Breast Dose Research Articles

Technical feasibility of delivering a simultaneous integrated boost in partial breast irradiation

Feasibility of volumetric modulated arc therapy (VMAT) for partial breast irradiation (PBI) with simultaneous integrated boost (SIB) to tumour bed was investigated. Four plans were created for 10 patients: 30 Gy/5 fractions, 26 Gy/5 fractions with 30 Gy SIB, 40.05 Gy/15 fractions, and 40.05 Gy/15 fractions with 48 Gy SIB. SIB in the 5 fraction arm had reduced ipsilateral breast dose relative to uniform dose. SIB in the 15 fraction arm had noninferior conformity compared to uniform dose. Addition of SIB did not increase other organ-at-risk doses or plan complexity. VMAT PBI with SIB was feasible for both fractionation regimens.

Proton Pencil Beam Scanning Facilitates the Safe Treatment of Extended Radiation Targets for Hodgkin Lymphoma: A Report from the Proton Collaborative Group Registry.

Because proton beam therapy (PBT) can lower the dose of radiation to the heart, lungs, and breast, it is an established radiation modality for patients with Hodgkin lymphoma (HL). Pencil beam scanning (PBS) PBT facilitates the treatment of more extensive targets. This may be especially of value for lymphoma patients who require RT to both mediastinal and axillary targets, defined here as extended target RT (ETRT), given the target distribution and need to minimize the lung, heart, and breast dose. Using the Proton Collaborative Group registry, we identified patients with HL treated with PBT to both their mediastinum and axilla, for which DICOM-RT was available. All patients were treated with PBS. To evaluate the dosimetric impact of PBS, we compared delivered PBS plans with VMAT butterfly photon plans optimized to have the same target volume coverage, when feasible. Between 2016 and 2021, twelve patients (median 26 years) received PBS ETRT (median 30.6 Gy (RBE)). Despite the large superior/inferior (SI, median 22.2 cm) and left/right (LR, median 22.8 cm) extent of the ETRT targets, all patients were treated with one isocenter except for two patients (both with SI and LR > 30 cm). Most commonly, anterior beams, with or without posterior beams, were used. Compared to photons, PBS had greater target coverage, better conformity, and lower dose heterogeneity while achieving lower doses to the lungs and heart, but not to the breast. No acute grade 3+ toxicities were reported, including pneumonitis. Proton ETRT in this small cohort was safely delivered with PBS and was associated with an improved sparing of the heart and lungs compared to VMAT.

Pediatrics organ dose and lifetime attributable cancer risk estimates in routine computed tomography

ObjectivesEvaluating organ doses received by pediatric patients and estimating lifetime attributable risk (LAR) in Riyadh, Saudi Arabia from chest and abdominal pelvic Computed Tomography (CT) scans. MethodsA total of 155 patients under the age of 15 were divided into four age groups: under 1, 1–5, 5–10, and 10–15. The organ dose was determined using the National Cancer Institute dosimetry system for (NCICT) software, and the LAR if cancer incident was measured according to the BEIR VII report. The 1st, 2nd, and 3rd quartiles were calculated for organs received primary X-ray beams. ResultsThe highest and lowest median doses were for the kidney in the 10-15-year-old group 4.84 mGy (Cl95%, 0.15–9.54) and the prostate in the >1-year-old group 0.02 mGy (Cl95%, −0.01 – 0.05), respectively. Furthermore, there was a correlation between age and breast doses in chest scans, as median doses increased from 0.08 mGy to 3.70 mGy. Breast cancer in females had a highest LAR from chest CT and colon cancer in abdomen-pelvic CT. The group 1–5 years old had the highest risk of breast cancer, followed by chest CT (LAR = 25.94). However, colon cancer (LAR = 10.39), followed by an abdomen-pelvic CT, had the highest risk in the same group in both genders. Colon and breast cancers had the highest LAR among males and females in all groups. ConclusionThe study found that older patients received higher median organ doses for the same examination than younger patients. Females have greater organ doses in the thorax compared to males, resulting in a higher mean LAR. While CT scans are useful tools for diagnosis, it's essential to consider the patient's dose, particularly in pediatric cases.

