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Aims: To measure cardiac tissue doses in left-sided breast cancer patients receiving supine tangential field radiotherapy with multileaf collimation (MLC) cardiac shielding of the heart and to assess the effect on target volume coverage., Materials and Methods: Sixty-seven consecutive patients who underwent adjuvant radiotherapy to the left breast (n = 48) or chest wall (n = 19) in 2009/2010 were analysed. The heart, left anterior descending coronary artery (LAD), whole breast and partial breast clinical target volumes (WBCTV and PBCTV) were outlined retrospectively (the latter only in patients who had undergone breast-conserving surgery [BCS]). The mean heart and LAD NTDmean and maximum LAD doses (LADmax) were calculated for all patients (NTDmean is a biologically weighted mean dose normalised to 2 Gy fractions using a standard linear quadratic model). Coverage of WBCTV and PBCTV by the 95% isodose was assessed (BCS patients only)., Results: The mean heart NTDmean (standard deviation) was 0.8 (0.3) Gy, the mean LAD NTDmean 6.7 (4.3) Gy and the mean LADmax 40.3 (10.1) Gy. Coverage of the WBCTV by 95% isodose was <90% in one in three patients and PBCTV coverage <95% (range 78-94%) in one in 10 BCS patients., Conclusion: The use of MLC cardiac shielding reduces doses to cardiac tissues at the expense of target tissue coverage. Formal target volume delineation in combination with an assessment of the likelihood of local relapse is recommended in order to aid decisions regarding field and MLC placement., (Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Objectives: The FAST (FASTer radiotherapy for breast radiotherapy) trial is a UK Phase 2 multicentre randomised clinical trial evaluating a five-fraction schedule of whole-breast radiotherapy following local excision of early breast cancer. The purpose of this quality assurance study was to analyse the radiotherapy planning data in order to confirm compliance with the trial protocol., Methods: 915 patients were recruited between 2004 and 2007 from 18 centres. The protocol required that all centres should use three-dimensional dose compensations to optimise radiotherapy plans. Planning techniques, maximum dose (D(max)) and dose-volume histograms from treatment plans were evaluated and compared between centres. The homogeneity of plans was tested by creating a cut-off value of 5% for the percentage of breast volume receiving >105% of the prescribed dose., Results: 672 data sets from 15 centres were available. 93% (624/672) of plans were treated using forward-planned multileaf collimator (MLC) segments, 6% with breast compensators and 1% with inverse-planned MLC segments. 94% (635/672) of patients had a D(max)≤107% of the prescribed dose. 11% (74/672) of plans delivered >105% of the prescribed dose to >5% of the breast volume., Conclusion: Reviewing the data in this study, 95% of plans submitted by centres complied with the protocol. With the improved breast radiotherapy standards shown in FAST centres, the following recommendations were suggested for future UK breast radiotherapy trials: (i) the minimum, mean and maximum dose to the whole-breast planning target volume (PTV) should be recorded and assessed; (ii) apart from having a D(max)≤107% of the prescribed dose, ≤5% of PTV should a receive dose >105% of the prescription dose.

