Prostate HDR Dose Escalavon. âHDR brachytherapy can provide beøer sparing of rectum and bladder while delivering a higher dose to the prostate. Even with ...
4th Annual Conference of Indian Brachytherapy Society at All India InsFtute of Medical Sciences (AIIMS-‐IBS conference 2014)
Advances in Brachytherapy Delivery and Treatment Planning By Vibha Chaswal, Ph.D. (Independent Researcher and Collaborator, USA) (Invited faculty at AIIMS-‐IBS Conference)
Brachytherapy Today! • High precision targeted Radiotherapy Modality with significant pa=ent benefit • High Precision image guided adap=ve brachytherapy (IGABT)
Prostate Carcinoma (Over past almost 15 years…)
alpha/beta for prostate tumors • Alpa/beta = 1.5 – 3 Gy • possibly lower than the expected values of about 3 Gy for late complicaFons • Not a rapidly re-‐populaFng carcinoma • reversal of the relaFve sensiFviFes to dose-‐fracFon size, of tumours versus late-‐responding normal Fssues at-‐risk in convenFonal radiotherapy • a few large fracFons – hypo-‐frac=ona=on – might be advantageous for killing prostate carcinoma Brenner DJ, Hall EJ. “Fractionation and protraction for radiotherapy of prostate carcinoma.” Int J Radiat Oncol Biol Phys. Vol 43(5) 1999 Fowler J1, Chappell R, Ritter M., “Is alpha/beta for prostate tumors really low? “, Int J Radiat Oncol Biol Phys. Vol 50(4) 2001
Latest (FINAL?) word on alpha/beta: Fowler et. al. 2013 • Three large staFsFcal overviews are criFqued, with results for 5,000, 6,000 and 14,000 paFents with prostate carcinoma • PuZng 15 years of controversy to rest, Open doors to opportunity • Agree in finding the average α/β ra=o to be less than 2 Gy • hypo-‐fracFonaFon = therapeuFc gain Fowler JF et. al., “Is the α/β ratio for prostate tumours really low and does it vary with the level of risk at diagnosis?” Anticancer Res. Vol 33(3) 2013
HDR-‐BT of the prostate HypofracFonaFon and Dose escalaFon
Prostate HDR Dose EscalaFon “HDR brachytherapy can provide be_er sparing of rectum and bladder while delivering a higher dose to the prostate. Even with the increased late effects of high dose per fracFon, there is sFll a poten=al for dose escala=on beyond external radiotherapy limits using HDR brachytherapy.” I C Hsu et. al., “Normal tissue dosimetric comparison between HDR prostate implant boost and conformal external beam radiotherapy boost: potential for dose escalation” Int J Radiat Oncol Biol Phys. Vol 46(4) 2000
Prostate -‐ HDR • TRUS: real-‐Fme imaging, good image quality of the prostate boundary, clear visualisaFon of the needles. • But poor soc-‐Fssue resoluFon; • A marker wire or aerated gel is inserted into the urinary catheter to visualise the bladder and urethra • The anterior of the rectum is visualised in contact with the ultrasound probe and image quality is improved with the aid of a saline-‐ filled endorectal balloon on the ultrasound probe
A Challapalli, E Jones, C Harvey et. al., “ High dose rate prostate brachytherapy: and overview of the raFonale, experience, and emerging applicaFons in the treatment of prostate cancer,” BJR, 85(2012)
Treatment Plan Scan: CT/MR • PaFent in Tx posiFon, Foley Catheter in place • ConFguous slices with scan thickness ≤ 0.3 cm • MUST include enFre prostate + at least 3 slices (9 mm) above and below the prostate • include the perineum for visualizaFon of the catheters from Fps to outside the paFent • MUST include Fps of ALL the catheters • PaFent’s external Body contours should not be included in FoV to maximize image quality AMERICAN BRACHYTHERAPY SOCIETY PROSTATE HIGH-DOSE RATE TASK GROUP I-Chow Hsu, MD, Yoshiya Yamada MD, Er ic Vigneault MD, Jean Pouliot, PhD August, 2008
Treatment Planning EssenFals • • • • • • • •
Volumes ICRU Report 58 Turn off dwell locaFons outside PTV Geometric/inverse/Manual opFmizaFon V100 prostate >90% V75 rectum/Bladder < 1cc V125 urethra < 1cc EvaluaFon Isodoses – 50%, 100%, 150% DVH – sample minimum of 5000 points/ ROI for cumulaFve DVH AMERICAN BRACHYTHERAPY SOCIETY PROSTATE HIGH-DOSE RATE TASK GROUP I-Chow Hsu, MD, Yoshiya Yamada MD, Er ic Vigneault MD, Jean Pouliot, PhD August, 2008
Treatment Delivery and Image guidance • First HDR fracFon delivered on the day of the catheter placement. • mulFple fracFons: consecuFve fracFons within 24 hours acer the first treatment, but no less than 6 hours between treatments • Visual inspec=on of the catheters prior to delivery of each treatment is a MUST • Fluoroscopy or CT • Readjust catheters if required • If reposi=oning or readjustment of TX plan cannot address the catheter displacement, postpone treatment un=l a sa=sfactory implant may be done AMERICAN BRACHYTHERAPY SOCIETY PROSTATE HIGH-DOSE RATE TASK GROUP I-Chow Hsu, MD, Yoshiya Yamada MD, Er ic Vigneault MD, Jean Pouliot, PhD August, 2008
A Challapalli, E Jones, C Harvey et. al., BJR, 85(2012)
HDR-‐BT pre-‐planning
Picture courtesy: Janusz Skowronek, MD, PhD, Greater Poland Cancer Center
HDR-‐BT real-‐Fme planning
Picture courtesy: Janusz Skowronek, MD, PhD, Greater Poland Cancer Center
Excitement conFnues… • New Hypofrac=ona=on schemes – UW-‐ Madison and many others! • BrachyView, a novel inbody imaging system for HDR prostate brachytherapy: design and Monte Carlo feasibility study. • Real-‐=me monitoring and verifica=on of in vivo high dose rate brachytherapy using a pinhole camera.
