Open Access

Whole breast radiotherapy in prone and supine position: is there a place for multi-beam IMRT?

  • Thomas Mulliez1Email author,
  • Bruno Speleers2,
  • Indira Madani1,
  • Werner De Gersem2,
  • Liv Veldeman1 and
  • Wilfried De Neve1
Contributed equally
Radiation Oncology20138:151

https://doi.org/10.1186/1748-717X-8-151

Received: 28 January 2013

Accepted: 18 June 2013

Published: 24 June 2013

Abstract

Background

Early stage breast cancer patients are long-term survivors and finding techniques that may lower acute and late radiotherapy-induced toxicity is crucial. We compared dosimetry of wedged tangential fields (W-TF), tangential field intensity-modulated radiotherapy (TF-IMRT) and multi-beam IMRT (MB-IMRT) in prone and supine positions for whole-breast irradiation (WBI).

Methods

MB-IMRT, TF-IMRT and W-TF treatment plans in prone and supine positions were generated for 18 unselected breast cancer patients. The median prescription dose to the optimized planning target volume (PTVoptim) was 50 Gy in 25 fractions. Dose-volume parameters and indices of conformity were calculated for the PTVoptim and organs-at-risk.

Results

Prone MB-IMRT achieved (p<0.01) the best dose homogeneity compared to WTF in the prone position and WTF and MB-IMRT in the supine position. Prone IMRT scored better for all dose indices. MB-IMRT lowered lung and heart dose (p<0.05) in supine position, however the lowest ipsilateral lung doses (p<0.001) were in prone position. In left-sided breast cancer patients population averages for heart sparing by radiation dose was better in prone position; though non-significant. For patients with a PTVoptim volume ≥600 cc heart dose was consistently lower in prone position; while for patients with smaller breasts heart dose metrics were comparable or worse compared to supine MB-IMRT. Doses to the contralateral breast were similar regardless of position or technique. Dosimetry of prone MB-IMRT and prone TF-IMRT differed slightly.

Conclusions

MB-IMRT is the treatment of choice in supine position. Prone IMRT is superior to any supine treatment for right-sided breast cancer patients and left-sided breast cancer patients with larger breasts by obtaining better conformity indices, target dose distribution and sparing of the organs-at-risk. The influence of treatment techniques in prone position is less pronounced; moreover dosimetric differences between TF-IMRT and MB-IMRT are rather small.

Keywords

Whole-breast irradiation Prone position Supine position Wedged tangential fields Intensity-modulated radiotherapy Tangential field-IMRT Multi-beam-IMRT

Background

Conventional radiotherapy (RT) using wedged tangential fields (W-TF) after breast-conserving surgery improves disease control and breast-cancer related survival. However prolonged follow-up showed an increased RT-induced risk of cardiac events and secondary lung and breast cancer in long-term survivors [13]. Therefore strategies for sparing organs-at-risk (OARs), while maintaining an adequate dose coverage of the target are warranted.

In supine position the whole-breast clinical target volume (CTVWBI) is concave 1) enwrapping the lung and heart at the left side, and 2) medially adjoining the contralateral breast. Therefore parts of the ipsilateral lung, heart, and contralateral breast may receive intermediate to high doses with W-TF.

Intensity-modulated radiotherapy (IMRT) can provide advantages compared to W-TF. In supine position IMRT using a tangential two-beam set-up (TF-IMRT) can improve dose homogeneity; however its ability to reduce high-dose regions to the underlying heart and lung tissue appear to be limited [4, 5]. Supine multi-beam IMRT (MB-IMRT) may overcome those limitations often at cost of low- or intermediate-dose spread over the contralateral breast and ipsilateral thoracic region [610].

Prone position modifies the target volume by gravity and moves the breast away from the chest wall. Prone W-TF has previously been used for large, pendulous breasts [11] to reduce fibrosis and improve cosmesis [12, 13]. There are a few studies reporting improved dosimetry by prone TF-IMRT [1416], though data on whole-breast MB-IMRT in prone position are lacking. Moreover, all dosimetric studies comparing prone and supine position used only non-multi-beam techniques [1620]. We performed the present study to establish the effect of treatment technique (W-TF, TF-IMRT or MB-IMRT) and position (prone or supine) on dose coverage and heart and lung sparing.

