Correlation of breast dose heterogeneity with breast size using 3D CT planning and dose-volume histograms

Automatic segmentation of MRI in prospective breast volume evaluation: Comparison of different assessments for immediate breast reconstruction

BACKGROUND

Assessment of breast volume is essential in preoperative planning of immediate breast reconstruction (IBR) surgery to achieve satisfactory cosmetic outcome. This study introduced a breast volume measurement tool that can be used to perform automatic segmentation of magnetic resonance images (MRI) and calculation of breast volume. We compared the accuracy and reliability of this measurement method with four other conventional modalities.

METHODS

Patients who were scheduled to undergo mastectomy with IBR between 2016 and 2021 were enrolled in the study. Five different breast volume assessments, including automatic segmentation of MRI, manual segmentation of MRI, 3D surface imaging, mammography, and the BREAST-V formula, were used to evaluate different breast volumes. The results were validated using water displacement volumes of the mastectomy specimens.

RESULTS

In this pilot study, a total of 50 female patients met the inclusion criteria and contributed 54 breast specimens to the volumetric analysis. There was a strong linear association between the MRI and water displacement methods (automatic segmentation: r = 0.911, p < 0.001; manual segmentation: r = 0.924, p < 0.001), followed by 3D surface imaging (r = 0.858, p < 0.001), mammography (r = 0.841, p < 0.001), and Breast-V formula (r = 0.838, p < 0.001). Breast volumes measured using automatic and manual segmentation of MRI had lower mean relative errors (30.3% ± 22.0% and 28.9% ± 19.8, respectively) than 3D surface imaging (38.9% ± 31.2), Breast-V formula (44.8% ± 25.8), and mammography (60.3% ± 37.6).

CONCLUSION

Breast volume assessment using the MRI methods had better accuracy and reliability than the other methods used in our study. Breast volume measurement using automatic segmentation of MRI could be more efficient compared to the conventional methods.

Evaluation of Intraoperative Volumetric Assessment of Breast Volume Using 3D Handheld Stereo Photogrammetric Device

Methods for assessing three-dimensional (3D) breast volume are becoming increasingly popular in breast surgery. However, the precision of intraoperative volumetric assessment is still unclear. Until now, only non-validated scanning systems have been used for intraoperative volumetric analyses. This study aimed to assess the feasibility, handling, and accuracy of a commercially available, validated, and portable device for intraoperative 3D volumetric evaluation. All patients who underwent breast surgery from 2020 to 2022 were identified from our institutional database. Intraoperative 3D volumetric assessments of 103 patients were included in this study. Standardized 3D volumetric measurements were obtained 3 months postoperatively to compare the intraoperatively generated volumetric assessment. All of the study participants were women with a mean age of 48.3 ± 14.7 years (range: 20-89). The mean time for intraoperative volumetric assessment was 8.7 ± 2.6 min. The postoperative 3D volumetric assessment, with a mean volume of 507.11 ± 206.29 cc, showed no significant difference from the intraoperative volumetric measurements of 504.24 ± 276.61 cc (p = 0.68). The mean absolute volume difference between the intraoperative simulations and postoperative results was 27.1 cc. Intraoperative 3D volumetric assessment using the VECTRA H2 imaging system seems to be a feasible, reliable, and accurate method for measuring breast volume. Based on this finding, we plan to investigate whether volumetric objective evaluations will help to improve breast symmetry in the future.

Quantifying inter- and intra-fraction variations of breast cancer radiotherapy with skin dose measurements

Aim. The aim of the current study was to compare between the deep inspiration breath-hold (DIBH) technique and free-breathing (FB) method in the treatment delivery uncertainty of breast cancer radiotherapy using skin dose measurements.Methods. In a prospective manner, eighty patients were randomly selected for skin dose measurements, and they were assigned to two groups. DIBH (40 patients) and FB (40 patients). The systematic inter-fraction dose variation was quantified using the mean percentage error (MPE) between the average measured total dose per session in three consecutive sessions and the corresponding calculated point dose from the treatment planning system. The random inter-fraction dose variation was quantified using the standard deviation (SD) of the dose delivered by the medial or lateral tangential fields, or the total session dose in the three sessions (SD_MT, SD_LT, or SD_total, respectively). While the random intra-fraction dose variation was quantified using the SD of the dose difference between the medial and lateral tangential fields in three consecutive sessions (SD_MT-LT).Results. There was no statistically significant difference in MPE between the DIBH and FB groups (p = 0.583). Moreover, the mean SD_totaland SD_MTof the DIBH group were significantly lower than that of the FB group (2.75 ± 2.33 cGy versus 4.45 cGy ± 4.33, p = 0.048) and (1.94 ± 1.63 cGy versus 3.76 ± 3.42 cGy, p = 0.007), respectively. However, there was no significant difference in the mean SD_LTand SD_MT-LTbetween the two groups (p > 0.05).Conclusion. In addition to the advantage of reducing the cardiopulmonary radiation doses in left breast cancer, the DIBH technique could reduce the treatment delivery uncertainty compared to the FB method due to the significant reduction in the random inter-fraction dose variations.

Analysis of Geometric and Dosimetric Effects of Bra Application to Support Large or Pendulous Breasts During Radiotherapy Planning: A Retrospective Single-Center Study

Purpose:

To evaluate geometric and dosimetric effects of bra application during radiotherapy planning for breast cancer patients with large and pendulous breasts.

Materials and Methods:

Twenty patients with chest sizes >38 inches between April 2019 and July 2019 underwent radiotherapy planning with and without a radiation bra (Chabner XRT^®). Geometric and dosimetric parameters included the breast volume, superior-inferior (SI) distance, separation (S) as the distance of the longest diameter of the clinical target volume (CTV), conformity number (CN), and homogeneity index (HI) of CTV. The organs at risk (OARs) were defined as the lungs, heart, and liver.

Results:

The use of the radiation bra provided mean changes of −0.51 cm for S, −1.45 cm for SI, and −61.18 cc for breast volume (all P < 0.05). Breast volume was correlated with bra-related changes in cross diameter (r = 0.641, P = 0.002) and volume (r = 0.680, P = 0.001). Significant dose reductions were observed for the lungs (mean V₁₀: 19.58 cc, V₂₀: 17.13 cc, D_mean: 86.24 cGy) and heart (D_mean: 170.23 cGy). No significant differences were observed for CN (0.62-0.67) and HI (0.19-0.20) of the CTV.

Conclusion:

The application of a radiation bra was associated with better geometric and dosimetric planning parameters, with a smaller CTV and lower doses to the OARs (lungs and heart) in the radiotherapy field. In addition, we expect that bra use during radiotherapy would provide emotional benefits.

Dosimetric comparative study of 3DCRT, IMRT, VMAT, Ecomp, and Hybrid techniques for breast radiation therapy

Purpose

To assess and compare the dosimetric parameters obtained between three-dimensional conformal radiotherapy (3DCRT), three-dimensional field-in-field (3DFIF), 5-field intensity-modulated radiotherapy (IMRT MF5), tangential IMRT (tIMRT), tangential volumetric modulated arc therapy (tVMAT), electronic tissue compensation (Ecomp), and Hybrid treatment plans.

Material and Methods

Thirty planning computed tomography datasets obtained from patients previously treated with whole breast radiation therapy (WBRT) were utilized in this study. Treatment plans were created for 3DCRT, 3DFIF, IMRT MF5, tIMRT, tVMAT, Ecomp, and Hybrid techniques using Eclipse Treatment Planning System (version 13.6) with a prescribed dose of 42.5 Gy in 16 fractions.