Can’t forget sFll the gold standard most common Prostate BT procedure……
Prostate LDR – new radioisotopes
• Rx: 85 Gy (Cs-‐131), 110 Gy (I-‐125), 100 Gy (Pd-‐103) • Seed strengths employed: 1.6 U (Cs-‐131) and 1.8 U (Pd-‐103) 0.54 U (I-‐125) • 45 treatment plan comparisons. For similar dose coverage (V100 and D90), V200 and V150 reduced. • More “homogeneous” implants using Cs-‐131
Slide courtesy: R Miller, B R Thomadsen, “Brachytherapy Physics: Everything you need to know and controversial Issues”, AAPM 2009
Slide courtesy: R Miller, B R Thomadsen, “Brachytherapy Physics: Everything you need to know and controversial Issues”, AAPM 2009
Prostate LDR-‐BT future! -‐ InteresFng simulaFons: “Direc=onal I-‐125 seed and ROI -‐ Sensi=vity profiles based op=miza=on” – UW-‐Madison MrBoT: “Automa=c Brachytherapy Seed Placement Under MRI Guidance” – John Hopkins University Auto-‐segmenta=on of prostate (do pubmed search)
Needle placement clinical consideraFons – Prostate LDR/HDR BT
Breast Cancer
Breast Brachytherapy evoluFon in last decade Historically, Breast Brachytherapy: treated as "boost” to lumpectomy cavity following external whole breast radiation therapy Now, as Accelerated Partial Breast Irradiation (APBI): sole radiation treatment modality following breastconserving surgery
Cox, J. A. & Swanson, T. A. (2013) Current modalities of accelerated partial breast irradiation Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2013.65
APBI: MulFcatheter HDR
The Godmother HDR-breast Brachytherapy technique 3D CT-guidance or TRUS based volumetric implant Cox, J. A. & Swanson, T. A. (2013) Current modalities of accelerated partial breast irradiation Nat. Rev. Clin. Oncol. doi:10.1038/nrclinonc.2013.65
APBI: Mammosite
FDA clearance: 2002 most widely used modern APBI device and with the longest track record, becoming new gold-standard of dosimetry comparison Availability as Single/Multiple central lumen device Ir-192 HDR (image courtesy of MammoSite, Hologic Inc., Bedford, MA, USA)
APBI: Mammosite Pre- and post-manipulation images of patient: Air-cavity reduction by a net addition of 10 cm3 to the balloon volume And/or massage of the implant area
Manipulating the cavity and adjusting the balloon volume may salvage an implant and assist in meeting the strict geometric and dosimetric criteria imposed by the RTOG 0413 protocol.
J.B. Wojcicka et. al., “Clinical and dosimetric experience with mammosite-‐based brachytherapy under the RTOG 0413 protocol, JACMP, Vol. 8(4), 2007
Mammosite: Single Lumen Vs MulFple lumen Mammosite implant
Contura MulF-‐Lumen Balloon catheter • surgeons and radiaFon oncologists are familiar and comfortable with Balloon type devices now • Drainage channels: air and blood around the cavity could be removed before treatment, potenFally reducing air pockets and seroma formaFon (image courtesy) Bard Medical Systems
SAVI: Strut Adjusted Volume Implant (not balloon) Single-entry multi-channel catheter system
CT image of a SAVI applicator inside of a lumpectomy cavity.