Methods

Eighteen unselected early stage breast cancer patients - 6 right-sided and 12 left-sided - presenting for whole-breast irradiation (WBI) without nodal irradiation after breast conserving surgery were included in this study. Three-mm thick computer-tomography scans were acquired with an Aquilion scanner (Toshiba Medical Systems, Tokyo, Japan) in all patients in prone and supine position. Patient set-up and delineation of the clinical and planning target volumes for WBI (CTVWBI and PTVWBI, respectively) and OARs in both treatment positions can be found elsewhere [16, 17]. Extension of the PTVWBI outside the skin into the air accounted for respiration-related breast movement or swelling of the breast during treatment. A flash region was created outside the patient’s external contour by expanding the PTVWBI with a 10 mm margin followed by subtraction of the patient’s total scanned volume. This flash region was subsequently used in the optimization. A planning target volume for optimization (PTVoptim), a structure used during plan optimization, was generated by removing the in-air part and a 7 mm-wide build-up region underneath the skin from the PTVWBI.

The dosimetric comparison was made for 6 MV photon beams of an Elekta SLi18 linear accelerator (Elekta, Crawley, UK) equipped with a standard 1 cm leaf-width multileaf collimator (MLC). A median prescription dose to the PTVoptim was 50 Gy in 25 fractions of 2.0 Gy with the objective of ≥95% of the PTVoptim receiving >95% of the prescribed dose and minimization of maximum dose, dose heterogeneity and “hot spots”. In both positions TF-IMRT used the same gantry angles as W-TF with the collimator set at 0° and the beams shaped around the PTVWBI with the aid of the MLC. Figure 1 shows the 6-beam setup used in the MB-IMRT plans for right-sided breast tumors in supine position (a) and prone position (b). In both positions MB-IMRT used 6 coplanar beams shaped around the PTVWBI and as in TF-IMRT plans field-in-field segments were created avoiding the ipsilateral lung, heart (in case of left-sided breast tumors) and contralateral breast (for lateral beams in supine position, since medial beams did not traverse the contralateral breast).
Figure 1

Multi-beam set-up in the prone and supine position. A 6-beam set-up used in the multi-beam intensity-modulated radiotherapy (MB-IMRT) plans for right-sided breast tumors in supine (a) and prone position (b). Gantry angles expressed in the Elekta coordinate system. The most inclined medial beam has the gantry angle of a tangential beam set by virtual simulation [21]. The gantry angles are 0°, |α|, |2α|, 180° - 0.5|α|, 180° + 0.5|α|, and 180° + 1.5|α| for supine MB-IMRT. The lateral gantry angles in prone MB-IMRT are |α|, |α|+/−24°, the medial gantry angles are |β|, |β|+/− 12°.

A forward planning approach was used for the intensity-modulated and W-TF plans. The convolution-superposition dose engine of a Pinnacle version 9.0 treatment planning system (Philips Medical Systems, Andover, US) was used for dose computations between optimization cycles of intensity-modulated plans as well as for final plans. Monitor units and MLC shapes were optimized using the optimization tools described before [21]. During optimization, two patient geometries were taken into account: 1) dose computation for PTVWBI was performed using a density override (1 g/cm3) to the above-mentioned flash region; 2) dose computation for the PTVWBI without build-up and OARs was performed without density overrides. To be able to compute both dose distributions in parallel, the patient data at the Pinnacle treatment planning system were duplicated: for the first patient dataset the flash region was set water-equivalent, while for the second patient dataset, the flash region remained at the density of the CT data (in essence, air outside the patient outline). To avoid hot spots outside regions of interest, a “matroska” sequence of shell structures [22] was generated outside the PTVWBI, which were taken into account during optimization. Dose computation for these shell structures was performed using the above-mentioned density override in the flash region. Also the dose update mechanism for changes in leaf positions during optimization took both patient geometries into account. This method was used mainly to account for substantial deformations of the breast during the course of treatments.

D2 and D98, or the dose exceeding 2% and 98% of the dose-volume histogram (DVH) points, respectively, were used as surrogates for maximum and minimum dose. These were evaluated for the PTVoptim, as well as dose homogeneity (1-(D2-D98/median dose)). For the heart and ipsilateral lung D2, mean dose (Dmean), V5, V10, V20 and V25 or the proportion of the volume receiving at least 5 Gy, 10 Gy, 20 Gy and 25Gy, respectively, were extracted from the DVH data. For the contralateral breast D2 and Dmean were evaluated.

