Split X-Jaw techniques of volumetric modulated arc radiotherapy in nasopharyngeal cancer: A dosimetric comparison.

PURPOSE: The current study aims to compare the split x-jaw planning technique of volumetric modulated arc radiotherapy (VMAT) with the traditional open and limited jaw techniques of VAMT in nasopharyngeal carcinoma treatment. The multi-leaf collimators on the varian linear accelerator move on a carriage with a maximum leaf span of 15 cm. Therefore, treatment of larger planning target volumes, such as in nasopharyngeal cancer with traditional open and limited jaw technique, yields compromised dose distribution. METHOD: Computed tomography data sets of 10 nasopharynx cancer patients were enrolled for the study. For each case, three separate treatment plans were generated viz. open, limited, and split x-jaw planning techniques with similar planning objectives. Only PTVs requiring a field size larger than 18 cm in the x-jaw position were considered. RESULTS: Comparable results were obtained regarding organs at risk (OAR) sparing in all the techniques. The target dose coverage with split x-jaw VMAT was superior to both open and limited jaw planning techniques, with a statistically significant difference in the intermediate dose planning target volumes (PTVs) (PTV59.4), P < 0.05. However, the split technique's dose to the spinal cord and larynx was significantly lower (P < 0.05). CONCLUSION: The split x-jaw planning technique of VMAT can be adapted for larger PTVs requiring an x-jaw of more than 15 cm. The only concern with this technique is the increased MU.

Role of external radiation in benign tumors: A clinical outcome and safety audit of 7 years from a tertiary care center in India.

PURPOSE: Radiotherapy (RT) is a well-established modality for treating malignancies, but its role in treatment of benign lesions has not been well explored. Herein, we present a retrospective analysis of a 7-year data regarding the benefit and the safety profile of RT for treating benign tumors in our institute. MATERIALS AND METHODS: Data of 23 patients who received RT for benign tumors from January 2015 to April 2022 were retrieved, and a retrospective analysis was conducted. All the pertinent demographic data, treatment and follow-up data were retrieved. The most common presentations were nasopharyngeal angiofibroma, vertebral hemangioma, paraganglioma, and others. The most common sites of occurrence were head and neck (43%) and paravertebral region (22%). Volumetric modulated arc therapy was the most commonly employed RT technique (39%), followed by three-dimensional conformal RT (34%) and two-dimensional conventional radiotherapy (26%). The median RT dose delivered was 36 Gy (range: 20-54 Gy). RESULTS: The median follow-up duration was 53 months (range: 3-120 months). Nine (39%) patients had progressive disease with a median time to progression of 8 months (range: 1-30 months). The median disease-free survival (DFS) was 70 months, while the 1-, 3-, and 5-year DFS rates were 97%, 88%, and 62%, respectively. Four patients (17%) died, all due to disease progression. The 1-, 3-, and 5-year overall survival rates was 97%, 85%, and 50%, respectively. The rate of radiation-induced cancer (RIC) was 0% as none of the patients had developed RIC secondary to radiation. CONCLUSION: RT is a safe and an effective option to manage benign tumors either in an adjuvant setting or in inoperable patients requiring definitive treatment, as well as in a setting to alleviate symptoms, providing excellent survival benefits. However, further prospective studies with much higher sample size are required to establish the absolute benefit and to estimate the risk of RIC, which will further direct for a better utilization of RT in treating benign tumors.

A prospective study on the effect of tumor shrinkage on exit fluence gamma pass rate in high precision radiotherapy and influence of phantom setup error in patient-specific quality assurance.

PURPOSE: Objective parameters for decision on adaptive radiotherapy depend on patient, tumor and treatment related factors. Present study reports geometric uncertainties occurring during high precision radiotherapy, beam fluence analysis and serial exit dose measurement as a patient-specific tool for adaptive radiotherapy. MATERIALS AND METHODS: Serial exit dose fluence of 24 patients (at baseline and mid-treatment) undergoing IMRT/VMAT treatment were measured. Baseline and midtreatment exit dose evaluation was done using gafchromic films in predefined region of interest. Difference of volume of GTV at baseline (from simulation CT scan) and midtreatment CBCT scan was calculated (ΔGTV). RESULTS: Population based systematic errors (mm) were 4.15, 2.26, 0.88 and random errors (mm) were 2.56, 3.69, and 2.03 in mediolateral (ML), craniocaudal (CC) and anteroposterior (AP) directions respectively. Gamma pass rate reduced with incremental shift. For a 5 mm shift, maximum deviation was found in anteroposterior axis (22.16 ± 7.50) and lowest in mediolateral axis (12.85 ± 4.95). On serial measurement of exit dose fluence, tumor shrinkage significantly influenced gamma pass rate. The mean gamma pass rate was significantly different between groups with 50% shrinkage of tumor volume (86.36 vs 96.24, P = 0.008, on multivariate analysis P = 0.026). CONCLUSION: Rapid fall of gamma pass rate was observed for set up error of ≥3 mm. Serial measurement of exit dose fluence by radiochromic film is a feasible method of exit dose comparison in IMRT/VMAT, where EPID dosimetry is not available with linear accelerator configuration. Our study suggests that there is a significant difference between gamma pass rates of baseline and mid treatment exit dose fluence with greater than 50% tumor shrinkage.