Background and Purpose: We describe a feasibility study testing the use of gold seeds for the identification of post-operative tumour bed after breast conservation surgery (BCS)., Materials and Methods: Fifty-three patients undergoing BCS for invasive cancer were recruited. Successful use was defined as all six seeds correctly positioned around the tumour bed during BCS, unique identification of all implanted seeds on CT planning scan and ≥ 3 seeds uniquely identified at verification to give couch displacement co-ordinates in 10/15 fractions. Planning target volume (PTV) margin size for four correction strategies were calculated from these data. Variability in tumour bed contouring was investigated with five radiation oncologists outlining five CT datasets., Results: Success in inserting gold seeds, identifying them at CT planning and using them for on-treatment verification was recorded in 45/51 (88%), 37/38 (97%) and 42/43 (98%) of patients, respectively. The clinicians unfamiliar with CT breast planning consistently contoured larger volumes than those already trained. Margin size ranged from 10.1 to 1.4mm depending on correction strategy., Conclusion: It is feasible to implant tumour bed gold seeds during BCS. Whilst taking longer to insert than surgical clips, they have the advantage of visibility for outlining and verification regardless of the ionising radiation beam quality. Appropriate correction strategies enable margins of the order of 5mm as required by the IMPORT trials however, tackling clinician variability in contouring is important., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Background and Purpose: Large breast size is associated with an increased risk of late adverse effects after breast conservation surgery and radiotherapy, even when 3D dosimetry is used. The purpose of this study is to test the hypothesis that residual dose inhomogeneity is sufficient to explain the association., Methods: Patients previously treated after breast conservation surgery with whole breast radiotherapy using 3D dosimetry and followed up in the UK FAST hypofractionation trial were selected for this analysis. The residual level of dose inhomogeneity across the whole breast treatment volume was used to test for association between residual dosimetry and post-treatment change in breast appearance at 2 years post-radiotherapy., Results: At 2 years, 201/279 (72%) of women had no change in photographic breast appearance, 61 (22%) had mild change and 17 (6%) had marked change. Breast size and dosimetry were both significantly associated with late effects in univariate analyses, but only breast size remained an independent significant risk factor for change in breast appearance when included in a multiple regression model together with other prognostic factors (p=0.006 for trend)., Conclusion: Large-breasted women are more likely to suffer change in breast size and shape after whole breast radiotherapy delivered using 3D dosimetry, but residual dose inhomogeneity is insufficient to explain the association., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To establish planning solutions for a concomitant three-level radiation dose distribution to the breast using linear accelerator- or tomotherapy-based intensity-modulated radiotherapy (IMRT), for the U.K. Intensity Modulated and Partial Organ (IMPORT) High trial., Methods and Materials: Computed tomography data sets for 9 patients undergoing breast conservation surgery with implanted tumor bed gold markers were used to prepare three-level dose distributions encompassing the whole breast (36 Gy), partial breast (40 Gy), and tumor bed boost (48 or 53 Gy) treated concomitantly in 15 fractions within 3 weeks. Forward and inverse planned IMRT and tomotherapy were investigated as solutions. A standard electron field was compared with a photon field arrangement encompassing the tumor bed boost volume. The out-of-field doses were measured for all methods., Results: Dose-volume constraints of volume >90% receiving 32.4 Gy and volume >95% receiving 50.4 Gy for the whole breast and tumor bed were achieved. The constraint of volume >90% receiving 36 Gy for the partial breast was fulfilled in the inverse IMRT and tomotherapy plans and in 7 of 9 cases of a forward planned IMRT distribution. An electron boost to the tumor bed was inadequate in 8 of 9 cases. The IMRT methods delivered a greater whole body dose than the standard breast tangents. A contralateral lung volume >2.5 Gy was increased in the inverse IMRT and tomotherapy plans, although it did not exceed the constraint., Conclusion: We have demonstrated a set of widely applicable solutions that fulfilled the stringent clinical trial requirements for the delivery of a concomitant three-level dose distribution to the breast., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The purpose of this study was to investigate methods used to modulate dose distributions in radiotherapy planning, to determine the fundamental features of these and to establish the attainable dose uniformity. Published modulation methods were categorized, and a simple physical model devised to predict the weight of the wedged beam and the relative dose distribution for each category. Each technique was applied to patient data with planning target volume sizes ranging from below 500 cm(3) to 2200 cm(3). The spatial distribution of high-dose regions in the breast, and maximum dose for the heart and lung, were determined for each plan. The dose uniformity was analysed by evaluating the volume of the breast (V(I)) receiving <95% and <105% of the prescribed dose. The difference between V(105%) and V(95%) for each method for each patient data set was also calculated. The simple model predicted the trend in percentage weight of the wedge beam and the form of the dose distribution in the transverse plane with the modulation method. Improvements in the dose uniformity were seen for the majority of modulation methods. The magnitude of the change was between 5.6% and 11.1% (p<0.05) of the breast volume for breast sizes above 500 cm(3). Some modulation methods introduced high dose at the chest wall. In conclusion, the majority of the methods improved dose uniformity for breast sizes of 500 cm(3) or greater. No method showed a clear advantage over the others. The use of modulation methods should be governed by consideration of its effects relative to a simple wedge plan.

