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Intensity modulated radiotherapy and 3D conformal radiotherapy for whole breast irradiation: a comparative dosimetric study and introduction of a novel qualitative index for plan evaluation, the normal tissue index.

Yim J, Suttie C, Bromley R, Morgia M, Lamoury G - J Med Radiat Sci (2015)

Bottom Line: These were compared with the 3DCRT plans of the treatment previously received by the patients.The hIMRT technique was significantly more homogenous than the 3DCRT technique, while maintaining target coverage.The hIMRT technique was also superior at minimising the amount of tissue receiving D 105% and above (P < 0.0001).

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Royal North Shore Hospital St Leonards, New South Wales, Australia.

ABSTRACT

Introduction: We report on a retrospective dosimetric study, comparing 3D conformal radiotherapy (3DCRT) and hybrid intensity modulated radiotherapy (hIMRT). We evaluated plans based on their planning target volume coverage, dose homogeneity, dose to organs at risk (OARs) and exposure of normal tissue to radiation. The Homogeneity Index (HI) was used to assess the dose homogeneity in the target region, and we describe a new index, the normal tissue index (NTI), to assess the dose in the normal tissue inside the tangent treatment portal.

Methods: Plans were generated for 25 early-stage breast cancer patients, using a hIMRT technique. These were compared with the 3DCRT plans of the treatment previously received by the patients. Plan quality was evaluated using the HI, NTI and dose to OARs.

Results: The hIMRT technique was significantly more homogenous than the 3DCRT technique, while maintaining target coverage. The hIMRT technique was also superior at minimising the amount of tissue receiving D 105% and above (P < 0.0001). The ipsilateral lung and contralateral breast maximum were significantly lower in the hIMRT plans (P < 0.05 and P < 0.005), but the 3DCRT technique achieved a lower mean heart dose in left-sided breast cancer patients (P < 0.05).

Conclusion: Hybrid intensity modulated radiotherapy plans achieved improved dose homogeneity compared to the 3DCRT plans and superior outcome with regard to dose to normal tissues. We propose that the addition of both HI and NTI in evaluating the quality of intensity modulated radiotherapy (IMRT) breast plans provides clinically relevant comparators which more accurately reflect the new paradigm of treatment goals and outcomes in the era of breast IMRT.

No MeSH data available.


Related in: MedlinePlus

Planning target volume breast eval structure.
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fig01: Planning target volume breast eval structure.

Mentions: The PTV volumes that had been previously delineated on the 3DCRT plans by a radiation oncologist (RO) were used for the hybrid IMRT plans. The delineation of the breast tissue was guided by the clinical mark up, and using standard anatomical boundaries. The PTV Breast Eval structure is a modification of the PTV contour that excludes the pectoralis major and the skin surface, 5 mm deep from the body contour. We consider this volume to be a better surrogate than the PTV Breast for the evaluation of dose to the breast alone. (See Fig.1).


Intensity modulated radiotherapy and 3D conformal radiotherapy for whole breast irradiation: a comparative dosimetric study and introduction of a novel qualitative index for plan evaluation, the normal tissue index.

Yim J, Suttie C, Bromley R, Morgia M, Lamoury G - J Med Radiat Sci (2015)

Planning target volume breast eval structure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4592672&req=5

fig01: Planning target volume breast eval structure.
Mentions: The PTV volumes that had been previously delineated on the 3DCRT plans by a radiation oncologist (RO) were used for the hybrid IMRT plans. The delineation of the breast tissue was guided by the clinical mark up, and using standard anatomical boundaries. The PTV Breast Eval structure is a modification of the PTV contour that excludes the pectoralis major and the skin surface, 5 mm deep from the body contour. We consider this volume to be a better surrogate than the PTV Breast for the evaluation of dose to the breast alone. (See Fig.1).

Bottom Line: These were compared with the 3DCRT plans of the treatment previously received by the patients.The hIMRT technique was significantly more homogenous than the 3DCRT technique, while maintaining target coverage.The hIMRT technique was also superior at minimising the amount of tissue receiving D 105% and above (P < 0.0001).

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Royal North Shore Hospital St Leonards, New South Wales, Australia.

ABSTRACT

Introduction: We report on a retrospective dosimetric study, comparing 3D conformal radiotherapy (3DCRT) and hybrid intensity modulated radiotherapy (hIMRT). We evaluated plans based on their planning target volume coverage, dose homogeneity, dose to organs at risk (OARs) and exposure of normal tissue to radiation. The Homogeneity Index (HI) was used to assess the dose homogeneity in the target region, and we describe a new index, the normal tissue index (NTI), to assess the dose in the normal tissue inside the tangent treatment portal.

Methods: Plans were generated for 25 early-stage breast cancer patients, using a hIMRT technique. These were compared with the 3DCRT plans of the treatment previously received by the patients. Plan quality was evaluated using the HI, NTI and dose to OARs.

Results: The hIMRT technique was significantly more homogenous than the 3DCRT technique, while maintaining target coverage. The hIMRT technique was also superior at minimising the amount of tissue receiving D 105% and above (P < 0.0001). The ipsilateral lung and contralateral breast maximum were significantly lower in the hIMRT plans (P < 0.05 and P < 0.005), but the 3DCRT technique achieved a lower mean heart dose in left-sided breast cancer patients (P < 0.05).

Conclusion: Hybrid intensity modulated radiotherapy plans achieved improved dose homogeneity compared to the 3DCRT plans and superior outcome with regard to dose to normal tissues. We propose that the addition of both HI and NTI in evaluating the quality of intensity modulated radiotherapy (IMRT) breast plans provides clinically relevant comparators which more accurately reflect the new paradigm of treatment goals and outcomes in the era of breast IMRT.

No MeSH data available.


Related in: MedlinePlus