Comparison of Lung and Contralateral Scattered Breast Dose between Field-in-Field and Wedge Techniques in Patients with Early Breast Cancer

Purpose: This study aims to evaluate the dosimetric result of the Field-In-Field (FIF) plans compared with Tangential Wedged Beams (TWB) plans for whole breast radiotherapy of patients. Materials and Methods: In this survey, we entered fifty patients with breast-conserving surgery and postoperative whole-breast radiotherapy. FIF and a TWB plan were made for each patient to compare dosimetric outcomes. Results: The Homogeneity Index (HI) and Conformity Index (CI) were specified for the evaluation of Planning Target Volume (PTV). The mean dose of the ipsilateral lung and contra-lateral breast for the evaluation of organs at risk dose were used. The FIF plans had significantly lower HI (p < 0.01) and CI (p < 0.01) than those of the TWB plans. It means in the dosimetric comparisons of the PTV, the FIF plans were better than the TWB plans. The V10lung (31.152vs. 32.72%, p < 0.01), V20lung (25.6064vs. 26.6%, p < 0.01) V30lung (17.4% vs. 18.4%, p < 0.01) were lower with the FIF plans compared with those of the TWB plans, with statistical significance. The FIF plans had a lower mean dose for the lung than those of TWB plans (1225.48 vs. 1670.32 cGy) but no statistical significance (p=0.06). The mean dose in the contra-lateral of the breast in FIF plans was lower than in TWB plans (61.666 vs. 163.45 cGy), with statistical significance (p < 0.01). Conclusion: The FIF plans increased the dose homogeneity, and conformity of the target volume for the whole-breast irradiation compared with the TWB plans. Moreover, the doses of organs at risk (ipsilateral lung and contralateral breast) were reduced with FIF plans.

Absorbed dose, effective dose and lifetime attributable risk of breast and thyroid cancers in coronary CT angiography: A comparison between 64 and 128 slice CT scanners

The attentive consideration of absorbed dose impact on the breast, a radiosensitive organ, remains pivotal in coronary computed tomography angiography (CCTA). Additionally, the thyroid is subjected to scatter radiation during this diagnostic procedure. The primary objective of this study was to comprehensively investigate and quantify the absorbed dose, effective dose, and lifetime attributable risks (LARs) associated with breast and thyroid cancers in the context of CCTA. This investigation enrolled a cohort of 180 patients (90 men and 90 women) who underwent CCTA utilizing three distinct CT scanners: the SOMATOM Definition AS 128 slice (Siemens 128), the Lightspeed VCT 64 Slice (GE 64), and the Brilliance 64 Slice (Philips 64). The precise quantification of absorbed doses to the breast and thyroid was achieved through the utilization of a thermoluminescence dosimeter (TLD). LAR for breast and thyroid cancers was evaluated in accordance with the BEIR VII report. Kruskal–Wallis test was employed to compare the means of absorbed doses and LARs. The average absorbed doses to the breast during CCTA with Siemens 128, GE 64, and Philips 64 scanners were 116.32 ± 39.02, 82.88 ± 18.33, and 84.11 ± 15.18 mGy, respectively (P < 0.05). Correspondingly, the average LAR for breast cancer was found to be 84, 68, and 52 cases per 100,000 persons, respectively. Notably, a significant discrepancy in breast cancer LARs was observed among different age groups (P < 0.05). Regarding thyroid doses with Siemens 128, GE 64, and Philips 64 scanners, average values were 11.82 ± 7.51, 12.20 ± 10.87, and 14.49 ± 5.43 mGy, respectively (P > 0.05). Additionally, the average LAR for thyroid cancer was determined as 0.32, 0.56, and 0.22 cases per 100,000 persons, respectively. Across all age groups, the LAR for thyroid cancer exhibited higher values among women compared to men. However, these differences did not achieve statistical significance (P > 0.05), indicating a need for further investigation. The findings prominently indicated high absorbed doses to the breast in CCTA using protocols investigated in this study (with an average of 93.7 ± 30.26 mGy). Particularly, the LAR for breast cancer was higher among younger women, specifically those aged between 20 and 40 years (249 cases per 100,000). These results underscore the necessity for further justification and optimization of CCTA protocols.

Hybrid Treatment Planning for Chest Wall Irradiation Utilizing Three-Dimensional Conformal Radiotherapy (3DCRT), Intensity-Modulated Radiation Therapy (IMRT), and Volumetric Modulated Arc Therapy (VMAT): A Systematic Review.