Dose modulation up to 11 channels
Improved skin dose sparing as compared with Mammosite and Contoura*
*S Gurdalli, “Dosimetric comparison of three brachytherapy applicators for partial breast irradiation”, World congress of brachytherapy 2008
APBI: Clearpath single entry MulFcatheter device (Hybrid) Both HDR as well as LDR compa=ble faciliFes without high-‐rate-‐rate equipment can now offer APBI Strands of I-‐125 seeds are inserted in the outer catheters Pa=ents must wear a fully shielded bra if low-‐dose con=nuous release treatment is given
Electronic brachytherapy • FDA clearance: 2006 • Balloon brachytherapy with electronic 50 kilo-‐ voltage x-‐ray source • No radio-‐isotopes • miniature x-‐ray tube that is inserted into the balloon catheter and delivers the radiaFon therapy
Electronic brachytherapy
• Minimal Shielding • No rigorous radiaFon source regulaFons • IORT with EBX -‐ TARGIT trial
References • C F Njeh et. al. “Accelerated Par=al Breast Irradia=on (APBI): A review of available techniques” Radia2on Oncology, 5:90, 2010 • Brent Herron et. al. “A Review of Radia=on Therapy’s Role in Early-‐ Stage Breast Cancer and an Introduc=on to Electronic Brachytherapy” • *S Gurdalli, “Dosimetric comparison of three brachytherapy applicators for parFal breast irradiaFon”, World congress of brachytherapy 2008 • J.B. Wojcicka et. al., “Clinical and dosimetric experience with mammosite-‐based brachytherapy under the RTOG 0413 protocol, JACMP, Vol. 8(4), 2007 • Cox, J. A. & Swanson, T. A. (2013) Current modaliFes of accelerated parFal breast irradiaFon Nat. Rev. Clin. Oncol. doi:10.1038/ nrclinonc.2013.65
Cervical Cancer (Aha!)
Cervical cancer Brachytherapy plays fundamental role in the therapeuFc approach of paFents with FIGO stage I-‐IV cervical carcinoma High precision image guided (Dose Adap=ve) Brachytherapy
Brachytherapy of the cervix • AP-‐PA radiographs to volumetric imaging guided – CT, CBCT, TRUS, MRI • On road from Point-‐dose prescripFon to Volume-‐based prescripFon….. • IGABT: Image Guided AdapFve Brachytherapy • HDR: Intracavitary (most common), IntersFFal-‐ intracavitary or intersFFal only
Image Guidance • Image guidance for applicator placement – Fluoroscopy, TRUS, radiographs… • Volumetric image set for treatment planning CT, MRI, CBCT • Fluro radiographs before/acer CT/MRI for applicator posi=onal assessment • Volumetric CT image set for post-‐implant assessment
Intracavitary BT for Cervical cancer • TradiFonally, Rx and Tx planning: Either reference points (points A and B) or reference isodoses (60Gy according to ICRU recommendaFons) to report doses to the target volume. • Doses to criFcal organs were reported at bladder and rectum ICRU points. • long-‐standing clinical experience has yielded an acceptable therapeu=c ra=o
Good to be_er…...
CT-‐based BT: ICRU Point Doses vs Volumetric Doses • 20 paFents • The median EBRT dose 45Gy. • CT-‐MRI compaFble T&O BT, median dose 24 Gy, Treatment planning using 3D CT image set • bladder, rectum and sigmoid were retrospecFvely contoured • OAR doses assessed by DVH criteria were higher than ICRU point doses S K Vinod et. al., “A comparison of ICRU point doses and volumetric doses of organs at risk (OARs) in brachytherapy for cervical cancer” J Med Imaging Radiat Oncol. Vol 55(3) 2011
CBCT guided promise! • 3D planning in the brachytherapy suite using a cone beam CT (CBCT) scanner dedicated to brachytherapy • No pa=ent movement between imaging and treatment procedures • adequate image quality to reconstruct the applicators in the treatment planning system • More prac=cal and feasible Reniers B, Verhaegen F., “Technical note: cone beam CT imaging for 3D image guided brachytherapy for gynecological HDR brachytherapy.” Med Phys. 38(5)2011
Slide courtesy: J Siewerdsen and G-‐H Chen, Johns Hopkins University and UW-‐Madison
Most Promising IGBT…. MRI guided Intracavitary BT with its excellent soc Fssue contrast! FuturisFc for many…..but on road to future!
MRI-‐BT
Red: >10% dose deviation for at least 10% of the patients Green: longer guide wire travel => Cranial (T) and Posterior (o) • ± 1.5, ±3, ±5, ±6, ±7.5, ±10, ± 20 mm increments acer dose calculaFon • Compare a shiced plan with an unshiced one • Assessment of impact on both Point A plans and MRIG-‐CBT plans
SimulaFng Recon uncertainty • applicator shics along central axis only • + shic => longer guide wire travel => Cranial (T) and Posterior (o) • ± 1.5, ±3, ±5, ±6, ±7.5, ±10, ± 20 mm increments acer dose calculaFon
Methods • Compare a shiced plan with an unshiced one • Assessment of impact on both Point A plans and MRIG-‐CBT plans • Point A plan based on reference opFmizaFon lines and manual opFmizaFon • MRIG-‐CBT plans using hybrid-‐inverse opFmizaFon • Dosimetric parameters: HR-‐CTV (D100, D90), Rectum D2cc, Bladder D2cc, Sigmoid D2cc, ICRU rectum and bladder points
Dosimetric impact of Applicator displacement • The dosimetric impact of simulated applicator displacements ( 7.5mm) • ICRU bladder point more sensiFve than Bladder D2cc • RoT: For dosimetric change < 10% … limit Reconstruc=on uncertainty
