Mean Lung Dose Research Articles

Retrospective Analysis for Dose Reduction to Organs at Risk with New Personalized Breast Holder (PERSBRA) in Left Breast IMRT.

This study evaluated dose differences in normal organs at risk, such as the lungs, heart, left anterior descending artery (LAD), right coronary artery, left ventricle, and right breast under personalized breast holder (PERSBRA), when using intensity-modulated radiation therapy (IMRT). This study evaluated the radiation protection offered by PERSBRA in left breast cancer radiation therapy. Here, we retrospectively collected data from 24 patients with left breast cancer who underwent breast-conserving surgery as well as IMRT radiotherapy. We compared the dose differences in target coverage and organs at risk with and without PERSBRA. For target coverage, tumor prescribed dose 95% coverage, conformity index, and homogeneity index were evaluated. For organs at risk, we compared the mean heart dose, mean left ventricle dose, LAD maximum and mean dose, mean left lung receiving 20 Gy, 10 Gy, and 5 Gy of left lung volume, maximum and mean coronary artery of the right, maximum of right breast, and mean dose. Good target coverage was achieved with and without PERSBRA. When PERSBRA was used with IMRT, the mean dose of the heart decreased by 42%, the maximum dose of LAD decreased by 26.4%, and the mean dose of LAD decreased by 47.0%. The mean dose of the left ventricle decreased by 54.1%, the volume (V20) of the left lung that received 20 Gy decreased by 22.8%, the volume (V10) of the left lung that received 10 Gy decreased by 19.8%, the volume (V5) of the left lung that received 5 Gy decreased by 15.7%, and the mean dose of the left lung decreased by 23.3%. Using PERSBRA with IMRT greatly decreases the dose to organs at risk (left lung, heart, left ventricle, and LAD). This study found that PERSBRA with IMRT can achieve results similar to deep inspiration breath-hold radiotherapy (DIBH) in terms of reducing the heart radiation dose and the risk of developing heart disease in patients with left breast cancer who cannot undergo DIBH.

Efficacy, safety, and feasibility of volumetric modulated arc therapy for synchronous bilateral breast cancer management.

Volumetric Modulated Arc Therapy (VMAT) exhibits potent advantages regarding target volume coverage and protection of organs at risk, notably in the context of anatomical constraints. Nevertheless, reports concerning VMAT for the treatment of synchronous bilateral breast cancers (SBBC) have been scarce to date. As such, we conducted this observational study to assess efficacy, safety and feasibility of VMAT in SBBC. From August 2011 to December 2017, 54 consecutive patients with SBBC with or without axillary nodes involvement underwent a treatment protocol containing radiotherapy using VMAT. A total dose (TD) of 52.2Gy in 29 fractions was delivered to breast and internal mammary chain (IMC) nodes Planning Target Volume (PTV) plus, if applicable, a TD of 49.3Gy in 29 fractions to the supra- and infra-clavicular nodes PTV and a TD of 63.22Gy in 29 fractions to tumor boost PTV. Lungs, heart, esophagus, trachea, liver, thyroid and spinal cord were considered as organs at risk. VMAT feasibility and organ at risk sparing were evaluated by treatments planning of the 20 first enrolled patients. Tolerance and patients' outcome were prospectively monitored by acute/late toxicities records and by the analysis of overall survival (OS), locoregional recurrence-free survival (LRFS) and recurrence-free survival (RFS). Breast, supraclavicular nodes and boost PTV coverage was adequate with at least 98% of PTV encompassed by more than 95% of the prescribed dose. Less than 90% of IMC PTV was encompassed by 95% of the prescribed dose. Mean lung dose was 12.3Gy (range: 7.7 - 18.7); mean heart dose was 10.7Gy (range: 6.2 - 22.3). Concerning acute toxicities, only 2 patients experienced grade 3 skin toxicity (3.7%) and only 1 patient developed grade 1 pneumonitis. After a median follow-up of 5.3 years, grade 2 fibrosis and/or shrinking was observed in 5 patients (10%), and grade 3 fibrosis in 1 patients (2%). The 5-year LRFS-rate, RFS-rate and OS were 98% [95% CI= 86.12-99.70%], 96% [95% CI= 84.63-98.96%] and 100%, respectively.

Imaging features of radiation-induced lung disease and its relationship with clinical and dosimetric factors in breast cancer patients.