Results

Techniques with tangential beams produced statistically significantly better organs-at-risk (OARs) dosimetry (p < 0.001). Planning target volume Homogeneity Index (HI) was found to be significantly different among all techniques (p < 0.001), with Ecomp resulting in better HI (1.061 ± 0.029). Ecomp was also observed to require relatively shorter planning time (p < 0.001).

Conclusions

Techniques using tangential fields arrangements produced improved OARs dosimetry. Of all the treatment planning techniques employed in this study, Ecomp was found to be relatively easy to plan and produce acceptable dosimetry for WBRT in a short time.

Is the Vectra 3D Imaging System a Reliable Tool for Predicting Breast Mass?

BACKGROUND

In selecting breast implants for breast reconstruction, current preoperative planning largely relies on 2-dimensional measurements, which are often limited in suboptimal accuracy and objectivity. Although the introduction of 3-dimensional imaging modalities has further improved preoperative planning, they require in-depth analysis of accuracy if they are to be considered as a standardized part of preoperative planning. Thus, the present study analyzes the reliability of the Vectra 3D Imaging System in predicting breast mass and explores potential confounding variables that may limit its accuracy.

METHODS

A retrospective review of 202 breasts that received direct-to-implant reconstruction by a single surgeon between February 2015 and February 2019 was conducted. Variables recorded included Vectra predicted mass (VPM; in grams), mastectomy mass (MM; in grams), ptosis grade, and body mass index (BMI). Body mass index was classified as follows: underweight (BMI < 20 kg/m), normal (20 kg/m ≤ BMI < 25 kg/m), overweight (25 kg/m ≤ BMI < 30 kg/m), and obese (BMI ≥ 30 kg/m). Cup size was approximated as follows: A and smaller (MM ≤250 g), B (250 g < MM ≤ 450 g), C (450 g < MM ≤ 600 g), and D and larger (MM ≥ 600 g). Correlation between MM and VPM was evaluated using 2-tailed Pearson correlation coefficients (r), and associated formula was derived from a linear model. Equality of variances was assessed with the Bartlett test. Correlation coefficients calculated for ptosis and BMI categories were then compared with the overall correlation coefficient. Significance was set at α = 0.05, and analyses were conducted in R 3.6.0, version 1.70.

RESULTS

There was a strong correlation between MM and VPM (R = 0.90, P < 0.0001). The following equation was derived to predict MM: [MM] = 0.8 × [VPM] + 32 (adjusted r = 0.81). The Bartlett test indicated that VPM varies significantly across cup sizes (P < 0.0001). Comparison of correlation coefficients for ptosis and BMI categories revealed a significantly reduced correlation coefficient for pseudoptosis (0.90 vs 0.75, P = 0.0425).

CONCLUSIONS

The present study suggests that the reliability of Vectra in predicting breast mass varies across cup sizes and that there exists a significantly decreased association between VPM and MM among pseudoptotic breasts. These are important considerations when using this technology in surgical planning.

Correlation of hot spot to breast separation in patients treated with postlumpectomy tangent 3D-CRT using field-in-field technique and mixed photon energies

Radiotherapy to an intact breast was previously determined to have a positive correlation between breast separation measurement and hot spot dose. As breast separation measurement increased, hot spot dose increased. The purpose of this retrospective study was to determine if this correlation persisted despite current techniques including field-in-field (FiF) blocking and mixed photon energies. Radiation treatment plans on unilateral intact breasts from 90 female, early stage breast cancer patients treated with lumpectomy were analyzed. Plans were created using 3-dimensional conformal radiation therapy (3D-CRT) nondivergent opposing tangent beams, FiF technique, and 6 MV with or without higher energy photons. Data collected included breast separation measurement, hot spot point dose and location, number of beams, photon energy, clinical target volume (CTV) coverage and breast volume coverage. Correlations between breast separation measurement and each of these values were determined. The positive correlation between breast separation measurement and hot spot dose persisted despite incorporating FiF and mixed photon energies. Correlations were also found between breast separation and the number of beams as well as breast separation and photon energy. Larger breast separations tended to be treated with additional beams of higher photon energy. There were no correlations found between breast separation and CTV or breast volume coverage. The data in this study suggested the medical dosimetrist should expect hot spots above prescription dose of 106%, 107%, and 108% for small, medium and large breast separation sizes respectively. Additionally, adding a high energy photon bean may be indicated with medium and large breast separations.

Dosimetric effects of the kV based image-guided radiation therapy of prone breast external beam radiation: Towards the optimized imaging frequency

PURPOSE

For prone breast treatment, daily image-guided radiation therapy (IGRT) allows couch shifting to correct breast position relative to the treatment field. This work investigates the dosimetric effect of reducing kV imaging frequencies and the feasibility of optimizing the frequency using patient anatomy or their first 3-day shifts.

METHOD

Thirty-seven prone breast patients who had been treated with skin marker alignment followed by daily kV were retrospectively analyzed. Three IGRT schemes (daily-kV, weekly-kV, no-kV) were simulated, assuming that fractions with kV imaging deliver a dose distribution equivalent to that in computed tomography (CT) planning, whereas other fractions yield a dose distribution as recreated by shifting the CT plan isocenter back to its position before the couch shift was applied. Treatment dose to targets (breast and lumpectomy cavity [LPC]) and organs at risks (OAR)s (heart, ipsilateral lung) in different schemes were calculated. Patient anatomy information on CT plans and first 3-day couch shift data were analyzed to investigate whether these factors could guide imaging scheme optimization.

RESULTS

When kV imaging frequency was reduced, the percentage dose changes (δD) for breast and LPC objectives (average <1%) were smaller than those for heart and lung (average 28%-31% for D_mean ). In general, the δD of no-kV imaging was approximately that of weekly kV imaging × a factor of 1.2-1.4. Although most dose objectives were not affected, the potential higher heart dose may be of concern. No strong correlation was found between δD for different kV frequencies and patient anatomy size/distance or the first 3-day couch shift data.

CONCLUSIONS

Despite resulting in lower imaging dose, time, cost, and similar target coverage, a reduction in kV imaging frequency may introduce higher heart complication risk. Daily kVs are needed more in left-sided breast patients. A less frequent imaging schedule, if considered, cannot be individually optimized using CT anatomic features or early shift data.

Model-based cardiac dose estimation in radiation treatment of left breast cancer

OBJECTIVE:

To develop a mathematical model for cardiac dose estimation for patients who have been treated for left-sided breast cancer without CT data.

METHODS:

After obtaining institutional review board approvals, 147 patients with left-sided breast cancer were selected that were treated supine with opposed tangents. The heart blocks from the tangential fields were removed and dose calculations were performed with 6 MV beams using an advanced algorithm. This study was performed with CT data with DRR to represent a radiographic simulator image of yesteryear treatments. The beam's eye-view images showing delineated breast, lung and heart were created to represent views on radiograph. The maximum heart distance (MHD) was recorded and irradiated heart area (AREA) was computed by combination of triangles and rectangles. Based on accurate 3D dose calculation, mean dose (D_mean) and V₁₀ to V₅₀ of heart were analyzed with respect to MHD and AREA for dosimetric parameters using linear and quadratic fit.

RESULTS:

The treatment parameters calculated by MHD and segments using 2D radiographs were within 2% of the actual dosimetric parameters computed from the 3D planning system. The MHD and AREA vs D_mean, V₁₀, V₂₀, V₃₀ and V₅₀ showed very good correlation with linear model (R² > 0.91); however the correlation was significantly better with quadratic model (R² > 0.92). The analysis of the dosimetric error with our linear and quadratic model is remarkable within <3% error for most cases.

