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result sql = Clinical impact of the detector size effect in 3D-CRT.
Clinical impact of the detector size effect in 3D-CRT.
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char = r;code = 114
char = a;code = 97
char = n;code = 110
char = g;code = 103
char = e;code = 101
char = ;code = 32
char = o;code = 111
char = f;code = 102
char = ;code = 32
char = d;code = 100
char = e;code = 101
char = t;code = 116
char = e;code = 101
char = c;code = 99
char = t;code = 116
char = o;code = 111
char = r;code = 114
char = ;code = 32
char = s;code = 115
char = i;code = 105
char = z;code = 122
char = e;code = 101
char = s;code = 115
char = ;code = 32
char = c;code = 99
char = o;code = 111
char = m;code = 109
char = m;code = 109
char = o;code = 111
char = n;code = 110
char = l;code = 108
char = y;code = 121
char = ;code = 32
char = u;code = 117
char = s;code = 115
char = e;code = 101
char = d;code = 100
char = ;code = 32
char = t;code = 116
char = o;code = 111
char = ;code = 32
char = m;code = 109
char = e;code = 101
char = a;code = 97
char = s;code = 115
char = u;code = 117
char = r;code = 114
char = e;code = 101
char = ;code = 32
char = r;code = 114
char = a;code = 97
char = d;code = 100
char = i;code = 105
char = a;code = 97
char = t;code = 116
char = i;code = 105
char = o;code = 111
char = n;code = 110
char = ;code = 32
char = p;code = 112
char = r;code = 114
char = o;code = 111
char = f;code = 102
char = i;code = 105
char = l;code = 108
char = e;code = 101
char = s;code = 115
char = ;code = 32
char = f;code = 102
char = o;code = 111
char = r;code = 114
char = ;code = 32
char = 3;code = 51
char = D;code = 68
char = -;code = 45
char = C;code = 67
char = R;code = 82
char = T;code = 84
char = .;code = 46
char = ;code = 32
char = D;code = 68
char = o;code = 111
char = s;code = 115
char = e;code = 101
char = -;code = 45
char = v;code = 118
char = o;code = 111
char = l;code = 108
char = u;code = 117
char = m;code = 109
char = e;code = 101
char = ;code = 32
char = h;code = 104
char = i;code = 105
char = s;code = 115
char = t;code = 116
char = o;code = 111
char = g;code = 103
char = r;code = 114
char = a;code = 97
char = m;code = 109
char = s;code = 115
char = ;code = 32
char = (;code = 40
char = D;code = 68
char = V;code = 86
char = H;code = 72
char = s;code = 115
char = );code = 41
char = ,;code = 44
char = ;code = 32
char = r;code = 114
char = a;code = 97
char = d;code = 100
char = i;code = 105
char = o;code = 111
char = b;code = 98
char = i;code = 105
char = o;code = 111
char = l;code = 108
char = o;code = 111
char = g;code = 103
char = i;code = 105
char = c;code = 99
char = a;code = 97
char = l;code = 108
char = ;code = 32
char = i;code = 105
char = n;code = 110
char = d;code = 100
char = e;code = 101
char = x;code = 120
char = e;code = 101
char = s;code = 115
char = ,;code = 44
char = ;code = 32
char = t;code = 116
char = u;code = 117
char = m;code = 109
char = o;code = 111
char = r;code = 114
char = ;code = 32
char = c;code = 99
char = o;code = 111
char = n;code = 110
char = t;code = 116
char = r;code = 114
char = o;code = 111
char = l;code = 108
char = ;code = 32
char = p;code = 112
char = r;code = 114
char = o;code = 111
char = b;code = 98
char = a;code = 97
char = b;code = 98
char = i;code = 105
char = l;code = 108
char = i;code = 105
char = t;code = 116
char = y;code = 121
char = ;code = 32
char = (;code = 40
char = T;code = 84
char = C;code = 67
char = P;code = 80
char = );code = 41
char = ;code = 32
char = a;code = 97
char = n;code = 110
char = d;code = 100
char = ;code = 32
char = n;code = 110
char = o;code = 111
char = r;code = 114
char = m;code = 109
char = a;code = 97
char = l;code = 108
char = ;code = 32
char = t;code = 116