The following indices were also calculated for the PTVoptim:
Jaccard index = A B / A B
Where A is the volume covered by the PTVoptim and B is the volume covered by the 95% isodose, i.e., the volume receiving 47.5 Gy or more. The Jaccard index increases with increase in similarity or overlap between the target volume and the 95% isodose and is a measure of dose conformity of the treatment plan.
Dose coverage index = A B 1 / A
Where B1 is the volume covered by the 95-107% isodose, i.e. the volume receiving between 47.5 Gy and 53.5 Gy. The dose-coverage index calculates the proportion of the target, in which the treatment-planning objectives for the target are met.
Mismatch index = B 2 / B

Where B2 is the volume covered by the 95% isodose and lying outside the PTVoptim.. It is the fraction of the 95% isodose non-overlapping the target. If the mismatch index is large, large amounts of normal tissues receive 95% of the prescription dose, i.e., 47.5 Gy.

One-way analysis of variance (ANOVA) was used for a pairwise comparison of dose-volume parameters and indices between MB-IMRT, TF-IMRT and W-TF in the 2 treatment positions.

Results

One hundred-and-eight plans were generated. Figure 2 illustrates typical dose distributions obtained with the 3 techniques in prone and supine position.
Figure 2

Isodose distributions (in Gy) of the 6 treatment plans for a left-sided patient in a transverse plane. Abbreviations: W-TF = wedged tangential fields; TF-IMRT = tangential field intensity-modulated radiotherapy; MB-IMRT = multi-beam intensity-modulated radiotherapy.

Dose homogeneity and dose coverage of the target

Table 1 provides numerical data on target coverage and target dose distribution obtained with the 3 techniques in the prone and supine position. D2 is lowered in prone position resulting in improved dose homogeneity since D98 was similar for both positions. Significance was obtained for prone MB-IMRT versus all supine techniques and a trend (p=0.05) for prone TF-IMRT compared to supine W-TF regarding D2; moreover prone MB-IMRT obtained better (p<0.01) dose homogeneity compared to supine W-TF and MB-IMRT. Intensity-modulated techniques were able to improve dose homogeneity compared to conventional techniques in both positions, though significance (p=0.002) was only gained for prone MB-IMRT versus prone W-TF.
Table 1

Dose-volume parameters (a) and conformity indices (b) for the optimized planning target volume (PTV optim )

 

D2[Gy]

D98[Gy]

Dose homogeneity [%]

 

Prone

Supine

Prone

Supine

Prone

Supine

 

mean

SEM

SD

mean

SEM

SD

mean

SEM

SD

mean

SEM

SD

mean

SEM

SD

Mean

SEM

SD

(a)

W-TF

52.3

0.1

0.6

53.1

0.2

0.9

47.6

<0.1

0.1

47.9

<0.1

0.4

90.6

0.3

1.1

89.7

0.5

2.1

TF-IMRT

52.0

0.2

0.8

52.6

0.2

0.8

47.8

<0.1

0.3

47.9

0.1

0.5

91.8

0.4

1.7

90.7

0.5

2.3

MB-IMRT

51.6

0.2

0.7

52.6

0.1

0.6

47.9

<0.1

0.2

47.7

<0.1

0.2

92.5

0.3

1.4

90.3

0.3

1.2

 

Jaccard index [%]

Dose-coverage index [%]

Mismatch index [%]

 

Prone

Supine

Prone

Supine

Prone

Supine

 

mean

SEM

SD

mean

SEM

SD

mean

SEM

SD

mean

SEM

SD

mean

SEM

SD

mean

SEM

SD

(b)

W-TF

74.9

2.0

8.5

52.9

3.6

15.2

97.2

0.2

1.0

96.2

0.6

2.4

23.9

2.0

8.6

46.8

3.6

15.4

TF-IMRT

74.8

1.5

6.2

64.6

2.1

8.9

97.7

0.2

0.8

96.6

0.3

1.2

24.4

1.5

6.4

34.7

2.1

9.1

MB-IMRT

77.1

1.4

5.9

70.5

1.6

6.7

97.8

0.1

0.6

96.5

0.2

1.0

22.1

1.4

6.0

28.5

1.6

6.8

Abbreviations: SEM Standard error of the mean, SD Standard deviation, W-TF Wedged tangential fields, TF-IMRT Tangential field intensity-modulated radiation therapy, MB-IMRT Multi-beam intensity-modulated radiation therapy.

