MV CBCT based assessment of setup uncertainties and planning target volume margin in head and neck cancer.

Background: Set-up errors are an undesirable part of the radiation treatment process. The goal of online imaging is to increase treatment accuracy by reducing the set-up errors. This study aimed to determine the daily variation of patient set-up uncertainties and planning target volume (PTV) margins for head and neck cancer patients using pre-treatment verification by mega voltage cone-beam computed tomography (MV-CBCT). Materials and methods: This retrospective study was internal record base of head and neck (H&N) cancer patients treated with definitive radiotherapy, adjuvant radiotherapy, and hypo-fractionated radiotherapy at our institution since the implementation of HalcyonTM 2.0 machine (Varian, US). Errors collected from each patient setup were recorded and evaluated for each direction [medio-lateral (ML), supero-inferior (SI), antero-posterior (AP)] discretely. For each patient, the systematic error (∑) and random error (σ) were collected. Clinical target volume (CTV) to planning target volume (PTV) margin was calculated using International Commission on Radiation Units and Measurements (ICRU) 62 ( PTV margin = ( Σ 2 + σ 2 ) ), Stroom's (PTV margin = 2∑ + 0.7σ), and Van Herk's (PTV margin = 2.5∑ + 0.7σ) formula. Results: A total of 7900 pre-treatment CBCT scans of 301 patients were analyzed and a total of 23,000 error measurements in the ML, SI, and AP directions were recorded. For all of our H&N cancer patients, the CTV to PTV margin, calculated from the van Herk formula for the head and neck patients was 0.49 mm in the anteroposterior axis. Conclusions: An isometric PTV margin of 5 mm may be considered safe if daily imaging is not being done. In case daily online pretreatment imaging is being utilized, further reduction of PTV margin is possible.

Target coverage and organs at risk dose in hypofractionated salvage radiotherapy after prostatectomy.

Background and purpose: Introducing moderately hypofractionated salvage radiotherapy (SRT) following prostatectomy obligates investigation of its effects on clinical target volume (CTV) coverage and organ-at-risk (OAR) doses. This study assessed interfractional volume and dose changes in OARs and CTV in moderately hypofractionated SRT and evaluated the 8-mm planning target volume (PTV) margin. Materials and methods: Twenty patients from the PERYTON-trial were included; 10 received conventional SRT (35 × 2 Gy) and 10 hypofractionated SRT (20 × 3 Gy). OARs were delineated on 539 pre-treatment Cone Beam CT (CBCT) scans to compare interfractional OAR volume changes. CTVs for the hypofractionated group were delineated on 199 CBCTs. Dose distributions with 4 and 6 mm PTV margins were generated using voxel-wise minimum robustness evaluation of the original 8-mm PTV plan, and dose changes were assessed. Results: Median volume changes for bladder and rectum were -26 % and -10 %, respectively. OAR volume changes were not significantly different between the two treatment schedules. The 8-mm PTV margin ensured optimal coverage for prostate bed and vesicle bed CTV (V95 = 100 % in >97 % fractions). However, bladder V60 <25 % was not achieved in 5 % of fractions, and rectum V60 <5 % was unmet in 33 % of fractions. A 6-mm PTV margin resulted in CTV V95 = 100 % in 92 % of fractions for prostate bed, and in 86 % for vesicle bed CTV. Conclusions: Moderately hypofractionated SRT yielded comparable OAR volume changes to conventionally fractionated SRT. Interfractional changes remained acceptable with a PTV margin of 6 mm for prostate bed and 8 mm for vesicle bed.

Dose conformity and falloff in single-lesion intracranial SRS with DCA and VMAT methods.