The aim is to extensively evaluate imaging features of radiation induced lung disease in breast cancer patients and to determine the relationship of imaging alterations with dosimetric parameters and patient related characteristics. A total of 76 breast cancer patients undergoing radiotherapy (RT) were studied retrospectively by case notes, treatment plans, dosimetric parameters, and chest computed tomography (CT) scans. Time intervals, that chest CT scans were acquired, were grouped as 1-6 months, 7-12 months, 13-18 months and more than 18 months after RT. Chest CTs (one or more for each patient) were assessed for the presence of ground glass opacity, septal thickening, consolidation/patchy pulmonary opacity/alveolar infiltrates, subpleural air cyst, air bronchogram, parenchymal bands, traction bronchiectasis, pleural/subpleural thickening and pulmonary volume loss. These alterations were scored by applying a system devised by Nishioka et al. Nishioka scores were analyzed for the relationship with clinical and dosimetric factors. IBM SPSS Statistics for Windows, version 22.0 (IBM Corp., Armonk, N.Y., USA) was used to analyze data. Median follow-up time was 49 months. Advanced age and aromatase inhibitor intake were correlated with higher Nishioka scores for 1-6 months' period. However, both were found nonsignificant in multivariate analysis. Nishioka scores of CT scans acquired more than 12 months after RT were positively correlated with mean lung dose, V5, V20, V30, and V40. Receiver operating characteristic analysis revealed that V5 for ipsilateral lung was the most robust dosimetric parameter predicting chronic lung injury. V5 >41% indicates the development of radiological lung changes. Keeping V5 ≤41% for ipsilateral lung could provide avoiding chronic lung sequelae.

Total body irradiation using volumetric modulated arc therapy, experience of a cancer hospital in Pakistan

Abstract Introduction: To report the planning parameters, efficacy and toxicity of total body irradiation using volumetric modulated arc therapy (VMAT). Methods: From July 2019 till May 2021, nine patients treated with VMAT-based total body irradiation as a part of the myeloablative regimen for homologous stem cell transplant were evaluated. The CT acquisition, planning parameters, doses to target volume and critical structures were evaluated retrospectively. Results: Median age was 24 with median height 172 cm. Average Mean Lung dose was 9·5 Gy, mean dose to kidney was kidney dose 8·4 Gy, planning target volume (PTV) 95% was 98 % and mean heterogeneity index of PTV was 1·2 all patients. Total fraction delivery time including setup was 3·1 h while beam on time was 23 min. Main toxicity observed was mucositis and fatigue, while no Grade 3 or more acute radiation toxicity was observed. Conclusion: At our institution, high dose TBI performed with multi-isocentric VMAT is now a standard procedure. Though it is cumbersome and time-consuming process but VMAT offers an advantage of increased dose homogeneity in the target volume with reduction in doses to critical organs especially lungs and kidneys in comparison to standard source to skin distance technique, longer follow-up time is necessary to evaluate our method and long-term toxicity.

Comprehensive Pneumonitis Profile of Thoracic Radiotherapy Followed by Immune Checkpoint Inhibitor and Risk Factors for Radiation Recall Pneumonitis in Lung Cancer.

PurposeWhilst survival benefits of thoracic radiotherapy (TRT) followed by immune checkpoint inhibitor (ICI) have been reported in patients with lung cancer, the potential high risk of treatment-related pneumonitis remains a concern. Asians may be more sensitive to lung toxicity than other races. This retrospective study intended to provide a comprehensive pneumonitis profile of TRT followed by ICI and investigate the risk factors from a Chinese cohort of lung cancer.Methods and MaterialsFrom January 2016 to July 2021, 196 patients with lung cancer who received TRT prior to ICI were retrospectively analyzed. Treatment-related pneumonitis, including checkpoint inhibitor pneumonitis (CIP), radiation pneumonitis (RP), and radiation recall pneumonitis (RRP), were recorded and graded through medical records and chest computed tomography. Characteristics predictive of pneumonitis were assessed using logistic regression models, and the receiver operating characteristic analyses were performed to identify optimal cut points for quantitative variables.ResultsWith a median follow-up of 18 months, a total of 108 patients (55.1%) developed treatment-related pneumonitis during ICI therapy, with an incidence of 25.5% for grade 2 or higher (G2+) and 4.1% for G3+. The overall rates of CIP, RP and RRP were 8.2% (n=16), 46.9% (n=92) and 7.1% (n=14), respectively. With a total mortality rate of 1.5%, vast majority of the patients recovered from pneumonitis or remained stable. No patients died of RRP. Half of the patients with G2+ RP who withheld ICI therapy restarted ICI safely after resolution of RP. The history of chronic pulmonary diseases (P=0.05), mean lung dose (MLD, P=0.038), percent volume of lung receiving ≥5 Gy (V5, P=0.012) and percent volume of lung receiving ≥20 Gy (V20, P=0.030) predicted the occurrence of RRP in univariate analyses. Interval between TRT and ICI less than 3 months was an independent predictor for G2+ treatment-related pneumonitis in a multivariate model (Odds ratio OR=2.787, P=0.004).ConclusionsTreatment-related pneumonitis, especially RRP, is acceptable and manageable in the setting of TRT followed by ICI in this Asian population. Dosimetric parameters MLD, V5 and V20 may improve the predictions of RRP in clinical practice.