Prone WBI scored better for Jaccard and mismatch indices (Table 1). Prone MB-IMRT achieved better results than any supine treatment technique (p≤0.03, both indices); followed by prone TF-IMRT versus supine TF-IMRT and W-TF (p≤0.001, both indices). In supine position MB-IMRT (p<0.001) was the best and W-TF (p<0.001) was the worst technique for both indices. Prone IMRT improved significantly (p<0.01) dose coverage index: prone TF-IMRT vs. supine MB-IMRT and prone MB-IMRT vs. supine MB-IMRT and TF-IMRT.

Dose-volume parameters in OARs

Figure 3 illustrates cumulative DVHs of the ipsilateral lung (all patients) and heart (only left-sided patients), numerical data are presented in Table 2. Sparing (p<0.001) of the ipsilateral lung by radiation dose was always superior in prone. There was little difference in ipsilateral lung dose between the 3 techniques in prone position, although V10 and V20 were significantly lower in prone MB-IMRT vs. prone W-TF. In supine position treatment technique did alter lung dose (p<0.05), MB-IMRT achieved the best and W-TF the worst lung avoidance by radiation dose. A remarking feature is the modified (p=0.003) ipsilateral lung volume in both positions. Mean ± standard deviation for ipsilateral lung volume is 1504 ± 401cc for prone position versus 1409 ± 431cc for supine position.
Figure 3

Cumulative dose-volume histograms of the ipsilateral lung (a) and heart (b). All patients were included for the ipsilateral lung, while for the heart only left-sided breast cancer patients were evaluated. Abbreviations: W-TF = wedged tangential fields, TF-IMRT = tangential field intensity-modulated radiotherapy, MB-IMRT = multi-beam intensity-modulated radiotherapy.

Table 2

Mean ± standard deviation for ipsilateral lung (all patients) and heart (only left-sided patients) dose metrics

Technique

 

Ipsilateral lung

  

Heart

 
 

Dmean[Gy]

V20[%]

V25[%]

Dmean[Gy]

V20[%]

V25[%]

 

Prone

Supine

Prone

Supine

Prone

Supine

Prone

Supine

Prone

Supine

Prone

Supine

W-TF

1.2±0.6

7.7±4.5

0.9±1.0

13.5±10.2

0.7±0.8

12.1±9.3

1.9±1.1

3.9±3.4

1.2±0.6

4.9±1.9

0.8±1.7

4.0±5.8

TF-IMRT

1.1±0.5

5.7±3.1

0.5±0.7

9.8±7.0

0.3±0.5

8.5±6.4

1.6±0.5

3.3±2.5

0.4±0.2

3.4±1.4

0.3±0.6

2.9±4.3

MB-IMRT

0.9±0.4

5.1±2.6

0.2±0.4

7.6±6.2

0.1±0.3

6.4±5.5

1.6±0.4

2.5±1.7

0.3±0.1

1.9±0.9

0.2±0.3

1.4±2.2

Abbreviations: D mean Mean dose, V 20 and V 25 Partial volume receiving at least 20 Gy and 25 Gy, respectively, W-TF Wedged tangential fields, TF-IMRT Tangential field intensity-modulated radiation therapy, MB-IMRT Multi-beam intensity-modulated radiation therapy.

Heart dose was lowered with MB-IMRT compared to TF-IMRT (D2, Dmean, V5; p=0.07, 0.05 and 0.03, respectively) and W-TF (D2, V5, p= 0.009 and 0.07, respectively) in supine position. While in prone position the effect of treatment technique on heart dose is less pronounced. Population averages for heart dose metrics were non-significantly lowered in prone compared to supine position. Better heart sparing by radiation dose was consistently obtained in prone position for patients with a PTVoptim volume > 600cc. While for patients with a PTVoptim volume <600cc heart dose metrics were comparable (2/5 patients) or worse (3/5 patients) in prone position compared to supine MB-IMRT.

Neither treatment technique, nor set-up significantly changed doses in the contralateral breast, all procedures achieved a maximum dose <5Gy and mean dose <1.5Gy for all patients.