Low-dose radiation therapy for COVID-19 pneumonia: Comparison of dosimetry and life-time attributable risk of cancer with conventional AP-PA fields and bone marrow sparing VMAT.

PURPOSE: Low-dose radiation therapy (LDRT) to lungs did show encouraging results in COVID-19 patients in some clinical trials. However, there has been some concern regarding the long-term risk of radiation-induced cancer (RIC). Compared to the conventional AP-PA field technique, volumetric modulated arc therapy (VMAT) can potentially reduce the dose to the marrow and other organs at risk (OARs) and thus minimize the risk of cancer. We designed a dosimetry study to study if VMAT can reduce the exposure to the marrow and other OAR doses and curtail the estimated life-time attributable risk (LAR) of cancer. METHODS AND MATERIALS: We retrieved the computed tomography scan data of 10 patients (aged 40-60 years, median 48 years) who have been already treated for any malignancy in the region of the thorax. A dose of 1.0 Gy in single fraction was prescribed to both lungs. All the organs were delineated as per the established guidelines. The dosimetry achieved by the two plans was compared to find the difference. Mean OAR doses were used to estimate the LAR for both plans and compared. RESULTS: Planning target volume coverage parameters like conformity index and homogeneity index were significantly better with VMAT (P value < 0.05 for all). The mean dose to most OARs was significantly lower with VMAT (P value < 0.05 for all). The mean dose to the marrow was significantly lower with VMAT (59.05 vs 81.9 cGy with P value < 0.05). The overall LAR was significantly lower with VMAT as compared to the conventional plan (0.357% vs 0.398%, P value < 0.05). CONCLUSION: Compared to the conventional technique, VMAT provides better OAR dosimetry for lung irradiation (a prescription dose of 1.0 Gy or more) in COVID-19 pneumonia. VMAT significantly reduces the risk of RIC. We therefore suggest if lung LDRT is used for COVID-19 patients, VMAT is the preferred technique for a prescription dose of ≥1.0 Gy.

Survival outcomes and failure patterns for oropharyngeal cancers treated with simultaneous integrated boost in intensity modulated radiotherapy (SIB-IMRT) and concurrent chemotherapy.

BACKGROUND: Intensity modulated radiotherapy (IMRT) has become a standard radiotherapy treatment delivery option owing to the advantages it offers in terms of target coverage and organ sparing. Furthermore, the ability to introduce different fractionation for different targets lets us deliver higher doses to the high-risk areas and lower doses to the elective volumes at the same sitting, referred to as simultaneous integrated boost (SIB). In the current study, we intended to retrospectively analyze the clinical outcomes and patterns of the failure of oropharyngeal cancers treated with SIB-IMRT and concurrent chemotherapy at our centre and analyze the factors contributing to poorer outcomes. MATERIAL AND METHODS: Data of oropharyngeal cancer patients treated with SIB-IMRT and concurrent chemotherapy were retrieved from the institutional database. Patient demographic details, histopathological features, staging, treatment details, failure patterns and outcomes were documented. All potential factors were evaluated for outcomes. Radiation was delivered by using the SIB-IMRT technique. High-risk planning target volume (PTV) received 66 Gy in 2.2 Gy/fraction, intermediate and low-risk PTV received 60 Gy and 54 Gy, respectively. Primary endpoint was to assess local control (LC), regional control (RC) and loco-regional control (LRC) rates and secondary end point was to evaluate the survival outcomes - overall survival (OS) and cancer-specific mortality. All survival analyzes were performed using the Kaplan-Meier method. RESULTS: A total of 169 cases were included in the final analysis. The median age was 55 years (range 20-78) with 95.3% males. The base of tongue was the most common primary site. Around 54% cases were node negative with 38% patients having stage IV disease. The local control rates for N0 vs. N+ cases were 74.1 vs. 62.3% (P = 0.046), respectively. Similarly, the 4-year RC rates for N0 vs. N+ cases were 94.4 vs. 83.5% (P = 0.024), respectively. On multivariate analysis, only 4-year RC rates showed significant difference between the two (P = 0.039). No differences were found between T stages in LRC and OS. The 4-year LRC rates for stages 1, 2 vs. 3, 4 were non-significant (69.2 vs. 66.3%; P = 0.178). The 4-year OS rate was 81.3%. The 4-year LC and LRC rates were 67.8 and 89.5%, respectively. There were 54 local and 17 regional failures. The median time to failure was 13 months (range 3.6-82.9). CONCLUSION: SIB-IMRT provides comparable outcomes for oropharyngeal cancers. OS and loco-regional recurrences were significantly worse for nodal positive disease.