CONCLUSION:

The proposed mathematical model for the cardiac dose estimation is accurate within ±3% using a radiograph without CT data. This provides avenues for patient pooling in future studies related to radiation dose and cardiac toxicity. These results will help in estimating cardiac dose analysis accurately from previous studies as well as in centers still using 2D planning.

ADVANCES IN KNOWLEDGE:

The evidence of cardiac risk following radiotherapy continues to be one of the important considerations for the management of left-sided breast cancer patients. One of the problem in the estimation of dose-risk effects is the reconstruction of heart dose for pre-CT treatments. In this study, a simple mathematical model is presented that could estimate cardiac dose within ±3% in left breast cancer treatment from 2D radiograph where CT data do not exist.

Hypofractionated postmastectomy radiotherapy with helical tomotherapy in patients with immediate breast reconstruction: dosimetric results and acute/intermediate toxicity evaluation

The aim of this study was to evaluate the dosimetry and toxicity of hypofractionation in postmastectomy radiotherapy (PMRT) with intensity-modulated radiotherapy (IMRT) in breast cancer (BC) patients. Stage II-III BC patients with implant-based immediate breast reconstruction received PMRT to the chest wall (CW) and to the infra/supraclavicular nodal region (NR) using a 15-fraction schedule (2.67 Gy/fraction) and helical IMRT (Tomotherapy^® System, Accuray Incorporated, Sunnyvale, CA). A score was assigned to each treatment plan in terms of planning target volume (PTV) coverage of CW and NR and the sparing of the organs at risk (OARs). The total score for each plan was calculated. Toxicity was prospectively assessed according to validated scales. Data from 120 consecutive patients treated in the period 2012-2015 were analysed with a median follow-up from the end of radiotherapy of 13.2 months (range 0.0-35 months). 70.8% (85/120) of the plans had high total scores as a result of an optimal coverage of both CW and RN and optimal sparing of all OARs. The maximum acute toxicity was of grade 2 in 36.7% of the cases. Early late toxicity was mild in the majority of cases. In the study population, helical tomotherapy-based IMRT produced optimal treatment plans in most cases. Acute and late toxicity was mild/moderate. Hypofractionated helical IMRT appears to be safe and feasible in the moderate term for PMRT.

Static beam tomotherapy as an optimisation method in whole-breast radiation therapy (WBRT)

INTRODUCTION

TomoTherapy (Accuray, Sunnyvale, CA) has recently introduced a static form of tomotherapy: TomoDirect™ (TD). This study aimed to evaluate TD against a contemporary intensity modulated radiation therapy (IMRT) alternative through comparison of target and organ at risk (OAR) doses in breast cancer cases. A secondary objective was to evaluate planning efficiency by measuring optimisation times.

METHODS

Treatment plans of 27 whole-breast radiation therapy (WBRT) patients optimised with a tangential hybrid IMRT technique were replanned using TD. Parameters included a dynamic field width of 2.5 cm, a pitch of 0.251 and a modulation factor of 2.000; 50 Gy in 25 fractions was prescribed and planning time recorded. The planning metrics used in analysis were ICRU based, with the mean PTV minimum (D99 ) used as the point of comparison.

RESULTS

Both modalities met ICRU50 target heterogeneity objectives (TD D99 = 48.0 Gy vs. IMRT = 48.1 Gy, P = 0.26; TD D1 = 53.5 Gy vs. IMRT = 53.0 Gy, P = 0.02; Homogeneity index TD = 0.11 vs. IMRT = 0.10, P = 0.03), with TD plans generating higher median doses (TD D50 = 51.1 Gy vs. IMRT = 50.9 Gy, P = 0.03). No significant difference was found in prescription dose coverage (TD V50 = 85.5% vs. IMRT = 82.0%, P = 0.09). TD plans produced a statistically significant reduction in V5 ipsilateral lung doses (TD V5 = 23.2% vs. IMRT = 27.2%, P = 0.04), while other queried OARs remained comparable (TD ipsilateral lung V20 = 13.2% vs. IMRT = 14.6%, P = 0.30; TD heart V5 = 2.7% vs. IMRT = 2.8%, P = 0.47; TD heart V10 = 1.7% vs. IMRT = 1.8%, P = 0.44). TD reduced planning time considerably (TD = 9.8 m vs. IMRT = 27.6 m, P < 0.01), saving an average planning time of 17.8 min per patient.

CONCLUSIONS

TD represents a suitable WBRT treatment approach both in terms of plan quality metrics and planning efficiency.

Implementation and CT sampling characterization of a third-generation SPECT-CT system for dedicated breast imaging

Stand-alone cone beam computed tomography (CT) and single-photon emission computed tomography (SPECT) systems capable of complex acquisition trajectories have previously been developed for breast imaging. Fully three-dimensional (3-D) motions of SPECT systems provide views into the chest wall and throughout the entire volume. The polar tilting capability of the CBCT system has shown improvement in sampling close to the chest wall, while eliminating cone beam artifacts. Here, a single hybrid SPECT-CT system, with each individual modality capable of independently traversing complex trajectories around a common pendant breast volume, was developed. We present the practical implementation of this design and preliminary results of the CT system. The fully 3-D SPECT was nested inside the suspended CT gantry and oriented perpendicular to the CT source-detector pair. Both subsystems were positioned on a rotation stage, with the combined polar and azimuthal motions enabling spherical trajectories. Six trajectories were used for initial evaluation of the tilt capable CT system. The developed system can achieve polar tilt angles with a [Formula: see text] positioning error and no hysteresis. Initial imaging results demonstrate that additional off-axis projection views of various geometric resolution phantoms facilitate more complete sampling, more consistent attenuation value recovery, and markedly improved reconstructions. This system could have various applications in diagnostic or therapeutic breast imaging.

Evaluation of discrepancies in weights of fresh and fixed specimens in breast surgery: a retrospective cohort study

BACKGROUND

Handling of breast specimen is not well monitored and there is limited data on the impact of fixative solutions on specimen weights. Weight of resected breast tissue acts as a guide for future reconstructive and symmetrisation procedures. The aim is to quantitatively evaluate the discrepancies in weight of fresh breast specimen and the weight of specimen after being kept in a fixative solution for a variable length of time.

METHODS

Single centre retrospective cohort study including patients undergone breast surgery for both diagnostic and therapeutic purposes between January of 2013 and June 2015. Demographic details were collected from case notes, pathology reports and operation room management information system (ORMIS).

RESULTS

A total of 229 patients with a median age of 63 [interquartile range (IQR) 51-73] years were included. The median body mass index (BMI) was 27.9 (IQR 24.3-31.75) kg/m². Median weight of the fresh specimens was 104 (IQR 44-535) g and that of fixed specimen was 99 (IQR 43-525) g (P value <0.05, Wilcoxon test). The variation was not unidirectional and factors which were important in influencing this variation were: inclusion of overlying skin and larger specimens (P value <0.05, Mann-Whitney U test). Age, BMI, duration of preservation in fixative solution and density of breast did not have significant influence.

CONCLUSIONS

Fixative solution does have significant influence on breast specimen weights. This is more pronounced with heavier specimens and those including overlying skin. It is advisable to measure the weight and volume of fresh breast specimen to aid future surgery with best aesthetic outcome.

Three-Dimensional Surface Imaging is an Effective Tool for Measuring Breast Volume: A Validation Study

Background

Accurate breast volume assessment is a prerequisite to preoperative planning, as well as intraoperative decision making in breast reconstruction surgery. The use of three-dimensional surface imaging (3D scanning) to assess breast volume has many advantages. However, before employing 3D scanning in the field, the tool's validity should be demonstrated. The purpose of this study was to confirm the validity of 3D-scanning technology for evaluating breast volume.