Background: Radiation dose distributions created by two dimensional (2D) treatment planning are responsible for partial volumes receiving >107% of the prescribed dose in a proportion of patients prescribed whole breast radiotherapy after tumour excision of early breast cancer. These may contribute to clinically significant late radiation adverse effects., Aim: To test three dimensional (3D) intensity modulated radiotherapy (IMRT) against 2D dosimetry using standard wedge compensators in terms of late adverse effects after whole breast radiotherapy., Methods: Three hundred and six women prescribed whole breast radiotherapy after tumour excision for early stage cancer were randomised to 3D IMRT (test arm) or 2D radiotherapy delivered using standard wedge compensators (control arm). All patients were treated with 6 or 10MV photons to a dose of 50Gy in 25 fractions to 100% in 5 weeks followed by an electron boost to the tumour bed of 11.1Gy in 5 fractions to 100%. The primary endpoint was change in breast appearance scored from serial photographs taken before radiotherapy and at 1, 2 and 5 years follow up. Secondary endpoints included patient self-assessments of breast discomfort, breast hardness, quality of life and physician assessments of breast induration. Analysis was by intention to treat., Results: 240 (79%) patients with 5-year photographs were available for analysis. Change in breast appearance was identified in 71/122 (58%) allocated standard 2D treatment compared to only 47/118 (40%) patients allocated 3D IMRT. The control arm patients were 1.7 times more likely to have a change in breast appearance than the IMRT arm patients after adjustment for year of photographic assessment (95% confidence interval 1.2-2.5, p=0.008). Significantly fewer patients in the 3D IMRT group developed palpable induration assessed clinically in the centre of the breast, pectoral fold, infra-mammary fold and at the boost site. No significant differences between treatment groups were found in patient reported breast discomfort, breast hardness or quality of life., Conclusion: This analysis suggests that minimisation of unwanted radiation dose inhomogeneity in the breast reduces late adverse effects. Incidence of change in breast appearance was statistically significantly higher in patients in the standard 2D treatment arm compared with the IMRT arm. A beneficial effect on quality of life remains to be demonstrated.

Purpose: A method that uses electronic portal imaging to design intensity-modulated beams for compensation in breast radiotherapy was implemented using multiple static fields in a planning study. We present the results of the study to verify the algorithm, and to assess improvements to the dosimetry., Methods and Materials: Fourteen patients were imaged with computed tomography (CT) and on a treatment unit using an electronic portal imager. The portal imaging data were used to design intensity-modulated beams to give an ideal dose distribution in the breast. These beams were implemented as multiple static fields added to standard wedged tangential fields. Planning of these treatments was performed on a commercial treatment planning system (Target 2, IGE Medical Systems, Slough, U.K.) using the CT data for each patient. Dose-volume histogram (DVH) analysis of the plans with and without multileaf collimator (MLC) compensation was carried out. This work has been used as the basis for a randomized clinical trial investigating whether improvements in dosimetry are correlated with the reduction of long-term side effects from breast radiotherapy., Results: The planning analysis showed a mean increase in target volume receiving 95-105% of prescribed dose of 7.5% (range -0.8% to 15.9%) when additional MLC compensation was applied. There was no change to the minimum dose for all 14 patient data sets. The change in the volume of breast tissue receiving over 105% of prescribed dose, when applying MLC compensation, was between -1.4% and 11.9%, with positive numbers indicating an improvement. These effects showed a correlation with breast size; the larger the breast the greater the amount of improvement., Conclusions: The method for designing compensation for breast treatments using an electronic portal imager has been verified using planning on CT data for 14 patients. An improvement was seen in planning when applying MLC compensation and this effect was greater the larger the breast size.

Background and Purpose: A method of using electronic portal imaging to design compensators for tangential breast irradiation has been developed. We describe how this has been implemented., Materials and Methods: The compensator design method generates wedged and unwedged beam weights, in conjunction with templates for multiple lead-sheet compensators and pseudo-CT outlines. The latter describe the breast and lung profiles in a set of transverse slices. The layers of the compensator and pseudo-CT outlines are transferred to a treatment planning system for verification. The accuracy of the planning system for the high transmission blocks used to describe the compensators has been verified using a plotting tank system. Dose volume histogram data and transaxial and sagittal plan slices have been compared for both standard and compensated treatments for a sample set of five patients., Results: The planning system predicted the dose at depths of 1.5 and 5 cm to within 2% for the compensators tested. The biggest source of discrepancy was a consequence of the planning system requiring blocks to have integer percentage transmission. For all patients studied, the compensated treatment resulted in a significant reduction in the percentage volume outside the 95-105% dose, with an average reduction of 10.2%. The percentage volume outside the 95-107% dose was also reduced by typically 3.4%. The implementation was found to yield a convenient automatic method of designing compensators using electronic portal imaging and verifying the results using a planning system., Conclusions: These results indicate that this method of implementation can be used in practice. The dosimetric accuracy of the treatment planning system is limited by the requirement that blocks should be of integer transmission, but this effect is small.

