Indra J. Das/ Small Fields (Page-1)

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1 Indra J. Das/ Small Fields (Page-1) Improving Dose Prescriptions for Safety, Reporting, and Clinical Guideline Consistency Jean Moran, Univ of Michigan, Ann Arbor Mark Langer, Indianian Univeristy, Indianapolis IJDas (1) ICRU-83: Guidelines and Compliance in IMRT Indra J. Das, PhD, FAAPM, FACR, FASTRO Department of Radiation Oncology New York University Langone Medicine Center New York, NY ICRU:International Commission on Radiation Units and Measurements 1978, ICRU-29; Dose specification for reporting external beam therapy with photon and electron beams. 1993, ICRU-5; Prescribing, recording and reporting photon beam therapy. 1999, ICRU-62; Prescribing, recording and reporting photon beam therapy (Supplement to ICRU 5). IJDas (2) Dose Prescription & Outcome Isocenter dose 5% dose diff 5% dose diff Isocenter dose IJDas (3) Dische et al, Radiother Oncol, 29, , 1993

2 Prescription Deviation: (Planned/Prescribed Dose) Indra J. Das/ Small Fields (Page-2) Need for Dose Specification IJDas (4) Brahme, Acta Oncologica, 36, , 1997 Variations in doses in 3 patients among institutions Institution 1 Institution 2 Institution 3 Institution 4 Institution 5 46% % Minimum Maximum Median Isocenter Patient Number IJDas (5) Das et al. J Natl Cancer Inst (5), 3-37, 28 IMRT Dose Prescription: ICRU 83 D 2% is defined as Maximum dose D 5% is Mean/median dose, prescription dose and very close to reference dose (ICRU-5) D 98%, considered as minimum dose in PTV HI = (D 2% -D 98% )/ D 5% Definition of sub volume with overlaps IJDas (6)

3 Indra J. Das/ Small Fields (Page-3) Optimization & Cost Function IJDas (7) S S S w ijk (D opt -D cal ) 2 = minimum i,j,k w ijk = weight for constraint of an organ ICRU-83 DVH Parameters IJDas (8) ICRU-83, 21 ICRU-Definitions IJDas (9) ICRU-81, 21

4 Volume (%) Cost Function Cost Function Indra J. Das/ Small Fields (Page-4) Minimization Gradient, Newtonian optimization Stochastic optimization B B A Iteration, Search routine A Iteration, Search routine IJDas (1) Concept of Dose Prescription D % D 98% D 95% 5 D 5% A DD B What should be the dose tolerance? D 2% IJDas (11) Dose Among Institutions I-1 I-2 I-3 I-4 I-5 I-6 I-7 I-8 I-9 I-1 D D98 D5 D Number 25 of patients IJDas (12) Das et al, Pr Radiat Oncol, 7, e145-c155, 217

5 % Dose Extre mities Liv er Oth er % Dose Indra J. Das/ Small Fields (Page-5) D2% D5% D98% Global Trends Institutions IJDas (13) Dose Distributions Among Sites Breast Head & Neck Lung Pelvis D D98 D5 Thorax 11 IJDas (14) Number of patients Dose Trends in Site D2% D5% D98% Breast Extremity HN Liver Lung Pelvis Thorax Other Treatment Site IJDas (15)

6 Frequency (%) Frequency (%) Frequency (%) Indra J. Das/ Small Fields (Page-6) Frequency Distribution of Dose Parameters IJDas (16) D2 D5 D98 D Das et al, Pr Radiat Oncol, 7, e145-c155, Frequency Distribution of and D5 D5 I-1 I-1 D5 I-2 I-2 D5 I-3 I-3 D5 I-4 I-4 D5 I-5 I-5 D5 I-6 I-6 D5 I-7 I-7 D5 I IJDas (17) Das et al, Pr Radiat Oncol, 7, e145-c155, 217 Frequency Distribution of and D5 among Sites Thorax D5 Pelvis D5 H&N D5 Liver D5 Lung D5 Breast D5 IJDas (18)

7 Volume (cm 3 ) Indra J. Das/ Small Fields (Page-7) Target Volume Variations Among Institutions H&N 4 2 IJDas (19) Institution Das et al, Pr Radiat Oncol, 7, e145-c155, 217 Variability Among Treatment Techniques D2 D5 D98 D IJDas (2) IMRT VMAT TOMO SBRT Treatment Techniques Outcome and Clinical Trials IJDas (21) Ohri et al. JNCI, 15, , 213

8 Indra J. Das/ Small Fields (Page-8) Outcome With Excess Dose IJDas (22) Moore et al. IJROBP, 15, , 213 Outcome With Prostate Dose IJDas (23) Kalbashi et al. JAMA Oncol, 7, 896-6, 215 Conclusions Adoption of target volume nomenclature is extremely poor and variable even after ICRU-5 (1993) for 3DCRT ICRU-83 adoption is poor indicated in large variability in dose prescription/delivery in IMRT and even in academic institutions Head & Neck and pelvis have better uniformity in dose prescription compared to other disease sites Clinical trials should emphasize the need for uniformity in dose prescription for a meaningful treatment outcome Mere ±1% dose difference has shown significant outcome difference IJDas (24)

9 Indra J. Das/ Small Fields (Page-9) Thanks IJDas (25)