ICRU Reports

Technical Note: Is bulk electron density assignment appropriate for MRI-only based treatment planning for lung cancer?

“…The rED values used in our investigation, derived from the International Commission on Radiation Units and Measurements (ICRU) Report 46, are rED = the mean value from CT, 0.26, 1.06, 1.355, 1.05, and 1.022 for the ITV, lung, aorta, bone, heart, and patient (nonspecified tissue) respectively. 25 Planning 4DCTs acquired for six lung cancer patients (11 total tumors) were used to generate CT-based IMRT plans (Table I). Free breathing 4DCT images were acquired using an infrared camera motion-monitoring system (RPM System, Varian) to record the real time respiratory signal that was interfaced with a multislice RT CT scanner (LightSpeed, GE).…”

“…[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] The specific values can either be derived from the International Commission on Radiation Units and Measurements (ICRU) Report 46 or set to a value chosen by the planner to be appropriate for that organ or tissue. 25 Several groups have investigated the dosimetric impact of bulk density assignment for tumors in the brain, 15,16,22,26,27 head and neck, 16,17,21 thorax, 16 pelvis, 21 pancreas, 23 and prostate. [10][11][12][13]16,[19][20][21]28 These studies report dosimetric differences of ≤ 2% and ≤ 5% for target and organs at risk (OAR), respectively, between the bulk rED plans and the planning CT.…”

Impact of lung density on isolated lung tumor dose in VMAT using inline MR-Linac

“…where D 95,ρ,B represents the D 95 in the PTV at magnetic field of B T in the thorax phantom with a lung density of ρ g/cm 3 . The difference of D 95 in PTV for tumor sizes of 1, 2 and 3 cm was normalized to D 95,ρ=0.3,B=0 which is the D 95 in PTV for each tumor size in a lung density of 0.3 g/cm 3 at 0 T. This was set based on the International Commission on Radiation Units and Measurements (ICRU) Report 46 [31] that defined normal lung density as 0.26 g/cm 3 .…”

Automated deep learning auto-segmentation of air volumes for MRI-guided online adaptive radiation therapy of abdominal tumors

“…In current practice, the air volumes are manually delineated, and their relative ED is overridden with a constant (e.g. 0.01 per ICRU report) (White et al 1992) before the onset of plan adaptation (Paulson et al 2020). It is desirable to automate the delineation of air volumes on the MR images to improve speed, consistency, and potentially to allow for more frequent plan adaptation schemes.…”