Prone Breast and Lymph Node Irradiation in 5 or 15 Fractions: A Randomized 2 × 2 Design Comparing Dosimetry, Acute Toxicity, and Set-Up Errors

PurposeProne whole breast irradiation results in lower dose to organs at risk compared with supine position, especially lung dose. However, the adoption of prone position for whole breast irradiation + lymph node irradiation remains limited and data on lymph node irradiation in 5 fractions are lacking. Although the study was ended prematurely for the primary endpoint (breast retraction at 2 years), we decided to report acute toxicity for prone and supine positions and 5 and 15 fractions. Additionally, dosimetry and set-up accuracy between prone and supine positions were evaluated. Methods and MaterialsA randomized open-label factorial 2 × 2 design was used for an acute toxicity comparison between prone and supine positions and 5 and 15 fractions. The primary endpoint of the trial was breast retraction 2 years after treatment. In total, 57 patients were evaluated. Dosimetry and set-up errors were compared between prone and supine positions. All patients were positioned on either our in -house developed prone crawl breast couch or a Posirest-2 (Civco). ResultsNo difference in acute toxicity between prone and supine positions was found, but 5 fractions did result in a lower risk of desquamation (15% vs 41%; P = .04). Prone positioning resulted in lower mean ipsilateral lung dose (2.89 vs 4.89 Gy; P < .001), mean thyroid dose (3.42 vs 6.61 Gy; P = .004), and mean contralateral breast dose (0.41 vs 0.54 Gy; P = .007). No significant difference in mean heart dose (0.90 vs 1.07 Gy; P = .22) was found. Set-up accuracy was similar between both positions. ConclusionsUnfortunately, the primary endpoint of the trial was not met due to premature closure of the trial. Acceleration in 5 fractions resulted in a lower risk of desquamation. Prone positioning did not influence acute toxicity or set-up accuracy, but did result in lower ipsilateral mean lung dose, thyroid dose, and contralateral breast dose.

Effect of dosimetric parameters on postoperative respiratory morbidity in locally advanced esophageal cancer treated with preoperative chemoradiotherapy (CRT).

e16075 Background: Postoperative pulmonary complications are common after neoadjuvant CRT of locally advanced esophageal cancers. Using data from the French multicenter randomized phase II PROTECT trial (NCT02359968), we aimed to evaluate the dosimetric parameters which could be associated with the occurrence of postoperative respiratory morbidities in patients (pts) who underwent preoperative CRT. Methods: Key eligibility criteria for the PROTECT trial were stage II or III resectable adenocarcinoma or squamous cell carcinoma of the esophagus located below the carina. Pts received FOLFOX or Carboplatin-Paclitaxel, combined with radiotherapy (RT): total dose of 41.4 Gy, 5 fractions of 1.8 Gy per week, starting at day 1 of chemotherapy. The patient's position and definition of the target volumes and organs at risk were the same as in the CROSS trial (van Hagen, 2012). Pts were treated using 3D conformal RT or IMRT. Surgery occurred 4 to 8 weeks after completion of CRT through a transthoracic or mini-invasive approach with a two field extended lymphadenectomy. Pts recruited in the PROTECT trial up to Sept. 2019 who underwent surgery after CRT were eligible for this ancillary study. The primary endpoint of our translational study was the occurrence of postoperative respiratory morbidity, of any grade (Clavien-Dindo classification for early morbidity &lt; 31 days; NCI-CTCAE v4 for later events), up to 1 year following surgery, considering disease progression or death as competing events. Cause-specific Cox models were used to model the risk of respiratory morbidity, considering the following factors: performance status, BMI, smoking, histological subtype, tumor site, FEV1, RT technique, time interval between CRT and surgery, and dosimetric parameters derived from the Dose-Volume Histogram analysis (mean lung dose, V10Gy, V20Gy and V30Gy, as other parameters strongly correlated to these 4 ones). Results: Among the 98 pts recruited in the PROTECT trial from Feb. 2015 to Sept. 2019, 78 underwent surgery after CRT and were included in our translational study. Median age was 63.5 years (range 33 to 79). Tumor was located at the middle or lower third of the esophagus for 67% of pts. Mean lung dose was 10.2 Gy (sd = 3.2). Mean PTV volume was 566 cc (sd = 272). A total of 33 pts experienced at least one respiratory morbidity (16 pneumonia, 7 pleural effusion, 4 ARDS, 21 miscellaneous events). The cumulative incidence of respiratory morbidity was 42% one month after surgery (95% CI, 32-54), 44% at 3 months (32-54), and 46% at 6 months (35-57). None of the dosimetric parameters and other studied factors appeared associated with postoperative respiratory morbidity. Conclusions: We did not identify dosimetric factors that could predict the risk of postoperative respiratory morbidity after treatment with preoperative CRT with FOLFOX or Carboplatin-Paclitaxel. Clinical trial information: NCT02359968.

Pre-existing interstitial lung abnormalities are independent risk factors for interstitial lung disease during durvalumab treatment after chemoradiotherapy in patients with locally advanced non–small lung cancer.