Novel hybrid approaches for chest wall irradiation show promising outcomes regarding target coverage and sparing organs at risk (OARs). In this systematic review, we compared hybrid volumetric modulated arc therapy (H-VMAT) or hybrid intensity-modulated radiotherapy (H-IMRT) techniques with non-hybrid techniques, such as three-dimensional conformal radiation therapy (3DCRT), field-in-field (FIF), intensity-modulated arc therapy (IMRT), and volumetric modulated arc therapy (VMAT), for breast cancer patients with mastectomy. Our focus was the plan quality and dose distribution to the OARs. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, we performed a systematic review and quality appraisal of primary studies evaluating hybrid therapy to the chest wall and the OARs. An extensive online search of PubMed and Scopus databases was conducted using appropriate keywords. The dose to the OARs (lung, heart, and contralateral breast), planning target volume (PTV), homogeneity index (HI), and conformity index (CI) were extracted. The data were then tabulated and compared for the outcomes between modalities among the studies.Nine studies that met the search criteria were selected to evaluate the PTV coverage and dosimetric results of hybrid and non-hybrid techniques. In terms of 95% PTV coverage, among nine reviewed studies, the largest difference between the two techniques was between VMAT (47.6 Gy) and H-VMAT (48.4 Gy); for the conformity index, the largest difference was noted between 3DCRT (0.58) and H-VMAT (0.79). In both cases, differences were statistically significant (P < 0.005). Two studies showed dose homogeneity improvement within the treatment target in H-VMAT (0.15 and 0.07) compared with 3DCRT (0.41 and 0.12), with a P value of <0.001. Two studies did not report on the homogeneity index, and three others observed no statistical difference. Regarding OARs, in the comparison of H-VMAT and VMAT, the largest significant change was in the volume receiving 5 Gy (V5Gy) of the ipsilateral lung and the V10Gy of the contralateral lung. For the ipsilateral lung, V5Gy was 90.7% with VMAT versus 51.45% with H-VMAT. For the contralateral lung, V10Gy was 54.9% with VMAT versus 50.5% with H-VMAT. In six studies, the mean dose of the contralateral breast was lower in hybrid techniques than in single modalities: VMAT (4.2%, 6.0%, 1.9%, 7.1%, 4.57%) versus H-VMAT (1.4%, 3.4%, 1.8%, 3.5%, 2.34%)and IMRT (9.1%) versus H-IMRT (4.69%). Although most studies did not report on monitor units and treatment time, those that included them showed that hybrids had lower monitor units and shorter treatment times.Hybridtechniques in radiotherapy, such as combining two modalities, can indeed facilitate lower doses to OARsfor patients with a high risk of toxicities. Prospective clinical studies are needed to determine the outcomes of breast cancer treated with hybrid techniques.

Abstract PO5-22-02: Evaluation of a surface-guided and tattoo-less approach to setup for whole breast radiotherapy

Abstract Background: In preparation for adjuvant breast radiation therapy (RT), several small but permanent skin tattoo marks are often placed to assist with surface alignment for treatment setup and delivery. With advancements in surface-guided technologies, it may be possible to achieve setup accuracy with a “tattoo-less” approach, which can improve cosmetic and quality of life outcomes. This study evaluates the feasibility, accuracy, and potential dosimetric implications of a tattoo-less setup technique. Method: A retrospective analysis of 10 patients diagnosed with right-sided breast cancer who received adjuvant whole breast RT using a tattoo-less approach were included in this study. All patients received an initial whole breast dose of 42.56 Gray (Gy) in 16 daily fractions using a tangential three-dimensional conformal planning technique. This was followed by a 10Gy boost to the lumpectomy site delivered in 4 daily fractions. Daily setup for whole breast treatment was performed by aligning each patient to their individual reference breast surface generated from the planning computed tomography (CT) images via the Vision RT system. Bony landmarks were then verified via daily kV imaging, and translational shifts were recorded for each fraction. The kV imaging was performed to confirm the treatment positioning since the tattoo-less approach was new to the department. For 5 patients, dosimetric differences between initial surface alignment and shifts performed based on bony landmarks were evaluated by recalculating the original clinical plan with a new isocenter position using kV image shifts for each of their 16 treatment fractions. A plan sum of the 16 recalculated plans for each patient was used in further dosimetric analysis. Boost fractions were not included in this study, as setup was verified using surgical clips instead of bony anatomy. Results: Translational shifts for 158 fractions were reviewed as no kV imaging was performed for the other 2 fractions. The mean absolute kV imaging shift was 0.29 cm (CI (95%): 0.25, 0.32; range: 0 to 1.25) in the vertical axis, 0.28 cm (0.23, 0.32; 0 to 1.27) in the longitudinal axis, and 0.24 cm (0.20, 0.28; 0 to 1.98) in the lateral axis. Clinical plans for 5 patients were evaluated with a mean absolute kV shift of 0.27 cm (range: 0.15 to 0.39) in the vertical, 0.32 cm (0.13 to 0.77) in the longitudinal, and 0.29 cm (0.18 to 0.38) in the lateral directions. Dosimetric analysis revealed a slight increase in mean heart dose from the original clinical plan, with an average difference of 4.12 cGy (range: 0.7 to 10.5 cGy). The maximum increase in V20Gy of the ipsilateral lung was 2.7%. Less than 1% of change was observed in the maximum plan dose, as well as in the V95% coverage, expect for one patient, whose V95% was decreased from 99.6% to 94.6%. This difference was caused by a large longitudinal shift which could be attributed to possible patient movement. Conclusions: These findings demonstrate the feasibility and accuracy of a tattoo-less treatment approach in a small cohort of breast cancer patients receiving whole breast RT. Further investigation with larger cohorts is warranted. Citation Format: Xinxin Zhang, Swati Mamidanna, Yin Zhang, Xiao Wang, Ning Yue, Shicha Kumar, Lindsay Potdevin, Maria Kowzun, Mridula George, Lara Hathout, Bruce Haffty, Nisha Ohri. Evaluation of a surface-guided and tattoo-less approach to setup for whole breast radiotherapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-22-02.

