2012 and January 2015, 64 consecutive prostate cancer patients underwent brachytherapy with IBCL seeds (n = 32) or loose seeds (n = 32). All the patients were treated with 144 Gy of brachytherapy alone. Brachytherapy was performed using a dynamic dose calculation technique. Computed tomography/magnetic resonance imaging fusion-based dosimetry was performed 1 month after brachytherapy. Post-implant dose-volume histogram (DVH) parameters, prostate sector dosimetry, operation time, seed migration, and toxicities were compared between the IBCL seed group and the loose seed group. A sector analysis tool was used to divide the prostate into six sectors (anterior and posterior sectors at the base, mid-gland, and apex). V100 (95.3% vs 89.7%; P = 0.014) and D90 (169.7 Gy vs 152.6 Gy; P = 0.013) in the anterior base sector were significantly higher in the IBCL seed group than in the loose seed group. The seed migration rate was significantly lower in the IBCL seed group than in the loose seed group (6% vs 66%; P < 0.001). Operation time per seed was significantly longer in the IBCL seed group than in the loose seed group (1.31 min vs 1.13 min; P = 0.003). Other post-implant DVH parameters and toxicities did not differ significantly between the two groups. Our study showed more dose coverage post-operatively in the anterior base prostate sector and less seed migration in IBCL seed implantation compared with loose seed implantation.

Radiofrequency Ablation of Lung Tumors Using a Multitined Expandable Electrode: Impact of the Electrode Array Diameter on Local Tumor Progression.

PURPOSE: To retrospectively investigate the impact of the electrode array diameter on local tumor progression after lung radiofrequency ablation. MATERIALS AND METHODS: This study included 651 lung tumors treated using multitined expandable electrodes and followed for ≥ 6 months. The mean long-axis tumor diameter was 12 mm ± 7 (range, 2-42 mm). The difference between electrode array diameter and tumor diameter (DAT) was used to investigate the impact of the electrode array diameter. All tumors were classified into 2 groups according to various variables including DAT (≥ 10 mm or < 10 mm). The primary technique efficacy rates were calculated using Kaplan-Meier analysis and compared between the 2 groups of each variable using the log-rank test. In addition, crude and multivariate multilevel survival analyses were performed by sequentially including DAT and the other variables in 5 models. RESULTS: The median DAT for 651 tumors was 12 mm (range, -15 to 24 mm). The technique efficacy rate was significantly lower in the < 10 mm DAT group than in the ≥ 10 mm group (P < .001). In the crude and multivariate multilevel survival analyses, < 10 mm DAT was a significant risk factor for local progression in all models except model 5 (P = .067). In the ≥ 10 mm group, the technique efficacy rates were not significantly different between the 2 ≥ 10 mm DAT subgroups (10 to <15 mm DAT vs ≥ 15 mm DAT). CONCLUSIONS: DAT is an important risk factor for local progression. We recommend an electrode that is ≥ 10 mm larger than the tumor diameter.