char = i;code = 105
char = s;code = 115
char = s;code = 115
char = u;code = 117
char = e;code = 101
char = ;code = 32
char = c;code = 99
char = o;code = 111
char = m;code = 109
char = p;code = 112
char = l;code = 108
char = i;code = 105
char = c;code = 99
char = a;code = 97
char = t;code = 116
char = i;code = 105
char = o;code = 111
char = n;code = 110
char = ;code = 32
char = p;code = 112
char = r;code = 114
char = o;code = 111
char = b;code = 98
char = a;code = 97
char = b;code = 98
char = i;code = 105
char = l;code = 108
char = i;code = 105
char = t;code = 116
char = y;code = 121
char = ;code = 32
char = (;code = 40
char = N;code = 78
char = T;code = 84
char = C;code = 67
char = P;code = 80
char = );code = 41
char = ;code = 32
char = w;code = 119
char = e;code = 101
char = r;code = 114
char = e;code = 101
char = ;code = 32
char = a;code = 97
char = n;code = 110
char = a;code = 97
char = l;code = 108
char = y;code = 121
char = s;code = 115
char = e;code = 101
char = d;code = 100
char = ;code = 32
char = a;code = 97
char = n;code = 110
char = d;code = 100
char = ;code = 32
char = c;code = 99
char = o;code = 111
char = m;code = 109
char = p;code = 112
char = a;code = 97
char = r;code = 114
char = e;code = 101
char = d;code = 100
char = ;code = 32
char = f;code = 102
char = o;code = 111
char = r;code = 114
char = ;code = 32
char = p;code = 112
char = l;code = 108
char = a;code = 97
char = n;code = 110
char = n;code = 110
char = i;code = 105
char = n;code = 110
char = g;code = 103
char = ;code = 32
char = t;code = 116
char = a;code = 97
char = r;code = 114
char = g;code = 103
char = e;code = 101
char = t;code = 116
char = ;code = 32
char = v;code = 118
char = o;code = 111
char = l;code = 108
char = u;code = 117
char = m;code = 109
char = e;code = 101
char = s;code = 115
char = ;code = 32
char = (;code = 40
char = P;code = 80
char = T;code = 84
char = V;code = 86
char = s;code = 115
char = );code = 41
char = ;code = 32
char = a;code = 97
char = n;code = 110
char = d;code = 100
char = ;code = 32
char = o;code = 111
char = r;code = 114
char = g;code = 103
char = a;code = 97
char = n;code = 110
char = s;code = 115
char = ;code = 32
char = a;code = 97
char = t;code = 116
char = ;code = 32
char = r;code = 114
char = i;code = 105
char = s;code = 115
char = k;code = 107
char = ;code = 32
char = (;code = 40
char = O;code = 79
char = A;code = 65
char = R;code = 82
char = );code = 41
char = ;code = 32
char = s;code = 115
char = t;code = 116
char = u;code = 117
char = d;code = 100
char = i;code = 105
char = e;code = 101
char = d;code = 100
char = .;code = 46
char = <;code = 60
char = b;code = 98
char = r;code = 114
char = /;code = 47
char = >;code = 62
char = <;code = 60
char = b;code = 98
char = r;code = 114
char = /;code = 47
char = >;code = 62
char = <;code = 60
char = b;code = 98
char = >;code = 62
char = R;code = 82
char = E;code = 69
char = S;code = 83
char = U;code = 85
char = L;code = 76
char = T;code = 84
char = S;code = 83
char = ;code = 32
char = :;code = 58
char = ;code = 32
char = <;code = 60
char = /;code = 47
char = b;code = 98
char = >;code = 62
char = I;code = 73
char = m;code = 109
char = p;code = 112
char = o;code = 111
char = r;code = 114
char = t;code = 116
char = a;code = 97
char = n;code = 110
char = t;code = 116
char = ;code = 32
char = d;code = 100
char = i;code = 105
char = f;code = 102
char = f;code = 102
char = e;code = 101
char = r;code = 114
char = e;code = 101
char = n;code = 110
char = c;code = 99
char = e;code = 101
char = s;code = 115
char = ;code = 32
char = i;code = 105
char = n;code = 110
char = ;code = 32
char = D;code = 68
char = V;code = 86
char = H;code = 72
char = ;code = 32
char = w;code = 119
char = e;code = 101
char = r;code = 114