BACKGROUND: Intracranial stereotactic radiosurgery (SRS) aims at achieving highly conformal dose distribution and, at the same time, attaining rapid dose falloff outside the treatment target. SRS is performed using different techniques including dynamic conformal arcs (DCA) and volumetric modulated arc therapy (VMAT). PURPOSE: In this study, we compare dose conformity and falloff in DCA and VMAT plans for SRS with a single target. METHODS: To compare dose conformity in SRS plans, we employ a novel conformity index C I d e x p $C{I}_{{d}_{exp}}$ , RTOG conformity index ( C I R T O G $C{I}_{RTOG}$ ), and Riet-Paddick conformity index ( C I R P $C{I}_{RP}$ ). In addition, we use indices R 50 % $R50\% $ , V 10 G y ${V}_{10Gy}$ , and V 12 G y ${V}_{12Gy}$ to evaluate dose falloff. For each of the considered 118 cases of SRS, two plans were created using DCA and VMAT. A two-tailed Student's t-test was used to evaluate the difference between the employed indices for the DCA and VMAT plans. RESULTS: The studied VMAT plans were characterized by higher dose conformity than the DCA plans. The differences between the conformity indices for the DCA plans and VMAT plans were statistically significant. The DCA plans had a smaller number of monitor units (MUs) and smaller indices R50%, V10 Gy, and V12 Gy than the VMAT plans. However, the differences between R50%, V10 Gy, and V12 Gy for the DCA and VMAT plans were not statistically significant. CONCLUSIONS: Although the studied VMAT plans had higher dose conformity, they also had larger MUs than the DCA plans. In terms of dose falloff characterized by parameters R50%, V10 Gy, and V12 Gy, DCA serves as a reasonable alternative to VMAT in the case of a single brain metastasis.

Evaluation of PTV margin in CBCT-based online adaptive radiation therapy for gastric mucosa-associated lymphoid tissue lymphoma.

The aim of this study was to investigate planning target volume (PTV) margin in online adaptive radiation therapy (oART) for gastric mucosa-associated lymphoid tissue (MALT) lymphomas. Four consecutive patients with gastric MALT lymphoma who received oART (30 Gy in 15 fractions) on the oART system were included in this study. One hundred and twenty cone-beam computed tomography (CBCT) scans acquired pre- and post-treatment of 60 fractions for all patients were used to evaluate intra- and interfractional motions. Patients were instructed on breath-holding at exhalation during image acquisition. To assess the intrafraction gastric motion, different PTVs were created by isotropically extending the CTV contoured on a pre-CBCT image (CTVpre) at1 mm intervals. Intrafraction motion was defined as the amount of expansion covering the contoured CTV on post-CBCT images (CTVpost). Interfractional motion was defined as the amount of reference CTV expansion that could cover each CTVpre, as well as the evaluation of the intrafractional motion. PTV margins were estimated from the cumulative proportion of fraction covering the intra- and interfractional motions. The extent of expansion covering the CTVs in 90% of fractions was adopted as the PTV margin. The PTV margin for intrafractional gastric motion using the oART system with breath-holding was 14 mm. In contrast, the PTV margin for interfractional gastric organ motion without the oART system was 25 mm. These results indicated that the oART system can reduce the PTV margin by >10 mm. Our results could be valuable data for oART cases.

Malignant transformation of primary ameloblastoma of skull: case report and review of current literature.

Background: Since 1964, there has been a scarcity of reported cases of primary ameloblastoma (AM) or ameloblastic carcinoma (AMCa) of the skull. The clinical presentation and distinctive features of this uncommon condition at specific anatomical sites remain unclear. We report a case of malignant transformation of a primary AM of the skull situated in the frontal-temporal-parietal region and highlight its similarities to other cases reported in the literature. Clinical presentation: A 53-year-old female patient presented with a 20-day history of headaches and bilateral lower limb weakness for 10 days. Physical examination revealed slow and unsteady gait. An occupying lesion was observed in the right frontal-temporal-parietal region of the skull on the Cranial imaging. A right cranial bone tumor margin expansion resection was performed. The patient's motor functions recovered normally after surgery. Postoperative imaging examinations showed10 tumor resection. Follow-up imaging examinations showed tumor recurrence. The patient underwent resection of the recurrent tumor. Postoperative pathological analysis revealed malignant transformation of the AM.Follow-up imaging examinations showed tumor recurrence again. The patient was admitted for stereotactic radiotherapy. Follow-up imaging examinations demonstrated no evidence of tumor recurrence and subsequent chest CT revealed no signs of metastasis. Conclusion: Primary AM or AMCa of the skull is increasingly being described in the literature, but detailed reports on the malignant transformation of primary AM of the skull are lacking. The pathogenesis of this condition remains unclear. Aggressive treatment and close follow-up may be crucial for preventing disease recurrence and malignant transformation.

Patient Cranial Angle and Intrafractional Stability in CyberKnife Robotic Radiosurgery: A Retrospective Analysis.