Bryonia aspera Root Extracts Induce Programmed Cell Death in Selected Cell Lines of Glioblastoma, Ovarian, and Breast Cancer

Background. Medicinal plants have been remarkable sources of current chemotherapeutic agents. Ethnobotanical utilization of Bryonia species goes back to the old era, and contemporary but preliminary studies have evidenced the anticancer effects of this kind of plant. Methods. The MTT assay was used to investigate the cytotoxicity of a range of concentrations from different extracts of Bryonia aspera root in cancer and noncancer cells. The apoptosis was assessed using annexinV-FITC/PI flow cytometry assay. The expression of selected hallmark genes from different cell death modalities, including apoptosis, necroptosis, ferroptosis, and pyroptosis, was investigated using the qPCR method. The ROS production was also measured by the fluorescence technique. Results. Compared to the normal cells, all three extracts could induce significant cell death in lower doses in breast, ovarian, and glioblastoma cancer cells. Flow cytometry and gene expression studies revealed that different extracts of Bryonia aspera tend to induce different types of cell death in the selective cancer cell lines. ROS production was not impacted significantly by any of those three extracts in none of the cancer cells. Conclusion. The findings showed that all three extracts of Bryonia aspera root contain biologically active compounds that induce different types of programmed cell death in the investigated breast, ovarian, and glioblastoma cancer cells in concentrations significantly less than the doses affecting normal cells.

Monte Carlo study on nanogold dose enhancement for breast radiotherapy using an ICRP female computational phantom

Due to distinct photoelectric absorption properties and physiochemical features, high-atomic-element nanomaterials are frequently used as radiosensitizer for radiotherapy, such as gold nanoparticles. which in-turn can increase radiation dose to tumours while minimizing exposure to normal tissues. The aim of this study is to investigate the dose enhancement due to the presence of nanogold particles mixed with breast tissue using a real radiotherapy plan with two photon energies, with and without flattening filter. A fully validated linac head was used to model a complete field-in-field (FIF) radiotherapy breast plan using 4 and 6 MV with a flattening filter (FF) and flattening filter-free (FFF) using BEAMnrc/EGSnrc MC code. The dose distributions were simulated in a female ICRP voxel computational phantom. The dose enhancement ratio (DER) and flattening filter-free enhancement ratio (FFFER) were calculated for a range of nanogold concentrations. The results showed that the DER increased with increasing nanogold concentration. The maximum DER was achieved when FFF was used and the increase was higher for 4 MV than 6 MV. The FFFER was higher for the 4 MV beam than 6 MV when 40 mg/ml nanogold was used. The combination of higher nanogold concentrations, lower photon energies, and FFF resulted in a higher dose enhancement. The implementation of nanogold particles in breast tissue enhanced the dose deposition, especially with FFF, as presented in this study. The results would improve nanogold-enhanced breast radiotherapy and dose delivery with an increase in patient throughput.

Dosimetric Comparison of CPAP and DIBH for Left-sided Breast Cancer Radiation Therapy

PurposeDespite the increasing interest in using continuous positive airway pressure (CPAP) in radiotherapy (RT), direct comparisons with the more widely employed deep inspiration breath-hold (DIBH) have been limited. This planning study aimed to offer comprehensive geometric and dosimetric evidence by comparing CPAP and DIBH-based RT plans. Materials and MethodsA retrospective dataset of 35 left-sided breast cancer patients with planning CT (pCT) scans under three breathing conditions (free breathing, CPAP with 10 cmH2O pressure, and DIBH) was collected. Volumetric arc therapy plans aimed for 95% dose coverage to 95% of the planning target volume with a maximum dose below 107%. A comparative dosimetric analysis among the three plans was conducted. Additionally, geometric differences were assessed by calculating the minimum distance between the heart and the clinical target volume (CTV) in each pCT. ResultsCPAP and DIBH plans demonstrated comparable mean heart doses (1.05 Gy), which were significantly lower than the FB plan (1.34 Gy). The maximum dose to the left anterior descending artery was smallest in the CPAP plan (4.44 Gy), followed by DIBH (4.73 Gy) and FB (7.33 Gy). Other organ-at-risk doses for CPAP and DIBH were similar, with mean contralateral breast doses of 2.27 and 2.21 Gy, mean ipsilateral lung doses of 4.09 and 4.08 Gy, V20 at 6.11 and 6.31%, and mean contralateral lung doses of 0.94 and 0.92 Gy, respectively. No significant difference was found in the minimum heart-to-CTV distance between CPAP and DIBH. DIBH exhibited the greatest lung volume (3908 cc), followed by CPAP (3509 cc), and FB (2703 cc). ConclusionThe comparison between CPAP and DIBH shows their similarity in both geometric and dosimetric aspects, providing strong evidence for CPAP's effectiveness and feasibility in RT. This suggests its potential as an alternative to DIBH for left-sided breast cancer patients.

