PMID- 29296395
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20220331
IS  - 2156-4639 (Print)
IS  - 2156-4647 (Electronic)
VI  - 3
IP  - 2
DP  - 2014
TI  - Prescription to 50-75% isodose line may be optimum for linear accelerator based 
      radiosurgery of cranial lesions.
PG  - 139-147
AB  - PURPOSE: The prescribed percentage-isodose-line (PIDL) in linac-based SRS varies 
      among institutions. For plans with similar tumor coverage and conformity index, 
      the one with sharper dose falloff outside the tumor volume would be preferred 
      because the probability of brain necrosis is related to the irradiated volume 
      (for example V(12Gy)) outside the tumor. The aim of this study is to investigate 
      the optimal isodose line that yields the steepest dose falloff for linac-based 
      SRS using dynamic conformal arc technique (DCA). METHODS: 30 patients with brain 
      tumors were retrospectively studied. The MLC-based DCA was used for planning. For 
      each patient, 5-7 plans with different PIDLs but similar conformity indices were 
      generated. All plans were normalized such that 95% of target volume receives the 
      prescription dose (PD). Gradient index was calculated. The plan with minimum GI 
      was considered optimal. RESULTS: Optimal GI decreases (3.9 to 2.2) as target 
      volumes increases (0.15 to 50.1cm(3)), and the optimal PIDL shifts to higher 
      percentile. Median optimal PIDL is 40.0+/-7.2% (range 33.2-53.1%) for targets 
      <1cm(3) and 62.3+/-8.3% (range 44.6-72.9%) for those >1cm(3). The average planned 
      PIDL used for treatment was 83.6+/-3.3%. The lower optimal PIDL results in smaller 
      V(0.5PD) and higher mean dose to the tumor. CONCLUSION: The optimal PIDL appears 
      to be between 50% and 75% which is lower than the commonly used PIDLs in 
      published studies. Larger targets tend to have higher optimal PIDLs. By choosing 
      an optimal PIDL, we could reduce the volume of irradiated normal brain while 
      delivering higher mean dose to the tumor.
FAU - Zhao, Bo
AU  - Zhao B
AD  - Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, 
      Detroit, MI 48202, USA.
FAU - Jin, Jian-Yue
AU  - Jin JY
AD  - Department of Radiology, Georgia Regents University Cancer Center, 1120 15th St, 
      Augusta, GA 30912, USA.
FAU - Wen, Ning
AU  - Wen N
AD  - Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, 
      Detroit, MI 48202, USA.
FAU - Huang, Yimei
AU  - Huang Y
AD  - Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, 
      Detroit, MI 48202, USA.
FAU - Siddiqui, M Salim
AU  - Siddiqui MS
AD  - Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, 
      Detroit, MI 48202, USA.
FAU - Chetty, Indrin J
AU  - Chetty IJ
AD  - Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, 
      Detroit, MI 48202, USA.
FAU - Ryu, Samuel
AU  - Ryu S
AD  - Department of Radiation Oncology, Henry Ford Health System, 2799 W Grand Blvd, 
      Detroit, MI 48202, USA.
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Radiosurg SBRT
JT  - Journal of radiosurgery and SBRT
JID - 101565296
PMC - PMC5675486
OTO - NOTNLM
OT  - SRS
OT  - block margin
OT  - conformity index
OT  - gradient index
OT  - optimum isodose
OT  - radiation necrosis
EDAT- 2014/01/01 00:00
MHDA- 2014/01/01 00:01
PMCR- 2014/01/01
CRDT- 2018/01/04 06:00
PHST- 2018/01/04 06:00 [entrez]
PHST- 2014/01/01 00:00 [pubmed]
PHST- 2014/01/01 00:01 [medline]
PHST- 2014/01/01 00:00 [pmc-release]
AID - RSBRT-3-147 [pii]
PST - ppublish
SO  - J Radiosurg SBRT. 2014;3(2):139-147.