char = e;code = 101
char = ;code = 32
char = f;code = 102
char = o;code = 111
char = u;code = 117
char = n;code = 110
char = d;code = 100
char = .;code = 46
char = ;code = 32
char = O;code = 79
char = A;code = 65
char = R;code = 82
char = ;code = 32
char = r;code = 114
char = e;code = 101
char = c;code = 99
char = e;code = 101
char = i;code = 105
char = v;code = 118
char = e;code = 101
char = d;code = 100
char = ;code = 32
char = h;code = 104
char = i;code = 105
char = g;code = 103
char = h;code = 104
char = e;code = 101
char = r;code = 114
char = ;code = 32
char = d;code = 100
char = o;code = 111
char = s;code = 115
char = e;code = 101
char = ;code = 32
char = l;code = 108
char = e;code = 101
char = v;code = 118
char = e;code = 101
char = l;code = 108
char = s;code = 115
char = ;code = 32
char = w;code = 119
char = h;code = 104
char = e;code = 101
char = n;code = 110
char = ;code = 32
char = a;code = 97
char = ;code = 32
char = 5;code = 53
char = .;code = 46
char = 5;code = 53
char = ;code = 32
char = m;code = 109
char = m;code = 109
char = ;code = 32
char = d;code = 100
char = e;code = 101
char = t;code = 116
char = e;code = 101
char = c;code = 99
char = t;code = 116
char = o;code = 111
char = r;code = 114
char = ;code = 32
char = w;code = 119
char = a;code = 97
char = s;code = 115
char = ;code = 32
char = u;code = 117
char = s;code = 115
char = e;code = 101
char = d;code = 100
char = ;code = 32
char = t;code = 116
char = o;code = 111
char = ;code = 32
char = m;code = 109
char = e;code = 101
char = a;code = 97
char = s;code = 115
char = u;code = 117
char = r;code = 114
char = e;code = 101
char = ;code = 32
char = p;code = 112
char = r;code = 114
char = o;code = 111
char = f;code = 102
char = i;code = 105
char = l;code = 108
char = e;code = 101
char = s;code = 115
char = ;code = 32
char = c;code = 99
char = o;code = 111
char = m;code = 109
char = p;code = 112
char = a;code = 97
char = r;code = 114
char = e;code = 101
char = d;code = 100
char = ;code = 32
char = t;code = 116
char = o;code = 111
char = ;code = 32
char = t;code = 116
char = h;code = 104
char = e;code = 101
char = ;code = 32
char = c;code = 99
char = a;code = 97
char = s;code = 115
char = e;code = 101
char = ;code = 32
char = i;code = 105
char = n;code = 110
char = ;code = 32
char = w;code = 119
char = h;code = 104
char = i;code = 105
char = c;code = 99
char = h;code = 104
char = ;code = 32
char = a;code = 97
char = ;code = 32
char = 2;code = 50
char = .;code = 46
char = 0;code = 48
char = ;code = 32
char = m;code = 109
char = m;code = 109
char = ;code = 32
char = d;code = 100
char = e;code = 101
char = t;code = 116
char = e;code = 101
char = c;code = 99
char = t;code = 116
char = o;code = 111
char = r;code = 114
char = ;code = 32
char = w;code = 119
char = a;code = 97
char = s;code = 115
char = ;code = 32
char = u;code = 117
char = s;code = 115
char = e;code = 101
char = d;code = 100
char = .;code = 46
char = ;code = 32
char = A;code = 65
char = ;code = 32
char = 2;code = 50
char = ;code = 32
char = G;code = 71
char = y;code = 121
char = ;code = 32
char = i;code = 105
char = n;code = 110
char = c;code = 99
char = r;code = 114
char = e;code = 101
char = m;code = 109
char = e;code = 101
char = n;code = 110
char = t;code = 116
char = ;code = 32
char = i;code = 105
char = n;code = 110
char = ;code = 32
char = t;code = 116
char = h;code = 104
char = e;code = 101
char = ;code = 32
char = m;code = 109
char = e;code = 101
char = a;code = 97
char = n;code = 110
char = ;code = 32
char = r;code = 114
char = e;code = 101
char = c;code = 99
char = t;code = 116
char = a;code = 97
char = l;code = 108
char = ;code = 32
char = d;code = 100
char = o;code = 111
char = s;code = 115
char = e;code = 101
char = ;code = 32
