Objective:To explore the related factors and independent risk factors of radiation pneumonitis (RP) in breast cancer patients after radiotherapy, and to guide the optimization of treatment plan for BC and reduce the incidence of RP.Methods:A retrospective analysis was conducted on 770 female breast cancer patients who received postoperative radiotherapy at Deyang People's Hospital between July 2021 and September 2024. The occurrence of RP was observed, and potential clinical and dosimetric factors were analyzed. Continuous variables were assessed using the t-test, categorical variables with the chi-square test, and univariate analysis was used to identify factors associated with RP. Multivariate logistic regression analysis was used to find out the independent risk factors of RP, and receiver operating characteristic (ROC) curves were used to evaluate the predictive value of each factor. Results:Among 770 patients, 46 developed RP (34 grade 1, 12 grade 2). Univariate analysis showed that surgical method, chemotherapy regimen, interval between chemotherapy and radiotherapy, age, planning target volume, and maximum dose of the ipsilateral lung were not associated with RP (all P>0.05). Clinical stage ( χ2=7.84, P=0.020), chest wall + supraclavicular + internal mammary lymph node irradiation ( χ2=104.50, P<0.001), supraclavicular + internal mammary lymph node irradiation ( χ2=8.90, P=0.003), number of chemotherapy cycles ( t=9.88, P<0.001), and ipsilateral lung V 5 Gy( t=16.47, P<0.001), V 10 Gy( t=18.70, P<0.001), V 15 Gy( t=20.23, P<0.001), V 20 Gy( t=23.39, P<0.001), V 25 Gy( t=21.68, P<0.001), V 30 Gy( t=21.67, P<0.001), V 35 Gy( t=20.67, P<0.001), V 40 Gy( t=19.96, P<0.001), V 45 Gy( t=18.59, P<0.001), V 50 Gy( t=11.69, P<0.001), D mean( t=30.76, P<0.001) were significantly correlated with the occurrence of RP. Multivariate analysis revealed that ipsilateral lung V 5 Gy ( OR=1.258, 95% CI: 1.143-1.384, P<0.001), number of chemotherapy cycles ( OR=2.767, 95% CI: 1.781-4.299, P<0.001), and chest wall + supraclavicular + internal mammary lymph node irradiation ( OR=7.926, 95% CI: 2.943-21.349, P<0.001) were independent risk factors for RP. Using V 5 Gy=51.65% as the diagnostic cutoff, the sensitivity and specificity for predicting RP were 0.870 and 0.804, respectively. Taking the number of chemotherapy cycles=6.50 as the cutoff, the sensitivity and specificity of predicting RP were 0.891 and 0.586, respectively. Taking 0.50 as the diagnostic cutoff point, the sensitivity and specificity of chest wall + supraclavicular + internal mammary lymph node irradiation for RP were 0.870 and 0.797, respectively. Conclusions:The number of chemotherapy cycles, ipsilateral lung V 5 Gy, and chest wall + supraclavicular + internal mammary lymph node irradiation are independent risk factors for RP in postoperative female breast cancer patients.

Objective:To apply statistical process control (SPC) techniques to the quality assurance of non-normal radiotherapy plans through Johnson transformation, establishing patient-specific tolerance and action limits based on treatment sites and dose/distance assessment criteria, thereby enhancing the intensity-modulated radiation therapy (IMRT) verification accuracy and dose delivery precision.Methods:In this study, 951 gamma analysis data of patient-specific quality assurance (PSQA) executed on the Halcyon accelerator platform were selected and categorized into six groups based on treatment sites, including brain (102 cases), head and neck (100 cases), breast (229 cases), lung (154 cases), esophagus (223 cases), and pelvic (143 cases) groups. The six groups of data were statistically analyzed through Anderson-Darling normality tests ( α = 0.05) using Minitab 21 software. Non-normal data were transformed into normal data through Johnson transformation and then were used to establish treatment site-specific tolerance and action limits, which were compared with the Shewhart control charts based on normal distributions. Results:The PSQA result of the six groups all exhibited non-normal distributions ( P < 0.05). Through Johnson transformation, the tolerance and action limits for the head and neck, breast, lung, esophagus, and pelvic areas under the 3%/2 mm criterion ranged from 95.13% to 96.16% and 94.19% to 95.91%, respectively. In contrast, the tolerance and action limits ranged from 91.15% to 94.86% and 89.94% to 94.78% under the 2%/2 mm criterion. Directly applying Shewhart control charts without normality assumptions yielded higher tolerance limits compared to the application of Johnson transformation, increasing the false positive rate in the non-normal PSQA process. Conclusions:Applying the SPC techniques directly to a non-normal process can lead to an increased false alarm rate and wrong process interpretation. The SPC techniques combined with Johnson transformation enable more effective monitoring of a non-normal PSQA process, facilitating timely identification of potential factors that may lead to an out-of-control process based on the treatment site-specific limits.