Dosimetric Impact of Voluntary Deep Inspiration Breath Hold (DIBH) in Mediastinal Hodgkin Lymphomas: A Comparative Evaluation of Three Different Intensity Modulated Radiation Therapy (IMRT) Delivery Methods Using Voluntary DIBH and Free Breathing Techniques.

Hodgkin lymphomas are radiosensitive and curable tumors that often involve the mediastinum. However, the application of radiation therapy to the mediastinum is associated with late effects including cardiac and pulmonary toxicities and secondary cancers. The adoption of conformal IMRT and deep inspiration breath- hold (DIBH) can reduce the dose to healthy normal tissues (lungs, heart and breast). We compared the dosimetry of organs at risk (OARs) using different IMRT techniques for two breathing conditions, i.e., deep inspiration breath hold (DIBH) and free breathing. Twenty-three patients with early-stage mediastinal Hodgkin lymphomas were accrued in the prospective study. The patients were given treatment plans which utilized full arc volumetric modulated arc therapy (F-VMAT), Butterfly VMAT (B-VMAT), and fixed field IMRT (FF-IMRT) techniques for both DIBH and free breathing methods, respectively. All the plans were optimized to deliver 95% of the prescription dose which was 25.2 Gy to 95% of the PTV volume. The mean dose and standard error of the mean for each OAR, conformity index (CI), and homogeneity index (HI) for the target using the three planning techniques were calculated and compared using Student's t-test for parametric data and Wilcoxon signed-rank test for non-parametric data. The HI and CI of the target was not compromised using the DIBH technique for mediastinal lymphomas. The mean values of CI and HI for both DIBH and FB were comparable. The mean heart doses were reduced by 2.1 Gy, 2.54 Gy, and 2.38 Gy in DIBH compared to FB for the F-VMAT, B-VMAT, and IMRT techniques, respectively. There was a significant reduction in V5Gy, V10Gy, and V15Gy to the heart (p < 0.005) with DIBH. DIBH reduced the mean dose to the total lung by 1.19 Gy, 1.47 Gy, and 1.3 Gy, respectively. Among the 14 female patients, there was a reduction in the mean right breast dose with DIBH compared to FB (4.47 Gy vs. 3.63 Gy, p = 0.004). DIBH results in lower heart, lung, and breast doses than free breathing in mediastinal Hodgkin Lymphoma. Among the different IMRT techniques, FF-IMRT, B-VMAT, and F-VMAT showed similar PTV coverage, with similar conformity and homogeneity indices. However, the time taken for FF-IMRT was much longer than for the F-VMAT and B-VMAT techniques for both breathing methods. B-VMAT and F-VMAT emerged as the optimal planning techniques able to achieve the best target coverage and lower doses to the OARs, with less time required to deliver the prescribed dose.

Validating the safety of low-dose CTPA in pregnancy: results from the OPTICA (Optimised CT Pulmonary Angiography in Pregnancy) Study.