char = w;code = 119
char = a;code = 97
char = s;code = 115
char = ;code = 32
char = f;code = 102
char = o;code = 111
char = u;code = 117
char = n;code = 110
char = d;code = 100
char = ;code = 32
char = w;code = 119
char = h;code = 104
char = e;code = 101
char = n;code = 110
char = ;code = 32
char = t;code = 116
char = h;code = 104
char = e;code = 101
char = ;code = 32
char = l;code = 108
char = a;code = 97
char = r;code = 114
char = g;code = 103
char = e;code = 101
char = r;code = 114
char = ;code = 32
char = d;code = 100
char = e;code = 101
char = t;code = 116
char = e;code = 101
char = c;code = 99
char = t;code = 116
char = o;code = 111
char = r;code = 114
char = ;code = 32
char = w;code = 119
char = a;code = 97
char = s;code = 115
char = ;code = 32
char = u;code = 117
char = s;code = 115
char = e;code = 101
char = d;code = 100
char = .;code = 46
char = ;code = 32
char = I;code = 73
char = n;code = 110
char = ;code = 32
char = t;code = 116
char = h;code = 104
char = e;code = 101
char = ;code = 32
char = s;code = 115
char = a;code = 97
char = m;code = 109
char = e;code = 101
char = ;code = 32
char = w;code = 119
char = a;code = 97
char = y;code = 121
char = ,;code = 44
char = ;code = 32
char = N;code = 78
char = T;code = 84
char = C;code = 67
char = P;code = 80
char = ;code = 32
char = o;code = 111
char = f;code = 102
char = ;code = 32
char = b;code = 98
char = r;code = 114
char = a;code = 97
char = i;code = 105
char = n;code = 110
char = ;code = 32
char = s;code = 115
char = t;code = 116
char = e;code = 101
char = m;code = 109
char = ;code = 32
char = i;code = 105
char = n;code = 110
char = ;code = 32
char = h;code = 104
char = y;code = 121
char = p;code = 112
char = o;code = 111
char = p;code = 112
char = h;code = 104
char = y;code = 121
char = s;code = 115
char = i;code = 105
char = s;code = 115
char = ;code = 32
char = c;code = 99
char = h;code = 104
char = o;code = 111
char = r;code = 114
char = d;code = 100
char = o;code = 111
char = m;code = 109
char = a;code = 97
char = ;code = 32
char = t;code = 116
char = r;code = 114
char = e;code = 101
char = a;code = 97
char = t;code = 116
char = m;code = 109
char = e;code = 101
char = n;code = 110
char = t;code = 116
char = s;code = 115
char = ;code = 32
char = w;code = 119
char = a;code = 97
char = s;code = 115
char = ;code = 32
char = d;code = 100
char = o;code = 111
char = u;code = 117
char = b;code = 98
char = l;code = 108
char = e;code = 101
char = d;code = 100
char = ;code = 32
char = w;code = 119
char = h;code = 104
char = e;code = 101
char = n;code = 110
char = ;code = 32
char = t;code = 116
char = h;code = 104
char = i;code = 105
char = s;code = 115
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char = d;code = 100
char = e;code = 101
char = t;code = 116
char = e;code = 101
char = c;code = 99
char = t;code = 116
char = o;code = 111
char = r;code = 114
char = ;code = 32
char = w;code = 119
char = a;code = 97
char = s;code = 115
char = ;code = 32
char = u;code = 117
char = s;code = 115
char = e;code = 101
char = d;code = 100
char = .;code = 46
char = <;code = 60
char = b;code = 98
char = r;code = 114
char = /;code = 47
char = >;code = 62
char = <;code = 60
char = b;code = 98
char = r;code = 114
char = /;code = 47
char = >;code = 62
char = <;code = 60
char = b;code = 98
char = >;code = 62
char = C;code = 67
char = O;code = 79
char = N;code = 78
char = C;code = 67
char = L;code = 76
char = U;code = 85
char = S;code = 83
char = I;code = 73
char = O;code = 79
char = N;code = 78
char = ;code = 32
char = :;code = 58
char = ;code = 32
char = <;code = 60
char = /;code = 47
char = b;code = 98
char = >;code = 62
char = T;code = 84
char = h;code = 104
char = e;code = 101
char = ;code = 32
char = c;code = 99
char = u;code = 117