[Ectopic Injection of Hydrogel Spacer in IMRT for Prostate Cancer-A Case Study].

A hydrogel spacer injection between the prostate and rectum is reported to reduce the risk of rectal toxicity in radiotherapy for prostate cancer. We present a case of an ectopic injection of hydrogel spacer. The patient was a 77-year-old male with intermediate-risk prostate cancer. It was planned that he would receive intensity modulated radiation therapy(IMRT), and a hydrogel spacer was inserted. Three days after insertion, the patient had a fever of 38.6℃ and presented frequent urination and perineal pain. Swelling and heat sensation were observed in the perineum. CRP was 12.00 mg/dL and the white blood cell count was as high as 9,300/µL. T2-weighted images showed a 5.3×1.9 cm high-intensity area around the lower urethra. Ectopic injection of hydrogel spacer and concomitant infection were diagnosed. Upon administering antibiotic treatment, his symptoms and inflammation improved immediately. Four months after hydrogel spacer insertion, T2-weighted images showed a high-intensity area in the lower urethra and around the ischial bone, which was attributed to the remaining hydrogel spacer. The hydrogel spacer and his symptoms completely disappeared at 9 months after hydrogel spacer insertion.

[Photon field junction for external beam radiotherapy of breast cancer involving axillary and supraclavicular lymph nodes]. / Koplanáris fotonmezok illesztése axilláris, illetve szupraklavikuláris nyirokcsomók régióját érinto emlodaganatok külso besugárzásánál.

We present evaluation of junction of coplanar external beam photon fields and its portal dosimetric analysis for breast cancer with positive lymph nodes. In our work, we compared twelve patients affected by breast cancer with axillary and supraclavicular lymph nodes, using conformal external beam plans from a dosimetric point of view. 3-3 plans were prepared per patient. Three methods were used for the conformal technique to investigate the potential of lymph nodes treatment field's collimations. During the evaluation of the portal dosimetry images, it was concluded that the junction plane at isocenter appeared as a discrete coldline, when fitted the regional field with or without collimation manually and by the software. However, the coverage of the isocenter plane is strongly influenced by the linear accelerator and the fitted field edges. Based on our results, in order to avoid uncertainties arising from field junctions and the overdosed areas of the target volume, it is more appropriate to choose another advanced irradiation technique such as intensity-modulated radiation therapy.

Whole-brain radiation therapy plus simultaneous integrated boost for brain metastases from breast cancers.

Background: The effect of whole-brain radiation therapy (WBRT) plus simultaneous integrated boost (SIB) in brain metastasis from breast cancers has not been demonstrated. Method: In this single-center retrospective study, we reviewed consecutive breast cancer patients who developed brain metastasis and were treated with hypofractionated radiation therapy plus WBRT using intensity-modulated radiation therapy (IMRT)-SIB approaches. We analyzed clinical outcomes, prognostic factors and patterns of treatment failure. Result: A total of 27 patients were eligible for analysis. Four (14.8%) patients achieved clinical complete response and 14 (51.9%) had partial response of brain lesions. The other nine patients were not evaluated for brain tumor response. The median brain progression-free survival was 8.60 (95% CI [6.43-13.33]) months and the median overall survival was 16.8 (95% CI [13.3-27.7]) months. Three patients had in-field failure, five had out-field failure and two had in-field and out-field failure. Conclusion: WBRT plus SIB led to improved tumor control and clinical outcome in breast cancer patients with brain metastasis.

Clinical application of a GPU-accelerated monte carlo dose verification for cyberknife M6 with Iris collimator.