Methods

We reviewed the charts of 25 patients who underwent breast reconstruction surgery immediately after total mastectomy. Breast volumes using the Axis Three 3D scanner, water-displacement technique, and magnetic resonance imaging (MRI) were obtained bilaterally in the preoperative period. During the operation, the tissue removed during total mastectomy was weighed and the specimen volume was calculated from the weight. Then, we compared the volume obtained from 3D scanning with those obtained using the water-displacement technique, MRI, and the calculated volume of the tissue removed.

Results

The intraclass correlation coefficient (ICC) of breast volumes obtained from 3D scanning, as compared to the volumes obtained using the water-displacement technique and specimen weight, demonstrated excellent reliability. The ICC of breast volumes obtained using 3D scanning, as compared to those obtained by MRI, demonstrated substantial reliability. Passing-Bablok regression showed agreement between 3D scanning and the water-displacement technique, and showed a linear association of 3D scanning with MRI and specimen volume, respectively.

Conclusions

When compared with the classical water-displacement technique and MRI-based volumetry, 3D scanning showed significant reliability and a linear association with the other two methods.

Tangential intensity modulated radiation therapy (IMRT) to the intact breast

INTRODUCTION

Inverse-planned intensity modulated radiation therapy (IP-IMRT) has potential benefits over other techniques for tangential intact breast radiotherapy. Possible benefits include increased homogeneity, faster planning time, less inter-planner variability and lower doses to organs at risk (OAR). We therefore conducted a pilot study of previously treated intact breast patients to compare the current forward-planned 'field-in-field' technique (FP-IMRT) with an IP-IMRT alternative.

METHODS

The IP-IMRT plans of 20 patients were generated from a template created for the planning system. All patients were prescribed adjuvant whole breast radiotherapy using a hypofractionated regimen of 40.05 Gy in 15 fractions over 3 weeks. Plans were assessed based on visual inspection of coverage as well as statistical analysis and compared to the clinically acceptable FP-IMRT plans. Patients were planned retrospectively in Monaco 3.2^® using a laterality-specific, tangential planning template. Minor adjustments were made as necessary to meet the planning criteria in the protocol. Dose coverage, maximums, homogeneity indices and doses to OAR were recorded.

RESULTS

The IP-IMRT plans provided more consistent coverage (38.18 Gy vs. 36.08 Gy of D95; P = 0.005), a comparable though higher average maximum (D2 = 42.52 Gy vs. 42.08 Gy; P = 0.0001), more homogeneous plans (homogeneity index = 0.908 vs. 0.861; P = 0.01) and somewhat lower V20 heart and lung doses (0.11% vs. 0.89% for heart; 5.4% vs. 7.52% for lung) than FP-IMRT (P > 0.05).

CONCLUSION

Clinically acceptable plans have been generated using the IP-IMRT templates in Monaco. Improvements in consistency and quality were seen when compared to the FP-IMRT plans. The template-based process is an efficient method to inversely plan IMRT for breast patients.

The impact of breast size on mean lung dose for patients receiving tangential radiotherapy to the whole breast

Purpose

To explore the impact of breast size on mean lung dose (MLD) for patients receiving breast radiotherapy.

Methodology

Chest wall separation (CWS), volume of tissue receiving 95% isodose and MLD were measured on 80 radiotherapy treatment plans of patients receiving tangential radiotherapy treatment to the whole breast. Breast size was categorised as small (CWS<25 cm and planned target volume (PTV)<1,500 cm3) and large (CWS>25 cm and PTV>1500 cm3). Pearson’s correlation and independent sample t-test were used to analyse data.

Results

MLD was not affected by CWS (r=−0·13, p=0·24) nor volume of tissue receiving 95% isodose (r=−0·08, p=0·49). Significant variation between small and large breasts was noted for CWS (t=8·24, p=0·00) and volume of tissue receiving 95% isodose (t=5·68, p=0·00). No significant variation was noted between small and large breast for MLD (t=−0·26, p=0·80) and between left and right breasts for CWS (t=1·42, p=0·16) and volume of tissue receiving 95% isodose (t=−1·08, p=0·28). Significant difference between left (18–808 cGy) and right breast (325–365 cGy) was demonstrated for MLD (t=3·03, p=0·00).

Conclusion

This study demonstrated lack of correlation between breast size and MLD. Further research is recommended for justification of alternative techniques for this subgroup of patients to provide optimised radiotherapy delivery.

Three dimensional dose distribution comparison of simple and complex acquisition trajectories in dedicated breast CT

PURPOSE

A novel breast CT system capable of arbitrary 3D trajectories has been developed to address cone beam sampling insufficiency as well as to image further into the patient's chest wall. The purpose of this study was to characterize any trajectory-related differences in 3D x-ray dose distribution in a pendant target when imaged with different orbits.

METHODS

Two acquisition trajectories were evaluated: circular azimuthal (no-tilt) and sinusoidal (saddle) orbit with ±15° tilts around a pendant breast, using Monte Carlo simulations as well as physical measurements. Simulations were performed with tungsten (W) filtration of a W-anode source; the simulated source flux was normalized to the measured exposure of a W-anode source. A water-filled cylindrical phantom was divided into 1 cm(3) voxels, and the cumulative energy deposited was tracked in each voxel. Energy deposited per voxel was converted to dose, yielding the 3D distributed dose volumes. Additionally, three cylindrical phantoms of different diameters (10, 12.5, and 15 cm) and an anthropomorphic breast phantom, initially filled with water (mimicking pure fibroglandular tissue) and then with a 75% methanol-25% water mixture (mimicking 50-50 fibroglandular-adipose tissues), were used to simulate the pendant breast geometry and scanned on the physical system. Ionization chamber calibrated radiochromic film was used to determine the dose delivered in a 2D plane through the center of the volume for a fully 3D CT scan using the different orbits.

RESULTS

Measured experimental results for the same exposure indicated that the mean dose measured throughout the central slice for different diameters ranged from 3.93 to 5.28 mGy, with the lowest average dose measured on the largest cylinder with water mimicking a homogeneously fibroglandular breast. These results align well with the cylinder phantom Monte Carlo studies which also showed a marginal difference in dose delivered by a saddle trajectory in the central slice. Regardless of phantom material or filled fluid density, dose delivered by the saddle scan was negligibly different than the simple circular, no-tilt scans. The average dose measured in the breast phantom was marginally higher for saddle than the circular no tilt scan at 3.82 and 3.87 mGy, respectively.

CONCLUSIONS

Not only does nontraditional 3D-trajectory CT scanning yield more complete sampling of the breast volume but also has comparable dose deposition throughout the breast and anterior chest volume, as verified by Monte Carlo simulation and physical measurements.

Oncoplastic Breast Surgery: What, When and for Whom?

Oncoplastic surgery is integral to all breast cancer surgeries. The use of an aesthetic approach to breast conservation or mastectomy greatly enhances the range of options that can be offered to women with breast cancer and facilitates better outomes from it. It should be the standard of care. However, a structured approach to selecting appropriate techniques is essential, and although many operative procedures are reported, this article sets out to describe a set of principles and an algorithm by which the what, when and for whom for oncoplastic surgery can be defined.

Breast volumetric analysis for aesthetic planning in breast reconstruction: a literature review of techniques

BACKGROUND

Accurate volumetric analysis is an essential component of preoperative planning in both reconstructive and aesthetic breast procedures towards achieving symmetrization and patient-satisfactory outcome. Numerous comparative studies and reviews of individual techniques have been reported. However, a unifying review of all techniques comparing their accuracy, reliability, and practicality has been lacking.

