Interstitial brachytherapy in detail according to standard books

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Interstitial Brachytherapy - Detailed Overview

(Sourced from Campbell-Walsh-Wein Urology, Smith & Tanagho's General Urology, Berek & Novak's Gynecology, and Grainger & Allison's Diagnostic Radiology)

1. Definition and Basic Principle

Brachytherapy refers to a treatment technique that places radioactive sources in close proximity to or directly into the tumor (from the Greek brachy = short distance). Interstitial brachytherapy specifically involves the placement of radioactive needles, afterloaded needles or catheters, or radioactive seeds directly into the tissue - as opposed to intracavitary brachytherapy, which places sources inside a body lumen or orifice.

A fundamental physical advantage is that radiation dose falls off rapidly according to the inverse square law - irradiation affects only a highly localized area around the source, meaning very high doses can be delivered to the target while healthy tissue further away receives minimal exposure.

Smith & Tanagho's General Urology, p. 436
Grainger & Allison's Diagnostic Radiology, p. 1726

2. Classification

Brachytherapy is classified along two axes:

Axis	Categories
By placement	Interstitial vs. Intracavitary
By dose rate	Permanent/LDR vs. Temporary/HDR (vs. PDR)

By Placement

Interstitial: Radioactive needles, afterloaded catheters, or seeds placed directly into tissue (prostate, bladder, penis, periurethral soft tissues, gynecologic tumors)
Intracavitary: Placement of sources into a lumen or orifice (uterine canal, vagina, urethra)
Combined intracavitary/interstitial: Newer applicators that incorporate interstitial needles into standard intracavitary tandem-and-ring geometry

By Dose Rate

Low-dose rate (LDR): Continuous radiation over weeks-months via permanent seeds; dose rate <0.4 Gy/hour (technically, isotopes like Cs-137 fall here in traditional use)
High-dose rate (HDR): Short but high-dose radiation using temporary catheters; >12 Gy/hour with Ir-192 remote afterloading
Pulsed-dose rate (PDR): Uses an Ir-192 HDR source with a pulsed regimen designed to mimic the radiobiologic effects of LDR treatment; mostly seen at specialized academic centers
Smith & Tanagho's General Urology, p. 436
Berek & Novak's Gynecology, p. 2253

3. Isotopes Used

For Permanent (LDR) Interstitial Implants

Isotope	Energy	Half-life	90% dose delivered in	Monotherapy dose
¹²⁵Iodine	27 keV x-rays	59.6 days	204 days	140-160 Gy
¹⁰³Palladium	21 keV x-rays	17 days	58 days	110-125 Gy
¹³¹Cesium (since 2004)	30 keV x-rays	9.7 days	33 days	100-115 Gy

¹²⁵I is considered more "forgiving" dosimetrically due to slightly higher energy offering better prostatic coverage
A randomized trial comparing ¹²⁵I vs. ¹⁰³Pd in low-risk disease found no difference in biochemical control; urinary symptoms were worse at 1 month with ¹⁰³Pd but resolved more rapidly

For Temporary (HDR) Interstitial Implants

Iridium-192 (¹⁹²Ir): 400 keV gamma radiation; used via remote afterloading systems; single source migrated along catheter length at variable positions and dwell times
Campbell-Walsh-Wein Urology, p. 4700-4701

4. Technique: LDR Permanent Seed Implant (Prostate Prototype)

Pre-procedure Planning

Volume study using transrectal ultrasound (TRUS)
Preoperative dosimetric planning determines number of seeds, seed activity, and needle/seed positions
Seeds are peripherally loaded to minimize dose to the central urethra

Procedure

Patient under spinal or general anesthesia
TRUS probe placed transrectally for real-time imaging
A perineal template grid is used to guide transperineal needle insertion
Seeds are deposited at calculated positions as needles are withdrawn
Typically 60-120 seeds placed using 15-25 needles

LDR prostate brachytherapy: plain radiograph (A) showing I-125 seeds, and fused CT/MRI at day 28 (B) confirming seed positions

LDR brachytherapy for prostate cancer - plain radiograph and fused CT/MRI post-implant (Grainger & Allison)