PURPOSE: To apply an independent GPU-accelerated Monte Carlo (MC) dose verification for CyberKnife M6 with Iris collimator and evaluate the dose calculation accuracy of RayTracing (TPS-RT) algorithm and Monte Carlo (TPS-MC) algorithm in the Precision treatment planning system (TPS). METHODS: GPU-accelerated MC algorithm (ArcherQA-CK) was integrated into a commercial dose verification system, ArcherQA, to implement the patient-specific quality assurance in the CyberKnife M6 system. 30 clinical cases (10 cases in head, and 10 cases in chest, and 10 cases in abdomen) were collected in this study. For each case, three different dose calculation methods (TPS-MC, TPS-RT and ArcherQA-CK) were implemented based on the same treatment plan and compared with each other. For evaluation, the 3D global gamma analysis and dose parameters of the target volume and organs at risk (OARs) were analyzed comparatively. RESULTS: For gamma pass rates at the criterion of 2%/2 mm, the results were over 98.0% for TPS-MC vs.TPS-RT, TPS-MC vs. ArcherQA-CK and TPS-RT vs. ArcherQA-CK in head cases, 84.9% for TPS-MC vs.TPS-RT, 98.0% for TPS-MC vs. ArcherQA-CK and 83.3% for TPS-RT vs. ArcherQA-CK in chest cases, 98.2% for TPS-MC vs.TPS-RT, 99.4% for TPS-MC vs. ArcherQA-CK and 94.5% for TPS-RT vs. ArcherQA-CK in abdomen cases. For dose parameters of planning target volume (PTV) in chest cases, the deviations of TPS-RT vs. TPS-MC and ArcherQA-CK vs. TPS-MC had significant difference (P < 0.01), and the deviations of TPS-RT vs. TPS-MC and TPS-RT vs. ArcherQA-CK were similar (P > 0.05). ArcherQA-CK had less calculation time compared with TPS-MC (1.66 min vs. 65.11 min). CONCLUSIONS: Our proposed MC dose engine (ArcherQA-CK) has a high degree of consistency with the Precision TPS-MC algorithm, which can quickly identify the calculation errors of TPS-RT algorithm for some chest cases. ArcherQA-CK can provide accurate patient-specific quality assurance in clinical practice.

Localized fine-tuning and clinical evaluation of deep-learning based auto-segmentation (DLAS) model for clinical target volume (CTV) and organs-at-risk (OAR) in rectal cancer radiotherapy.

BACKGROUND AND PURPOSE: Various deep learning auto-segmentation (DLAS) models have been proposed, some of which have been commercialized. However, the issue of performance degradation is notable when pretrained models are deployed in the clinic. This study aims to enhance precision of a popular commercial DLAS product in rectal cancer radiotherapy by localized fine-tuning, addressing challenges in practicality and generalizability in real-world clinical settings. MATERIALS AND METHODS: A total of 120 Stage II/III mid-low rectal cancer patients were retrospectively enrolled and divided into three datasets: training (n = 60), external validation (ExVal, n = 30), and generalizability evaluation (GenEva, n = 30) datasets respectively. The patients in the training and ExVal dataset were acquired on the same CT simulator, while those in GenEva were on a different CT simulator. The commercial DLAS software was first localized fine-tuned (LFT) for clinical target volume (CTV) and organs-at-risk (OAR) using the training data, and then validated on ExVal and GenEva respectively. Performance evaluation involved comparing the LFT model with the vendor-provided pretrained model (VPM) against ground truth contours, using metrics like Dice similarity coefficient (DSC), 95th Hausdorff distance (95HD), sensitivity and specificity. RESULTS: LFT significantly improved CTV delineation accuracy (p < 0.05) with LFT outperforming VPM in target volume, DSC, 95HD and specificity. Both models exhibited adequate accuracy for bladder and femoral heads, and LFT demonstrated significant enhancement in segmenting the more complex small intestine. We did not identify performance degradation when LFT and VPM models were applied in the GenEva dataset. CONCLUSIONS: The necessity and potential benefits of LFT DLAS towards institution-specific model adaption is underscored. The commercial DLAS software exhibits superior accuracy once localized fine-tuned, and is highly robust to imaging equipment changes.

The impact of baseline health factors on second primary cancer risk after radiotherapy for prostate cancer.

