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BACKGROUND: The inherent problems in the existence of electron equilibrium and steep dose fall-off pose difficulties for small- and narrow-field dosimetry. OBJECTIVE: To investigate the cutout factors for keloid electron radiotherapy using various dosimetry detectors for small and narrow fields. METHOD: The measurements were performed in a solid water phantom with nine different cutout shapes. Five dosimetry detectors were used in the study: pinpoint 3D ionization chamber, Farmer chamber, semiflex chamber, Classic Markus parallel plate chamber, and EBT3 film. RESULTS: The results demonstrated good agreement between the semiflex and pinpoint chambers. Furthermore, there was no difference between the Farmer and pinpoint chambers for large cutouts. For the EBT3 film, half of the cases had differences greater than 1%, and the maximum discrepancy compared with the reference chamber was greater than 2% for the narrow field. CONCLUSION: The parallel plate, semiflex chamber and EBT3 film are suitable dosimeters that are comparable with pinpoint 3D chambers in small and narrow electron fields. Notably, a semiflex chamber could be an alternative option to a pinpoint 3D chamber for cutout widths≥3 cm. It is very important to perform patient-specific cutout factor calibration with an appropriate dosimeter for keloid radiotherapy. [ABSTRACT FROM AUTHOR]

Objective: The incidence of radiation pneumonitis (RP) has a highly linear relationship with low‐dose lung volume. We previously established a volume‐based algorithm (VBA) method to improve low‐dose lung volume in radiotherapy (RT). This study assessed lung inflammatory changes by integrating fluorine‐18‐fluorodeoxyglucose positron emission tomography/computed tomography (18F‐FDG PET/CT) with VBA for esophageal cancer patients undergoing arc‐based RT. Methods: Thirty esophageal cancer patients received 18F‐FDG PET/CT imaging pre‐RT and post‐RT were included in a retrospective pilot study. We fused lung doses and parameters of PET/CT in RT planning. Based on VBA, we used the 5Gy isodose curve to define high‐dose (HD) and low‐dose (LD) regions in the lung volume. We divided patients into non‐RP (nRP) and RP groups. The maximum, mean standardized uptake value (SUVmax, SUVmean), global lung glycolysis (GLG), mean lung dose (MLD) and V5–30 in lungs were analyzed. Area under the curve values were utilized to identify optimal cut‐off values for RP. Results: Eleven patients in the nRP group and 19 patients in the RP group were identified. In 30 RP lungs, post‐RT SUVmax, SUVmean and GLG of HD regions showed significant increases compared to values for pre‐RT lungs. There were no significant differences in values of 22 nRP lungs. Post‐RT SUVmax and SUVmean of HD regions, MLD, and lung V5 and V10 in RP lungs were significantly higher than in nRP lungs. For detecting RP, the optimal cut‐off values were post‐RT SUVmax > 2.28 and lung V5 > 47.14%. Conclusion: This study successfully integrated 18F‐FDG PET/CT with VBA to assess RP in esophageal cancer patients undergoing RT. Post‐RT SUVmax > 2.28 and lung V5 > 47.14% might be potential indicators of RP. [ABSTRACT FROM AUTHOR]

Abstract Background To compare the differences in dose-volume data among coplanar intensity modulated radiotherapy (IMRT), noncoplanar IMRT, and helical tomotherapy (HT) among patients with hepatocellular carcinoma (HCC) and portal vein thrombosis (PVT). Methods Nine patients with unresectable HCC and PVT underwent step and shoot coplanar IMRT with intent to deliver 46 - 54 Gy to the tumor and portal vein. The volume of liver received 30Gy was set to keep less than 30% of whole normal liver (V30 < 30%). The mean dose to at least one side of kidney was kept below 23 Gy, and 50 Gy as for stomach. The maximum dose was kept below 47 Gy for spinal cord. Several parameters including mean hepatic dose, percent volume of normal liver with radiation dose at X Gy (Vx), uniformity index, conformal index, and doses to organs at risk were evaluated from the dose-volume histogram. Results HT provided better uniformity for the planning-target volume dose coverage than both IMRT techniques. The noncoplanar IMRT technique reduces the V10 to normal liver with a statistically significant level as compared to HT. The constraints for the liver in the V30 for coplanar IMRT vs. noncoplanar IMRT vs. HT could be reconsidered as 21% vs. 17% vs. 17%, respectively. When delivering 50 Gy and 60-66 Gy to the tumor bed, the constraints of mean dose to the normal liver could be less than 20 Gy and 25 Gy, respectively. Conclusion Noncoplanar IMRT and HT are potential techniques of radiation therapy for HCC patients with PVT. Constraints for the liver in IMRT and HT could be stricter than for 3DCRT.