Post-implant Dosimetry

CT with or without MRI fusion performed 4-6 weeks post-implant (not immediately) because seed migration occurs due to bleeding and swelling from the trauma of implantation
Key dosimetric parameters: D90 (dose covering 90% of prostate) and V100 (% of prostate volume receiving 100% prescribed dose)
MRI offers superior prostate delineation; CT better identifies metallic seed positions - fused images combine both advantages
Campbell-Walsh-Wein Urology, p. 4701-4702
Grainger & Allison's Diagnostic Radiology, p. 1729

5. Technique: HDR Interstitial Brachytherapy

Mechanism

Hollow catheters are placed transperineally into the prostate (or through templates into other tissue targets) using the same grid-and-TRUS technique as LDR
A single ¹⁹²Ir source is robotically driven ("afterloaded") along the length of each catheter
The source dwells for seconds to minutes at 5 mm intervals - dwell times are modulated to optimize dose distribution
All radioactive material is removed at the end of treatment - no sources remain in the patient
Treatment is delivered in a shielded room via remote activation

Fractionation (Prostate HDR as Boost)

Common EBRT schedules combined with HDR boost include:

45 Gy in 25 fractions (5 weeks) + HDR
46 Gy in 23 fractions (4.5 weeks) + HDR
35.7 Gy in 13 fractions (2.5 weeks) + HDR

HDR monotherapy (without EBRT) is increasingly used for low-to-intermediate risk prostate cancer.

Campbell-Walsh-Wein Urology, p. 4702-4703

6. Advantages and Disadvantages: HDR vs. LDR

Advantages of HDR over LDR

Advantage	Explanation
Greater target flexibility	Catheter-based placement allows easier inclusion of extracapsular disease and seminal vesicles
Dose optimization	Modifying dwell times and positions allows real-time dose sculpting
Biological dose advantage	High dose per fraction exploits low alpha/beta ratio of prostate cancer
Radiation safety	No personnel handling of radioactive source; no sources left in patient
Cost-effectiveness	Single multipurpose ¹⁹²Ir source used for all patients
No post-implant dosimetry needed	Sources removed after treatment

Disadvantages of HDR over LDR

Disadvantage	Explanation
Treatment inaccuracies	Catheter/organ movement between imaging and source insertion; interobserver contouring variability
Patient convenience	Multiple fractions require repeated catheter placements or maintained catheter access
Shielded room required	High activity ¹⁹²Ir source requires dedicated infrastructure
Less pathologic response	Available post-treatment biopsy studies favor LDR
Limited phase III data	No comparable randomized data for HDR in high-risk prostate cancer

Campbell-Walsh-Wein Urology, p. 4703

7. Gynecologic Applications (Cervix Cancer)

Combined Intracavitary/Interstitial Brachytherapy

Newer applicators incorporate interstitial needles into the standard tandem-and-ring or tandem-and-ovoids geometry (e.g., the Vienna applicator)
Interstitial needles extend reach beyond what standard intracavitary geometry can dose
Especially useful for bulky or irregularly shaped tumors that extend beyond the standard applicator coverage
In the retroEMBRACE study: combined intracavitary/interstitial BT vs. intracavitary alone showed a 10% improvement in local control for larger tumors (cervix + tumor volume >30 cm³)
Can often eliminate the need for more morbid techniques such as the Syed template or MUPIT template needle implants

2D vs. 3D Image-Guided Brachytherapy (IGA-BT)

Classical 2D: Dose prescribed to "Point A" (2 cm superior to the cervical os, 2 cm lateral to the intrauterine canal); typical dose 7,000-8,000 cGy to Point A, limiting bladder/rectum to <6,000 cGy
Modern 3D IGA-BT: MRI/CT-based volumetric planning; dose prescribed to the high-risk CTV D90 (8,500-9,500 cGy cumulative)
The French STIC multicenter trial (705 patients) prospectively demonstrated 3D brachytherapy gave improved local control with half the toxicity of 2D brachytherapy
Dose constraints (GEC-ESTRO): bladder D2cc <90 Gy EQD2; rectum D2cc <75 Gy EQD2; sigmoid D2cc <75 Gy EQD2

LDR vs. HDR for Cervix Cancer

LDR (Cs-137): Manual placement, requires inpatient admission 1-3 days, patient immobilization, DVT prophylaxis, radiation precautions for staff
HDR (Ir-192): Ambulatory, shorter total treatment time, remote afterloading eliminates staff exposure
A Cochrane review found no significant differences in OS, disease-specific survival, local control, or complications between LDR and HDR for locally advanced cervix cancer (based on 4 qualifying trials)
Berek & Novak's Gynecology, pp. 2253-2255