Purpose: The aim of this study was to investigate whether variations in cranial angles and treatment accuracy during CyberKnife robotic radiosurgery necessitate adjustment of the margins of the planning target volume. Patients and Methods: Data from 66 patients receiving CyberKnife treatment for brain tumors were retrospectively analyzed. Patients were immobilized using a thermoplastic mask and headrest. The cranial angle was measured on planning CT and patients were divided into 2 groups: ≤10° (Group A) and >10° (Group B). Intrafractional motion was recorded using the CyberKnife tracking system over 50 min. Translational and rotational errors were compared between groups, and planning target volume margins were calculated. Results: In Group A, significant translational error differences were found along with the X-axis over time (P < .02). In Group B, significant differences occurred along with the Z-axis (P < .03). No significant rotational or 3-dimensional vector differences were found in either group. Group A had significantly lower Y-axis (P < .045) and roll axis (P < .005) errors compared to Group B. Estimated planning target volume margins in Group A were 0.56 mm (X), 0.46 mm (Y), and 0.47 mm (Z). In Group B, margins were 0.62 mm (X), 0.48 mm (Y), and 0.46 mm (Z). Margins covering 95% of intrafraction motion were 0.49 to 0.50 mm (X, Y, Z) and 0.69 mm (3-dimensional vector) for Group A, and 0.48 to 0.60 mm and 0.79 mm for Group B. With a 1-mm margin, complete coverage was achieved in Group A while 2.1% of vectors in Group B exceeded 1 mm. Conclusion: Adjusting cranial angle to ≤10° during thermoplastic mask molding provided better or similar intrafractional stability compared to >10°.

Analysis of Individualized Silicone Rubber Bolus Using Fan Beam Computed Tomography in Postmastectomy Radiotherapy: A Dosimetric Evaluation and Skin Acute Radiation Dermatitis Survey.

Objective: To investigate the dosimetric effects of using individualized silicone rubber (SR) bolus on the target area and organs at risk (OARs) during postmastectomy radiotherapy (PMRT), as well as evaluate skin acute radiation dermatitis (ARD). Methods: A retrospective study was performed on 30 patients with breast cancer. Each patient was prepared with an individualized SR bolus of 3 mm thickness. Fan-beam computed tomography (FBCT) was performed at the first and second fractions, and then once a week for a total of 5 times. Dosimetric metrics such as homogeneity index (HI), conformity index (CI), skin dose (SD), and OARs including the heart, lungs, and spinal cord were compared between the original plan and the FBCTs. The acute side effects were recorded. Results: In targets' dosimetric metrics, there were no significant differences in Dmean and V105% between planning computed tomography (CT) and actual treatments (P > .05), while the differences in D95%, V95%, HI, and CI were statistically significant (P < .05). In OARs, there were no significant differences between the Dmean, V5, and V20 of the affected lung, V5 of the heart and Dmax of the spinal cord (P > .05) except the V30 of affected lung, which was slightly lower than the planning CT (P < .05). In SD, both Dmax and Dmean in actual treatments were increased than plan A, and the difference was statistically significant (P < .05), while the skin-V20 and skin-V30 has no difference. Among the 30 patients, only one patient had no skin ARD, and 5 patients developed ARD of grade 2, while the remaining 24 patients were grade 1. Conclusion: The OR bolus showed good anastomoses and high interfraction reproducibility with the chest wall, and did not cause deformation during irradiation. It ensured accurate dose delivery of the target and OARs during the treatment, which may increase SD by over 101%. In this study, no cases of grade 3 skin ARD were observed. However, the potential of using OR bolus to reduce grade 1 and 2 skin ARD warrants further investigation with a larger sample size.

Impact of technological advances in treatment planning, image guidance, and treatment delivery on target margin design for prostate cancer radiotherapy: an updated review.

Recent innovations in image guidance, treatment delivery, and adaptive radiotherapy (RT) have created a new paradigm for planning target volume (PTV) margin design for patients with prostate cancer. We performed a review of the recent literature on PTV margin selection and design for intact prostate RT, excluding post-operative RT, brachytherapy, and proton therapy. Our review describes the increased focus on prostate and seminal vesicles as heterogenous deforming structures with further emergence of intra-prostatic GTV boost and concurrent pelvic lymph node treatment. To capture recent innovations, we highlight the evolution in cone beam CT guidance, and increasing use of MRI for improved target delineation and image registration and supporting online adaptive RT. Moreover, we summarize new and evolving image-guidance treatment platforms as well as recent reports of novel immobilization strategies and motion tracking. Our report also captures recent implementations of artificial intelligence to support image guidance and adaptive RT. To characterize the clinical impact of PTV margin changes via model-based risk estimates and clinical trials, we highlight recent high impact reports. Our report focusses on topics in the context of PTV margins but also showcase studies attempting to move beyond the PTV margin recipes with robust optimization and probabilistic planning approaches. Although guidelines exist for target margins conventional using CT-based image guidance, further validation is required to understand the optimal margins for online adaptation either alone or combined with real-time motion compensation to minimize systematic and random uncertainties in the treatment of patients with prostate cancer.