METHODS

A review of the published English literature dating from 1950 to 2015 using databases, such as PubMed, Medline, Web of Science, and EMBASE, was undertaken.

RESULTS

Since Bouman's first description of water displacement method, a range of volumetric assessment techniques have been described: thermoplastic casting, direct anthropomorphic measurement, two-dimensional (2D) imaging, and computed tomography (CT)/magnetic resonance imaging (MRI) scans. However, most have been unreliable, difficult to execute and demonstrate limited practicability. Introduction of 3D surface imaging has revolutionized the field due to its ease of use, fast speed, accuracy, and reliability. However, its widespread use has been limited by its high cost and lack of high level of evidence. Recent developments have unveiled the first web-based 3D surface imaging program, 4D imaging, and 3D printing.

CONCLUSIONS

Despite its importance, an accurate, reliable, and simple breast volumetric analysis tool has been elusive until the introduction of 3D surface imaging technology. However, its high cost has limited its wide usage. Novel adjunct technologies, such as web-based 3D surface imaging program, 4D imaging, and 3D printing, appear promising.

Does breast composition influence late adverse effects in breast radiotherapy?

BACKGROUND

Large breast size is associated with increased risk of late adverse effects after surgery and radiotherapy for early breast cancer. It is hypothesised that effects of radiotherapy on adipose tissue are responsible for some of the effects seen. In this study, the association of breast composition with late effects was investigated along with other breast features such as fibroglandular tissue distribution, seroma and scar.

METHODS

The patient dataset comprised of 18 cases with changes in breast appearance at 2 years follow-up post-radiotherapy and 36 controls with no changes, from patients entered into the FAST-Pilot and UK FAST trials at The Royal Marsden. Breast composition, fibroglandular tissue distribution, seroma and scar were assessed on planning CT scan images and compared using univariate analysis. The association of all features with late-adverse effect was tested using logistic regression (adjusting for confounding factors) and matched analysis was performed using conditional logistic regression.

RESULTS

In univariate analyses, no statistically significant differences were found between cases and controls in terms of breast features studied. A statistically significant association (p < 0.05) between amount of seroma and change in photographic breast appearance was found in unmatched and matched logistic regression analyses with odds ratio (95% CI) of 3.44 (1.28-9.21) and 2.57 (1.05-6.25), respectively.

CONCLUSIONS

A significant association was found between seroma and late-adverse effects after radiotherapy although no significant associations were noted with breast composition in this study. Therefore, the cause for large breast size as a risk factor for late effects after surgery and optimally planned radiotherapy remains unresolved.

Objective Measurement of Cosmetic Outcomes of Breast Conserving Therapy Using BCCT.core

PURPOSE

The purpose of this study is to evaluate objective cosmetic outcomes and factors related to breast-conserving therapy (BCT) using the BCCT.core software.

MATERIALS AND METHODS

Fifty-one patients who received BCT with informed consent were evaluated using the BCCT.core software. Patients were divided into two groups based on the BCCT score: excellent or good (n=42) vs. fair or poor (n=9). Analysis of clinical factors was performed to determine factors affecting cosmetic outcomes.

RESULTS

The objective cosmetic outcome of BCT measured using the BCCT.core software was excellent in 10% of patients, good in 72%, and fair in 18%. None of the patients were classified as poor outcome. Tumor characteristics, systemic adjuvant therapy (chemotherapy and hormonal therapy), and radiation dose or energy of electron boost did not show correlation with the score measured by the BCCT.core program (p > 0.05). In univariate analysis, maximum dose within the breast (Dmax), width of tangential field, and excised tumor volume were smaller in patients with excellent or good by the BCCT.core compared to those with fair or poor (Dmax, 110.2 ± 1.5% vs. 111.6 ± 1.7%, p=0.019; width of tangential field, 8.0 ± 1.1 cm vs. 8.6 ± 0.7 cm, p=0.034; excised tumor volume, 64.0 ± 35.8 cm(3) vs. 95.3 ± 54.4 cm(3), p=0.067). In multivariate analysis, only Dmax was a significant factor for breast cosmetic outcome with a risk ratio of 1.697 (95% confidence interval, 1.006 to 2.863; p=0.047).

CONCLUSION

Objective measurement of cosmetic outcome of BCT using the BCCT.core software was feasible. The cosmetic outcome of BCT may be affected by the maximum dose within the breast.

Comparison of plan optimization for single and dual volumetric-modulated arc therapy versus intensity-modulated radiation therapy during post-mastectomy regional irradiation

The aim of the present study was to investigate volumetric-modulated arc therapy (VMAT) with single arc (1ARC) and dual arc (2ARC), and intensity-modulated radiation therapy (IMRT), and to evaluate the quality and delivery efficiency of post-mastectomy regional irradiation. A total of 24 female patients who required post-mastectomy regional irradiation were enrolled into the current study, and 1ARC, 2ARC and IMRT plans were designed for each individual patient. The quality of these plans was evaluated by calculating the homogeneity index (HI), conformity index (CI) and specific volume dose to the ipsilateral lung, double lungs, contralateral breast, heart and spinal cord. For the delivery efficiency of these plans, the total treatment time (TTT) and the number of monitor units (MUs) were evaluated. The 1ARC and 2ARC VMAT plans exhibited significantly better HIs and CIs than IMRT. For dose-volume histogram analysis, 1ARC and 2ARC VMAT spared a more specific volume dose to the ipsilateral lung, double lungs, contralateral breast, heart and spinal cord than IMRT (P<0.05). A lower MU per 2.0-Gy fraction was required for 1ARC (539 MU) and 2ARC (608 MU) than for IMRT (1,051 MU). Thus, TTT was correspondingly reduced in 1ARC and 2ARC compared to IMRT (P<0.05). There was no significant dose-volume difference in all the organs at risk (OARs) between the 1ARC and 2ARC plans (P>0.05), and 2ARC VMAT displayed a better HI and CI than 1ARC VMAT (P<0.05). By contrast, 1ARC VMAT was superior to 2ARC VAMT with regard to MU and TTT (P<0.05). The 1ARC and 2ARC VMAT plans demonstrated significantly better dose distribution in a shorter treatment time than IMRT for post-mastectomy regional irradiation, and spared the majority of OARs without compromising target coverage. The results of the present study suggest that 2ARC VMAT may be an alternative to 1ARC in order to obtain a more optimal HI and CI.

Morphological factors and cardiac doses in whole breast radiation for left-sided breast cancer

BACKGROUND

To investigate the impact of the breast size, shape, maximum heart depth (MDH), and chest wall hypotenuse (the distance connecting middle point of the sternum and the length of lung draw on the selected transverse CT slice) on the volumetric dose to heart with whole breast irradiation (WBI) of left-sided breast cancer patients.

MATERIALS AND METHODS

Fifty-three patients with left-sided breast cancer undergoing adjuvant intensity-modulated radiotherapy (IMRT) were enrolled in the study. The primary breast size and shape, MHD and DCWH (chest wall hypotenuse) were contoured on radiotherapy (RT) planning CT slices. The dose data of hearts were obtained from the dose-volume histograms (DVHs). Data were analyzed by one-way analysis of variance (ANOVA), Student's t-test and linear regression analysis.

RESULTS

Breast size was independent of heart dose, whereas breast shape, MHD and DCWH were correlated with heart dose. The shapes of breasts were divided into four types, as the flap type, hemisphere type, cone type and pendulous type with heart mean dose being 491.8±234.6 cGy, 752.7±219.0 cGy, 620.2±275.7 cGy, and 666.1±238.0 cGy, respectively. The flap type of breasts shows a strong statistically reduction in heart dose, compared to others (p=0.008 for V30 of heart). DCWH and MHD were found to be the most important parameters correlating with heart dose in WBI.