8528 Background: The standard treatment for locally advanced non-small cell lung cancer (NSCLC) is chemoradiotherapy (CRT) followed by treatment of durvalumab, one of immune checkpoint inhibitors (ICI). Interstitial lung disease (ILD) is a clinically life-threatening toxicity of CRT or durvalumab. The patient-characteristics or dose-volume histogram parameters of radiotherapy have been reported to be the risk factors for radiation-induced pneumonitis. However, the risk factors for ILD during durvalumab therapy has not been established. Interstitial lung abnormalities (ILA) are generated by aging or smoking, and manifest as minor interstitial shadow on lung computed tomography (CT). We previously reported that ILA were risk factors for ICI-induced ILD in patients with advanced NSCLC, as well as non-lung cancer. Therefore, we investigated whether ILA could be risk factors for ILD during the durvalumab therapy. Methods: We retrospectively enrolled NSCLC patients who received durvalumab after CRT at 10 institutions from July 2018 to June 2021. Patient-information, patient-characteristics, dose-volume histogram parameters, chest CT findings, and laboratory data, were obtained. CT findings were examined using CT obtained after CRT and prior to durvalumab therapy. Results: A total of 153 patients were enrolled, and the prevalence of ILA was 37.8% (56 patients) before durvalumab treatment. Among the enrolled patients, 94 (63.5%) developed ILD during durvalumab therapy. The proportion of patients with grade 1, grade 2, or grade 3 ILD was observed to be 29.7% (44 patients), 25.7% (38 patients), and 8% (12 patients), respectively. Univariate logistic regression analysis revealed that higher age, higher dose volume histogram parameters (V5, V20, mean lung dose), and the presence of ILA were significant risk factors for grade 2 or more ILD. Multivariate logistic regression analysis showed that ILA, especially ground grass attenuation in ILA, was an independent risk factor for grade 2 or more ILD (odds ratio: 7.02, 95% CI: 2.95-16.69, p &lt; 0.0001). Conclusions: Pre-existing ILA are risk factors for ILD during durvalumab treatment after CRT. This observation is consistent with previously reported findings in patients with advanced lung cancer and non-lung cancer. Therefore, we should pay more attention to the development of grade 2 or more ILD during durvalumab treatment in patients with ILA.

A phase 1 study in patients with advanced non-small cell lung cancer treated with stereotactic radiotherapy to the primary tumor combined with durvalumab and tremelimumab.

e21121 Background: Cancers can be recognized by the immune system and immunotherapy (ICI) has become an important treatment for lung cancer. Compared to chemotherapy, combining an anti-CTLA-4 and PD-L1 inhibitor increases response- and survival rates independent of PD-L1 status. We hypothesized that adding stereotactic radiotherapy (SBRT) to increase the release of cancer cell antigens might improve treatment results even further. Because of accumulating tumor heterogeneity it may be important to irradiate the primary tumor (addressing trunk mutations), rather than its metastases (branch mutations). We assessed toxicity of adding SBRT to (dual) ICI. Methods: In 3 sequential cohorts, ICI regimes combined with SBRT were studied in stage IIIB/IV NSCLC patients progressing on chemotherapy. All patients were irradiated on an FDG avid part of the primary tumor (1x20 Gy on 9cc) 1 week after the 1st dose of ICI; in case of dual ICI the 1st dose of the 2nd ICI was administered within 1 week following SBRT. Following treatments both ICI were combined. The 1st cohort (n = 3) received durvalumab (D) monotherapy for up to 1 year. The 2nd cohort starting with tremelimumab (T) and the 3rd cohort starting with D (both n = 6) received a combination of D and T (4 cycles) followed by D monotherapy for up to 1 year. The 2nd and 3rd cohort only proceeded when dose limiting toxicities (DLT) occurred in ≤33% of cases in the previous cohort. DLT was defined as any grade ≥3 toxicity that occurred during the first 8 weeks of therapy. Treatment related adverse events (TRAEs) were categorized using NCI CTCAE version 4.3. Descriptive statistics were used to summarize baseline characteristics and TRAEs. Results: Fifteen patients were included from June 2018 to November 2020. Last study visit was in September 2021. Baseline characteristics of the groups were comparable. The median irradiated tumor volume was 9.13 cc (8.98-9.60 cc) with a mean lung dose of 0.44 Gy (0.14-0.73 Gy). The V20 was nihil (0-0.1%) and the V5 1.8% (0-4%). There was 1 DLT in cohort 3 (colitis grade 3). There was 1 low grade TRAE (pneumonitis grade 2) in cohort 1. In cohort 2, 6 low grade TRAEs (CTC 1-2) were observed and 2 high grade (CTC 3) in 1 patient, who discontinued treatment. In cohort 3, 4 low grade and 1 high grade TRAE occurred. Median progression free survival was 2 months, median overall survival 10 months. Conclusions: No additional toxicity was observed by adding SBRT to the primary tumor to (dual) ICI. Clinical trial information: 2017-002797-39. [Table: see text]

Does the Use of BioZorb® Result in Smaller Breast Seroma Volume?

