78 Aryana K et al. / Efficacy of high energy collimator TABLE 2. Some of the gamma camera specifications used in the current study Specifications 53.3 × 38.7 cm 63.5 cm 59.1 × 44.5 cm 69.2 cm 9.5 cm 9.5 mm 12.7 mm ≤3.8 mm ≤3.9 mm ≤9.9% 7.4 mm 59 Bialkali high-efficiency box-type dynodes Hexagonal Field-of-view (FOV) Diagonal FOV Crystal Size Diagonal Thickness Photomultiplier tubes Total number Type Array Shielding Back Sides Intrinsic spatial resolution FWHM in CFOV FWHM in UFOV Intrinsic energy resolution TABLE 3. Patients characteristics System spatial resolution without scatter with LEHR collimator at 10 cm FWHM = full width at half maximum; CFOV = central field of view; useful field of view UFOV; LEHR = low energy high resolution collimator 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Age 31 34 56 57 80 43 44 36 47 58 55 45 45 78 56 32 36 45 30 34 Tumour size (in cm) 1.2 2.2 2.3 2.4 3.1 3.6 2 2.1 2.4 1.3 1.5 3 1.3 1.4 2.5 2.2 2.3 1.7 1.8 1.9 History of exci- sional biopsy No No Yes No No Yes Yes Yes No Yes No Yes Yes No No No No Yes No Yes Tumour lo- cation UM UL UL UL LL LM UL Central LL UL UL LL UM UL LL LM Central UL UL UL Number of detected lymph nodes with LEHR collimator 1 2 0 0 1 1 1 2 2 1 1 1 1 1 1 1 1 0 1 1 Number of detected lymph nodes with HE collimator 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 LEHR = low energy high resolution; HE = high energy; UM = upper medial quadrant; UL = upper lateral quadrant; LM = lower medial quadrant; LL = lower lateral quadrant Radiol Oncol 2012; 46(1): 75-80.