CONCLUSIONS

More attention should be paid to the heart dose of non-flap type patients. The MHD was found to be the most important parameter to correlate with heart dose in tangential WBI, closely followed by the DCWH, which could help radiation oncologists and physicsts evaluate heart dose and design RT plan in advance.

Reducing the Human Burden of Breast Cancer: Advanced Radiation Therapy Yields Improved Treatment Outcomes

Radiation therapy is an important modality in the treatment of patients with breast cancer. While its efficacy in the treatment of breast cancer was known shortly after the discovery of x-rays, significant advances in radiation delivery over the past 20 years have resulted in improved patient outcomes. With the development of improved systemic therapy, optimizing local control has become increasingly important and has been shown to improve survival. Better understanding of the magnitude of treatment benefit, as well as patient and biological factors that confer an increased recurrence risk, have allowed radiation oncologists to better tailor treatment decisions to individual patients. Furthermore, significant technological advances have occurred that have reduced the acute and long-term toxicity of radiation treatment. These advances continue to reduce the human burden of breast cancer. It is important for radiation oncologists and nonradiation oncologists to understand these advances, so that patients are appropriately educated about the risks and benefits of this important treatment modality.

Do breast cups improve breast cancer dosimetry? A comparative study for patients with large or pendulous breasts

PURPOSE

Treating patients with large or pendulous breasts is challenging. Although brassiere cups are currently in use, no study has yet been carried out to assess their dosimetric impact. The aim of the present study was to evaluate the possible dosimetric advantages of the use of breast cups on patients with large or pendulous breasts.

MATERIALS AND METHODS

Two CT studies were carried out on 12 breast cancer patients with large or pendulous breasts, with one study involving the use of breast cups. Radiation plans were developed in accordance with each of the CT studies. The following were compared: planning target volume (PTV), volume irradiated by the 95% isodose, conformity index, homogeneity index, mean lung dose, and mean heart dose was also compared for left breast treatment. The plan involving the use of cups was found to be the best option, leading to all patients being treated with cups. The resulting acute toxicity and cosmesis were also recorded. Both scenarios involved the use of film dosimetry to evaluate the skin doses.

RESULTS

The use of breast cups resulted in a significant reduction of the PTV volume (from 1640 cm3 to 1283 cm3), of the irradiated volume (from 2154 cm3 to 1477 cm3) and of the conformity index (from 1383 to 1213). Despite slight improvements in the homogeneity index (from 0.12 to 0.10), statistical significance was not attained. The use of breast cups also led to significant dose reductions in V20 for lung (from 13.7% to 1.7%) and V5 for heart (from 9.8% to 2.7%). No differences in acute toxicity or cosmesis were observed compared to patients treated without cups.

CONCLUSIONS

Our results show that the use of brassiere cups during breast radiation therapy leads to improvements in the main dosimetric factors analyzed. Furthermore, modifications to standard irradiation protocols are not required. In summary, we consider the technique of using breast cups with radiation therapy highly appropriate when treating breast cancer patients with large or pendulous breasts.

Accuracy of the method for estimating breast volume on three-dimensional simulated magnetic resonance imaging scans in breast reconstruction

BACKGROUND

The authors have developed a simple and intuitive method for measuring breast volume based on three-dimensional simulated images of magnetic resonance imaging scans to accurately estimate breast volume before breast reconstruction.

METHODS

The authors performed a retrospective review of the medical records of 18 patients (20 breasts) who had undergone breast reconstruction at Yeouido St. Mary's Hospital from March of 2009 to July of 2012. All of the patients underwent preoperative assessment of breast volume with two methods: a plaster cast maneuver and a three-dimensional simulated magnetic resonance imaging scan. To determine the accuracy of each method, the authors compared the mastectomy volume with the plaster cast maneuver and with three-dimensional simulated magnetic resonance imaging.

RESULTS

In the authors' series, the mean values of the plaster cast maneuver, three-dimensional simulated magnetic resonance imaging, and mastectomy volume were 433.85 ± 176.65 ml, 529 ± 193.33 ml, and 495.25 ± 192.45 ml, respectively. In addition, the mean error between the plaster cast maneuver and mastectomy volume was 137.4 ± 97.66 ml and that between three-dimensional simulated magnetic resonance imaging and mastectomy volume was 54.63 ± 46.30 ml. From a linear regression curve, the correlation coefficient (r2) of the plaster cast maneuver was 0.629 (p = 0.003) and that of three-dimensional simulated magnetic resonance imaging was 0.945 (p < 0.001).

CONCLUSIONS

The authors' method for preoperatively measuring breast volume on three-dimensional simulated magnetic resonance imaging scans was both efficient and accurate. It would therefore be useful for achieving better aesthetic outcomes of breast reconstruction.

Dosimetric comparison between intensity-modulated radiotherapy and standard wedged tangential technique for whole-breast radiotherapy in Asian women with relatively small breast volumes

We sought to investigate whether intensity-modulated radiotherapy (IMRT) has a dosimetric advantage compared to the standard wedged tangential technique (SWT) for whole-breast radiotherapy (WBRT) in Asian women with relatively small breast volume. Computed tomography images of 25 Asian patients with early-stage breast cancer (right 15, left 10) used for WBRT planning were examined. After contouring the target volumes and bilateral lungs and, for left-side treatment, the heart, 4 plans were made for each patient: namely, SWT, tangential-field IMRT (T-IMRT), 3-field IMRT (3F-IMRT), and 4-field IMRT (4F-IMRT). The prescribed dose was 5000 cGy. The median planning target volume (PTV) for WBRT was 552.6 cc (range 288.8-1518.4 cc). Compared to SWT, (1) T-IMRT achieved significant improvement for dose homogeneity in the PTV (p < 0.001) and the dose received by 2% (D2) of the PTV (p < 0.001). T-IMRT also reduced the bilateral lung mean dose (p < 0.001) and the ipsilateral lung volume which received more than 20 Gy (V20) (p = 0.01). (2) 3F-IMRT resulted in a significant increase in the mean dose to the ipsilateral lung (p < 0.001) and to the contralateral lung (p < 0.001). (3) 4F-IMRT also resulted in a significant increase in the mean dose to the ipsilateral lung (p < 0.001) and to the contralateral lung (p < 0.001). Tangential-field IMRT provided an improved dose distribution compared with SWT for WBRT in Asian women with a relatively small breast volume.

Calculation of organ doses from breast cancer radiotherapy: a Monte Carlo study

The current study aimed to: a) utilize Monte Carlo simulation methods for the assessment of radiation doses imparted to all organs at risk to develop secondary radiation induced cancer, for patients undergoing radiotherapy for breast cancer; and b) evaluate the effect of breast size on dose to organs outside the irradiation field. A simulated linear accelerator model was generated. The in-field accuracy of the simulated photon beam properties was verified against percentage depth dose (PDD) and dose profile measurements on an actual water phantom. Off-axis dose calculations were verified with thermoluminescent dosimetry (TLD) measurements on a humanoid physical phantom. An anthropomorphic mathematical phantom was used to simulate breast cancer radiotherapy with medial and lateral fields. The effect of breast size on the calculated organ dose was investigated. Local differences between measured and calculated PDDs and dose profiles did not exceed 2% for the points at depths beyond the depth of maximum dose and the plateau region of the profile, respectively. For the penumbral regions of the dose profiles, the distance to agreement (DTA) did not exceed 2 mm. The mean difference between calculated out-of-field doses and TLD measurements was 11.4% ± 5.9%. The calculated doses to peripheral organs ranged from 2.32 cGy up to 161.41 cGy depending on breast size and thus the field dimensions applied, as well as the proximity of the organs to the primary beam. An increase to the therapeutic field area by 50% to account for the large breast led to a mean organ dose elevation by up to 85.2% for lateral exposure. The contralateral breast dose ranged between 1.4% and 1.6% of the prescribed dose to the tumor. Breast size affects dose deposition substantially.