PURPOSE: In evaluating second primary cancers (SPCs) following External Beam Radiotherapy (EBRT), the role of lifestyle factors is frequently not considered due to data limitations. We investigated the association between smoking, comorbidities, and SPC risks within EBRT-treated patients for localized prostate cancer (PCa). PATIENTS & METHODS: The study included 1,883 PCa survivors aged 50-79, treated between 2006 and 2013, with intensity-modulated radiotherapy (IMRT) or three-dimensional conformal radiotherapy (3D-CRT). Clinical data were combined with SPC and survival data from the Netherlands Cancer Registry with a 12-month latency period. Standardized Incidence Ratios (SIRs) were calculated comparing the EBRT cohort with the general Dutch population. To explore the effect of patient and treatment characteristics on SPCs we conducted a Cox regression analysis. Lastly, we estimated cumulative incidences of developing solid SPC, pelvis SPC, and non-pelvis SPC using a competing risk analysis. RESULTS: Significantly increased SIRs were observed for all SPC (SIR = 1.21, 95% confidence interval [CI]: 1.08-1.34), pelvis SPC (SIR = 1.46, 95% CI: 1.18-1.78), and non-pelvis SPC (SIR = 1.18, 95% CI [1.04-1.34]). Smoking status was significantly associated with pelvic and non-pelvic SPCs. Charlson comorbidity index (CCI) ≥ 1 (Hazard Ratio [HR] = 1.45, 95% CI: 1.10-1.91), cardiovascular disease (HR = 1.41, 95% CI: 1.05-1.88), and chronic obstructive pulmonary disease (COPD) (HR = 1.91, 95% CI: 1.30-2.79) were significantly associated with non-pelvis SPC. The proportion of active smoking numbers in the cohort was similar to the general population. INTERPRETATION: We conclude that the presence of comorbidities in the EBRT population might be a relevant factor in observed excess non-pelvis SPC risk, but not for excess pelvis SPC risk.

Adaptive radiotherapy for muscle invasive bladder cancer: a retrospective audit of two bladder filling protocols.

BACKGROUND: Radical radiotherapy for muscle-invasive bladder cancer (MIBC) is challenging due to large variations in bladder shape, size and volume during treatment, with drinking protocols often employed to mitigate geometric uncertainties. Utilising adaptive radiotherapy together with CBCT imaging to select a treatment plan that best fits the bladder target and reduce normal tissue irradiation is an attractive option to compensate for anatomical changes. The aim of this retrospective study was to compare a bladder empty (BE) protocol to a bladder filling (BF) protocol with regards to variations in target volumes, plan of the day (PoD) selection and plan dosimetry throughout treatment. METHODS: Forty patients were included in the study; twenty were treated with a BE protocol and twenty with a BF protocol to a total prescribed dose of 55 Gy in 20 fractions. Small, medium and large bladder plans were generated using three different CTV to PTV margins. Bladder (CTV) volumes were delineated on planning CTs and online pre-treatment CBCTs. Differences in CTV volumes throughout treatment, plan selection, PTV volumes and resulting dose metrics were compared for both protocols. RESULTS: Mean bladder volume differed significantly on both the planning CTs and online pre-treatment CBCTs between the protocols (p < 0.05). Significant differences in bladder volumes were observed between the planning CT and pre-treatment CBCTs for BF (p < 0.05) but not for BE (p = 0.11). Both protocols saw a significant decrease in bladder volume between first and final treatment fractions (p < 0.05). Medium plans were preferentially selected for BE whilst when using the BF protocol the small plan was chosen most frequently. With no significant change to PTV coverage between the protocols, the volume of body receiving 25.0-45.8 Gy was found to be significantly smaller for BE patients (p < 0.05). CONCLUSIONS: This work provides evidence in favour of a BE protocol compared to a BF protocol for radical radiotherapy for MIBC. The smaller treatment volumes observed in the BE protocol led to reduced OAR and total body doses and were also observed to be more consistent throughout the treatment course. These results highlight improvements in dosimetry for patients who undergo a BE protocol for MIBC.

Development and validation of an automated Tomotherapy planning method for cervical cancer.

PURPOSE: This study aimed to develop an automated Tomotherapy (TOMO) planning method for cervical cancer treatment, and to validate its feasibility and effectiveness. MATERIALS AND METHODS: The study enrolled 30 cervical cancer patients treated with TOMO at our center. Utilizing scripting and Python environment within the RayStation (RaySearch Labs, Sweden) treatment planning system (TPS), we developed automated planning methods for TOMO and volumetric modulated arc therapy (VMAT) techniques. The clinical manual TOMO (M-TOMO) plans for the 30 patients were re-optimized using automated planning scripts for both TOMO and VMAT, creating automated TOMO (A-TOMO) and automated VMAT (A-VMAT) plans. We compared A-TOMO with M-TOMO and A-VMAT plans. The primary evaluated relevant dosimetric parameters and treatment plan efficiency were assessed using the two-sided Wilcoxon signed-rank test for statistical analysis, with a P-value < 0.05 indicating statistical significance. RESULTS: A-TOMO plans maintained similar target dose uniformity compared to M-TOMO plans, with improvements in target conformity and faster dose drop-off outside the target, and demonstrated significant statistical differences (P+ < 0.01). A-TOMO plans also significantly outperformed M-TOMO plans in reducing V50Gy, V40Gy and Dmean for the bladder and rectum, as well as Dmean for the bowel bag, femoral heads, and kidneys (all P+ < 0.05). Additionally, A-TOMO plans demonstrated better consistency in plan quality. Furthermore, the quality of A-TOMO plans was comparable to or superior than A-VMAT plans. In terms of efficiency, A-TOMO significantly reduced the time required for treatment planning to approximately 20 min. CONCLUSION: We have successfully developed an A-TOMO planning method for cervical cancer. Compared to M-TOMO plans, A-TOMO plans improved target conformity and reduced radiation dose to OARs. Additionally, the quality of A-TOMO plans was on par with or surpasses that of A-VMAT plans. The A-TOMO planning method significantly improved the efficiency of treatment planning.