Discussion

In supine position IMRT techniques obtain a higher Jaccard index, i.e. superior dose conformity, and less mismatch compared to W-TF with MB-IMRT being the superior technique for both indices. Dose conformity, coverage and mismatch are even better for the prone techniques, becoming statistically significant in prone IMRT plans. This is not surprising, since prone position results in a less concave breast volume. Therefore dose to the axillary and shoulder region is substantially reduced and less of the prescription dose can be expected to be out of the target. Our results confirm the reduction of dose inhomogeneity, with IMRT-techniques compared to standard W-TF. Though differences were rather small and non-significant in supine position, which could be explained by the use of non-mixture beam energies. Prone as compared to supine IMRT does improve dose homogeneity and hot spots with the best results in prone MB-IMRT plans. Our results are in agreement with other publications on prone IMRT. Goodman et al. [15] demonstrated a maximum dose in the target exceeding 110% with prone W-TF in 16 of 20 patients as compared to 1 patient with prone IMRT (TF-IMRT). Another study comparing MB-IMRT, TF-IMRT and 3D-CRT treatment plans of 5 patients planned in prone position reported significantly higher dose homogeneity of MB-IMRT plans vs. TF-IMRT (p=0.003) and 3D-CRT plans (p=0.03) [23]. Hardee et al. [14] observed a maximum dose reduction and improved median dose homogeneity in a prone TF-IMRT vs. 3D-CRT patient cohort. Moreover a 9%-decrease of grade 2 dermatitis and a 16%-reduction of grade ≥2 hyperpigmentation were found in the IMRT group. We expect that improved dose homogeneity and hot spots achieved by prone IMRT – either MB-IMRT or TF-IMRT - will yield lower skin toxicity and better cosmesis [4, 5, 24].

Lung irradiation was lowered with the MB-IMRT technique in supine position, though sparing of the ipsilateral lung appeared to be depending more on the treatment position than on the treatment technique. Prone position resulted in a spectacular decrease in lung dose, which is in coherence with other data [1620]. The decrease in lung dose in prone position might also be attributed by the 7% increase in ipsilateral lung volume, for which we don’t have an explanation. All prone treatment techniques showed similar lung dose metrics.

Left-sided breast cancer patients are at risk of radiation-induced cardiac events [2], emphasizing the importance of using more sophisticated techniques to lower the heart dose. In supine position, MB-IMRT is able to lower the heart dose compared to the other techniques as shown both in our data and in other publications [79]. In prone position different treatment techniques have less effect on heart dose, especially between IMRT-techniques. Even with MB-IMRT, only the minority of patients (3/12) benefitted from supine position; which is in coherence with other data [18, 20]. Moreover consistent better heart dose metrics were achieved in prone position for patients with a PTVoptim volume of > 600cc. A limitation of this study is the absence of dose parameters of the left descending coronary artery, since this is likely associated with increased cardiac mortality.

The introduction of supine MB-IMRT was not successful because of its complexity, increase in dose to the contralateral breast and higher integral dose [79]. In contrast with these studies we selected beams that avoided the contralateral breast and removed beams that included too much lung tissue. In this way reducing the dose in the ipsilateral lung with MB-IMRT, both in supine and prone position, was not at cost of low-dose spread over the lung or heart as illustrated by the DVHs (Figure 3). The dose to the contralateral breast was not increased with MB-IMRT either, moreover a maximum dose <5Gy and mean dose <1.5Gy was obtained for all patients.

As a consequence of the reduced ipsilateral lung and heart dose, better dose distribution and dose coverage, prone IMRT is superior to any supine technique for left-sided patients with larger breasts (PTVoptim> 600cc) and all right-sided patients. While for left-sided patients with smaller breasts individual comparative planning should be made between supine MB-IMRT and prone IMRT in order to choose the best technique for clinical execution. The dosimetric differences between prone TF-IMRT and prone MB-IMRT are rather small. Whether these “small” dosimetric benefits would cause a clinical benefit is unknown. The more complex and time consuming planning procedure and beam delivery of prone MB-IMRT should also be considered.

Conclusions

MB-IMRT is the preferred technique in supine position by providing better coverage indices of the target and sparing of organs-at-risk. However, prone IMRT is superior to any supine technique for right-sided breast cancer patients and left-sided breast cancer patients with larger breasts. The impact of treatment techniques in prone position is less prominent; moreover dosimetric differences between both IMRT-techniques are rather small.