char = r;code = 114
char = r;code = 114
char = e;code = 101
char = n;code = 110
char = t;code = 116
char = ;code = 32
char = u;code = 117
char = s;code = 115
char = e;code = 101
char = ;code = 32
char = o;code = 111
char = f;code = 102
char = ;code = 32
char = i;code = 105
char = o;code = 111
char = n;code = 110
char = i;code = 105
char = s;code = 115
char = a;code = 97
char = t;code = 116
char = i;code = 105
char = o;code = 111
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char = ;code = 32
char = c;code = 99
char = h;code = 104
char = a;code = 97
char = m;code = 109
char = b;code = 98
char = e;code = 101
char = r;code = 114
char = s;code = 115
char = ;code = 32
char = o;code = 111
char = f;code = 102
char = ;code = 32
char = a;code = 97
char = b;code = 98
char = o;code = 111
char = u;code = 117
char = t;code = 116
char = ;code = 32
char = 5;code = 53
char = ;code = 32
char = m;code = 109
char = m;code = 109
char = ;code = 32
char = a;code = 97
char = c;code = 99
char = t;code = 116
char = i;code = 105
char = v;code = 118
char = e;code = 101
char = ;code = 32
char = d;code = 100
char = i;code = 105
char = a;code = 97
char = m;code = 109
char = e;code = 101
char = t;code = 116
char = e;code = 101
char = r;code = 114
char = ;code = 32
char = t;code = 116
char = o;code = 111
char = ;code = 32
char = g;code = 103
char = e;code = 101
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char = ;code = 32
char = t;code = 116
char = h;code = 104
char = e;code = 101
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char = n;code = 110
char = e;code = 101
char = c;code = 99
char = e;code = 101
char = s;code = 115
char = s;code = 115
char = a;code = 97
char = r;code = 114
char = y;code = 121
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char = d;code = 100
char = a;code = 97
char = t;code = 116
char = a;code = 97
char = ;code = 32
char = t;code = 116
char = o;code = 111
char = ;code = 32
char = m;code = 109
char = o;code = 111
char = d;code = 100
char = e;code = 101
char = l;code = 108
char = ;code = 32
char = t;code = 116
char = r;code = 114
char = e;code = 101
char = a;code = 97
char = t;code = 116
char = m;code = 109
char = e;code = 101
char = n;code = 110
char = t;code = 116
char = ;code = 32
char = m;code = 109
char = a;code = 97
char = c;code = 99
char = h;code = 104
char = i;code = 105
char = n;code = 110
char = e;code = 101
char = s;code = 115
char = ;code = 32
char = i;code = 105
char = n;code = 110
char = ;code = 32
char = r;code = 114
char = a;code = 97
char = d;code = 100
char = i;code = 105
char = o;code = 111
char = t;code = 116
char = h;code = 104
char = e;code = 101
char = r;code = 114
char = a;code = 97
char = p;code = 112
char = y;code = 121
char = ;code = 32
char = t;code = 116
char = r;code = 114
char = e;code = 101
char = a;code = 97
char = t;code = 116
char = m;code = 109
char = e;code = 101
char = n;code = 110
char = t;code = 116
char = ;code = 32
char = p;code = 112
char = l;code = 108
char = a;code = 97
char = n;code = 110
char = n;code = 110
char = i;code = 105
char = n;code = 110
char = g;code = 103
char = ;code = 32
char = s;code = 115
char = y;code = 121
char = s;code = 115
char = t;code = 116
char = e;code = 101
char = m;code = 109
char = s;code = 115
char = ;code = 32
char = (;code = 40
char = T;code = 84
char = P;code = 80
char = S;code = 83
char = );code = 41
char = ;code = 32
char = i;code = 105
char = m;code = 109
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result sql = OBJECTIVE : The detector size artificially increases the measured penumbra of radiotherapy fields. The aim of this work is to determine the influence of the detector size when planning three-dimensional conformal radiation therapy (3D-CRT) treatments.