Dosimetric evaluation of intensity modulated photon versus proton reirradiation of head and neck cancer.

BACKGROUND: Reirradiation of head and neck cancer (HNC) became more accessible in the last decade, owing to modern irradiation techniques which offer a reduction in treatment related toxicities. The aim of this paper was to comparatively evaluate the dosimetric aspects derived from intensity modulated photon vs. proton treatment planning in reirradiated HNC patients. METHODS: Six recurrent HNC patients were enrolled in this retrospective study. For each patient two treatment plans were created: one IMRT/VMAT and one IMPT plan. The prescribed dose for the second irradiation was between 50 and 70 Gy RBE. The study comparatively analyzed the CTV coverage, doses to organs at risk (OARs) and low doses received by the healthy tissue (other than OAR). RESULTS: Similar CTV coverage was achieved for photon vs proton plans, with the latter presenting better homogeneity in four cases. Maximum dose to CTV was generally higher for photon plans, with differences ranging from 0.3 to 1.9%. For parotid glands and body, the mean dose was lower for proton plans. A notable reduction of low dose to healthy tissue (other than OARs) could be achieved with protons, with an average of 60% and 64% for D10% and Dmean, respectively. CONCLUSION: The dosimetric comparison between photon and proton reirradiation of HNC showed a great need for treatment individualization, concluding that protons should be considered for reirradiation on an individual basis.

Is Prophylactic Radiotherapy to the Lymphatic Drainage Area Necessary for Patients With Stage III Ovarian Cancer After Chemotherapy Following Surgery?

BACKGROUND: For patients with stage III epithelial ovarian cancer, there are limited studies on the effects of postoperative adjuvant radiotherapy (RT). Here we assessed the therapeutic efficacy and toxicity of postoperative radiotherapy to the abdominal and pelvic lymphatic drainage area for stage III epithelial ovarian cancer patients, who had all received surgery and chemotherapy (CT). METHODS: We retrospectively collected patients with stage III epithelial ovarian cancer after cytoreductive surgery (CRS) and full-course adjuvant CT. The chemoradiotherapy (CRT) group patients were treated with intensity modulated radiotherapy (IMRT) to the abdominal and pelvic lymphatic drainage area in our hospital between 2010 and 2020. A propensity score matching analysis was conducted to compare the results between the CRT and CT groups. Kaplan-Meier analysis estimated overall survival (OS), disease-free survival (DFS), and local control (LC) rates. The log-rank test determined the significance of prognostic factors. RESULTS: A total of 132 patients with median follow-up of 73.9 months (9.1-137.7 months) were included (44 and 88 for the CRT and RT groups, retrospectively). The baseline characteristics of age, histology, level of CA12-5, surgical staging, residual tumour, courses of adjuvant CT, and courses to reduce CA12-5 to normal were all balanced. The median DFS time, 5-year OS, and local recurrence free survival (LRFS) were 100.0 months vs 25.9 months (P = .020), 69.2% vs 49.9% (P = .002), and 85.9% vs 50.5% (P = .020), respectively. The CRT group mainly presented with acute haematological toxicities, with no statistically significant difference compared with grade III intestinal adverse effects (3/44 vs 6/88, P = .480). CONCLUSION: This report demonstrates that long-term DFS could be achieved in stage III epithelial ovarian cancer patients treated with IMRT preventive radiation to the abdominal and pelvic lymphatic area. Compared with the CT group, DFS and OS were significantly prolonged and adverse effects were acceptable.

Gastroscopic observation and dose-volume histogram parameter study on gastrointestinal mucous injury for pancreatic cancer treated with TOMO.