To evaluate the impact of BioZorb®, a 3D-bioabsorbable marker, on the tumor-bed boost volume and dosimetric parameters in adaptive boost planning for breast cancer. Records were reviewed for 51 breast-cancer patients who underwent breast-conserving surgery and adjuvant whole-breast irradiation between January 2017 and October 2018. Changes in lumpectomy boost volume (LBV), doses to organs at risk, toxicity and cosmesis were compared between patients with and without BioZorb® Chi-square test and paired and independent t-tests were used for comparisons of variables. Median follow-up was 35.5 months. Mean LBV on initial CT (LBV1; 32.2 vs. 33.8 cc, p=0.74) and on boost computed tomography (CT) (LBV2; 25.3 vs. 24.8 cc, p=0.87) were similar with and without BioZorb® The mean decrease from LBV1 to LBV2 was 9.0 cc and 6.8 cc with and without BioZorb®, respectively (p=0.42). LBV1 was significantly positively correlated with a 20% reduction in LBV (p=0.02). Mean heart and lung doses on adaptive boost planning CT were slightly lower compared to initial planning CT in both groups. Acute breast pain was reported in 18/51 patients, 9 of whom had BioZorb® (p=0.24). Grade-2 pain was reported in 5/51 patients, 3 of whom had BioZorb® (p=0.11). Excellent or good cosmesis was reported in 36/41 patients. Fair cosmesis was reported in 5/41 patients, of whom 2 had BioZorb® (p=0.64). BioZorb® placement does not impact the tumor-bed boost volume nor the variation of seroma volume within the period of treatment. More data and longer follow-up are needed to identify a measurable clinical impact of BioZorb® placement.

Comparison of plan dosimetry on multi-targeted lung radiotherapy: A phantom-based computational study using IMRT and VMAT

This work analyzed the dosimetric difference between the intensity modulated radiotherapy (IMRT), partial/single/double-arc volumetric modulated arc therapy (PA/SA/DA-VMAT) techniques in treatment planning for treating more than one target of lung cancer at different isocenters. IMRT and VMAT plans at different isocenters were created systematically using a Harold heterogeneous lung phantom. The conformity index (CI), homogeneity index (HI), gradient index (GI), dose-volume histogram and mean and maximum dose of the PTV were calculated and analyzed. Furthermore, the dose-volume histogram and mean and maximum doses of the OARs such as right lung, contralateral lung and non GTV were determined from the plans. The IMRT plans showed the superior target dose coverage, higher mean and maximum values than other VMAT techniques. PA-VMAT technique shows more lung sparing and DA-VMAT increases the V5/10/20 values of contralateral lung than other VMAT and IMRT techniques. The IMRT technique achieves highly conformal dose distribution to the target than other VMAT techniques. Comparing to the IMRT plans, the higher V5/10/20 and mean lung dose were observed in the contralateral lung in the DA-VMAT.

Towards mid-position based Stereotactic Body Radiation Therapy using online magnetic resonance imaging guidance for central lung tumours.

Background and purpose: Central lung tumours can be treated by magnetic resonance (MR)-guided radiotherapy. Complications might be reduced by decreasing the Planning Target Volume (PTV) using mid-position (midP)-based planning instead of Internal Target Volume (ITV)-based planning. In this study, we aimed to verify a method to automatically derive patient-specific PTV margins for midP-based planning, and show dosimetric robustness of midP-based planning for a 1.5T MR-linac.Materials and methods: Central(n = 12) and peripheral(n = 4) central lung tumour cases who received 8x7.5 Gy were included. A midP-image was reconstructed from ten phases of the 4D-Computed Tomography using deformable image registration. The Gross Tumor Volume (GTV) was delineated on the midP-image and the PTV margin was automatically calculated based on van Herk’s margin recipe, treating the standard deviation of all Deformation Vector Fields, within the GTV, as random error component. Dosimetric robustness of midP-based planning for MR-linac using automatically derived margins was verified by 4D dose-accumulation. MidP-based plans were compared to ITV-based plans. Automatically derived margins were verified with manually derived margins.Results: The mean D95% target coverage in GTV + 2 mm was 59.9 Gy and 62.0 Gy for midP- and ITV-based central lung plans, respectively. The mean lung dose was significantly lower for midP-based treatment plans (difference:-0.3 Gy; ). Automatically derived margins agreed within one millimeter with manually derived margins.Conclusions: This retrospective study indicates that mid-position-based treatment plans for central lung Stereotactic Body Radiation Therapy yield lower OAR doses compared to ITV-based treatment plans on the MR-linac. Patient-specific GTV-to-PTV margins can be derived automatically and result in clinically acceptable target coverage.