A retrospective study on improving the accuracy of radiotherapy for patients with breast cancer with lymph node metastasis using Styrofoam.

BACKGROUND: To retrospectively analyze the accuracy of radiotherapy using cone beam computed tomography (CBCT), Styrofoam fixation, and breast bracket fixation in the chest wall target area and supraclavicular lymphatic drainage area (supraclavicular target area) of patients with breast cancer.and compare the setting efficiency and comfort satisfaction. PATIENTS AND METHODS: A total of 65 patients with postoperative lymphatic metastasis of breast cancer, including 36 cases of Styrofoam fixation and 29 cases of breast bracket fixation, were recruited from March 2021 to August 2022 and retrospectively analyzed. All the patients underwent CBCT scans weekly, and the setup errors of the chest wall and supraclavicular target volume were compared and recorded. The planning target volume (PTV) margins of the two groups were calculated using the correlation MPTV = 2.5Σ + 0.7σ. The setup time and comfort satisfaction scores of the two groups were recorded and analyzed. The correlations among errors in each direction were analyzed using the Pearson correlation analysis. RESULTS: There was a significant difference in the left-right direction (X) axis of the chest wall target area between the Styrofoam and breast bracket groups (1.59 ± 1.47 mm vs. 2.05 ± 1.64 mm, P = 0.012). There were statistical differences in the ventrodorsal direction (Z) and bed angle of the supraclavicular target area, the data were (1.36 ± 1.27 mm vs. 1.75 ± 1.55 mm, P = 0.046; 0.47 ± 0.47° vs. 0.66 ± 0.59°, P = 0.006, respectively). In the X, Y, and Z directions, the respective PTV margins of the two groups in the chest wall target area were 5.01 mm, 5.99 mm, and 5.47 mm in the Styrofoam group, while those in the breast bracket group were 6.10 mm, 6.34 mm, and 6.10 mm, respectively. Moreover, the PTV margins of the supraclavicular target in the three directions were 3.69 mm, 3.86 mm, and 4.28 mm in the Styrofoam group, while those in the breast bracket group were 3.99 mm, 3.72 mm, and 5.45 mm, respectively. The setup time of the two groups was 3.4 ± 1.1 min and 5.5 ± 3.1 min (P = 0.007). The subjective comfort satisfaction scores of the two groups were 27.50 ± 1.24 and 25.44 ± 1.23 (P < 0.001). CONCLUSIONS: The application of Styrofoam fixation in radiotherapy of breast cancer in the supraclavicular lymph node area has several advantages as compared to breast bracket fixation, including higher positioning accuracy, smaller external expansion boundary, improved work efficiency, and patients' comfort, which might provide a reference for clinical work.

Target movement according to cervical lymph node level in head and neck cancer and its clinical significance.

PURPOSE: To evaluate set-up error for head and neck cancer (HNC) patients according to each neck lymph node (LN) level. And clinical factors affecting set-up error were analyzed. MATERIALS AND METHODS: Reference points (RP1, RP2, RP3, and RP4) representing neck LN levels I to IV were designated. These RP were contoured on simulation computed tomography (CT) and cone-beam CT of 89 HNC patients with the same standard. After image registration was performed, movement of each RP was measured. Univariable logistic regression analyses were performed to analyze clinical factors related to measured movements. RESULTS: The mean value of deviation of all axes was 1.6 mm, 1.3 mm, 1.8 mm, and 1.5 mm for RP1, RP2, RP3, and RP4, respectively. Deviation was over 3 mm in 24 patients. Movement of more than 3 mm was observed only in RP1 and RP3. In RP1, it was related to bite block use. Movement exceeding 3 mm was most frequently observed in RP3. Primary tumor and metastatic LN volume change were clinical factors related to the RP3 movement. CONCLUSION: Planning target volume margin of 4 mm for neck LN level I, 3 mm for neck LN level II, 5 mm for neck LN level III, and 3 mm for neck LN level IV was required to include all movements of each LN level. In patients using bite block, changes in primary tumor volume, and metastatic LN volume were related to significant movement.

