Dosimetric comparison of three dimensional conformal radiation therapy versus intensity modulated radiation therapy in accelerated partial breast irradiation.

AIM OF STUDY: Breast conserving surgery (BCS) is the standard treatment for stage I and II breast cancer. Multiple studies have shown that recurrences after lumpectomy occur mainly in or near the tumor bed. Use of accelerated partial breast irradiation (APBI) allows for significant reduction in the overall treatment time that results in increasing patient compliance and decreasing healthcare costs. We conducted a treatment planning study to evaluate the role of intensity modulated radiation therapy (IMRT) with regards to three-dimensional conformal radiation therapy (3DCRT) in APBI. MATERIALS AND METHODS: Computed tomography planning data sets of 33 patients (20 right sided and 13 left sided) with tumor size less than 3 cm and negative axillary lymph nodes were used for our study. Tumor location was upper outer, upper inner, central, lower inner, and lower outer quadrants in 10, 10, 5, 4 and 4 patients, respectively. Multiple 3DCRT and IMRT plans were created for each patient. Total dose of 38.5 Gy in 10 fractions were planned. Dosimetric analysis was done for the best 3DCRT and IMRT plans. RESULTS: The target coverage has been achieved by both the methods but IMRT provided better coverage (P = 0.04) with improved conformity index (P = 0.01). Maximum doses were well controlled in IMRT to below 108% (P < 0.01). Heart V2 Gy (P < 0.01), lung V5 Gy (P = 0.01), lung V10 Gy (P = 0.02), contralateral breast V1 Gy (P < 0.01), contralateral lung V2 Gy (P < 0.01), and ipsilateral uninvolved breast (P < 0.01) doses were higher with 3DCRT compared to IMRT. CONCLUSION: Dosimetrically, IMRT-APBI provided best target coverage with less dose to normal tissues compared with 3DCRT-APBI.

Fractionated stereotactic radiotherapy in the treatment of pituitary macroadenomas.

BACKGROUND: The use of fractionated stereotactic radiotherapy (FSRT) has evolved with technical advances in noninvasive immobilization, radiation delivery, and image guidance. The application of FSRT to pituitary tumours is aimed at reducing toxicity through improved dose conformality and reduced treatment margins. The aim of the present paper is to report our own experience and to review the published data on FSRT for pituitary macroadenomas. METHODS: Between September 2000 and October 2005, 13 patients with pituitary macroadenoma underwent FSRT at our institution. In 12 patients, radiotherapy treatment followed surgical resection (transsphenoidal resection in 8, frontal craniotomy in 3, and multiple transsphenoidal resections followed by craniotomy in 1). In 4 patients, the tumours were functional (2 adrenocorticotropic hormone-secreting, 1 prolactinoma, and 1 growth hormone-secreting); the tumours in the remaining patients were clinically non-secretory. Before radiation, 3 patients had panhypopituitarism, and 6 patients had visual field defects. All patients were treated with FSRT using non-coplanar micro-multileaf collimation portals. A median dose of 50.4 Gy (range: 45-60 Gy) was prescribed to the 76.9%-95.2% isodose surface and delivered in 1.8-Gy fractions. The median planning target volume (gross tumour plus 3 mm) was 33.5 cm3 (range: 3.2-75 cm3). RESULTS: After a median follow-up of 24 months (range: 6-60 months), local control was 100%. One patient achieved clinical complete response. Treatment was well tolerated acutely for all patients. Neither radiation-induced optic neuropathy nor any radiation-related endocrine dysfunction was observed in our patients. CONCLUSIONS: In accordance with published series, we found FSRT to be safe and effective in the management of large pituitary macroadenomas.