Acute and Late Pulmonary Effects After Radiation Therapy in Childhood Cancer Survivors: A PENTEC Comprehensive Review

The Pediatric Normal Tissue Effects in the Clinic (PENTEC) pulmonary task force reviewed dosimetric and clinical factors associated with radiation therapy (RT)-associated pulmonary toxicity in children. Comprehensive search of PubMed (1965-2020) was conducted to assess available evidence and predictive models of RT-induced lung injury in pediatric cancer patients (<21 years old). Lung dose for radiation pneumonitis (RP) was obtained from dose-volume histogram (DVH) data. RP grade was obtained from standard criteria. Clinical pulmonary outcomes were evaluated using pulmonary function tests (PFTs), clinical assessment, and questionnaires. More than 2,400 abstracts were identified; 460 articles had detailed treatment and toxicity data; and 11 articles with both detailed DVH and toxicity data were formally reviewed. Pooled cohorts treated during 1999 to 2016 included 277 and 507 patients age 0.04 to 22.7 years who were evaluable for acute and late RP analysis, respectively. After partial lung RT, there were 0.4% acute and 2.8% late grade 2, 0.4% acute and 0.8% late grade 3, and no grade 4 to 5 RP. RP risk after partial thoracic RT with mean lung dose (MLD) <14 Gy and total lung V20Gy <30% is low. Clinical and self-reported pulmonary outcomes data included 8,628 patients treated during 1970 to 2013, age 0 to 21.9 years. At a median 2.9- to 21.9-year follow-up, patients were often asymptomatic; abnormal PFTs were common and severity correlated with lung dose. At ≥10-year follow-up, multi-institutional studies suggested associations between total or ipsilateral lung doses >10 Gy and pulmonary complications and deaths. After whole lung irradiation (WLI), pulmonary toxicity is higher; no dose response relationship was identified. Bleomycin and other chemotherapeutics at current dose regimens do not contribute substantially to adverse pulmonary outcomes after partial lung irradiation but increase risk with WLI. After partial lung RT, acute pulmonary toxicity is uncommon; grade 2 to 3 RP incidences are <1%. Late toxicities, including subclinical/asymptomatic impaired pulmonary function, are more common (<4%). Incidence and severity appear to increase over time. Upon review of available literature, there appears to be low risk of pulmonary complications in children with MLD < 14 Gy and V20Gy <30% using standard fractionated RT to partial lung volumes. A lack of robust data limit guidance on lung dose/volume constraints, highlighting the need for additional work to define factors associated with RT-induced lung injury.

Treatment planning comparison in the PROTECT-trial randomising proton versus photon beam therapy in oesophageal cancer: Results from eight European centres

PurposeTo compare dose distributions and robustness in treatment plans from eight European centres in preparation for the European randomized phase-III PROTECT-trial investigating the effect of proton therapy (PT) versus photon therapy (XT) for oesophageal cancer. Materials and methodsAll centres optimized one PT and one XT nominal plan using delineated 4DCT scans for four patients receiving 50.4 Gy (RBE) in 28 fractions. Target volume receiving 95% of prescribed dose (V95%iCTVtotal) should be >99%. Robustness towards setup, range, and respiration was evaluated. The plans were recalculated on a surveillance 4DCT (sCT) acquired at fraction ten and robustness evaluation was performed to evaluate the effect of respiration and inter-fractional anatomical changes. ResultsAll PT and XT plans complied with V95%iCTVtotal >99% for the nominal plan and V95%iCTVtotal >97% for all respiratory and robustness scenarios. Lung and heart dose varied considerably between centres for both modalities. The difference in mean lung dose and mean heart dose between each pair of XT and PT plans was in median [range] 4.8 Gy [1.1;7.6] and 8.4 Gy [1.9;24.5], respectively. Patients B and C showed large inter-fractional anatomical changes on sCT. For patient B, the minimum V95%iCTVtotal in the worst-case robustness scenario was 45% and 94% for XT and PT, respectively. For patient C, the minimum V95%iCTVtotal was 57% and 72% for XT and PT, respectively. Patient A and D showed minor inter-fractional changes and the minimum V95%iCTVtotal was >85%. ConclusionLarge variability in dose to the lungs and heart was observed for both modalities. Inter-fractional anatomical changes led to larger target dose deterioration for XT than PT plans.

Repeated Stereotactic Body Radiotherapy for Lung Malignancies: Toxicity Can Be Reduced by Sparing Lung Irradiation.