Notes

Abbreviations

RT: 

Radiotherapy

WBI: 

Whole breast irradiation

OARs: 

Organs-at-risk

W-TF: 

Wedged tangential fields

IMRT: 

Intensity-modulated radiotherapy

TF-IMRT: 

Tangential field intensity-modulated radiotherapy

MB-IMRT: 

Multi-beam intensity-modulated radiotherapy

CTVWBI: 

Whole-breast clinical target volume

PTVWBI: 

Whole-breast planning target volume

PTVoptim: 

Planning target volume for optimization

DVH: 

Dose-volume histogram

Dmean: 

Mean dose

D2 and D98: 

Dose exceeding 2% and 98% of the DVH points, respectively

V5: 

V10 , V20 and V25: Partial volume receiving at least 5 Gy, 10 Gy, 20Gy and 25 Gy, respectively

ANOVA: 

Analysis of variance.

Declarations

Authors’ Affiliations

(1)
Department of Radiotherapy, Ghent University Hospital
(2)
Ghent University

References

  1. Henson KE, McGale P, Taylor C, Darby SC: Radiation-related mortality from heart disease and lung cancer more than 20 years after radiotherapy for breast cancer. Br J Cancer 2013, 108: 179-182. 10.1038/bjc.2012.575View ArticlePubMedPubMed CentralGoogle Scholar
  2. Clarke M, Collins R, Darby S, et al.: Effects of radiotherapy and of differences in the extent of surgery for early breast cancer on local recurrence and 15-year survival: an overview of the randomised trials. Lancet 2005, 366: 2087-2106.View ArticlePubMedGoogle Scholar
  3. Early Breast Cancer Trialists' Collaborative G, Darby S, McGale P, et al.: Effect of radiotherapy after breast-conserving surgery on 10-year recurrence and 15-year breast cancer death: meta-analysis of individual patient data for 10,801 women in 17 randomised trials. Lancet 2011, 378: 1707-1716.View ArticleGoogle Scholar
  4. Barnett GC, Wilkinson JS, Moody AM, et al.: Randomized controlled trial of forward-planned intensity modulated radiotherapy for early breast cancer: interim results at 2 years. Int J Radiat Oncol Biol Phys 2012, 82: 715-723. 10.1016/j.ijrobp.2010.10.068View ArticlePubMedGoogle Scholar
  5. Veldeman L, Madani I, Hulstaert F, De Meerleer G, Mareel M, De Neve W: Evidence behind use of intensity-modulated radiotherapy: a systematic review of comparative clinical studies. Lancet Oncology 2008, 9: 367-375. 10.1016/S1470-2045(08)70098-6View ArticlePubMedGoogle Scholar
  6. Borca VC, Franco P, Catuzzo P, et al.: Does TomoDirect 3DCRT represent a suitable option for post-operative whole breast irradiation? A hypothesis-generating pilot study. Radiat Oncol 2012, 7: 211. 10.1186/1748-717X-7-211View ArticlePubMedPubMed CentralGoogle Scholar
  7. Coon AB, Dickler A, Kirk MC, et al.: Tomotherapy and Multifield Intensity-Modulated Radiotherapy Planning Reduce Cardiac Doses in Left-Sided Breast Cancer Patients with Unfavorable Cardiac Anatomy. Int J Radiat Oncol Biol Phys 2010, 72: 104-110.View ArticleGoogle Scholar
  8. Beckham WA, Popescu CC, Patenaude VV, Wai ES, Olivotto IA: Is multibeam IMRT better than standard treatment for patients with left-sided breast cancer? Int J Radiat Oncol Biol Phys 2007, 69: 918-924. 10.1016/j.ijrobp.2007.06.060View ArticlePubMedGoogle Scholar
  9. Fogliata A, Clivio A, Nicolini G, Vanetti E, Cozzi L: A treatment planning study using non-coplanar static fields and coplanar arcs for whole breast radiotherapy of patients with concave geometry. Radiother Oncol 2007, 85: 346-354. 10.1016/j.radonc.2007.10.006View ArticlePubMedGoogle Scholar
  10. Rudat V, Alaradi AA, Mohamed A, Ai-Yahya K, Altuwaijri S: Tangential beam IMRT versus tangential beam 3D-CRT of the chest wall in postmastectomy breast cancer patients: a dosimetric comparison. Radiat Oncol 2011, 6: 26. 10.1186/1748-717X-6-26View ArticlePubMedPubMed CentralGoogle Scholar
  11. Merchant TE, McCormick B: Prone position breast irradiation. Int J Radiat Oncol Biol Phys 1994, 30: 197-203.View ArticlePubMedGoogle Scholar