Objective:To apply statistical process control (SPC) techniques to the quality assurance of non-normal radiotherapy plans through Johnson transformation, establishing patient-specific tolerance and action limits based on treatment sites and dose/distance assessment criteria, thereby enhancing the intensity-modulated radiation therapy (IMRT) verification accuracy and dose delivery precision.Methods:In this study, 951 gamma analysis data of patient-specific quality assurance (PSQA) executed on the Halcyon accelerator platform were selected and categorized into six groups based on treatment sites, including brain (102 cases), head and neck (100 cases), breast (229 cases), lung (154 cases), esophagus (223 cases), and pelvic (143 cases) groups. The six groups of data were statistically analyzed through Anderson-Darling normality tests ( α = 0.05) using Minitab 21 software. Non-normal data were transformed into normal data through Johnson transformation and then were used to establish treatment site-specific tolerance and action limits, which were compared with the Shewhart control charts based on normal distributions. Results:The PSQA result of the six groups all exhibited non-normal distributions ( P < 0.05). Through Johnson transformation, the tolerance and action limits for the head and neck, breast, lung, esophagus, and pelvic areas under the 3%/2 mm criterion ranged from 95.13% to 96.16% and 94.19% to 95.91%, respectively. In contrast, the tolerance and action limits ranged from 91.15% to 94.86% and 89.94% to 94.78% under the 2%/2 mm criterion. Directly applying Shewhart control charts without normality assumptions yielded higher tolerance limits compared to the application of Johnson transformation, increasing the false positive rate in the non-normal PSQA process. Conclusions:Applying the SPC techniques directly to a non-normal process can lead to an increased false alarm rate and wrong process interpretation. The SPC techniques combined with Johnson transformation enable more effective monitoring of a non-normal PSQA process, facilitating timely identification of potential factors that may lead to an out-of-control process based on the treatment site-specific limits.

Objective:To explore the related factors and independent risk factors of radiation pneumonitis (RP) in breast cancer patients after radiotherapy, and to guide the optimization of treatment plan for BC and reduce the incidence of RP.Methods:A retrospective analysis was conducted on 770 female breast cancer patients who received postoperative radiotherapy at Deyang People's Hospital between July 2021 and September 2024. The occurrence of RP was observed, and potential clinical and dosimetric factors were analyzed. Continuous variables were assessed using the t-test, categorical variables with the chi-square test, and univariate analysis was used to identify factors associated with RP. Multivariate logistic regression analysis was used to find out the independent risk factors of RP, and receiver operating characteristic (ROC) curves were used to evaluate the predictive value of each factor. Results:Among 770 patients, 46 developed RP (34 grade 1, 12 grade 2). Univariate analysis showed that surgical method, chemotherapy regimen, interval between chemotherapy and radiotherapy, age, planning target volume, and maximum dose of the ipsilateral lung were not associated with RP (all P>0.05). Clinical stage ( χ2=7.84, P=0.020), chest wall + supraclavicular + internal mammary lymph node irradiation ( χ2=104.50, P<0.001), supraclavicular + internal mammary lymph node irradiation ( χ2=8.90, P=0.003), number of chemotherapy cycles ( t=9.88, P<0.001), and ipsilateral lung V 5 Gy( t=16.47, P<0.001), V 10 Gy( t=18.70, P<0.001), V 15 Gy( t=20.23, P<0.001), V 20 Gy( t=23.39, P<0.001), V 25 Gy( t=21.68, P<0.001), V 30 Gy( t=21.67, P<0.001), V 35 Gy( t=20.67, P<0.001), V 40 Gy( t=19.96, P<0.001), V 45 Gy( t=18.59, P<0.001), V 50 Gy( t=11.69, P<0.001), D mean( t=30.76, P<0.001) were significantly correlated with the occurrence of RP. Multivariate analysis revealed that ipsilateral lung V 5 Gy ( OR=1.258, 95% CI: 1.143-1.384, P<0.001), number of chemotherapy cycles ( OR=2.767, 95% CI: 1.781-4.299, P<0.001), and chest wall + supraclavicular + internal mammary lymph node irradiation ( OR=7.926, 95% CI: 2.943-21.349, P<0.001) were independent risk factors for RP. Using V 5 Gy=51.65% as the diagnostic cutoff, the sensitivity and specificity for predicting RP were 0.870 and 0.804, respectively. Taking the number of chemotherapy cycles=6.50 as the cutoff, the sensitivity and specificity of predicting RP were 0.891 and 0.586, respectively. Taking 0.50 as the diagnostic cutoff point, the sensitivity and specificity of chest wall + supraclavicular + internal mammary lymph node irradiation for RP were 0.870 and 0.797, respectively. Conclusions:The number of chemotherapy cycles, ipsilateral lung V 5 Gy, and chest wall + supraclavicular + internal mammary lymph node irradiation are independent risk factors for RP in postoperative female breast cancer patients.