Breast bracket combined with polyurethane foam improves the accuracy of immobilization in breast cancer radiotherapy / 中华放射肿瘤学杂志

Objective:To compare the difference between breast bracket combined with polyurethane foam and single polyurethane foam in the accuracy of immobilization, providing a better immobilization for breast cancer radiotherapy.Methods:Fifty breast cancer patients who received radiotherapy in Sun Yat-sen University Cancer Center from March 2021 to July 2021 were selected. Among them, 25 patients were immobilized with polyurethane foam (foam group), and the other 25 patients were immobilized with polyurethane foam combined with breast bracket (combination group). All patients were scanned by CBCT once a week to obtain setup errors in the SI, LR and AP directions for t-test. The formula M PTV=2.5 Σ+0.7 σ was used to calculate the margin of the planning target volume(M PTV). Results:The setup errors in the foam group were SI (2.0±3.26) mm, LR (0.88±2.76) mm, AP (1.22±3.55) mm, Rtn -0.24°±0.85°, Pitch 0.16°±1.11°, Roll -0.32°±1.05°, and the M PTV were 6.75 mm, 8.46 mm and 8.73 mm, respectively. The setup errors in the combination group were SI (1.0±3.01) mm, LR (0.62±2.74) mm, AP (1.82±3.21) mm, Rtn 0.64°±0.59°, Pitch 0.71°±1.22°, Roll 0.29°±0.73°, and the M PTV were 6.35 mm, 7.47 mm, and 7.61 mm, respectively. After comparing the setup errors in the three-dimensional directions between two groups, the t value of LR, SI, AP and Rtn, Pitch, Roll was -4.304, -2.681, 1.384, and -9.457, -3.683, -5.323, respectively. And the differences in the LR, SI, Rtn, Pitch and Roll directions were statistically significant (all P<0.05). Conclusions:The immobilization effect of polyurethane foam combined with breast bracket is better and the M PTV is also smaller than those of polyurethane foam alone. Therefore, it is recommended to use polyurethane foam combined with breast bracket for immobilization in breast cancer radiotherapy.

Study on the significance of consistency of preoperative and postoperative bladder filling in patients with cervical cancer for target area and organ at risk in IMRT / 中华放射肿瘤学杂志

Objective Bladder filling in patients with cervical cancer before and after operation during intensity-modulated radiotherapy (IMRT) was controlled by using bladder volume measurement instrument (BVI 9400).The displacement errors of the target area and the changes of the irradiation dose and the morphology of the filling bladder were compared.The significance of consistency of preoperative and postoperative bladder filling in IMRT for cervical cancer was investigated.Methods Forty-five patients with cervical cancer treated with radiotherapy in our hospital in 2018 were recruited and divided into A,B and C groups (n=15).In group A,patients did not undergo surgery,patients in group B received radical resection of cervical cancer (bladder volume measurement (BVI 9400) was utilized to monitor the bladder urine volume in both A and B groups before treatment).In group C,patients who self-controlled urination without monitoring bladder urine volume before treatment were randomly selected.All patients in three groups underwent KV-CBCT scan before treatment for online registration analysis.The displacement errors in the x-(left and right),y-(head and foot),z-axis directions (ventral and dorsal),PTV coverage volume percentage (V10o) and percentage difference (△ V100) of the prescription dose were calculated.Results The average displacement errors in the x-,y-,z-axis directions were as follows:1.67 mm,1.55 mm and 1.67 mm in group A,1.43 mm,1.58 mm and 1.84 mm in group B,and 2.27 mm,2.30 mm and 2.08 mm in group C,respectively.In group A,the V1oo was calculated as 96.96％ and △ V1oo was 1.17％.In group B,V1oo was 9 5.9 ％ and △ V10o was 1.2 9 ％.In group C,V10o was 9 4.0 2 ％ and △ V100 was 2.1 7 ％.Conclusions Controlling the consistency of bladder filling can reduce the effect of inconsistency of bladder filling upon the displacement errors to certain extent,which can guarantee the accuracy of the target location and the irradiation dose of the target,protect the bladder,small intestine and rectum,and alleviate the radiation-induced response of cervical cancer patients.