Effect of Bra Use during Radiotherapy for Large-Breasted Women: Acute Toxicity and Treated Heart and Lung Volumes

PURPOSE

Large breast size presents special problems during radiation simulation, planning and patient treatment, including increased skin toxicity, in women undergoing breast-conserving surgery and radiotherapy (BCT). We report our experience using a bra during radiation in large-breasted women and its effect on acute toxicity and heart and lung dosimetry.

MATERIALS AND METHODS

From 2001 to 2006, 246 consecutive large-breasted women (bra size ≥ 38 and/or ≥ D cup) were treated with BCT using either 3D conformal (3D-CRT) or Intensity Modulated Radiation (IMRT). In 58 cases, at the physicians' discretion, a custom-fit bra was used during simulation and treatment. Endpoints were acute radiation dermatitis, and dosimetric comparison of heart and lung volumes in a subgroup of 12 left-sided breast cancer patients planned with and without a bra.

RESULTS

The majority of acute skin toxicities were grade 2 and were experienced by 90% of patients in a bra compared to 70% of patients not in a bra (p=0.003). On multivariate analysis significant predictors of grade 2/3 skin toxicity included 3D-CRT instead of IMRT (OR=3.9, 95% CI:1.8-8.5) and the use of a bra (OR=5.5, 95% CI:1.6-18.8). For left-sided patients, use of a bra was associated with a volume of heart in the treatment fields decreased by 63.4% (p=0.002), a volume of left lung decreased by 18.5% (p=0.25), and chest wall separation decreased by a mean of 1 cm (p=0.03).

CONCLUSIONS

The use of a bra to augment breast shape and position in large-breasted women is an alternative to prone positioning and associated with reduced chest wall separation and reduced heart volume within the treatment field.

Research on different techniques in breast cancer radiotherapy

In breast cancer radiotherapy, the internal mammary lymphatic chain is treated in the target volume in a group of patients with high risk criteria. There are a number of different techniques in breast radiotherapy because of the variability of the anatomic region, structures and risk criteria in the irradiation field. When irradiating the target volume we also consider homogeneity of dose distribution and minimizing the dose to critical structures such as the heart and lung. In this study, we have evaluated the dose distribution of different radiotherapy techniques in twelve patients with left breast cancer who had breast conserving surgery or mastectomy. A two-dimensional computerized planning system (2-DCPS) was used for each patient to compare wide-field, oblique photon-electron, perpendicular photon-electron and oblique-electron techniques in terms of dose homogeneities in the target volume, the doses received by the heart and lung, and the coverage of the internal mammary chain. Critical structures were irradiated with acceptable dose percentages besides the internal mammary chain with both wide-field, photon-electron and oblique-electron techniques. The wide-field technique was easy to perform and exposed the heart to a smaller radiation dose than photon-electron techniques. The oblique electron techniques provide a minimal radiation dose to critical structures. In oblique electron techniques, if the internal mammary chain was not covered in the target volume, the heart dose was minimized. In conclusion, we suggest using oblique-electron techniques in breast irradiation where the internal mammary is in the target volume.

Five-year results of whole breast intensity modulated radiation therapy for the treatment of early stage breast cancer: the Fox Chase Cancer Center experience

PURPOSE

To report the 5-year outcomes using whole-breast intensity-modulated radiation therapy (IMRT) for the treatment of early-stage-breast cancer at the Fox Chase Cancer Center.

METHODS AND MATERIALS

A total of 946 women with early-stage breast cancer (stage 0, I, or II) were treated with IMRT after surgery with or without systemic therapy from 2003-2010. Whole-breast radiation was delivered via an IMRT technique with a median whole-breast radiation dose of 46 Gy and median tumor bed boost of 14 Gy. Endpoints included local-regional recurrence, cosmesis, and late complications.

RESULTS

With a median follow-up of 31 months (range, 1-97 months), there were 12 ipsilateral breast tumor recurrences (IBTR) and one locoregional recurrence. The 5-year actuarial IBTR and locoregional recurrence rates were 2.0% and 2.4%. Physician-reported cosmestic outcomes were available for 645 patients: 63% were considered "excellent", 33% "good", and <1.5% "fair/poor". For physician-reported cosmesis, boost doses≥16 Gy, breast size>900 cc, or boost volumes>34 cc were significantly associated with a "fair/poor" cosmetic outcome. Fibrosis, edema, erythema, and telangectasia were also associated with "fair/poor" physician-reported cosmesis; erythema and telangectasia remained significant on multivariate analysis. Patient-reported cosmesis was available for 548 patients, and 33%, 50%, and 17% of patients reported "excellent", "good", and "fair/poor" cosmesis, respectively. The use of a boost and increased boost volume: breast volume ratio were significantly associated with "fair/poor" outcomes. No parameter for patient-reported cosmesis was significant on multivariate analysis. The chances of experiencing a treatment related effect was significantly associated with a boost dose≥16 Gy, receipt of chemotherapy and endocrine therapy, large breast size, and electron boost energy.

CONCLUSIONS

Whole-breast IMRT is associated with very low rates of local recurrence at 5 years, 83%-98% "good/excellent" cosmetic outcomes, and minimal chronic toxicity, including late fibrosis.

The impact of dose heterogeneity on late normal tissue complication risk after hypofractionated whole breast radiotherapy

BACKGROUND AND PURPOSE

Linear quadratic models predict that hypofractionation increases the biological effect of physical dose inhomogeneity. The clinical significance of this effect was tested retrospectively in a trial of adjuvant breast hypofractionation.

METHODS

The UK FAST trial randomised 915 women after breast conservation surgery between standard fractionation and two dose levels of a 5-fraction regimen delivering 5.7 or 6.0 Gy fractions in 5 weeks, using 3D dosimetry. Logistic regression tested for association between the absolute volumes receiving different isodose level >100% of prescribed dose (hotspots) and the risk of change in 2-year photographic breast appearance. The strength of this association was compared between control and hypofractionated groups.

RESULTS

Three hundred and ninety datasets from 11 participating centres were available for analysis. At 2 years post-randomisation, 81 (20.8%) had mild change and 24 (6.2%) had marked change in photographic breast appearance. After adjusting for breast size and surgical deficit, there was no statistically significant association between the risk of 2-year change in breast appearance and dose inhomogeneity in either the control or hypofractionated schedules, according to the various definitions of hotspots analysed. The magnitude of the effect of dosimetry on 2-year change in breast appearance did not vary significantly between control and hypofractionated schedules for any of the dosimetry parameters (p>0.05 for all heterogeneity tests).

CONCLUSION

Dose inhomogeneity had no greater impact on the risk of 2-year change in photographic breast appearance after hypofractionated breast radiotherapy than after standard fractionation.

Association of single nucleotide polymorphisms in the genes ATM, GSTP1, SOD2, TGFB1, XPD and XRCC1 with risk of severe erythema after breast conserving radiotherapy

PURPOSE

To examine the association of polymorphisms in ATM (codon 158), GSTP1 (codon 105), SOD2 (codon 16), TGFB1 (position -509), XPD (codon 751), and XRCC1 (codon 399) with the risk of severe erythema after breast conserving radiotherapy.