8. Other Interstitial Brachytherapy Applications

Site	Details
Prostate cancer	LDR seed implant (low-risk) or HDR boost/monotherapy (intermediate/high-risk)
Penile/urethral cancer	Both EBRT and interstitial BT may be used; circumcision required prior to BT to expose the lesion and prevent inflammation-related swelling
Head and neck cancers	Interstitial implants for base of tongue, lip, floor of mouth; IMRT with or without BT boost
Breast cancer	Interstitial multi-catheter implant as partial breast irradiation (APBI)
Endobronchial tumors	Catheter-based bronchoscopic placement for airway tumors
Bladder cancer	Interstitial BT for selected Ta/T1 and T2 tumors; not yet standard of care
Gynecologic (vaginal/cervical)	Combined intracavitary/interstitial for bulky disease
Liver metastases	Interstitial BT as one of multiple local ablative options

9. Dosimetry Principles

Dose from each source position is additive; superposition of contributions from all dwell positions defines the overall dose distribution
Inverse square law governs rapid dose fall-off away from each source
Imaging is mandatory: CT identifies applicator/seed positions precisely; MRI provides superior soft tissue definition (especially prostate and cervix)
For LDR prostate: post-implant CT/MRI fusion at 4-6 weeks - D90 and V100 are key quality indicators
For HDR: real-time or near-real-time planning at each fraction based on CT/MRI with applicators in situ
Grainger & Allison's Diagnostic Radiology, pp. 1726-1729

10. Comparison With External Beam Radiotherapy

Feature	Interstitial BT	EBRT
Dose fall-off	Rapid (inverse square law) - spares adjacent normal tissue	Gradual; requires margins around target
Patient setup variation	Minimal - sources move with tumor	Significant daily repositioning needed
Tumor motion	Not a concern - sources within tumor	Major challenge (breathing, organ filling)
Dose per fraction	Can exploit high doses per fraction biologically	Typically 1.8-2 Gy fractions
Access	Invasive procedure required	Non-invasive
Suitable volumes	Small to medium tumors; precise geometry	Any volume; irregular shapes

Sources:

Campbell-Walsh-Wein Urology, 3-Volume Set - Chapters 157 & 158 (LDR/HDR Prostate Brachytherapy)
Smith & Tanagho's General Urology, 19th Ed. - Chapter 26 (Brachytherapy classification and technique)
Berek & Novak's Gynecology - Chapter on Primary Radiation Therapy (Cervix cancer brachytherapy)
Grainger & Allison's Diagnostic Radiology - Chapter 67 (Principles of radiotherapy including brachytherapy)

Application in ent and head and neck surgery only

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Interstitial Brachytherapy in ENT and Head & Neck Surgery

(Sourced from Cummings Otolaryngology, Scott-Brown's Otorhinolaryngology Head & Neck Surgery, KJ Lee's Essential Otolaryngology, and Grainger & Allison's Diagnostic Radiology)

1. Historical Background and Basic Principles in H&N

Brachytherapy in head and neck cancer has deep roots - the first documented successful treatment was reported in 1899, when Thor Stenberg treated a nasal basal cell carcinoma with radium over 9 months, with the patient alive 30 years later. In 1901, Dr. Frand Williams in Boston reported successful treatment of a lip cancer. Radium was initially applied only to superficial sites because of severe toxicities; physicians later began inserting it directly into deep-seated tumors, founding the field of brachytherapy.

Core principle: Radiation dose from an implanted source obeys the inverse square law - it falls off rapidly with distance, allowing very high doses to be concentrated at the target (tumor) while sparing surrounding healthy tissues (including bone, nerve, major vessels).

Key advantage in H&N: Better dose localization → less radiation damage to surrounding healthy tissue, and prolonged time over which radiation is delivered.

Key disadvantage in H&N: Does not address subclinical nodal disease; requires general anesthesia in many cases; close proximity of mandible creates risk of osteoradionecrosis.