Interobserver variations in the delineation of planning target volume and with orgagans at risk different contouring methods in intensity-modulated radiation therapy for nasopharyngeal carcinoma / 中华放射肿瘤学杂志

Objective To assess the interobserver variations in delineating the planning target volume (PTV) and organs at risk (OAR) using different contouring methods during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC),aiming to provide references for the quality control of multi-center clinical trials.Methods The PTV and OAR of CT image of 1 NPC patient manually delineated by 10 physicians from 8 different radiation centers were defined as the "manual contour group",and the OAR auto-contoured using the ABAS software and modified by the physicians were defined as the "auto+manual contour group".The maximum/minimum ratio (MMR) of the PTV and OAR volumes,and the coefficient of variation (CV) for different delineated contours were comparatively evaluated.Results Large variation was observed in the PTV and OAR volumes in the manual contour group.The MMR and CV of the PTV were 1.72-3.41 and 0.16-0.39,with the most significant variation in the PTVnd (MMR=3.41 and CV =0.39 for the PTVnd-L).The MMR and CV of the manually contoured OAR were 1.30-7.89 and 0.07-0.67.The MMR of the temporal lobe,spinal cord,temporomandibular joint,optic nerve and pituitary gland exceeded 2.0.Compared with the manual contour group,the average contouring time in the auto+ manual group was shortened by 68％ and the interobserver variation of the OAR volume was reduced with an MMR of 1.04-2.44 and CV of 0.01-0.37.Conclusions Large variation may occur in the PTV and OAR contours during IMRT plans for NPC delineated by different clinicians from multiple medical centers.Auto-contouring+ manually modification can reduce the interobserver variation of OAR delineation,whereas the variation in the delineation of small organs remains above 1.5 times.The consistency of the PTV and OAR delineation and the possible impact upon clinical outcomes should be reviewed and evaluated in multi-center clinical trials.

Interobserver variations in the delineation of planning target volume and with orgagans at risk different contouring methods in intensity-modulated radiation therapy for nasopharyngeal carcinoma / 中华放射肿瘤学杂志

Objective@#To assess the interobserver variations in delineating the planning target volume (PTV) and organs at risk (OAR) using different contouring methods during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC), aiming to provide references for the quality control of multi-center clinical trials.@*Methods@#The PTV and OAR of CT image of 1 NPC patient manually delineated by 10 physicians from 8 different radiation centers were defined as the " manual contour group" , and the OAR auto-contoured using the ABAS software and modified by the physicians were defined as the " auto+ manual contour group" . The maximum/minimum ratio (MMR) of the PTV and OAR volumes, and the coefficient of variation (CV) for different delineated contours were comparatively evaluated.@*Results@#Large variation was observed in the PTV and OAR volumes in the manual contour group. The MMR and CV of the PTV were 1.72-3.41 and 0.16-0.39, with the most significant variation in the PTVnd (MMR=3.41 and CV=0.39 for the PTVnd-L). The MMR and CV of the manually contoured OAR were 1.30-7.89 and 0.07-0.67. The MMR of the temporal lobe, spinal cord, temporomandibular joint, optic nerve and pituitary gland exceeded 2.0. Compared with the manual contour group, the average contouring time in the auto+ manual group was shortened by 68% and the interobserver variation of the OAR volume was reduced with an MMR of 1.04-2.44 and CV of 0.01-0.37.@*Conclusions@#Large variation may occur in the PTV and OAR contours during IMRT plans for NPC delineated by different clinicians from multiple medical centers. Auto-contouring+ manually modification can reduce the interobserver variation of OAR delineation, whereas the variation in the delineation of small organs remains above 1.5 times. The consistency of the PTV and OAR delineation and the possible impact upon clinical outcomes should be reviewed and evaluated in multi-center clinical trials.

Comparison of CTV-PTV setup margins during IMRT for cervical cancer patients with different body mass index by bladder volume measurement device-assisted CBCT / 中华放射肿瘤学杂志

Objective To investigate the clinical target volume (CTV)-planned target volume (PTV) setup margins during intensity-modulated radiotherapy (IMRT) for cervical cancer patients with different body mass index (BMI),aiming to provide reference for precise individual therapy.Methods Forty patients diagnosed with cervical cancer undergoing IMRT in Cancer Hospital of Fudan University between March and September 2017 were recruited and assigned into the BMI ≤ 18.4,18.5-23.9,24.0-27.9 and ≥ 28 kg/m2 groups according to the BMI classification criteria proposed by National Health and Family Planning Commission (NHFPC) of the People's Republic of China.Assisted with the bladder volume measurement device,9 cycles of kilo-voltage cone beam computed tomography (CBCT) images were subject to online registration and imaging analysis.CTV-PTV setup margins were calculated based on the formula of MPTV =2.5∑+0.7σamong four groups.Single factor variance analysis was performed.LSD test was utilized for two-group comparison.Results Among four groups,the CTV-PTV setup margins in the x,y and z directions were (6.87 mm,6.06 mm,8.49 mm),(3.13 mm,3.02 mm,3.14 mm),(4.70 mm,4.86 mm,5.31 mm) and (7.63 mm,8.28 mm,8.54 mm),respectively (P=0.038,0.048 and 0.004).Conclusions The setup errors in the BMI ≤ 18.4 and ≥28 kg/m2 groups are significantly larger compared with those in the remaining groups Consequently,CTV-PTV setup margins should be enlarged to certain extent for patients with BMI≤ 18.4 and ≥≥28 kg/m2.