Pulmonary embolism (PE) is a leading cause of pregnancy-related mortality. CT pulmonary angiogram (CTPA) is the first-line advanced imaging modality for suspected PE in pregnancy at institutes offering low-dose techniques; however, a protocol balancing safety with low dose remains undefined. The wide range of CTPA doses reported in pregnancy suggests a lack of confidence in implementing low-dose techniques in this group. To define and validate the safety, radiation dose and image quality of a low-dose CTPA protocol optimised for pregnancy. The OPTICA study is a prospective observational study. Pregnant study participants with suspected PE underwent the same CTPA protocol between May 2018 and February 2022. The primary outcome, CTPA safety, was judged by the reference standard; the 3-month incidence of venous thromboembolism (VTE) in study participants with a negative index CTPA. Secondary outcomes defined radiation dose and image quality. Absorbed breast, maternal effective and fetal doses were estimated by Monte-Carlo simulation on gestation-matched phantoms. Image quality was assessed by signal-to-noise and contrast-to-noise ratios and a Likert score for pulmonary arterial enhancement. A total of 116 CTPAs were performed in 113 pregnant women of which 16 CTPAs were excluded. PE was diagnosed on 1 CTPA and out-ruled in 99. The incidence of recurrent symptomatic VTE was 0.0% (one-sided 95% CI, 2.66%) at follow-up. The mean absorbed breast dose was 2.9 ± 2.1mGy, uterine/fetal dose was 0.1 ± 0.2mGy and maternal effective dose was 1.4 ± 0.9mSv. Signal-to-noise ratio (SNR) was 11.9 ± 3.7. Contrast-to-noise ratio (CNR) was 10.4 ± 3.5. The OPTICA CTPA protocol safely excluded PE in pregnant women across all trimesters, with low fetal and maternal radiation. OPTICA (Optimised CT Pulmonary Angiography in Pregnancy) is the first prospective study to define the achievable radiation dose, image-quality and safety of a low-dose CT pulmonary angiogram protocol optimised for pregnancy (NCT04179487). It provides the current benchmark for safe and achievable CT pulmonary angiogram doses in the pregnant population. • Despite the increased use of CT pulmonary angiogram in pregnancy, an optimised low-dose protocol has not been defined and reported doses in pregnancy continue to vary widely. • The OPTICA (Optimised CT Pulmonary Angiography in Pregnancy) study prospectively defines the achievable dose, image quality and safety of a low-dose CT pulmonary angiogram protocol using widely available technology. • OPTICA provides a benchmark for safe and achievable CT pulmonary angiogram doses in the pregnant population.

Radiation doses received in the UK breast screening programmes 2019-2023.

To report the latest UK mammography dose survey results and to compare radiation doses from digital breast tomosynthesis (DBT) and full-field digital mammography (FFDM) in UK breast screening. Anonymized exposure factors were collected for 111 152 screening cases and 5113 assessment cases from 405 x-ray sets across the United Kingdom using an online submission system linked to a national database of mammography quality control data. Output and beam quality measurements from each set were combined with exposure data to estimate mean glandular doses (MGD). FFDM doses increased by ∼10% compared to the 2016-2019 national survey but compressed breast thicknesses (CBT) remained similar. DBT doses were 34%-40% higher than FFDM overall and 34% higher than FFDM for breasts 50-60mm thick. We found a possible overestimation of PMMA breast equivalent thicknesses at low CBTs, but the evidence was not conclusive. Recent changes to the mix of x-ray models in use in UK breast screening have resulted in higher FFDM breast doses. DBT doses in the NHSBSP are on average higher than FFDM by ∼34%-40%. This is the first national study to report DBT and FFDM MGDs in UK breast screening.

Evaluation of organ dose using size-specific dose estimation (SSDE) and related cancer risk due to chest CT scan during the COVID-19 pandemic.

This study aimed to estimate lung and breast doses for individual patients using the size-specific dose estimate (SSDE) method, as well as calculating effective doses, in patients who underwent chest CT scans during the COVID-19 pandemic. Cancer risk incidence was estimated using excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) models from the Biological Effects of Ionizing Radiation Report VII (BEIR-VII). Data from about 570 patients who underwent CT scans for COVID-19 screening were utilized for this study. Using the header of the CT images in a Python script, SSDE and effective dose were calculated for each patient. The SSDE obtained by water equivalent effective diameter (wSSDE) was considered as lung and breast dose, and applied in organ-specific cancer risk estimation. The mean wSSDE value for females (13.3mGy) was slightly higher than that for males (13.1mGy), but the difference was not statistically significant (P value=0.41). No significant differences were observed between males and females in terms of calculated EAR and ERR for lung cancer at 5 and 30years after exposure (P value=0.47, 0.46, respectively). Similarly, there was no significant difference in lung cancer LAR values between females and males (P value=0.48). The results also indicated a decrease in LAR values for both lung and breast cancers with increasing exposure age. In accordance with the ALARA (as low as reasonably achievable) principle, it is important for medical staff and the general public to consider the benefits of CT imaging in detecting such infections. Additionally, imaging medical physicists and CT scan experts should optimize imaging protocols and strike a balance between image quality for detecting abnormalities and radiation dose, all while adhering to the ALARA principle.

A Comparative Analysis of Implant-sparing Plan Versus Conventional Plans Utilizing Helical Tomotherapy in Breast Cancer Patients Undergoing Breast Reconstruction.