Evidence on the use of repeated stereotactic body radiotherapy (SBRT) is limited. We investigated the efficacy of repeated SBRT and predictors of lung toxicity. We reviewed 20 patients (27 lesions) with primary or metastatic lung cancer who underwent repeated SBRT with CyberKnife® We generated a composite plan for dosimetric analysis based on equivalent doses in 2.0-Gy fractions (α/β=3). Predictors of Grade 2+ radiation pneumonitis (RP) were examined. The median follow-up duration was 18.0 months. The 1-year and 2-year local control were both 95.2%. Five patients (25%) developed Grade 2+ RP, including a Grade 5 RP. The Grade 2+ RP group showed higher composite mean lung dose (MLD) and lower lung volumes spared from 5-20 Gy (VS5-VS20). Repeated SBRT with CyberKnife® showed favorable local control, but a high rate of Grade 2+ RP. Accumulated MLD and VS5-VS20 may predict RP.

Sol Meme Kanseri Radyoterapisi Simülasyonunda Pron pozisyon mu Supin pozisyon mu ?

Aim: The aim of this study was to compare radiation doses of target volumes and critical organs among prone and supine positions for left-sided breast cancer patients who were treated with breast-conserving surgery and adjuvant radiotherapy. &#x0D; Materials and Methods: The doses of critical organs and target volumes were evaluated by using dose-volume histograms on the new radiotherapy plans of twenty patients.&#x0D; Results: The mean heart dose was lower in the prone position (mean heart doses 656cGy and 933cGy respectively p = 0.01). Mean lung doses for prone and supine positions were 396 cGy and 1032 cGy (p =0.01); lung V5 13% and 33% (p =0.01); lung V10 8% and 25% (p =0.01); lung V20 5% and 17% (p =0.01). &#x0D; Conclusion: Considering that lower doses of normal structures may reduce side effects, prone position may be preferred in patients with left breast cancer.

Artificial Intelligence-Based Automated Treatment Planning of Postmastectomy Volumetric Modulated Arc Radiotherapy.

As a useful tool, artificial intelligence has surpassed human beings in many fields. Artificial intelligence-based automated radiotherapy planning strategies have been proposed in lots of cancer sites and are the future of treatment planning. Postmastectomy radiotherapy (PMRT) decreases local recurrence probability and improves overall survival, and volumetric modulated arc therapy (VMAT) has gradually become the mainstream technique of radiotherapy. However, there are few customized effective automated treatment planning schemes for postmastectomy VMAT so far. This study investigated an artificial intelligence based automated planning using the MD Anderson Cancer Center AutoPlan (MDAP) system and Pinnacle treatment planning system (TPS), to effectively generate high-quality postmastectomy VMAT plans. In this study, 20 patients treated with PMRT were retrospectively investigated, including 10 left- and 10 right-sided postmastectomy patients. Chest wall and the supraclavicular, subclavicular, and internal mammary regions were delineated as target volume by radiation oncologists, and 50 Gy in 25 fractions was prescribed. Organs at risk including heart, spinal cord, left lung, right lung, and lungs were also contoured. All patients were planned with VMAT using 2 arcs. An optimization objective template was summarized based on the dose of clinical plans and requirements from oncologists. Several treatment planning parameters were investigated using an artificial intelligence algorithm, including collimation angle, jaw collimator mode, gantry spacing resolution (GSR), and number of start optimization times. The treatment planning parameters with the best performance or that were most preferred were applied to the automated treatment planning method. Dosimetric indexes of automated treatment plans (autoplans) and manual clinical plans were compared by the paired t-test. The jaw tracking mode, 2-degree GSR, and 3 rounds of optimization were selected in all the PMRT autoplans. Additionally, the 350- and 10-degree collimation angles were selected in the left- and right-sided PMRT autoplans, respectively. The uniformity index and conformity index of the planning target volume, mean heart dose, spinal cord D0.03cc, mean lung dose, and V5Gy and V20Gy of the lung of autoplans were significantly better compared with the manual clinical plans. An artificial intelligence-based automated treatment planning method for postmastectomy VMAT has been developed to ensure plan quality and improve clinical efficiency.

Transparency in quality of radiotherapy for breast cancer in the Netherlands: a national registration of radiotherapy-parameters

BackgroundRadiotherapy (RT) is part of the curative treatment of approximately 70% of breast cancer (BC) patients. Wide practice variation has been reported in RT dose, fractionation and its treatment planning for BC. To decrease this practice variation, it is essential to first gain insight into the current variation in RT treatment between institutes. This paper describes the development of the NABON Breast Cancer Audit-Radiotherapy (NBCA-R), a structural nationwide registry of BC RT data of all BC patients treated with at least surgery and RT.MethodsA working group consisting of representatives of the BC Platform of the Dutch Radiotherapy Society selected a set of dose volume parameters deemed to be surrogate outcome parameters, both for tumour control and toxicity. Two pilot studies were carried out in six RT institutes. In the first pilot study, data were manually entered into a secured web-based system. In the second pilot study, an automatic Digital Imaging and Communications in Medicine (DICOM) RT upload module was created and tested.ResultsThe NBCA-R dataset was created by selecting RT parameters describing given dose, target volumes, coverage and homogeneity, and dose to organs at risk (OAR). Entering the data was made mandatory for all Dutch RT departments. In the first pilot study (N = 1093), quite some variation was already detected. Application of partial breast irradiation varied from 0 to 17% between the 6 institutes and boost to the tumour bed from 26.5 to 70.2%. For patients treated to the left breast or chest wall only, the average mean heart dose (MHD) varied from 0.80 to 1.82 Gy; for patients treated to the breast/chest wall only, the average mean lung dose (MLD) varied from 2.06 to 3.3 Gy. In the second pilot study 6 departments implemented the DICOM-RT upload module in daily practice. Anonymised data will be available for researchers via a FAIR (Findable, Accessible, Interoperable, Reusable) framework.ConclusionsWe have developed a set of RT parameters and implemented registration for all Dutch BC patients. With the use of an automated upload module registration burden will be minimized. Based on the data in the NBCA-R analyses of the practice variation will be done, with the ultimate aim to improve quality of BC RT.Trial registration Retrospectively registered.