Background and Purpose: Electronic portal images may be used to design the compensation required to maximise dose uniformity in the breast from opposed tangential beams., Materials and Methods: Four methods of implementing the desired compensation have been studied: a simple wedge, a physical compensator in conjunction with a wedge; one open field plus four shaped multi-leaf-collimated (MLC) fields, and one wedged field in conjunction with three shaped MLC fields. Evaluation was performed using thermoluminescent dosimeters (TLDs) placed inside a phantom which was designed to mimic the human breast. The measured results are compared with both the prediction of the in-house compensation design software and with the dose predicted by the GE Target II planning system. The implications of each method for the time taken to plan and deliver treatment were analysed., Results: The dose inhomogeneity, as measured at seven points in the central plane was greatest for the simple wedge (root mean square (rms) = 4.5%) compared to an open field plus four shaped MLC fields (rms = 2.2%), a wedged field plus three shaped MLC fields (rms = 3.3%), and the physical compensator (rms = 2.4%). The times required to plan and prepare these treatments varied considerably. The standard wedged treatment required under 15 min; both MLC-based and the physical compensator treatments required approximately 50 min. Differences of treatment delivery times were up to 8 min., Conclusions: These results indicate that the dose inhomogeneity can be reduced by beam intensity modulation designed using EPIDs.

A novel method of designing intensity modulated beams (IMBs) to achieve compensation in external beam radiotherapy of the breast, without the need for CT scans, is presented. The design method comprises three parts: (1) an electronic portal image is used to generate a map of radiological thickness; (2) this map is then used to obtain an estimate of the breast and lung outline; (3) a TMR-based dose calculation algorithm is then used to determine the optimum beam profile to achieve the best dose distribution. The dose distributions calculated for IMBs were compared with those calculated for the use of simple wedges. The results for two patients studied indicate that the dose inhomogeneity for IMBs is +/- 5%, compared with a value of +/- 10% for a wedged plan. The uncertainty in radiological thickness measurement corresponds to a dosimetric error of +/- 2%. Other errors associated with outline estimation are typically less than 2%, with a largest value of +5% for one of the patients who had a large and highly asymmetrical breast. The results for the two patients studied suggest that the uncertainties in the method are significantly smaller than the improvement in dose uniformity produced.

The aim of this study was to evaluate the effect of breast size on dose heterogeneity. Twenty women underwent a planning CT scan of the thorax. A three-dimensional treatment plan was devised for each patient using a standard technique of isocentric medial and lateral wedged tangential fields. Three-dimensional dose distributions were derived using an equivalent path length (EPL) inhomogeneity correction and cumulative dose-volume histogram (DVH) data calculated for the breast. Analysis of the DVHs for each patient reveals that 0.2-23.8% of the breast received an absorbed dose outside the desired 95-105% of that prescribed at the isocentre. The degree of dose heterogeneity was most strongly correlated with breast volume (r = 0.70, 95% confidence interval (C.I.) 0.37-0.87). There was also a positive correlation for breast dose heterogeneity versus brassière (bra) cup size (Spearman rank correlation rho = 0.62), breast area (r = 0.39, 95% C.I. -0.06-0.71) and chest wall separation (r = 0.31, 95% C.I. -0.15-0.66). We conclude that breast size is an important determinant of dose heterogeneity within the breast.

In 20 patients with invasive bladder cancer suitable for radical radiotherapy, a simple conformal planning technique has been compared with conventional beam arrangements in terms of normal tissue sparing. The median treatment volume for the group was reduced from 2275 to 1416 cm3 by the introduction of conformal planning. More specifically, in 13/20 patients (65%) the percentage volume of rectum irradiated to 90% of the isocentric dose was reduced by more than 30%, although the extent of rectal sparing varied greatly between patients. Overall, conformal planning appeared to be less successful at reducing the volume of large and small bowel irradiated to high dose. However, the data suggest that considerable benefit can be expected for those patients most at risk of morbidity by virtue of high bowel volumes included within the treatment length. A randomised trial is now being set up to determine the clinical impact of this planning technique in terms of reduced bowel morbidity.