To compare implant sparing irradiation with conventional radiotherapy (RT) using helical (H) and TomoDirect (TD) techniques in breast cancer patients undergoing immediate breast reconstruction (IBR). The dosimetric parameters of 40 patients with retropectoral implants receiving 50.4 Gy delivered in 28 fractions were analyzed. Three plans were created: H plan using conventional planning target volume (PTV) that included the chest wall, skin, and implant; TD plan using conventional PTV; and Hs plan using implant-sparing PTV. The H, TD, and Hs plans were compared for PTV doses, organ-at-risk (OAR) doses, and treatment times. Dose distribution in the Hs plan was less homogeneous and uniform than that in the H and TD plans. The TD plan had lower lung, heart, contralateral breast, spinal cord, liver, and esophagus doses than the Hs plan. Compared to the Hs plan, the H plan had lower lung volume receiving 5Gy (V5) (39.1±3.9 vs. 41.2±3.9 Gy; p<0.001), higher V20 (12.3±1.3 vs. 11.5±2.6 Gy; p=0.02), and higher V30 (7.5±1.6 vs. 4.4±1.7 Gy; p<0.001). H plan outperformed Hs plan in heart dosimetric parameters except V20. The Hs plan had significantly lower mean implant doses (43.4±2.1 Gy) than the H plan (51.4±0.5 Gy; p<0.001) and the TD plan (51.9±0.6 Gy; p<0.001). Implementing an implant sparing technique for silicone dose reduction decreases lung doses. Conventional H and TD plans outperform the implant sparing helical plan dosimetrically. Because capsular contracture during RT is unpredictable, long-term clinical outcomes are required to determine whether silicon should be spared.

Quality assurance of radiation therapy after breast-conserving surgery among patients in the BOOG 2013-08 trial

Background and purposeIn the BOOG 2013-08 trial (NCT02271828), cT1-2N0 breast cancer patients were randomized between breast conserving surgery with or without sentinel lymph node biopsy (SLNB) followed by whole breast radiotherapy (WBRT). While awaiting primary endpoint results (axillary recurrence rate), this study aims to perform a quality assurance analysis on protocol adherence and (incidental) axillary radiation therapy (RT) dose. Materials and methodsPatients were enrolled between 2015 and 2022. Data on prescribed RT and (in 25% of included patients) planning target volumes (PTV) parameters were recorded for axillary levels I-IV and compared between treatment arms. Multivariable linear regression analysis was performed to determine prognostic variables for incidental axillary RT dose. Results1,439/1,461 included patients (98.5%) were treated according to protocol and 87 patients (5.9%) received regional RT (SLNB 10.9%, no-SLNB 1.5 %). In 326 patients included in the subgroup analysis, the mean incidental PTV dose at axilla level I was 59.5% of the prescribed breast RT dose. In 5 patients (1.5%) the mean PTV dose at level I was ≥95% of the prescribed breast dose. No statistically or clinically significant differences regarding incidental axillary RT dose were found between treatment arms. Tumour bed boost (yes/no) was associated with a higher incidental mean dose in level I (R2 = 0.035, F(6, 263) = 1.532, p 0.168). ConclusionThe results indicate that RT-protocol adherence was high, and that incidental axillary RT dose was low in the BOOG 2013-08 trial. Potential differences between treatmentarms regarding the primary endpoint can thus not be attributed to different axillary radiation doses.

The Feasibility of Tube Current Modulation (TCM) to Reduce dose of the Surface Breast in Various Breast Sizes

This study aims to develop three sizes of breast phantoms from silicone rubber (SR) material and evaluate tube current modulation (TCM) to reduce surface doses of the developed breast phantoms. The in-house breast phantom has three sizes: small (cup 34), medium (cup 36), and large (cup 38). The cross-sectional areas of cup 34, 36, and 38 are 78.5, 113.04, and 153.87 cm2, respectively. The in-house phantom was attached to the adult anthropomorphic phantom for dose measurement. Dose measurement was performed using an Optically Stimulated Luminescence (OSL) dosimeter. Scans were performed with and without TCM technique. It was found that the TCM effectively reduce the radiation dose to the breast surface up to approximately 60%. However, the dose reduction was accompanied by a 66% increase in noise when using the TCM technique.

Evaluation of patient radiation dose and risk of cancer from CT examinations.

Computed tomography (CT) examinations have been increasingly requested and become the major sources of patient exposure. The cancer risk from CT scans is contingent upon the amount of absorbed dose of organs. This study aims to determine the organ doses and risk of cancer incidence and mortality from CT examinations at high dose (cumulative effective dose, CED ≥ 100mSv) in a single day to low dose (CED < 100mSv) from common CT procedures. Data were gathered from two academic centers of patients aged 15 to 75years old performed CT examinations during the period of 5years. CED and organ dose were calculated using Monte Carlo simulation software. Lifetime attributable risk (LAR) was determined following Biological Effects of Ionizing Radiation (BEIR) VII report based on life table and baseline cancer rates of Thai population. At high dose, the highest LAR for breast cancer incidence in young female was 82 per 100,000 exposed patients with breast dose of 148mGy (CT whole abdomen). The highest LAR for liver cancer incidence in male patient was 72 per 100,000 with liver dose of 133mGy (multiple CT scans). At low dose, the highest average LAR for breast cancer incidence in young female was 23 per 100,000 while for liver cancer incidence in male patients was 22 per 100,000 (CTA whole aorta). Even though the LAR of cancer incidence and mortality was less than 100 per 100,000, they should not be neglected. The risk of cancer incidence may be increased in later life, particularly in young patients.