Radiotherapy instead of axillary lymph node dissection: evaluation of axillary lymph node dose coverage with whole breast radiotherapy.

BackgroundThe purpose of this study was to investigate the dose coverage of sentinel lymph nodes (SLN), level I, II and III axillary volumes from tangent fields for breast cancer patients with positive SLN without axillary dissection.Materials and methodsIn 30 patients with cN0 invasive breast cancer treated with breast conserving surgery and SLN biopsy, the SLN area was intraoperatively marked with a titanium clip. Retrospectively, the SLN area and axillary target volumes were contoured, and three plans [standard tangent fields (STgF), high tangent fields (HTgF), and STgF + axillary-supraclavicular field] were generated for each patient. The prescribed dose was standardized to 50 Gy in 2 Gy fractions to the isocenter.ResultsThe mean dose with STgF or HTgF was 33.1 and 49.1 Gy (p = 0.0001) in the SLN area, 25.7 and 45.1 Gy (p < 0.0001) in the volume of level I, 7.2 and 28.9 Gy (p < 0.0001) in the level II and 3.5 and 12.7 Gy (p = 0.0003) in the level III. Adequate therapeutic doses to the level II or III volumes were delivered only with STgF + axillary-supraclavicular field. The mean dose of ipsilateral lung was the highest with the three-field-technique, 9.9 Gy. SLN area, level I, II or III were completely included in the HTgF with 93.3%, 73.3%, 13.3% and 0%, respectively.ConclusionsSLN area should be marked by surgical clip and axillary target volumes should be contoured to obtain accurate dose estimations. The use of HTgF improve axillary coverage.

A Dosimetric Study Comparing 3D-CRT vs. IMRT vs. VMAT in Left-Sided Breast Cancer Patients After Mastectomy at a Tertiary Care Centre in Eastern India.

IntroductionPost-mastectomy radiation in left-sided breast cancer in women continues to pose a significant risk to the underlying lungs and heart. This study analyzed the difference in planning target volume (PTV) coverage and dose to the organs at risk (OAR) by using three different planning methods for the same patient - three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric-modulated arc therapy (VMAT).Material and methodsThirty-five left-sided breast cancer patients’ post-mastectomy were included in this study, and three different plans for adjuvant radiation were created using 3D-CRT, IMRT, and VMAT. The prescribed dose was 50Gy in 25 fractions. Kruskal-Wallis analysis of variance (ANOVA) was done, followed by a pairwise t-test to establish a hierarchy of plan quality and dosimetric benefits. The plans were compared with PTV95, homogeneity index (HI), conformity index (CI), hotspot (V107%), left lung V20Gy, mean lung dose, heart V25Gy, mean heart dose, and integral dose (ID) to the body.ResultsBoth VMAT and IMRT led to improved PTV95% coverage (95.63±1.82%, p=0.000 in VMAT; 93.70±2.16 %, p=0.000; 81.40±6.27% in 3D-CRT arm) and improved CI (0.91±0.06 in IMRT [p<0.05] and 0.96±0.02 for VMAT plans [p<0.05]) as compared to 3D-CRT (0.66±0.11), which was statistically significant on pairwise analysis. In contrast, the difference in HI and reduction in hotspots were not significantly different. Left lung V20 was statistically very different between the three arms with the highest values in IMRT (36.64±4.45) followed by 3D-CRT (34.80±2.24) and the most negligible value in VMAT (33.03±4.20). Mean lung dose was also statistically different between the three arms. There was a statistically significant difference in mean heart dose between the three arms on pairwise analysis. Both the inverse planning methods led to a statistically significant increase in low dose volume (V5 and V10) of the ipsilateral lung, opposite lung, and heart, and increased ID to the body excluding the PTV.ConclusionWhile both the inverse planning modalities led to increased coverage, better CI, and better HI and decreased high dose volumes in OARs, there was increased low volume irradiation of heart, lungs, and body with VMAT faring marginally better than IMRT in coverage and decreasing lung irradiation with comparable heart irradiation.