MATERIAL AND METHODS : Two anatomical sites of interest in 3D-CRT were studied: prostate and hypophysis chordoma. Conventional 3D-CRT treatments for two cases in these locations were planned with a FOCUS 4.0.0 (Computerized Medical Systems, USA) treatment planning system (TPS) equipped with Fast Fourier Transform Convolution (FFTC) and Multigrid Superposition (MGS) algorithms, making use of beams modelled from radiation profiles measured either with a 2.0 mm diameter detector (PFD(3G) diode) or with a 5.5 mm diameter detector (PTW-31002 ionisation chamber). These detectors cover up the range of detector sizes commonly used to measure radiation profiles for 3D-CRT. Dose-volume histograms (DVHs), radiobiological indexes, tumor control probability (TCP) and normal tissue complication probability (NTCP) were analysed and compared for planning target volumes (PTVs) and organs at risk (OAR) studied.

RESULTS : Important differences in DVH were found. OAR received higher dose levels when a 5.5 mm detector was used to measure profiles compared to the case in which a 2.0 mm detector was used. A 2 Gy increment in the mean rectal dose was found when the larger detector was used. In the same way, NTCP of brain stem in hypophysis chordoma treatments was doubled when this detector was used.

CONCLUSION : The current use of ionisation chambers of about 5 mm active diameter to get the necessary data to model treatment machines in radiotherapy treatment planning systems (TPS) implies a significant overirradiation of OAR close to the PTV in 3D-CRT treatments due to errors in the measured penumbra of beam profiles. To avoid this overirradiation, the measured profiles should either being acquired with a suitable detector size (2-3 mm active diameter) or being deconvoluted.

Publication: Radiother Oncol 2005 Mar ;74(3)::315-22.
Publication Date: 2005 Mar
Study Author(s): García-Vicente, Feliciano;Béjar, Maria José;Pérez, Leopoldo;Torres, Juan J;
Institution: Department of Radiation Oncology and Medical Physics, Hospital Universitario de la Princesa, Diego de León 62, 28006 Madrid, Spain.
Shortcut link to this study:
OBJECTIVE : The detector size artificially increases the measured penumbra of radiotherapy fields. The aim of this work is to determine the influence of the detector size when planning three-dimensional conformal radiation therapy (3D-CRT) treatments.

MATERIAL AND METHODS : Two anatomical sites of interest in 3D-CRT were studied: prostate and hypophysis chordoma. Conventional 3D-CRT treatments for two cases in these locations were planned with a FOCUS 4.0.0 (Computerized Medical Systems, USA) treatment planning system (TPS) equipped with Fast Fourier Transform Convolution (FFTC) and Multigrid Superposition (MGS) algorithms, making use of beams modelled from radiation profiles measured either with a 2.0 mm diameter detector (PFD(3G) diode) or with a 5.5 mm diameter detector (PTW-31002 ionisation chamber). These detectors cover up the range of detector sizes commonly used to measure radiation profiles for 3D-CRT. Dose-volume histograms (DVHs), radiobiological indexes, tumor control probability (TCP) and normal tissue complication probability (NTCP) were analysed and compared for planning target volumes (PTVs) and organs at risk (OAR) studied.

RESULTS : Important differences in DVH were found. OAR received higher dose levels when a 5.5 mm detector was used to measure profiles compared to the case in which a 2.0 mm detector was used. A 2 Gy increment in the mean rectal dose was found when the larger detector was used. In the same way, NTCP of brain stem in hypophysis chordoma treatments was doubled when this detector was used.

CONCLUSION : The current use of ionisation chambers of about 5 mm active diameter to get the necessary data to model treatment machines in radiotherapy treatment planning systems (TPS) implies a significant overirradiation of OAR close to the PTV in 3D-CRT treatments due to errors in the measured penumbra of beam profiles. To avoid this overirradiation, the measured profiles should either being acquired with a suitable detector size (2-3 mm active diameter) or being deconvoluted.
PMID: 15763313

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