An investigation on protection properties of Tantalum (V) oxide reinforced glass screens on unexposed breast tissue for mammography examinations

IntroductionThe utilization of radiation shielding material positioned between the both breasts are crucial for the reduction of glandular dose and the safeguarding of the contralateral breast during mammographic procedures. This study proposes an alternative substance for shielding the contralateral breast from radiation exposure during mammography screening. MethodsIn this study, we present an analysis of the shielding effectiveness of transparent glass that has been doped with Tantalum (V) oxide encoded as BTZT6. The evaluation of this shielding material was conducted using the MCNPX code, specifically for the ipsilateral and contralateral breasts. The design of the left and right breast phantoms involved the creation of three-layer heterogeneous breast phantoms, consisting of varying proportions of glandular tissue (25%, 50%, and 75%). The design of BTZT6 and lead-acrylic shielding screens is implemented using the MCNPX code. The comparative analysis of dose outcomes is conducted to assess the protective efficacy of BTZT6 and lead-acrylic shielding screens. ResultsThe utilization of BTZT6 shielding material resulted in a reduction in both breast dose and skin dose exposure when compared to the lead-acrylic shield. ConclusionBased on the findings acquired, the utilization of BTZT6 shielding material screens during mammography procedures involving X-rays with energy levels ranging from 26 to 30 keV is associated with a decrease in radiation dose. Implications for practiceIt can be inferred that the utilization of BTZT6 demonstrates potential efficacy in mitigating excessive radiation exposure to the breasts and facilitating the quantification of glandular doses in mammography procedures.

Dose to Organ at Risk and its Characteristic Variation with the Clinically Used Different Prescription Levels for Early-stage Left-sided Breast Cancer

AimsTo evaluate the organ at risk (OAR) dose and its characteristic variation with different clinically usable prescription doses (RxD) for breast and chest wall radiotherapy in patients with early-stage left-sided breast cancer. Materials and methodsIn total, 145 patients with early-stage breast cancers (T1N0M0-T2N0M0) on the left side were treated with radiotherapy after a modified radical mastectomy or breast conservation surgery, with a mean age of 45.1 ± 21.6 years. The patient received 4050 cGy of field-in-field (three-dimensional conformal radiotherapy) treatment limited to the breast or chest wall, excluding the supraclavicular node, axillary node and internal mammary chain, over 15 fractions. Additional plans of 5000 cGy/25 fractions, 4500 cGy/20 fractions and 2600 cGy/5 fractions were created with no or minor changes to the original plan. Mathematical modelling was used to study the distinctive change in the dose–volume characteristics for various OARs as a function of the RxD. OAR dosages, both absolute and normalised, were expressed in terms of the RxD. The mathematical (functional) relationship between OAR doses and different prescription levels was deduced by the least squares fit method. ResultThe left lung mean dose, V5Gy (%), V10Gy (%) and V20Gy (%) and the heart mean dose, V10Gy (%) and V20Gy (%) were evaluated. The dose–volume parameters showed a parabolic variation (x2) with the RxD. Prescription normalised OAR doses showed a linear relationship with the RxD; relative dose increased with diminishing RxD. Normalised lung and heart mean doses exhibited saturation (linear relationship) with RxD variation. Paired sample t-test results between RxD versus all evaluated parameters were found to be statistically significant (P = 0.004). The Pearson correlation coefficient between different prescription levels for left lung mean dose (range 0.942–1.0), heart mean dose (range 1.0–1.0), left lung V5Gy (%) (range 0.987–1.0), left lung V10Gy (%) (range 0.991–0.999), heart V10Gy (%) (range 0.998–1.0). ConclusionThe functional form of absolute OAR dose–volume parameters versus RxD is parabolic and the RxD normalised OAR dose–volume parameter versus RxD is a straight line with a negative slope as RxD increases. This indicates an increase in the relative OAR dose–volume parameters if the RxD is reduced. This study is the first of its kind to compare the OAR doses as a function of clinically used degenerate prescription levels. These data will help to comprehend the OAR doses while adopting a new dose fractionation regimen and reviewing the radiotherapy treatment plans.