To explore the relationships between gastrointestinal radiation injuries of pancreatic cancer patients treated with TOMO and dose-volume histogram parameters prospectively. Seventy patients with pancreatic cancer who underwent TOMO were enrolled in this prospective study from February 2015 to May 2020. The clinical and dose-volume histogram parameters of the patients were collected. The optimal dose parameters for gastrointestinal radiation ulcers were confirmed based on the receiver operating characteristic curve (ROC) and the area below the ROC curve. Acute gastrointestinal tract toxic and side effect and injury grading correlation analyzed by Kruskal-Wallis rank sum test. Gastrointestinal injury often occurs during radiotherapy for pancreatic cancer, as observed using gastroscopy. The main adverse reactions were radioactive gastrointestinal inflammation (58.5%), radioactive gastrointestinal ulcers (41.4%), active bleeding (10%), newly-developed gastric retention (8.6%), and gastric varices (5.7%). As for the stomach, Dmean and V10 were related to radiation ulcer injury. ROC curve indicated that for stomach a Dmean of 13.39 Gy (area under ROC curves = 0.74, P = .048) and a V10 of 72.21% (area = 0.74, P = .048) was the tolerated dose for the injury of stomach radiation ulcer. As for duodenum, aV20 and aV25 are related to radiation ulcer injury. ROC curve indicated that aV20 of 22.82 cm3 (area = 0.68, P = .025) and aV25 of 32.04 cm3 (area = 0.66, P < .047) was the tolerated dose for the injury of duodenum radiation ulcer. The acute gastrointestinal tract toxic and side effects have no significant correlation with injury grading under gastroscope. Dmean > 13.39 Gy and V10 > 72.21% were the key dosimetric indices for predicting radiation-induced gastric ulcer, and aV20 > 22.82 cm3 and aV25 > 32.04 cm3 were for duodenal. Gastrointestinal reactions cannot be used as an overall basis for the diagnosis of gastrointestinal injury, and gastroscopy is recommended as a review item after radiotherapy.

Dosimetric analysis of six whole-breast irradiation techniques in supine and prone positions.

In breast cancer radiation therapy, minimizing radiation-related risks and toxicity is vital for improving life expectancy. Tailoring radiotherapy techniques and treatment positions can reduce radiation doses to normal organs and mitigate treatment-related toxicity. This study entailed a dosimetric comparison of six different external beam whole-breast irradiation techniques in both supine and prone positions. We selected fourteen breast cancer patients, generating six treatment plans in both positions per patient. We assessed target coverage and organs at risk (OAR) doses to evaluate the impact of treatment techniques and positions. Excess absolute risk was calculated to estimate potential secondary cancer risk in the contralateral breast, ipsilateral lung, and contralateral lung. Additionally, we analyzed the distance between the target volume and OARs (heart and ipsilateral lung) while considering the treatment position. The results indicate that prone positioning lowers lung exposure in X-ray radiotherapy. However, particle beam therapies (PBTs) significantly reduce the dose to the heart and ipsilateral lung regardless of the patient's position. Notably, negligible differences were observed between arc-delivery and static-delivery PBTs in terms of target conformity and OAR sparing. This study provides critical dosimetric evidence to facilitate informed decision-making regarding treatment techniques and positions.

The safety and efficacy of volumetric modulated Arc therapy combined with computer tomography-guided adaptive brachytherapy for locally advanced cervical cancer: a single institution experience.

BACKGROUND: Volumetric modulated arc therapy (VMAT) is a novel form of IMRT, which can deliver more accurate dose distribution and shorten treatment time. Compared to MRI-guided adaptive brachytherapy, which is recommended as gold standard imaging for cervical cancer contours, CT-guided adaptive brachytherapy (CTGAB) is more available, more widespread, and more affordable in many centers. This study aims to retrospectively analyze the efficacy and the safety of VMAT combined with CTGAB for patients with locally advanced cervical cancer. METHODS AND MATERIALS: This study retrospectively analyzed 102 patients with locally advanced cervical cancer who underwent VMAT and CTGAB. Clinical outcomes including local control (LC), overall survival (OS) and progression-free survival (PFS), tumor response to treatment evaluated by the Response Evaluation Criteria in Solid Tumors (RECIST) (version 1.1), and toxicities including gastrointestinal toxicity, urinary toxicity and hematologic toxicity evaluated by the Common Terminology Criteria for Adverse Events (CTCAE) (version 5.0) were analyzed. The Kaplan-Meier method was used to calculate LC, OS, and PFS. RESULTS: Median follow-up time was 19 months. Complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD) occurred in 68 (66.7%), 24 (23.5%), 4 (3.92%), and 6 (5.88%), respectively. The 2-year and 3-year OS were 89.6% and 83%, respectively. The 2-year and 3-year PFS were 84.2% and 74.3%, respectively. The 2-year and 3-year LC were 90.1% and 79.3%, respectively. The average cumulative D2cm3 in the rectum, the bladder, the colon, and the small intestine were 78.07 (SD: 0.46) Gy, 93.20 (SD: 0.63) Gy, 63.55 (SD: 1.03) Gy and 61.07 (SD: 0.75) Gy, respectively. The average cumulative D90% of the high-risk clinical target volume (HR-CTV) was 92.26 (SD: 0.35) Gy. Grade ≥ 3 gastrointestinal and urinary toxicities occurred in 4.9% and 0.98%, respectively. 1.96% of patients were observed grade ≥ 4 gastrointestinal toxicities and none of the patients observed grade ≥ 4 urinary toxicities. CONCLUSION: VMAT combined with CTGAB for locally advanced cervical cancer was an effective and safe treatment method, which showed satisfactory LC, OS, PFS, and acceptable toxicities.