Background: We compared the outcome of patients who received non-image-guided intensity-modulated radiotherapy (IMRT) with those who received helical tomotherapy (HT), a daily image-guided radiotherapy (IGRT), after surgery for oral cavity cancer (OCC).Methods: During the period November 2006 to December 2013, a total of 152 postoperative OCC patients underwent either IMRT (n = 79) or daily IGRT (n = 73) 4 to 6 weeks after surgery. Patients in the IMRT group received 6 MV photon beams to 7 fields and those in the IGRT group received daily fractions of 1.8 or 2 Gy on five consecutive days.Results: Patients who received daily IGRT had higher 5-year overall survival than those who received IMRT (87% versus 48%, p = 0.015). The local progression-free survival rate was also higher in patients who received IGRT (85% versus 58%, p = 0.006). More patients in the IGRT group completed the package of overall treatment time in ≤ 13 weeks and completed their course of radiation therapy in ≤ 8 weeks than patients in the IMRT group (89% versus 68%, p = 0.002; 84% versus 58%, p = 0.001), respectively. The rate of local failure in the primary tumor area was 24.0 % in the IMRT group and 6.8% in the IGRT group. Among patients with primary local failure, the marginal failure rate was 52.6% in the IMRT group and 0 % in the IGRT group.Conclusions: For patients with locally advanced OCC, postoperative IGRT results in better overall survival, better local progression-free survival, less marginal failure and shorter overall treatment time than postoperative non-image-guided IMRT. [ABSTRACT FROM AUTHOR]

Objective: The incidence of radiation pneumonitis (RP) has a highly linear relationship with low-dose lung volume. We previously established a volume-based algorithm (VBA) method to improve low-dose lung volume in radiotherapy (RT). This study assessed lung inflammatory changes by integrating fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT) with VBA for esophageal cancer patients undergoing arc-based RT., Methods: Thirty esophageal cancer patients received 18 F-FDG PET/CT imaging pre-RT and post-RT were included in a retrospective pilot study. We fused lung doses and parameters of PET/CT in RT planning. Based on VBA, we used the 5Gy isodose curve to define high-dose (HD) and low-dose (LD) regions in the lung volume. We divided patients into non-RP (nRP) and RP groups. The maximum, mean standardized uptake value (SUVmax, SUVmean), global lung glycolysis (GLG), mean lung dose (MLD) and V 5-30 in lungs were analyzed. Area under the curve values were utilized to identify optimal cut-off values for RP., Results: Eleven patients in the nRP group and 19 patients in the RP group were identified. In 30 RP lungs, post-RT SUVmax, SUVmean and GLG of HD regions showed significant increases compared to values for pre-RT lungs. There were no significant differences in values of 22 nRP lungs. Post-RT SUVmax and SUVmean of HD regions, MLD, and lung V 5 and V 10 in RP lungs were significantly higher than in nRP lungs. For detecting RP, the optimal cut-off values were post-RT SUVmax > 2.28 and lung V 5  > 47.14%., Conclusion: This study successfully integrated 18 F-FDG PET/CT with VBA to assess RP in esophageal cancer patients undergoing RT. Post-RT SUVmax > 2.28 and lung V 5  > 47.14% might be potential indicators of RP., (© 2022 The Authors. Thoracic Cancer published by China Lung Oncology Group and John Wiley & Sons Australia, Ltd.)

Aim: To review the experience and to evaluate the results of stereotactic body radiation therapy (SBRT) via helical tomotherapy (HT), for the treatment of brachytherapy-unsuitable cervical cancer., Methods: Between September 1, 2008 to January 31, 2012, nine cervical cancer patients unsuitable for brachytherapy were enrolled. All of the patients received definitive whole pelvic radiotherapy with or without chemotherapy, followed by SBRT via HT., Results: The actuarial locoregional control rate at 3 years was 78%. The mean biological equivalent dose in 2-Gy fractions of the tumor, rectum, bladder, and intestines was 76.0 ± 7.3, 73.8 ± 13.2, 70.5 ± 10.0, and 43.1 ± 7.1, respectively. Only two had residual tumors after treatment, and the others were tumor-free. Two patients experienced grade 3 acute toxicity: one had diarrhea; and another experienced thrombocytopenia. There were no grade 3 or 4 subacute toxicities. Three patients suffered from manageable rectal bleeding in months 11, 14, and 25, respectively. One stage I VA patient experienced fistula formation in month 3., Conclusion: SBRT via HT provides the possibility for treatment of locally advanced cervical cancer in patients who are unsuitable for brachytherapy. Long-term follow up and enrollment of more such patients to receive SBRT via the HT technique are warranted.

Background: The purpose of this study was to compare the efficacy of intensity-modulated radiotherapy (IMRT) and helical tomotherapy for endometrial cancer., Methods: Between November 1, 2006 and November 31, 2010, 31 patients with histologically confirmed endometrial cancer were enrolled. All enrolled patients received total abdominal hysterectomy and bilateral salpingo-oophorectomy with adjuvant whole pelvic IMRT or helical tomotherapy., Results: The actuarial 3-year overall survival, disease-free survival, locoregional control, and distant metastasis-free rates for the IMRT and helical tomotherapy groups were 87.5% versus 100%, 91.7% versus 51.7%, 91.7% versus 83.3%, and 91.7% versus 51.7%, respectively. The conformal index and uniformity index for IMRT versus helical tomotherapy was 1.25 versus 1.17 (P = 0.04) and 1.08 versus 1.05 (P < 0.01), respectively. Two of 31 patients with cervical stump failure were noted, one in the IMRT group and the other in the helical tomotherapy group. No acute or late grade 3 or 4 toxicities were noted, including proctitis, or genitourinary or gastrointestinal disturbances., Conclusion: Helical tomotherapy is as effective as IMRT and has better uniformity and conformal indices, and critical organ-sparing properties. Prospective clinical trials are needed to evaluate the comparative efficacy of IMRT versus helical tomotherapy.