Cummings Otolaryngology, p. 1343, 1361

2. Radioactive Sources Used in H&N Brachytherapy

Source	Type	Notes
Iridium-192 (¹⁹²Ir)	LDR afterloading or HDR	Most widely used; dose rate 0.4-0.8 Gy/hour (LDR); or >12 Gy/hour (HDR remote afterloading)
Cesium-137 (¹³⁷Cs)	LDR needles	Traditional use; being replaced by ¹⁹²Ir
Radium-226 (²²⁶Ra)	Historical	Needles for implants; now largely obsolete
Gold-198 (¹⁹⁸Au)	Permanent grains	Used for nasopharyngeal recurrences (grain implantation)
Iodine-125 (¹²⁵I)	Permanent seeds	Low energy; used in selected cases

A typical ¹⁹²Ir LDR implant delivers approximately 0.4-0.8 Gy/hour. HDR remote afterloading devices drive a single high-activity ¹⁹²Ir source through a set of interstitial catheters under computer control; typically 3.0-3.5 Gy is delivered to ~1 cm from the catheter periphery per treatment, with up to two daily treatments ~6 hours apart, each lasting 15-30 minutes depending on source strength and implant complexity.

Cummings Otolaryngology, p. 1361

3. Site-by-Site Applications

A. Oral Tongue (Mobile Tongue)

Radiotherapy (brachytherapy preferred over EBRT) has been advocated as a primary treatment modality because it conserves tongue volume and morphology - an enormous functional advantage.

Indications:

T1-T2 tumors of mobile tongue not suitable for surgery, or where organ preservation is prioritized
Brachytherapy alone or as a boost after EBRT

Technique: ¹⁹²Ir interstitial implant through the tongue tissue, using afterloading catheters placed to encompass the tumor with adequate margins.

Outcomes: Brachytherapy is considered preferable to EBRT for tongue primaries in terms of dose localization and functional preservation.

Key limitation - Osteoradionecrosis (ORN): The mandible lies in close proximity to the tongue. Up to 9% of patients develop some form of osseous complication following tongue brachytherapy. This is a recognized and major concern that has led some centers to prefer surgery as primary treatment, keeping radiotherapy in reserve for:

Poor pathologic prognostic indicators post-resection
Recurrence
Second primaries

An important additional consideration is that when surgery is not used as the primary modality, valuable histopathological prognostic information is lost - making decisions about elective neck dissection (END) more difficult.

Some authorities suggest surgery is superior to brachytherapy for Stage I/II tongue cancer for this reason (retaining radiotherapy as a reserve modality).

Scott-Brown's Otorhinolaryngology, p. 6861

B. Floor of Mouth

Indications:

T1/T2 floor-of-mouth carcinomas - brachytherapy (or EBRT) has been shown to give results comparable to surgery

Key limitation - ORN risk is particularly high here:

The floor of mouth lies in direct proximity to the mandible
Up to 8.5% of patients treated with brachytherapy for floor-of-mouth cancer require segmental mandibulectomy for osteoradionecrosis within 10 years (Gustave-Roussy Institute series; Pernot et al., Marsiglia et al.)
Several major units have changed practice from brachytherapy to surgery as the primary treatment modality for floor-of-mouth cancer, specifically because of this complication risk
T3/T4 lesions are best treated with surgery + post-operative radiotherapy (PORT)
Scott-Brown's Otorhinolaryngology, p. 6641-6652

C. Base of Tongue (Oropharynx)

Role of brachytherapy: RT for base of tongue is often performed as a combination of EBRT + interstitial ¹⁹²Ir implant.

Outcomes data (Cummings Otolaryngology):

Treatment	T1 Local Control	T2 Local Control
EBRT alone (primary)	78-96%	47-88%
EBRT + brachytherapy implant	71-100%	71-100%
EBRT alone vs. combined	EBRT alone = unacceptably high failure rate (2× other groups)

Houssef et al. compared surgery + adjuvant RT vs. EBRT + ¹⁹²Ir implant vs. EBRT alone for T1/T2 base-of-tongue cancers and found:

Surgery + adjuvant RT ≈ EBRT + implant (comparable results)
EBRT alone showed unacceptable failure rate - twice as high as the other two groups

For salvage/recurrent disease, afterloading techniques with ¹⁹²Ir have achieved local control of 59% and actuarial survival of 48%, though residual/recurrent tongue base disease remains a demanding problem.

Cummings Otolaryngology, p. 1793

D. Tonsillar Region / Oropharynx

Salvage surgery after primary RT in the tonsillar region carries high mortality and low 5-year survival (Gehanno et al.: 5-year survival 24%, mortality as high as 8% in 120 patients).