METHODS AND MATERIALS

Retrospective analysis of 83 breast cancer patients treated with breast conserving radiotherapy. A total dose of 50.4 Gy was administered, applying 1.8 Gy/fraction within 42 days. Erythema was evaluated according to the Radiation Therapy Oncology Group (RTOG) score. DNA was extracted from blood samples and polymorphisms were determined using either the Polymerase Chain Reaction based Restriction-Fragment-Length-Polymorphism (PCR-RFL) technique or Matrix-Assisted-Laser-Desorption/Ionization -Time-Of-Flight-Mass-Spectrometry (MALDI-TOF). Relative excess heterozygosity (REH) was investigated to check compatibility of genotype frequencies with Hardy-Weinberg equilibrium (HWE). In addition, p-values from the standard exact HWE lack of fit test were calculated using 100,000 permutations. HWE analyses were performed using R.

RESULTS

Fifty-six percent (46/83) of all patients developed erythema of grade 2 or 3, with this risk being higher for patients with large breast volume (odds ratio, OR = 2.55, 95% confidence interval, CI: 1.03-6.31, p = 0.041). No significant association between SNPs and risk of erythema was found when all patients were considered. However, in patients with small breast volume the TGFB1 SNP was associated with erythema (p = 0.028), whereas the SNP in XPD showed an association in patients with large breast volume (p = 0.046). A risk score based on all risk alleles was neither significant in all patients nor in patients with small or large breast volume. Risk alleles of most SNPs were different compared to a previously identified risk profile for fibrosis.

CONCLUSIONS

The genetic risk profile for erythema appears to be different for patients with small and larger breast volume. This risk profile seems to be specific for erythema as compared to a risk profile for fibrosis.

Dosimetric comparison of the field-in-field technique and tangential wedged beams for breast irradiation

PURPOSE

To analyze tangential wedged beam and field-in-field (FIF) technique doses using dose-volume histograms and conformality indices for target volume and healthy tissues within the irradiated volume.

MATERIALS AND METHODS

Thirty patients treated with breast-conserving surgery and postoperative whole breast radiotherapy were enrolled. Three plans were generated: a standard tangential plan with either one outer field wedge or bilateral wedges, and an FIF plan. Three indices were used: the dose homogeneity index (DHI), PTV dose improvement index (PDI(index)) and geometric conformity index (g). Also ipsilateral lung, heart and contralateral breast doses were compared for each plan.

RESULTS

Dose homogeneity index was significantly lower for the FIF (0.117 ± 0.021) than for the single wedge (0.131 ± 0.025, p = 0.02) and double wedged plan (0.128 ± 0.025, p = 0.04), respectively. The g was significantly less in the FIF (0.70 ± 0.14) compared to the wedge plans (0.80 ± 0.17, p = 0.02 and 0.83 ± 0.16, p = 0.003). Contralateral breast doses were significantly lower in the FIF plan. The FIF plan significantly lowered MU compared to both the single wedge and bilateral wedge plans.

CONCLUSION

The dose distribution within the target was more homogenous, and the doses for healthy tissue were less in the FIF plan compared to the tangential wedge plans.

Weight versus volume in breast surgery: an observational study

Objectives

The study hypothesis is to assess correlation of breast specimen weight versus volume.

Design

Consecutive patients undergoing breast surgery at a single tertiary referral centre during a 6-month period were included. Specimen weight was measured in grams. Direct volume measurements were performed using water displacement. Data including side of the breast, age and menstrual status of the patient were noted.

Setting

Knowledge of breast volume provides an objective guide in facilitating the achievements of balance in reconstructive operations. Surgeons use intraoperative weight measurements from individual breasts to calculate the breast volume assuming that weight is equal to the volume of the specimen. However, it is unclear whether weight accurately reveals the true volume of resection.

Participants

Forty-one patients were included in the study with 28 having bilateral surgeries, 13 having unilateral procedures giving a total of 69 breast specimens.

Main outcome measures

Breast specimen weight correlation to breast specimen volume.

Results

The mean age of the group was 42.4 years. Fifty-two specimens were from premenopausal patients and 17 were of postmenopausal. Thirty-five were left-sided. Twenty-six patients had bilateral breast reduction, two had bilateral mastectomy, nine had a unilateral mastectomy and four patients had a unilateral breast reduction. The difference between weight and volume of these breasts was 36.4 units (6.6% difference). The difference in measurement of weight and volume in premenopausal was 37.6 units compared to 32.6 units in postmenopausal women. The density was 1.07 and 1.06, respectively. This was statistically not significant.

Conclusions

No significant difference between volume and weight was seen in this series. Furthermore, we are unable to support the notion that premenopausal patients have a significant difference in the proportion of fatty and glandular tissue as there was little difference between the weight and the volume. An easy, clinically proper formula for the quantification of actual breast volume has yet to be derived.

Clinical and pathologic evaluation of implanted free dermal fat grafts after breast cancer surgery: a retrospective analysis

PURPOSE

The efficacy of immediate breast reconstruction using a free dermal fat graft (FDFG) was evaluated clinically.

PATIENTS AND METHODS

A total of 22 breasts in 21 patients who underwent partial mastectomy for early breast cancer involving mainly the inner upper quadrant were enrolled in this study. The defect was reconstructed immediately by filling it with an autologous FDFG. At 6 months and 1, 2, 3, 4, and 5 years postoperatively, the width (horizontal length) and thickness (distance perpendicular to skin) of the FDFG on computed tomography (CT) scans were measured. Histologic samples from the implanted FDFG were collected by core needle biopsy (CNB). The correlations between clinical findings and volume of the FDFG on CT and the proportion of fatty tissue in the CNB were examined statistically. Cosmetic results were also evaluated.

RESULTS

On CT, the mean width of the FDFG was 95%, 81%, 79%, 73%, 68%, and 47% and the mean thickness were 125%, 121%, 120%, 115%, 104%, and 103% at 6 months, and 1-5 years postoperatively, respectively. In the CNB samples, the mean fatty tissue distribution was 76%, 63%, and 54% at 1 year, 1-4 years, and >4 years postoperatively, respectively. The percent change in the width of the FDFG at 6 months after the operation displayed a significant negative correlation with the postmenopausal period and a significant positive correlation with the maximum surgical margin. On CT, thickness was negatively correlated with the size of the resected breast tissue, and thickness of the implanted FDFG. No clinicopathologic factors or technical factors were related to FDFG outcome and the proportion of fat tissue in the CNB sample, except for axillary dissection. Nineteen of 21 patients had good to excellent cosmesis.

CONCLUSION

FDFG implanted into breast defects after partial mastectomy undergo mild resorption and degeneration to fibrous tissue, but most patients have good to excellent cosmesis.

Objective breast symmetry evaluation using 3-D surface imaging

This study develops an objective breast symmetry evaluation using 3-D surface imaging (Konica-Minolta V910(®) scanner) by superimposing the mirrored left breast over the right and objectively determining the mean 3-D contour difference between the 2 breast surfaces. 3 observers analyzed the evaluation protocol precision using 2 dummy models (n = 60), 10 test subjects (n = 300), clinically tested it on 30 patients (n = 900) and compared it to established 2-D measurements on 23 breast reconstructive patients using the BCCT.core software (n = 690). Mean 3-D evaluation precision, expressed as the coefficient of variation (VC), was 3.54 ± 0.18 for all human subjects without significant intra- and inter-observer differences (p > 0.05). The 3-D breast symmetry evaluation is observer independent, significantly more precise (p < 0.001) than the BCCT.core software (VC = 6.92 ± 0.88) and may play a part in an objective surgical outcome analysis after incorporation into clinical practice.