  12. Gray JR, McCormick B, Cox L, Yahalom J: Primary breast irradiation in large-breasted or heavy women: analysis of cosmetic outcome. Int J Radiat Oncol Biol Phys 1991, 21: 347-354. 10.1016/0360-3016(91)90781-XView ArticlePubMedGoogle Scholar
  13. Grann A, McCormick B, Chabner ES, et al.: Prone breast radiotherapy in early-stage breast cancer: a preliminary analysis. Int J Radiat Oncol Biol Phys 2000, 47: 319-325. 10.1016/S0360-3016(00)00448-XView ArticlePubMedGoogle Scholar
  14. Hardee ME, Raza S, Becker SJ, et al.: Prone hypofractionated whole-breast radiotherapy without a boost to the tumor bed: comparable toxicity of IMRT versus a 3D conformal technique. Int J Radiat Oncol Biol Phys 2012, 82: e415-423. 10.1016/j.ijrobp.2011.06.1950View ArticlePubMedGoogle Scholar
  15. Goodman KA, Hong L, Wagman R, Hunt MA, McCormick B: Dosimetric analysis of a simplified intensity modulation technique for prone breast radiotherapy. Int J Radiat Oncol Biol Phys 2004, 60: 95-102. 10.1016/j.ijrobp.2004.02.016View ArticlePubMedGoogle Scholar
  16. Veldeman L, Speleers B, Bakker M, et al.: Preliminary results on setup precision of prone-lateral patient positioning for whole breast irradiation. Int J Radiat Oncol Biol Phys 2010, 78: 111-118. 10.1016/j.ijrobp.2009.07.1749View ArticlePubMedGoogle Scholar
  17. Veldeman L, De Gersem W, Speleers B, et al.: Alternated Prone and Supine Whole-Breast Irradiation Using IMRT: Setup Precision, Respiratory Movement and Treatment Time. Int J Radiat Oncol Biol Phys 2012, 82: 2055-2064. 10.1016/j.ijrobp.2010.10.070View ArticlePubMedGoogle Scholar
  18. Kirby AM, Evans PM, Donovan EM, Convery HM, Haviland JS, Yarnold JR: Prone versus supine positioning for whole and partial-breast radiotherapy: a comparison of non-target tissue dosimetry. Radiother Oncol 2010, 96: 178-184. 10.1016/j.radonc.2010.05.014View ArticlePubMedGoogle Scholar
  19. Varga Z, Hideghety K, Mezo T, Nikolenyi A, Thurzo L, Kahan Z: Individual positioning: a comparative study of adjuvant breast radiotherapy in the prone versus supine position. Int J Radiat Oncol Biol Phys 2009, 75: 94-100. 10.1016/j.ijrobp.2008.10.045View ArticlePubMedGoogle Scholar
  20. Lymberis SC, Dewyngaert JK, Parhar P, et al.: Prospective Assessment of Optimal Individual Position (Prone Versus Supine) for Breast Radiotherapy: Volumetric and Dosimetric Correlations in 100 Patients. Int J Radiat Oncol Biol Phys 2012, 84: 902-909. 10.1016/j.ijrobp.2012.01.040View ArticlePubMedGoogle Scholar
  21. Van Vaerenbergh K, De Gersem W, Vakaet L, et al.: Automatic generation of a plan optimization volume for tangential field breast cancer radiation therapy. Strahlenther Onkol 2005, 181: 82-8. 10.1007/s00066-005-1310-1View ArticlePubMedGoogle Scholar
  22. De Neve W, Wu Y, Ezzel G: Practical IMRT planning. In Image-guided IMRT. Edited by: Bortfeld T, Schmidt-Ulrich R, De Neve W, Wazer D. Berlin, Heidelberg: Springer; 2006:47-59.View ArticleGoogle Scholar
  23. Ahunbay EE, Chen GP, Thatcher S, et al.: Direct aperture optimization-based intensity-modulated radiotherapy for whole breast irradiation. Int J Radiat Oncol Biol Phys 2007, 67: 1248-1258. 10.1016/j.ijrobp.2006.11.036View ArticlePubMedGoogle Scholar
  24. Harsolia A, Kestin L, Grills I, et al.: Intensity-modulated radiotherapy results in significant decrease in clinical toxicities compared with conventional wedge-based breast radiotherapy. Int J Radiat Oncol Biol Phys 2007, 68: 1375-1380. 10.1016/j.ijrobp.2007.02.044View ArticlePubMedGoogle Scholar

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© Mulliez et al.; licensee BioMed Central Ltd. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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