A Dosimetric Comparison of Radiotherapy Techniques in the Treatment of Carcinoma of Breast

Zakiya Salem Al-Rahbi, Ramamoorthy Ravichandran, Johnson Pichy Binukumar, Cheriyithmanjiyil Antony Davis, Namrata Satyapal, Zahid Al-Mandhari

Department of Radiation Oncology, National Oncology Centre, The Royal Hospital, Muscat, Sultanate of Oman.

DOI: 10.4236/jct.2013.411A002                

Abstract

Objectives of present study are a) to compare the planning and delivery aspects of five different techniques, planned by a) forward, inverse planning and electronic tissue compensation methods; and b) to evaluate and verify the accuracy of the planning system using phantom to estimate the skin dose for target and contraletral breast from five techniques. In-vivo skin dosimetry is planned with TL detectors. Five different radiotherapy techniques for treatment of carcinoma breast were studied using archived computed tomography (CT) scans of 25 breast conserving surgery patients (leftsided whole breast), planned for 50 Gy in 25 fractions. Linear accelerator (Clinac 2300 CD) photon beams were used and thermoluminescent detectors (TLD) [LiF:Mg, Ti] estimated dose on humanoid phantom. Dose coverage (95%) (to PTV) and hot spot (105%) covering volumes did not show differences (p > 0.05) in all 5 plans; Electronic compensator plans are better than others. IP-IMRT plan showed the worst Homogeneity Index (HI) (p < 0.05) and needed more monitor units (MU) (437 ± 84), than other techniques. The mean doses to ipsi-lateral lung, contra-lateral breast (CB) and heart OARs (V_{20 ipsi.lung}, CB, V_{30 Heart},) are the least with IP-IMRT. IP-IMRT and E-COMP plans resulted in significantly lower mean dose to the superficial skin (D_mean, V_40skin, _45skin, _50skin) (p < 0.05). The mean doses estimated by TLDs were comparable or higher in 3D-CRT (D) and 3D-CRT (P) for PTV and CB; less for IP-IMRT and E-COMP compared to TPS. IP-IMRT and E-COMP techniques provide good target coverage, low doses to OARs, the least doses to the skin of PTV and contra-lateral breast and less hot spots; E-COMP showed better homogeneity, fewer MUs, and the least dose in non-target zones.

Keywords

Breast Radiotherapy; TL Detectors; Electronic Compensators; Second Malignancy

Conflicts of Interest

The authors declare no conflicts of interest.

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