An analysis on set-up errors by data of mugavoltage fan-beam computed tomography during intensity-mod-ulated radiotherapy for nasopharyngeal carcinoma / 实用医学杂志

Objective To explore the inter-fraction setup errors and affecting factors from data of daily fan-beam megavoltage computed tomography(MVCT). Methods A total of 37consecutive NPC patients treated with tomotherapy were hospitalized during the period of February 2015 to September 2015. For each patient,one MVCT scan was obtained after conventional positioning ,online correction and tomotherapy delivery daily ,and the scans were put into the planning computed tomography to determine inter-fraction setup errors. The MPTV was calculated with the equation:MPTV=2.5∑+0.7σ(∑:systematic error;σ:random error). Results The average absolute errors of the inter-fraction were(2.102 ± 0.0406)mm,(1.490 ± 0.0348)mm,(1.306 ± 0.335)mm and(1.392 ± 0.0384)° at three dimensions. The total MPTV accounting for inter-error was 3.4675 mm,2.9795 mm,and 2.8885 mm. Gradual increases in both inter-fraction three-dimensional displacement were observed with time and treatment(P < 0.05). Univariate analysis revealed that weight loss and retraction of neck lymph nodes were affecting factors of set-up errors. Conclusions 3 mm margins uniformly expended from clinical target volume to planning target volume may not be suitable. The personalized margin should be adopted for the design of IMRT planning. Displacement increases as a treatment course is prolonged.

Margins of planning target volume in cervix cancer with tomotherapy / 中华放射医学与防护杂志

Objective To determine the margins of planning target volume (MPTV) in primary cervical cancer patients with tomotherapy and evaluate the importance of automatic registration(AR) plus manual registration.Methods The setup errors of 29 primary cervical cancer patients receiving external radiation from June 2012 to Dec 2014 were measured by megavoltage computed tomography (MVCT),which were performed at least two times weekly before treatment and were registered with the planning CT.The setup errors between automatic registration and total shift (TS) including both AR and manual registration were compared MPTV was calculated.Results Setup errors were collecte from 443 sets of MVCT in 29 patients.AR and total shift (TS) values in the x,y,z directions and rotation angle were (-0.9±2.3),(0.0±3.1),(1.0±2.6) mm,0.2° ±0.8° and (-0.8±1.8),(-0.4±3.4),(l.4 ± 2.5) mm,0.1° ± 0.5°,respectively.There were statistically significant differences between the two groups in all directions except for the x axis (t =5.1,-5.2,3.2,P ＜ 0.05).MPTV were 4.6,5.7,3.3 mm in the x,y,z directions,respectively.Conclusions Manual registration is necessary after automatic registration in cervical cancer patients with tomotherapy.For patients with cervical cancer treated by tomotherapy,planning target volume MPTV parameters are suggested to be 5,6,4 mm in the x,y,z directions.

A comparative study of planning target volumes based on three-dimensional computed tomography, four-dimensional computed tomography, and positron emission tomography-computed tomography in thoracic esophageal cancer / 中华放射肿瘤学杂志