Enhancing the Contouring Efficiency for Head and Neck Cancer Radiotherapy Using Atlas-based Auto-segmentation and Scripting.

BACKGROUND/AIM: Intensity-modulated radiation therapy can deliver a highly conformal dose to a target while minimizing the dose to the organs at risk (OARs). Delineating the contours of OARs is time-consuming, and various automatic contouring software programs have been employed to reduce the delineation time. However, some software operations are manual, and further reduction in time is possible. This study aimed to automate running atlas-based auto-segmentation (ABAS) and software operations using a scripting function, thereby reducing work time. MATERIALS AND METHODS: Dice coefficient and Hausdorff distance were used to determine geometric accuracy. The manual delineation, automatic delineation, and modification times were measured. While modifying the contours, the degree of subjective correction was rated on a four-point scale. RESULTS: The model exhibited generally good geometric accuracy. However, some OARs, such as the chiasm, optic nerve, retina, lens, and brain require improvement. The average contour delineation time was reduced from 57 to 29 min (p<0.05). The subjective revision degree results indicated that all OARs required minor modifications; only the submandibular gland, thyroid, and esophagus were rated as modified from scratch. CONCLUSION: The ABAS model and scripted automation in head and neck cancer reduced the work time and software operations. The time can be further reduced by improving contour accuracy.

Intrafractional motion and dosimetric analysis in prostate stereotactic body radiation therapy with auto beam hold technique.

Objective: To summarize our institutional prostate stereotactic body radiation therapy (SBRT) experience using auto beam hold (ABH) technique for intrafractional prostate motion and assess ABH tolerance of 10-millimeter (mm) diameter.Approach: Thirty-two patients (160 fractions) treated using ABH technique between 01/2018 and 03/2021 were analyzed. During treatment, kV images were acquired every 20-degree gantry rotation to visualize 3-4 gold fiducials within prostate to track target motion. If the fiducial center fell outside the tolerance circle (diameter = 10 mm), beam was automatically turned off for reimaging and repositioning. Number of beam holds and couch translational movement magnitudes were recorded. Dosimetric differences from intrafractional motion were calculated by shifting planned isocenter.Main Results: Couch movement magnitude (mean ± SD) in vertical, longitudinal and lateral directions were -0.7 ± 2.5, 1.4 ± 2.9 and -0.1 ± 0.9 mm, respectively. For most fractions (77.5%), no correction was necessary. Number of fractions requiring one, two, or three corrections were 15.6%, 5.6% and 1.3%, respectively. Of the 49 corrections, couch shifts greater than 3 mm were seen primarily in the vertical (31%) and longitudinal (39%) directions; corresponding couch shifts greater than 5 mm occurred in 2% and 6% of cases. Dosimetrically, 100% coverage decreased less than 2% for clinical target volume (CTV) (-1 ± 2%) and less than 10% for PTV (-10 ± 6%). Dose to bladder, bowel and urethra tended to increase (Bladder: ΔD10%:184 ± 466 cGy, ΔD40%:139 ± 241 cGy, Bowel: ΔD1 cm3:54 ± 129 cGy; ΔD5 cm3:44 ± 116 cGy, Urethra: ΔD0.03 cm3:1 ± 1%). Doses to the rectum tended to decrease (Rectum: ΔD1 cm3:-206 ± 564 cGy, ΔD10%:-97 ± 426 cGy; ΔD20%:-50 ± 251 cGy).Significance: With the transition from conventionally fractionated intensity modulated radiation therapy to SBRT for localized prostate cancer treatment, it is imperative to ensure that dose delivery is spatially accurate for appropriate coverage to target volumes and limiting dose to surrounding organs. Intrafractional motion monitoring can be achieved using triggered imaging to image fiducial markers and ABH to allow for reimaging and repositioning for excessive motion.