Two investigations support brachytherapy salvage in the tonsillar region:

5-year survival rate: 64% (one series)
2-year survival rate: 42% (another series)
Cummings Otolaryngology, p. 1792

E. Nasopharynx (Recurrent/Salvage Setting)

Brachytherapy for nasopharyngeal carcinoma (NPC) is used specifically in the salvage setting for local failure following primary chemoradiation, as an alternative to re-irradiation with EBRT (which has poor outcomes due to proximity of brainstem, optic chiasm, and temporal lobe to the treatment field).

Rationale: Traditional 2D re-irradiation for NPC local failure has a 5-year survival of only 7.6% due to dose constraints protecting vital organs. Brachytherapy delivers a high dose with limited penetration - ideal for small recurrences without deep invasion.

Radioactive sources:

Iridium-192 (¹⁹²Ir): The source is loaded into a tailor-made plastic mould fitted into the nasopharynx. The mould is placed transorally (via the oral cavity) under local anaesthesia.
Gold-198 (¹⁹⁸Au) grains: Implanted directly into the nasopharynx after the soft palate is split open under general anaesthesia.

Patient selection: Both techniques are only suitable for small tumors <2 cm in maximal dimension (no deep invasion).

Outcomes:

5-year survival: 50-60% for salvage brachytherapy of NPC local recurrence

As an alternative to brachytherapy, stereotactic RT (3D/IMRT-based) for NPC local salvage has shown 5-year overall survival 40% and local control 57% (series of 30 patients) - brachytherapy outcomes are superior but patient selection is stricter (smaller tumors only).

Brachytherapy also has a potential role in nodal failure in NPC, used in conjunction with surgical resection of nodal metastasis (the limited penetration of brachytherapy makes it suitable as an adjunct after debulking surgery).

Scott-Brown's Otorhinolaryngology, p. 8504-8520

F. Orbit and Paranasal Sinuses (Intracavitary, H&N)

The orbit and nasopharynx are the most common intracavitary head and neck brachytherapy sites. Custom PMMA (acrylic) stents are constructed around catheters into which radioisotopic seeds are inserted:

The radiation oncologist/physicist prescribes catheter positions in consultation with the maxillofacial prosthodontic team, after generating a master cast from an impression of the site
Stents are retained in position by anatomic soft tissue undercuts or alveolar structures
After maxillectomy, intracavitary void-filling with tissue-equivalent material improves dose distribution (preventing uneven dosing of peripheral tissues around the surgical defect)
Cummings Otolaryngology, p. 1702

G. Lip Cancer

One of the original sites treated with brachytherapy historically (1901 - Dr. Williams, Boston). Lip carcinoma remains amenable to interstitial brachytherapy, particularly for:

Small T1-T2 squamous cell carcinomas of the lip
As an organ-preserving alternative to surgery for cosmetically sensitive sites
Cummings Otolaryngology, p. 1343

4. Technique Summary for H&N Interstitial BT

LDR ¹⁹²Ir Interstitial Implant (Standard Technique)

Planning phase: CT/MRI-based volumetric planning; catheter positions determined to achieve adequate dose to tumor with acceptable dose to adjacent mandible, vessels, nerves
Implant procedure: Under general anaesthesia (most cases); hollow plastic catheters or metal needles inserted through the tumor-bearing tissue
Afterloading: ¹⁹²Ir sources loaded into catheters; patient cared for in a shielded room during treatment
Dose delivery: 0.4-0.8 Gy/hour continuously over 2-6 days
Source removal: All sources and catheters removed at end of treatment

HDR Remote Afterloading (Modern Approach)

Computer-controlled robotic ¹⁹²Ir source driven through catheters
Dwells at 5 mm intervals; dwell times modulated to optimize dose distribution
Each fraction: 3.0-3.5 Gy to ~1 cm from catheter periphery
Up to 2 fractions per day (at least 6 hours apart)
Each treatment: 15-30 minutes
Advantages: Eliminates radiation exposure to nursing/medical staff; outpatient delivery possible

5. Combinations with EBRT

In head and neck cancer, interstitial brachytherapy is frequently used as a boost following a course of EBRT:

EBRT addresses the primary tumor plus regional lymphatics (elective or therapeutic nodal irradiation)
Brachytherapy delivers an additional dose increment to the primary tumor bed, achieving higher total doses than either modality alone
This combination is the standard approach for base-of-tongue carcinoma and is used in other oral cavity sites

6. Complications Specific to H&N Brachytherapy

Complication	Details
Osteoradionecrosis (ORN) of mandible	Most feared; up to 9% for tongue BT, up to 8.5% requiring segmental mandibulectomy for floor-of-mouth BT; high local doses from BT increase incidence; risk further raised by microvascular disease (atherosclerosis, diabetes) and post-RT dental extractions
Soft tissue necrosis	Histologically: epithelial hyperplasia → dermal fibrosis → necrosis; Marx characterized tissue as "hypoxic, hypocellular, hypovascular"
Mucositis	Acute; self-limiting; universal to varying degree with all H&N RT
Xerostomia	From inclusion of salivary glands in the radiation field
Trismus	Radiation fibrosis of masticator muscles
Radiation-related fistulae	In high-dose zones near mucosa
Radioprotection requirements	LDR implants require patient isolation in shielded room; HDR remote afterloading eliminates this (no radiation exposure to staff during treatment)

ORN pathophysiology (Scott-Brown's Vol. 2):

Impaired tissue repair capacity
Vasculitis → obliteration of blood vessels → avascular necrosis
Marx triad: hypoxic + hypocellular + hypovascular tissue
Macroscopically: loss of skin/soft tissue exposing bone, bony sequestration, secondary infection

Note on temporal bone: The compact (non-cancellous) nature of the petrous temporal bone and poor blood supply of the tympanic ring make this region particularly susceptible to ORN from brachytherapy of adjacent tumors.

Scott-Brown's Vol. 2, p. 1011
Cummings Otolaryngology (Key Points, p. 1702)

7. Contraindications and Patient Selection

Factor	Implication
Tumor > 2 cm in nasopharynx	Contraindication to NPC salvage BT
Deep invasion of tumor	Contraindication to BT (limited penetration cannot cover deep extension)
Prior high-dose RT to site	Increased ORN risk; careful re-treatment planning needed
Poor dental hygiene	Must optimize dental care pre-BT to reduce ORN risk
Diabetes / atherosclerosis	Increased ORN risk; relative contraindication to BT near mandible
Need for nodal treatment	BT alone insufficient; must add EBRT or neck dissection

8. Summary Table: BT Applications by H&N Site

Site	Role	Source/Technique	Key Outcome Data	Main Risk
Oral tongue (T1-T2)	Primary or EBRT boost; organ preservation	¹⁹²Ir LDR/HDR interstitial	Comparable to surgery for T1/T2	ORN 9%
Floor of mouth (T1-T2)	Primary (results = surgery); T3/T4 → surgery + PORT	¹⁹²Ir LDR interstitial	~= surgery; many units switching to surgery	ORN up to 8.5% → mandibulectomy
Base of tongue	EBRT + BT boost (standard); salvage afterloading	¹⁹²Ir LDR/HDR interstitial	T1: 71-100%; T2: 71-100% (EBRT + BT)	Functional swallowing
Tonsillar region	Salvage after RT failure	¹⁹²Ir afterloading	5-yr survival 64%; 2-yr survival 42%	High operative mortality if surgical salvage used
Nasopharynx (recurrent)	Salvage for small (<2 cm) recurrences	¹⁹²Ir mould or ¹⁹⁸Au grains	5-yr survival 50-60%	Limited to tumors without deep invasion
Orbit/sinus (intracavitary)	Post-maxillectomy/targeted	PMMA stent with ¹²⁵I seeds	Site-specific	Dosimetric consistency
Lip (T1-T2)	Primary; cosmetic preservation	Interstitial needles	Historically effective (first H&N site treated, 1901)	ORN (low risk, away from mandible)

Sources:

Cummings Otolaryngology Head and Neck Surgery - Chapter 75 (Radiation Therapy Principles) & Chapter 96 (Oropharyngeal Cancers)
Scott-Brown's Otorhinolaryngology Head & Neck Surgery - Oral tongue, floor of mouth, and nasopharynx chapters
Scott-Brown's Vol. 2 - Osteoradionecrosis chapter
KJ Lee's Essential Otolaryngology - Oral tongue cancer chapter
Grainger & Allison's Diagnostic Radiology - Brachytherapy principles chapter

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