Objective To investigate the differences in position and volume between planning target volumes (PTV) based on positron emission tomography?computed tomography (PET?CT) images with an standardized uptake value ( SUV) no less than 2?5, 20% of the maximum SUV ( SUVmax ), or 25% of SUVmax , three?dimensional ( 3D ) CT, and four?dimensional ( 4D ) CT in thoracic esophageal cancer. Methods Eighteen patients with thoracic esophageal cancer sequentially received chest 3DCT, 4DCT, and [18F]fluoro?2?deoxy?D?glucose (FDG) PET?CT scans. PTV3D was obtained by conventional expansion of 3DCT images;PTV4D was obtained by fusion of target volumes from 10 phases of 4DCT images. The internal gross tumor volumes ( IGTV) , IGTVPET2.5 , IGTVPET20%, and IGTVPET25%, were generated based on PET?CT images with an SUV no less than 2?5, 20% of SUVmax , and 25% of SUVmax , respectively. These IGTVs were expanded longitudinally by 3?5 cm and radically by 1 cm to make PTVPET2.5 , PTVPET20%, and PTVPET25%, respectively. Results PTV3D was significantly larger than both PTV4D and PTVPET(P=0?000 -0?044), while there was no significant difference between PTV4D and PTVPET ( P= 0?216 -0?633 ) . The mutual degrees of inclusion ( DIs ) between PTV3D and PTV4D were 0?70 and 0?95, respectively, which were negatively correlated with 3D?Vector ( P=0?039). The mutual DIs between PTVPET2.5, PTVPET20%, and PTVPET25% were 0?74, 0?72, 0?78, 0?73, 0?77, and 0?70, respectively, which showed no correlation with 3D?Vector (P=0?150 -0?822). The mutual DIs between PTV3D and PTVPET were 0?86, 0?84, 0?88, 0?63, 0?67, and 0?59, respectively. Conclusions It is difficult to achieve complete volumetric overlap of PTVs based on 3DCT, 4DCT and PET?CT in thoracic esophageal cancer due to different target volume information. PET scan during free breathing should be used with caution to generate PTVs in thoracic esophageal cancer.

Target volume definition using 4DCT and dosimetric evaluation for esophageal cancer / 中华放射肿瘤学杂志

Objective To study the PTV by ng 4DCT and compare target,target displacement and dose distribution of 3D and 4D planning for thoracic middle or lower esophageal cancer,evaluate the clinical value of 4DCT in esophageal cancer radiotherapy.Methods From Jan to Dec 2012patients with primary esophageal cancer underwent 3DCT simulation scans first,then followed by 4DCT simulation scan.PTV and OARs were sketched in the ordinary 3DCT and 4DCT respectively.And designing two sets of radiotherapy plan for each patient:3D and 4D plan.We compare PTV,PTV displacement and OARs dosimetry's differences in the 3D plan and 4D plan.Using the paired t-test or Wilcoxon sign-rank test to compare the difference between the two sets of plans.Results The volume of PTV4D was larger than the PTV3D (195.19 cm3 vs.175.67 cm3,P =0.001) in all patients.The center displacement had only significantly difference (displacement was 0.25 cm,P =0.014) in left-right direction for 10 patients of thoracic middle esophageal cancer.The center displacement had no significantly different in the three direction for 9 patients of thoracic under esophageal cancer (P=0.722,0.307,0.208).The dose target area of V100,V95 and V90 in Plan3DC were significantly than those in Plan-3D for 19 patients of thoracic middle-lower esophageal cancer (88.62％ vs.95.69％,P=0.000;95.17％ vs.99.79％,P=0.001;97.19％ vs.99.99％,P=0.001).In 4D plan the lung V5,V20 and Dmean of heart were higher than that in 3D plan for all patients (39.49％vs.37.44％,P=0.016;19.93％ vs.18.87％,P=0.018 and 2607.74 cGy vs.2389.16 cGy,P=0.004).Conclusions 4DCT positioning technology can accuracy determine individualized expanding boundary by target area of radiotherapy for thoracic middle or lower esophageal cancer.The enlarging target volume increase the dose of radiotherapy for lung,and in the dose range in the 4D plan,but the increased dose of heart should be noted.

Comparison study on 4D-CT and ABC techniques in respiratory management during lung radiotherapy / 重庆医学

Objective To evaluate the similarities and differences between four-dimensional radiotherapy (4D-CT ) and active breathing control techniques(ABC) in respiratory management in lung radiotherapy ,and investigate the indications and feasibility of different breathing control techniques for different patients .Methods Twenty-one patients treated with lung radiotherapy received respiratory management .4D-CT technology was used in 11 patients ,while ABC technology was adopted in the rest 10 .The ratios of planning target volume(PGTV) to gross tumor volume(GTV)[(PGTV/GTV)] were calculated .The differences between these two respiratory management technologies were compared in terms of the PGTV ,positioning time ,planning time and treatment time to investigate the indications .Results 4D-CT technology had higher PGTV/GTV ratio ,and shorter positioning time and irradiation time than ABC technology(P0 .05) .In patients with ABC and 4D-CT technology ,objective response rates were 50 .0% ,45 .5% ,respectively ,and the radiation pneumonitis rates were 30 .0% ,27 .3% ,respectively .There was no significant difference in both groups (P>0 .05) .Conclusion In lung tumor radiothera-py ,ABC can reduce irradiation volume ,suitable for patients with good performance status .4D-CT is time-saving and well tolerated , suitable for patients with smaller tumors .